final exam Flashcards
Nutrients
Diet = total food a person regularly eats
Our diet determines which nutrients we consume
Nutrients = food substances required for our maintenance, growth and survival
Some nutrients are essential
Essential nutrient = one that the body requires but that it cannot make itself
Ex. Essential amino acids, essential fatty acids, vitamins, minerals, water
There are six categories of nutrients…
The Macronutrients
(needed in larger amounts)
Water
Carbohydrates
Sugars, starches, fibre
Organic (carbon-containing)
Lipids (fats)
Triglycerides, fatty acids, sterols, phospholipids
Organic
Proteins
Made of amino acids
Organic
The Micronutrients
needed in smaller amounts
Vitamins
-Fat soluble and water soluble
-Organic
Minerals
- Chemical elements
- inorganic
Phytochemicals
Phytochemicals = plant chemicals Hundreds of them Found in a wide variety of plants Responsible for their bright colours May have positive health effects
ex. Flavonoids – give plants bright blue, red or dark pigmentation
Anti-inflammatory, anti-tumour, antioxidant effects
Carotenoids – give plants yellow, orange, red pigmentation
Antioxidant effects
Toxins
Naturally occurring substances found in plants and animals
Can have harmful effects on body beyond a threshold of intake
Their levels are limited in foods
To reduce exposure throw out old/mouldy/foul-smelling food
Fortification of food
Fortified aka enriched foods - involves the addition of nutrients to foods by the food manufacturer
Can be
mandatory ex. iodine to table salt
voluntary ex. Added vitamins to breakfast cereals
Whole foods vs. Processed foods
Most foods have some degree of processing
Whole foods = least amount of processing, associated with reduced disease risk
Ultra-processed foods = higher risk of type 2 diabetes, cardiovascular disease, mortality
Can use NOVA classification system to differentiate foods for degree of processing
4 NOVA food groups
NOVA Group 1: Unprocessed or Minimally Processed Foods
NOVA Group 2: Processed Culinary Ingredients
NOVA Group 3: Processed Foods
NOVA Group 4: Ultra-processed foods
Food Additives
Substances added to food to affect taste, appearance, safety, freshness etc.
Must first be approved through an evidence review
There amounts are controlled in foods
More common in processed, ultra-processed foods
Genetically Modified Food
GMFs = foods that have undergone alterations to their DNA
DNA can be altered through
Selective breeding ex. Seedless grapes, broccoflower
Use of a vector: ex. Golden rice, RoundUp Ready Soy
Do not change our DNA
“GM foods currently available on the international market have passed safety assessments and are not likely to present risks for human health” (World Health Organization, 2014)
Concerns/debates remain around biodiversity, allergic potential, ethics, labelling
why do we eat
Sustenance: the maintenance of our bodies and lives Nutrients contribute to Body structure Body function Energy provision Carbs, proteins = 4 kcal/g Lipids = 9 kcal/g Enjoyment Psychological Reasons
Gene-Diet Interactions
Genetics can influence nutrition in a number of ways
Ex. Genetic influences on appetite, nutrient absorption, nutrient use
Our diet can also influence the expression of genes (ie. Whether gene information leads to the formation of proteins)
=epigenetics
NOTE: diet does not change our DNA/genes!
Choosing a Healthy Diet
Balance = consuming nutrients and energy in the proportions that most promote health
Variety = consuming a diversity of foods
We are less likely to be deficient in nutrients if we consume a range of different whole foods.
Moderation = not too much, not too little
Nutrient density = amount of nutrients in a food/meal compared to a reference amount (ex. 100 kcal)
The Study of Nutrition
It is difficult to study nutrition for a number of reasons:
People change their diet constantly
We can’t force people to eat a certain way
It is difficult to know for certain what people eat
Other factors beyond nutrition also affect health
Difficult to establish causation
…..
The scientific method is used to study nutrition
Experiments and epidemiological research are the most common types of nutrition studies
Both use the scientific method
experimental Studies
randomized control trials
Usually involves two similar groups
Experimental group – undergoes the experimental treatment (ex. Dietary supplement)
Control group – does not undergo the experimental treatment; may use a placebo (ex. Sugar pill)
Only one factor is different between the two groups (ex. Experimental group received the supplement)
if there is a difference in the groups by the end (ex. Increase in perceived alertness in experimental group), it is most likely due to the factor being tested
Epidemiological Studies
Aka population-based studies: look at population trends without manipulating variables
Ex. Do Japanese people who eat a lot of fish have a lower risk of cardiovascular disease than Americans who do not eat a lot of fish?
Ex. Nurses’ Health Study:
gathered information about nurses habits, medical history etc.
Checked in on them over time
Questions: what factors increased risk of cardiovascular disease, cancer etc.?
Limitations of Epidemiology
Association does not equal causation!
Results could be for other reasons too
People change their diet over time
Also, our methods of determining people’s diet all have limitations…
Impossible to for sure know what and how much people eat
Evaluating Nutrition Sources
VETO is it valuable is it eviendence based is it trustworthy is it opinion based
Nutritional Status
= condition of the body with respect to nutrition
i.e. Does a person have the appropriate level of nutrients to meet their needs?
No perfect measure, but we may use:
Diet analyses
Laboratory tests
Health or disease state of individual
The Four DRIs
Estimated Average Requirement(EAR):
the intake level which meets the needs of 50% of the population. (The RDA is determined by first determining the EAR)
Recommended Dietary Allowance (RDA):
consumption of this amount of the nutrient meets the needs of 97% of the population (set 2 standard deviations above the EAR)
Adequate Intake (AI): Nutrient intakes that are used as a goal when evidence is insufficient to set an RDA. AI values approximate the amount of nutrient that sustains health
Tolerable Upper Limit (TUL/UL):
The highest amount of that nutrient that will not promote symptoms of toxicity in the majority of healthy individuals. Intake should not exceed this value
Estimated Energy Requirement
EER = amount of energy required to maintain current energy state (ie. Where fat mass and weight do not change substantially)
Depends on sex, age, weight, height and activity level (PA)
Acceptable Macronutrient Distribution Range
AMDR = recommended percentage of energy that should come from each of the three energy-yielding nutrients: carbohydrates, lipids and protein
First Nations Healthy Food Guidelines
Make the community healthier by working together to change the nutrition environment.
Increase the use of traditional foods by protecting, restoring and relying on them more.
Decrease the use of sugar-sweetened beverages to help protect teeth and children’s health.
Increase the intake of vegetables and fruits.
Serve healthier foods in reasonable portions.
Increase number of community gardens to both provide nutritious food and bring the community together
Canada’s Healthy Eating Strategy
= overhaul of Canadian food policy that began in 2013
Major changes
2019 Canadian food guide
Lowered sodium content in prepackaged foods
Reasonable sodium targets within food and hospitality industries
Expansion of vitamin D fortification program
Elimination of industrial trans fat from food supply
Changes to food labelling
Mandatory Features of Canadian Food Labels
Claims on Food Labels
Food packaging may contain certain claims to highlight a nutrient, health-associated factor or the nature of a food
There are different types of claims
Claims must meet standards set by Food and Drug Regulations
Nutrient Content Claims
Ex. Low in fat, lower in Calories, high in fibre
To be used, the product must comply with the requirements for that statement
Ex. High in fibre = 4+ grams per serving very high in fibre = 6+ grams per serving
Health Claims
Two main types
Disease-reduction claims
link a food or its ingredients with a reduced risk of developing a specific disease
Ex. A healthy diet with adequate calcium and vitamin D and regular physical acivity helps to reduce risk of osteoporosis
Function claims
note the association between consuming a nutrient or diet factor with its role in the normal biological function of the body
Ex. Calcium promotes strong bones and teeth
Natural Health Products (NHPs)
NHPs are neither foods nor drugs.
They are naturally occurring substances that may be used to address health needs
Ex. Items sold as vitamins, minerals, multivitamins, probiotics, amino acids and essential fatty acids, as well as homeopathic and traditional medicines
Regulated separately by the Natural and Nonprescription Health Products Directorate (NNHPD)
Review claims and available evidence before approving product for sale
Menu Labelling
There are no federal requirements in Canada for menu labelling
Ontario’s Healthy Menu Choice act is a mandatory program for restaurants with more than 20 locations
Must display:
Calories
Contextual statement: “Adults and youth (ages 13 and older) need an average of 2,000 calories a day, and children (ages 4 to 12) need an average of 1,500 calories a day. However, individual needs vary.”
The Informed Dining Program is a voluntary program where consumers have access to nutritional information by request
Digestion
Digestion separates the nutrients in food and breaks larger molecules into smaller ones so they can be absorbed
Polysaccharides → sugars
Triglycerides → fatty acids
Proteins → amino acids
Two types of digestion:
Mechanical/physical: uses physical process such as chewing to break food apart
Chemical digestion: uses enzymes to alter the chemical structure of nutrients
Enzymes
Enzymes speed up the rate of reaction
Provide a location for chemical reactions to occur
Enzymes can participate in hydrolysis and condensation reactions
Hydrolysis reaction: the input of water helps to break down the molecule:
Condensation reactions
the process of co sensation binds molecules such as amino acids, into larger chains of molecules. water is liberated in the process
the binding of amino acids into a specific chain begins the process of protein synthesis.
Hormones
Hormones are chemical messengers that are required for many physiological processes, including digestion
They are released form one area of the body and travel through the blood to different parts of the body
The Digestive Tract
Long, tube-like structure
Sphincters often separate different parts of the tube
Takes ~ 2+ days for material to pass through the entire tract
Food spends most time in the large intestine
The Mouth
Teeth rip food apart
Tongue pushes food towards teeth and mixes it with saliva
Salivary glands secrete saliva into mouth, which contains:
Salivary amylase digests amylose (starch)
Lingual lipase digests lipids
Mucus lubricates food
Lysozyme = antibacterial substance that disinfects food
When food leaves the mouth it is a bolus
The Pharynx
Aka throat
Common passageway for food and inspired air
No active digestion or absorption
The epiglottis directs food from the pharynx into the esophagus instead of down the wrong tube into the trachea (windpipe)
The Esophagus
No active digestion or absorption
Peristalsis is a type of movement that occurs here and in other parts of the tract
The Stomach
Temporary reservoir for food
Food remains here 4-5 hours
Three layers of muscles allow stomach to churn
Lower esophageal sphincter and pyloric sphincter close as stomach churns food and mixes it with gastric juice
When food leaves the stomach it is in a semi-liquid form = chyme
Gastric Juice
Cells in the stomach crypts secrete contents of gastric juice: Mucus Lubrication, medium for chemical reactions Gastric lipase Breaks down lipids Hydrochloric acid Unravels proteins, activates pepsinogen Pepsinogen Becomes pepsin, which digests protein
The Small Intestine
Primary site of digestion and absorption
Three sections: duodenum, jejunum, ileum
Long length (~6m), large circular folds, villi, microvilli contribute to its large surface area
Its total surface area is about the size of a tennis court!
Villi of the Small Intestine
The villus (plural = villi) is the main functional unit of the small intestine Villi are invaginations of the small intestine wall The cells on their surface have extensions called microvilli (collectively known as the brush border) which secrete enzymes Nutrient subunits are absorbed into the center of the villus where they then enter the blood or the lymph
The Pancreas
The pancreas secretes pancreatic juice into the small intestine =its exocrine function Pancreatic juice contains: Digestive enzymes Amylase, lipase, proteases Bicarbonate Neutralizes chyme
The Liver, Gallbladder and Bile
The liver makes bile; the gallbladder stores it.
Bile is a lipid emulsifier – it breaks larger lipid globules into smaller ones and allows them to be suspended in a watery environment
The Large Intestine
Approx 1.5 m in length The colon is the main part of the large intestine Here, any unabsorbed material is either: Packaged for removal Acted upon by bacteria = Microbiota
The Microbiome
The largest population of non-human cells is found in the large intestine
Microbiota = all the non-human organisms found in our body
Mostly bacteria
300-500 different species
Microbiome = the genetic material of the non-human organisms found in our body
The microbiota have roles in:
Vitamin synthesis (vitamin K, B2, B12)
Energy harvesting
Health/disease
Appetite
Probiotics and Prebiotics
Probiotics = cultures of living organisms (ex. Bacteria)
Found in yogurt, kombucha
Cannot treat or cure any disease, but may help in the management of certain conditions
Prebiotics = carbohydrates that act as food for the microbiota
Found in asparagus, garlic, banana…
Support the health of the microbiome
Ulcers
= weakened, damaged parts of the lining of the digestive tract
Ex. Canker sores
occur in mouth; resolve on own
Ex. Peptic Ulcers
Occur in esophagus, stomach, small intestine
Typically related to infection with H. pylori bacteria
Gastroesophageal Reflux Disease
Gastroesophageal reflux = when lower esophageal sphincter weakens; acidic stomach contents spill into esophagus
Aka “heart burn”
Can lead to gastroesophageal reflux disease (GERD)
Can then lead to ulcers, Barrett’s esophagus
Irritable Bowel Syndrome(IBS
Cause unknown
Symptoms of IBS include abdominal pain, bloating, cramping, diarrhea, constipation, flatulence
Treatment focuses on alleviating symptoms:
Avoiding trigger foods, managing stress, drinking plenty of fluids…
Diverticulitis
Diverticula = weakened walls of the large intestine form outpouchings
Diverticula can become inflamed = diverticulitis
Diverticula can blead = diverticulosis
Age, obesity, smoking, physical inactivity increase risk
Diets low in fibre and high in animal fat increase risk
Gallstones
Hardened bile deposits that form stones in the gallbladder
Can be painful, especially when fat is consumed and gallbladder contracts to release bile
Diets high in simple sugars, saturated fat and energy increase risk
Gallbladder may need to be removed
Digestive Tract Cancers
Cancer = uncontrolled multiplication of our cells
Can occur anywhere in digestive tract; most common in colon
Colorectal cancer has both genetic and lifestyle risk factors
Physical inactivity, obesity increase risk
Diets high in red and processed meats increase risk, those high in vegetables, fruits and fibre decrease risk
Constipation + Diarrhea
= bowel movements that are difficult to pass or less frequent
Stools tend to be dry, hard and can be painful to excrete
Increases risk for hemorrhoids
Risk factors include age, female sex, genetics, physical inactivity, the use of certain medications and IBS
Diet low in fruits, vegetables and water also increases risk
Occurs when matter passes too quickly through the large intestine
Stools are loose and have a liquid-like consistency
Typically due to bacterial and viral infections.
Can be caused by food poisoning
Delivery of Nutrients to the Liver
Nutrients that enter the blood capillaries at the villi will then enter veins that lead to the liver
= All nutrients except large lipids and fat-soluble vitamins
At the liver, material is stored, used, detoxified or sent off to the rest of the system
The material that enters the cardiovascular system can then be transported to where it is needed
Dietary Toxins and Detoxification
Recall that toxins are substances that can be found in food that can cause damage to the body.
Ex. Persistent organic pollutants (POPs)
Levels of toxins in a well-balanced diet are typically below the threshold for harm
Also, the liver, kidneys and lungs remove toxins form the body
Lack of evidence to support the use of commercial detox diets for detoxification/ improved health
Metabolism
Metabolism = sum of chemical reactions that occur in our bodies
Anabolism
smaller molecules come together to form larger ones
requires an input of energy
Catabolism
Larger molecules are broken down into smaller ones
Leads to a net release of energy
The catabolism of the energy-yielding nutrients (carbs, fats, proteins) leads to the release of energy
This energy is captured within ATP: the energy currency of the body
Cellular Respiration
Cellular respiration = the catabolism of the energy-yielding nutrients leading to the production of ATP
Primarily occurs in the mitochondria (“powerhouse”) of the cell
It occurs in several steps, collectively known as a metabolic pathway
The cellular respiration of glucose is summarized by the equation:
Once this is understood, the metabolism of triglycerides and amino acids can be understood
Glucose Metabolism
Step 1: Glycolysis
Glycolysis = breakdown of glucose
Anaerobic; produces minimal ATP
Step 2: The Breakdown of Pyruvate
Pyruvate catabolism depends on whether oxygen is present (aerobic conditions) or not (anaerobic conditions)
Aerobic conditions – acetyl CoA is formed
Anerobic conditions- pyruvate is formed
Some ATP is formed
Cannot be sustained
Reversible back to pyruvate when oxygen is again available
Step 3: Citric Acid Cycle
Citric Acid Cycle= complex set of reactions that begins when acetyl CoA combines with oxaloacetate
Produces CO2 , water, and the capture of energy in GTP (≈ATP)
Most notably, electron transporters (NADH + H+, FADH2) capture electrons and move to the mitochondrial membrane to begin the electron transport chain
Step 4: The Electron Transport Chain
Electrons are exchanged between the electron transporters (NADH + H+, FADH2) and membrane-bound proteins
This leads to a build up of protons (H+) on one side of the membrane
These protons will move through a protein pump that is associated with an enzyme called ATP synthase.
This process leads to the production of more than 30 molecules of ATP.
Lipid Metabolism
Triglycerides have three fatty acids attached to a glycerol backbone
Majority of energy is derived from fatty acids
Beta-oxidation splits the fatty acid two carbon atoms at a time
Each two-carbon molecule of a fatty acid can be used to form acetyl CoA
Proceeds through remaining stages of cellular respiration
Ketogenesis
Can occur when diet is high in fat and very low in carbohydrates
The citric acid cycle requires carbohydrates
On a very low carb diet, fatty acids cannot enter citric acid cycle, instead form ketones
Amino Acid Metabolism
First, the nitrogen group of the amino acid must be removed (deaminated)
There are 21 amino acids – each with a unique side chain
Therefore there are 21 possibilities for what remains
Deaminated amino acids will either be used to form:
Pyruvate
Acetyl CoA
Citric Acid Cycle Intermediates
Structure and Properties of Water
Water is a polar molecule
Other polar molecules are attracted to water
= hydrophilic
Nonpolar molecules are not attracted to water
Water helps structures maintain their form
Ex. Cells, humour of eye, synovial sacs…
Water Content of the Human Body
Human body is 60-70% water by weight 2/3 found within cells = intracellular water 1/3 found outside of cells (ie. In blood, spaces between cells…) = extracellular water
Movement of water
Osmosis is the movement of water towards charged particles
This is done in an effort to even out concentration differences
Blood pressure involves a force that pushes water out of blood and into the extracellular space
Hydrolysis
Hydrolysis reactions use water to split larger molecules into smaller ones
water functions
defense from infections: Water provides an environment for immune cells to fight off infection
Water is the main component of mucus, which helps remove infectious agents
protection from injuries: Water in synovial fluid protects joints
Mucus lines various structures and protects them from physical injuries
Water around brain and spinal cord helps protect them from various forces
Temperature Regulation: Body temperature is strictly controlled
Body uses water to regulate body temperature through two main mechanisms
When sweat evaporates, it cools down our body
Blood is shunted to the skin’s surface to help promote sweating, lower internal temp
Maintaining Water Balance
A main priority of the body is maintaining water homeostasis
Since we don’t store water, and we lose it everyday, the emphasis is on preserving body water levels through two main mechanisms:
Thirst response
Kidneys
Dehydration
Either due to insufficient consumption or excessive loss
Symptoms include thirst, dry mouth, fatigue, dizziness, irritability, dark urine
Chronic dehydration can lead to kidney damage, seizures, hypovolemic shock
Water Intoxication
AKA water poisoning
When water levels decrease the concentration of dissolved particles in the blood
Ex. hyponatremia
Potentially fatal
Symptoms include headache, confusion, personality changes, irritability, drowsiness
Typically due to excessive sweating that is replaced by water alone
Diuretics
Substances that promote water loss through urination
Ex. Diuretic pills, aka water pills, promote sodium excretion at the kidney, which also promotes water excretion
Alcohol and caffeine are also diuretics
They are not nutrients, they are psychoactive drugs
Caffeine
Compound naturally found in certain seeds, nuts, leaves
A diuretic, but mainly used for its stimulant effects
Promotes alertness, reduces tiredness
May have beneficial roles in disease reduction when consumed in coffee
Coffee is believed to have antioxidant and anti-inflammatory properties
May increase the risk of miscarriage and kidney stones
Alcohol
= psychoactive drug found in certain foods and beverages
Provides 7 kcal/g
Higher levels of consumption increase risk for cancers, liver cirrhosis, confusion, dementia, malnutrition, all-cause mortality…
However, light to moderate amounts (1-2 servings per day) may provide a slightly lower risk of CVD
Alcohol Metabolism
90% of alcohol is metabolized and eliminated at the liver
Alcohol dehydrogenase aldehyde dehydrogenase are the enzymes responsible for metabolizing alcohol
Genetic changes can negatively impact the activity of these enzymes
May result in facial redness, nausea, sweating, dizziness and racing heart rate when alcohol is consumed
Hangovers
Typically occur 6+ hours after drinking
Symptoms include vomiting, tiredness, decreased attention, decreased concentration, stomach pain and disturbed sleep
May be due to direct effect of alcohol, acetaldehyde buildup, or congeners
Best way to avoid a hangover is to moderate or abstain from alcohol consumption
Views of Water
western lens Important natural resource Commodity Used for industry, agriculture Used by humans as a nutrient
indigenous lens Tied to our existence Part of who we are Has a life of its own “Mother Life’s blood”
Whanganui River
Found in New Zealand
Following an 140-year long lobbying effort, was the first river in the world to be given the same legal rights as humans
“We can trace our genealogy to the origins of the universe. And therefore, rather than us being masters of the natural world, we are part of it. We want to live like that as our starting point. And that is not an anti-development, or anti-economic use of the river but to begin with the view that it is a living being, and then consider its future from that central belief”
Carbohydrates
The term carbohydrate denotes what their structure is composed of carbo (carbon) and hydrate (hydrogen and oxygen)
There are three main types of carbohydrates: sugars, starches and fibre
All three are made up of monosaccharides, or sugars
Monosaccharides (Single Sugars)
There are three main monosaccharides found in the foods we eat
Glucose is the most common monosaccharide
glucose =blood sugar
fructose = fruit sugar
galactose = milk sugar
Disaccharides (Double Sugars)
The dietary monosaccharides found on the last slide are used to make up the three most common dietary disaccharides
Extrinsic vs. Intrinsic Sugars
Intrinsic sugars are those naturally found in foods
Extrinsic sugars, AKA added sugars, are added into food by manufacturers to increase their sweetness
Extrinsic and intrinsic sugars are chemically identical
However, foods higher in extrinsic sugars are more likely to be nutrient poor and energy dense and may increase risk of disease
Extrinsic Sugars Must be Grouped Together on an Ingredients List
Oligosaccharides (Few Sugars)
Oligosaccharides have between 3 and 10 monosaccharides in their chain
They are considered fibres, because humans lack the enzymes needed to digest them
Most common oligos = fructooligosaccharides (FOSs) and galactooligosaccharides (GOSs)
They are prebiotics because digestive bacteria can use them for food
Polysaccharides (Many Sugars)
Polysaccharides have more than 10 monosaccharides in their chain
Polysaccharides are typically composed of long glucose chains
Two main types of polysaccharides:
Starch (humans have the enzymes needed to break it down)
Fibre (humans do not have the enzymes needed to break it down
Starch
= long glucose chain that is either straight (amylose) or branched (amylopectin)
Fibre
There are many types of fibre
Ex. cellulose, dextrin, inulin
They are classified as either soluble or insoluble (next slides)
Compared to starch, the bonds that hold adjacent glucose molecules together are different
We lack the enzymes needed to break these bonds
Accordingly, there is no chemical digestion of fibre in the small intestine
Soluble Fibre
Soluble fibre dissolves in water
It is found in apples, beans, peas, citrus fruits…
Soluble fibre may help to regulate blood glucose and lower blood cholesterol
Bacteria in the large intestine can ferment soluble fibre to produce short-chain fatty acids
Provide 2-3 kcal of energy
Insoluble Fibre
Does not dissolve readily in water
Passes through digestive tract virtually unchanged
Found in wheat, bran, beans, potatoes, cauliflower…
May promote digestive health
Glycogen
= storage form of carbohydrate
We can only store so much carbohydrate – typically around 0.5-2 kg
Glycogen is composed of long chains of glucose molecules
We have glycogen stored in our muscles and around out liver
Refined vs. Unrefined Carbohydrates
Unrefined sources of carbohydrates are those consumed in their entire form i.e. the entire grain is used
Ex. Whole grain wheat
They are more nutrient dense, higher in fibre, phytochemicals
Refined sources of carbohydrates have part of the grain removed, typically the bran and germ layer
Lactose Intolerance
Caused by insufficient secretion of the enzyme lactase
Since lactose cannot be digested in small intestine, bacteria in the large intestine ferment it
Leads to the production of methane gas
Symptoms include cramps, bloating, diarrhea, abdominal pain when lactose is consumed
Glycemic Response and Glycemic Index
Glycemic response = spike in blood glucose that follows a meal once glucose enters the general circulation
Diets that produce a lower GR associated with a lower risk of type 2 diabetes, CVD and obesity
= relative ranking of a food’s potential to spike blood sugar on a 100-point scale
Glucose scores 100
Glycemic load may be more accurate then glycemic index, because it also takes into account how much carbohydrate is actually in that food
Blood Sugar Regulation – the Role of Insulin and Glucagon
Our bodies try to establish glucose homeostasis
Insulin and glucagon are blood glucose-regulating hormones
They are secreted by the pancreas
When blood glucose is not in balance, it can have negative effects
Hypoglycemia, low blood glucose, can affect energy levels etc.
Hyperglycemia, high blood glucose, if chronic, can lead to diabetes
The Endocrine vs. Exocrine Pancreas
Pancreas secretes insulin and glucagon into the blood (endocrine function) in order to regulate blood glucose
Pancreas secretes pancreatic juice into the digestive tract (exocrine function) to facilitate digestion
Glucagon and Blood Glucose
When blood glucose levels drop, the pancreas releases glucagon
Glucagon increases blood glucose through three main processes:
Glycogenolysis: the conversion of glycogen to glucose.
Gluconeogenesis: the conversion of certain amino acids into glucose.
Lipolysis: the breakdown of stored lipids. The glycerol from triglycerides can then be used to make glucose.
Carbohydrates Spare Proteins
If the body does not consume enough carbohydrates, certain amino acids will be used to make glucose through process of gluconeogenesis
This leads to the breakdown of body proteins
Getting enough carbohydrate in the diet minimizes the breakdown of body proteins
Fat Burns in Carbohydrate Flame
Sufficient dietary carbohydrates are needed in order to maintain the citric acid cycle
If the diet is very low in carbohydrates, the products of lipid metabolism cannot enter the citric acid cycle and will instead form ketones
diabetes in indigenous lens
In Canada, Type 2 diabetes is 2-3 times more common in Indigenous populations
This is believed to be due, in part, to colonization and cultural loss
Indigenous individuals who retain their culture through language are less likely to develop diabetes
Type 1 Diabetes
Approx 10% of cases
Aka juvenile or insulin-dependent diabetes
The immune system attacks the insulin-secreting cells of the pancreas
= no insulin secretion, glucose cannot enter cells, blood glucose remains high
Type 2 Diabetes
Approx. 90% of cases
Mainly evidenced by insulin resistance
Cells lose their sensitivity to insulin, don’t respond to it
risk factors: Obesity Physical inactivity Diets high in processed foods, sugar, fat Genetics Family history Gestational diabetes
Gestational Diabetes
Elevated blood glucose and impaired glucose management that first occurs during pregnancy
Approx. 5% of pregnant women develop it
Increases future risk for type 2 diabetes in mother
Prevention of Diabetes
Type 1 No preventative measure has been established Type 2 Lifestyle changes Weight balance, loss Reduction in caloric intake, fat Physical activity Medication
Hypoglycemia
= low blood glucose
Symptoms include dizziness, extreme hunger, headache, irritability, tiredness and mental confusion
Reactive hypoglycemia = due to excessively high dose of insulin
Non-reactive hypoglycemia = various causes
may be due to fasting, medications, pregnancy, alcohol abuse and liver, heart, kidney disorders
FODMAPs and Irritable Bowel Syndrome
Short-chain carbohydrates are not fully absorbed in the small intestine and are fermented by bacteria in the large intestine, producing gas
May promote IBS symptoms
Reducing these FODMAPs (fermentable oligosaccharides, disaccharide, monosaccharide and polyols) may improve IBS symptoms
Fibre and Colon Cancer
Dietary fibre intake may reduce the risk of developing cancers of the large intestine
Individuals who consumed the most fibre had the lowest risk of developing cancers in different parts of the colon
Fibre may dilute the concentrations of cancer-causing agents, promote their removal and/or minimize the damage they can cause
Triglycerides
=the main dietary lipid
Have a glycerol backbone with three fatty acids (“fats”) attached to it
Fatty acids differ in their degree of saturation, length and/or their geometric organization
Degree of Saturation of Fatty Acids
Saturated fatty acids = no double bonds
They are accordingly saturated with hydrogens
Unsaturated fatty acids = one (mono-) or more (poly-) double bonds
Polyunsaturated fatty acids (PUFAs) are named according to where the double bond is when counting from the omega end
Ex. Omega-3 PUFAs
Essential Fatty Acids
PUFAs with the double bond before the 9th position
The body cannot make them itself, therefore they are essential
There are two essential fatty acids: alpha-linoleic acid (omega-3) and linolenic acid (omega-6)
They can be used to synthesize other omega-3/-6s
They can be used to form eicosanoids = hormone-like molecules
Length of Fatty Acids
Long-chain fatty acids are found in a variety of animal products, some plants
Medium-chain fatty acids are found in tropical oils
Short-chain fatty acids are made by bacteria when they ferment indigestible carbs
Geometric Structure of Fatty Acids
Unsaturated fatty acids can have a cis or trans configuration
This refers to the location of hydrogen atoms around the double bond
Trans fatty acids can be artificially made through the process of hydrogenation
These artificial/industrial trans fats significantly increase risk of CVD
Sterols
Have a hydrocarbon chain arranged in a ring formation
Also hydrophobic
Play a variety of structural and functional roles in the body
Ex. cell membrane structure, hormone formation
Can be consumed from both plant and animal sources
animal derived sterols: Most common = cholesterol
Has many important roles in the body
Cell membrane structure
Precursor for vitamin D
Precursor for estrogen, testosterone
Liver and other body structures can synthesize their own cholesterol, so it is not necessary from the diet
Phospholipids
Their amphiphilic nature (having a hydrophilic and a hydrophobic end) gives them special properties and functions
They can form a bilayer when immersed in water
Ex. Phospholipid bilayer of the cell membrane
They can act as emulsifiers
They can carry other lipids around the body
Ex. lipoproteins
Lipid Digestion
Triglycerides must first be digested into glycerol and fatty acids
Bile emulsifies lipids, lingual/gastric/pancreatic lipases digest them
Lipid Absorption
- the micelle breaks down. its loupes contents are absorbed into the small intestine cells through passive diffusion
- lipids gets wrapped in phospholipids as they exit the small intestine cell and enter the centre of villus. the resulting structure is called a chylomicron
- chylomicrons are too large to enter the blood. instead they enter lacteals
Lipid Transport
The hydrophobic nature of lipids makes them incapable of dissolving in the watery environments of the small intestine lumen, blood and lymph
They accordingly need lipoproteins, lipid transporters, to carry them around the body
Energy Provision
Lipids provide 9 kcal/gram
If carbohydrates are adequate in the diet, triglycerides are metabolized and their products enter the citric acid cycle and the electron transport chain to yield ATP
If carbohydrates are inadequate in the diet, ketones are formed
Lipid Storage vs. Lipid Metabolism
At an energy surplus, extra energy is stored as lipid in adipose tissue (fat tissue)
At an energy deficit, lipids are retrieved from adipose tissue
Membranes
The membranes of cells and the membranes of cellular organelle are composed of phospholipids
Transport and Storage of Fat Soluble Vitamins
Vitamins A, D, E, and K are fat-soluble vitamins
Since they are hydrophobic, they require a lipoprotein for their transport
They are also stored in adipose tissue
Synthesis of Other Key Molecules
Cholesterol-derived molecules include:
Steroid hormones, bile salts, vitamin D, estrogen, testosterone
Essential fatty acid-derived molecules include:
Eicosanoids, endocannabinoids
Lipids and Cardiovascular Disease
CVD compromises the cardiovascular system’s ability to deliver cellular needs (ex. Oxygen, nutrients) and remove wastes (ex. CO2)
Atherosclerosis, the build-up of fatty materials in artery walls, is a type of CVD that causes heart attacks and some strokes
Certain lipids can increase or decrease the risk of developing atherosclerosis
Depends on the lipid
Trans Fatty Acids and CVD
On a per-calorie basis, trans fats appear to increase the risk of [heart disease] more than any other macronutrient” (Mozaffarian et al., 2006).”
Are known to increase:
Ratio of LDL to HDL
Risk of CVD
Risk of CVD mortality
To reduce/avoid trans fats, minimize the consumption of processed and ultra-processed foods, especially those that are hydrogenated
Saturated Fatty Acids
Diets high in saturated fat:
Increase LDL → which increases risk of CVD = lipid hypothesis
However, a direct link between saturated fat and CVD has not been established
Replacing saturated fats (mainly found in animal products) with unsaturated fats (mainly found in plant products) may lower potential risk
Polyunsaturated Fatty Acids
When PUFAs replace saturated fat, LDL levels decrease
PUFAs that are essential amino acids have also been studied for their roles in CVD (next slide)
Essential Fatty Acids
Omega-3 fatty acids
Have several cardioprotective effects including decreasing inflammation, blood cholesterol, vasoconstriction and blood clotting
However, supplementation of omega-3 has not been shown to decrease cardiovascular events
Omega-6 fatty acids
Thought to increase risk of CVD because they Increase inflammation and blood clotting
However, results of RCTs have been mixed
Both omega-3 and omega-6 fatty acids have protective effects on the brain
Are being
Cholesterol
For most people, dietary cholesterol has a minimal effect on increasing LDL and cardiovascular risk
The body makes less cholesterol when more is consumed, LDL levels don’t rise
However, 25-30% of people are believed to be cholesterol hyper-responders
Their LDL does go up when more cholesterol is consumed
Protein Structure
Proteins are Folded Amino Acid Chains
Amino acids have three main groups: A nitrogen-containing amine group A carboxylic acid A side chain (Rx) There are 21 amino acids Structurally, they differ only in their side chain
Essential vs. Non-Essential Amino Acid
Nine amino acids are essential
The non-essential amino acids can be made by modifying other amino acids
Through process of transamination
Conditionally essential amino acids are non-essential amino acids that become essential when the body cannot synthesize enough of them
Complete vs. Incomplete Proteins
Complete proteins are foods that have all nine essential amino acids
All animal sources are complete, as are soy, quinoa, buckwheat
Incomplete proteins are foods that are missing one or more essential amino acids
Plant sources are typically incomplete
The amino acid that is lacking = limiting amino acid
Protein Synthesis
To become part of a fully functional protein, amino acids must bind together in a specific order
Our DNA holds the instructions for the sequence of amino acids needed in order to build specific proteins
We draw on the amino acid pool to make these chains
Primary Structure of a Protein
The first level of protein structure arises from adjacent amino acids bonding to each other
Peptide bonds lead to the formation of a polypeptide
This polypeptide is not yet a protein
Must fold into secondary, tertiary, perhaps quaternary structure
Secondary Structure of a Protein
Hydrogen bonds between non-adjacent amino acids lead to the formation of:
Alpha helices
Beta-pleated sheets
Tertiary Structure of a Protein
Interactions between amino acids side chains leads to further folding of the polypeptide chain
This may result in a functional protein
Quaternary Structure of Protein
Some proteins have a quaternary structure
=several proteins with a tertiary structure bind together to form the final protein
Each of these is called a protein subunit
Denaturation of a Protein
A protein is denatured when it loses its folded three-dimensional structure
Also loses its function
Acids, heat, agitation can all denature proteins
This is sometimes desirable
ex. Food preparation
protein body structure
Bones, muscles, skin and every body organ contain protein
Collagen is the main structural protein
Elastin is another key structural protein
Permits elasticity
protein transport
Protein tracks in cells allow substances to walk along them, permitting transport around the cell
Protein channels regulate movement into and out of the cell
The blood protein hemoglobin transports oxygen around the body
protein Movement
Myosin and actin are proteins found in muscle
When myosin proteins attach to actin proteins and kink their heads, muscle contraction occurs
Allows our bodies to produce movement
protein fluid balance
Water is attracted to the positive and negative charges of the amino acids found in blood proteins
This draw water into the blood and out of the extracellular space
If blood proteins are low, fluid can build up in the extracellular space, leading to edema
protein protection from disease
Collagen in skin helps to restrict what can enter the body
If infectious agents enter, proteins called antibodies stick to these agents, promoting their removal and limiting the harm they can cause
protein energy
While proteins provide 4 kcal/gram, they are a minor source of energy to the body
It is wasteful to deaminate an amino acid so it can be metabolized to generate ATP
The body prefers to use protein for all its various other functions
Protein Deficiency
Marasmus = wasting syndrome
Occurs when energy and protein are deficient
Promotes anemia, dehydration, heart irregularities, body temperate dysregulation
Kwashiorkor
Believed to occur when protein is deficient, but energy is sufficient
Evidenced by a distended, swollen abdomen and an otherwise slim appearance
Protein and Body Weight
The primary dietary factor that promotes weight gain is a caloric intake that is consistently above the body’s needs
Whether a high/low-protein diet leads to weight gain depends on the total calories consumed
However, protein may promote a caloric deficit by:
Promoting fullness
Contributing to carbohydrate and lipid metabolism
Requiring more energy to digest and absorb it
i.e. it has a higher thermic effect
Protein and Bone Health
In bone, collagen forms a matrix that minerals (ex. Calcium) harden
However, high protein diets can promote calcium excretion
Overall, high protein diets do not seem to negatively affect bone health
Protein and Kidney Health
High protein diets tax the kidneys because they have more waste products to excrete
For those with reduced kidney function, consuming protein at the recommended intake level (0.8 g/kg), and not beyond it, is recommended
Ways to Assess Protein Quality
Protein digestibility corrected amino acid score (PDCAAS)
Compares the amino acid content of a food against a standard amino acid profile. The highest score that can be achieved is 1.0
=industry standard
Digestible indispensable amino acid score (DIAAS)
Measures how well amino acids are digested in the ileum and more closely estimates the amount of amino acids absorbed by the body
Database is still being built
Protein efficiency ratio (PER)
How much weight an animal gains when consuming a specific amount of protein, divided by the amount of food it consumed
Used in Canada
Branched-Chain Amino Acids
=essential amino acids that have a branched side chain
They account for 35-40% of the dietary essential amino acids found in body protein
Have been shown to reduce muscle damage associated with weight training
Especially if consumed before exercise
Can be consumed from whole sources, do not have to come from supplements!
An Indigenous Lens: Protein Quality of Game Meats vs. Processed Meats
Traditional Indigenous diets were very high in protein due hunting and fishing practices
However, with colonization came limitations on these practices
With this, there has also been a shift towards processed meats
Believed to negatively affect protein quality of modern Indigenous diets
Game meats have more total protein and tryptophan than processed meats
Tryptophan is an essential amino acid involved in many processed including mood regulation and sleep
Shifting back to a traditional Indigenous diet may help correct potential deficiencies
Health Benefits of Vegetarian Diets
Diets are high in fibre and phytochemicals and low in saturated fats
Vegetarians are more likely to have lower BMIs, total cholesterol and LDL
They are also at lower risk for heart disease, cancer and CVD mortality
Risks of Vegetarian Diets
They are lower in vitamin D, omega-3 fatty acids, calcium, iron and zinc
Vitamin B12 is only found in animal products (with the exception of nutritional yeast)
Supplementation is recommended if these are not sufficient in diet
Vitamin Overview
Vitamins are organic micronutrients
They facilitate body processes
They are either fat-soluble or water-soluble
Vitamins Can Function as Coenzymes
water-soluble vitamins
B vitanmins, vitamin C
The B Vitamins
A group of eight vitamins that act as coenzymes for energy metabolism
Many have other roles as well
Plants and animals naturally contain B vitamins and they are also fortified into foods
Vitamin B1: Thiamine
Plays a roles in muscular contraction, nerve conduction and is required for ATP synthesis
Also part of the coenzyme thiamine pyrophosphate
Required for citric acid cycle
No known toxicity
Thiamine Deficiency
Rare in Canada
The brain is particularly susceptible to thiamine deficiency
Can promote neuronal death
In developed world, typically associated with alcoholism
Can lead to Wernicke/Korsakoff syndrome
short-term memory loss, confusion, disorientation and changes in eye movements
Korsakoff syndrome has more severe and permanent neurological symptoms
In developing world, associated with malnutrition
Can lead to BeriBeri
Wet BeriBeri
Negatively impacts the cardiovascular system and can lead to heart failure
Dry BeriBeri
Negatively impacts the nervous and muscular systems, potentially leading to muscle paralysis
Can also lead to Wernicke/Korsakoff syndrome
Vitamin B2: Riboflavin
Riboflavin helps form two important coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
Recall, FAD = electron transporter required for electron transport chain
They are also involved in:
Conversion of the amino acid tryptophan to niacin
Maintaining appropriate levels of homocysteine
sources: chicken, nuts, eggs, celery, cheese, milk
Riboflavin Deficiency
Rare More common in vegetarians Hormonal abnormalities may promote it Can lead to ariboflavinosis skin disorders, swelling in the mouth and throat, dry and cracked lips, red eyes and hair loss
Vitamin B3: Niacin
Forms the coenzyme nicotinamide adenine dinucleotide (NAD)
Recall, NAD = electron transporter required for electron transport chain
NAD is required by more than 400 enzymes!
Involved in more reactions than any other vitamin
Niacin Deficiency
Causes pellagra
4Ds of pellagra: dermatitis, diarrhea, dementia, death
Pellagra plagued the Southern US in the early 1900s before its cause was known
Southern diet was high in corn, wheat and rice
= low in niacin
Vitamin B5: Pantothenic Acid
Helps form coenzyme A
Required for acetyl CoA
Essential for energy metabolism
Deficiency, toxicity = rare
sources: Pantothen = everywhere
Found in a wide variety of food
Vitamin B5: Pantothenic Acid
Helps form coenzyme A
Required for acetyl CoA
Essential for energy metabolism
Deficiency, toxicity = rare
sources: Pantothen = everywhere
Found in a wide variety of food
Vitamin B6: Pyridoxine
= generic name for six vitamers
Act as coenzymes in more than 100 reactions
Ex. Energy metabolism
Also help form the neurotransmitters serotonin and norepinephrine
Also helps lower homocysteine levels by converting it to cysteine
special uses: upplementation has been used for:
Improving cognitive function
Reducing CVD risk
Reducing PMS symptoms
Reducing vomiting and nausea in pregnancy
Vitamin B6 Deficiency and Toxicity
Deficiency = rare, typically in combination with other B vitamin deficiencies
In pronounced cases can lead to microcytic anemia
Can promote fatigue, lethargy
Toxicity = rare; typically due to over-supplementation (>1000 mg/d)
Can promote loss of control over body movements
Vitamin B7: Biotin
Generic name for five vitamers that function as coenzymes
Involved in energy metabolism, cell-signalling, DNA structure/function
Special uses:
Biotin is sold to improve hair, nail, skin health
However, clear benefit has not been scientifically established
Biotin Deficiency and Toxicity
Deficiency = rare
May occur with a genetic disorder called biotinidase deficiency
Hari loss, red eyes, rashes
Can progress to seizures, depression, muscle disorders
Toxicity = rare
But over-supplementation can compromise laboratory test results
Vitamin B9: Folate/Folic Acid
Folate = basic form (food), Folic acid = acids form (supplements)
Coenzyme in DNA/RNA synthesis, amino acids metabolism
Also involved in conversion of homocysteine to methionine
Folate Deficiency
Deficiency during pregnancy can lead to neural tube defects
Can cause birth defects such as spina bifida and anencephaly
Can lead to megaloblastic anemia
Red blood cells are immature, large, misshapen and unable to properly carry oxygen
Symptoms include tiredness, weakness and heart irregularities
Folate deficiency has also been studied for its potential link with autism, but firm link has not been established
Vitamin B12: Cobalamin
Vitamin B12 vitamers are collectively known as cobalamins
Required for DNA synthesis, red blood cell formation, brain function
Also acts as coenzyme for conversion of homocysteine to methionine
Has also been studied for reduction in dementia risk – evidence is currently lacking to
sources:Found only in animal products
With exception of nutrition yeast
Supplementation is recommended for vegans, vegetarians
Vitamin B12 Absorption
Factors that negatively affect the stomach (ex. Atrophic gastritis) can compromise the release of intrinsic factor, negatively affecting B12 absorption
More common in older adults
Vitamin B12 Deficiency and Toxicity
Deficiency can lead to megaloblastic anemia
Can also promote balance issues, depression, poor memory, confusions
Toxicity = rare
However, can interact with certain medications
Vitamin C: Ascorbic Acid
Critical for collagen formation
Also involved in protein metabolism, iron absorption
Vitamin C is an Antioxidant
special uses: Immune system effects
Vitamin C supports the proper function of the immune system
May lower risk of developing colds if taken before they occur
Especially in certain athletes
Chronic disease prevention
Has been studied for potential to reduce cancer, CVD risk
However, supplementation has not been shown to reduce risk
Fat-Soluble Vitamins
vitamin A, D, E , K
Vitamin A
Vitamin A has several vitamers = retinoids
Provitamin A is found in plants and its vitamers are collectively known as carotenoids.
Must be converted into retinols
Preformed vitamin A is found in its almost-active forms: retinol and retinal ester; found in animal products
The body must convert retinols into retinal and retinoic acid = active form of vitamin A
Vitamin A is Critical for Visual Pathway
Other Functions and uses of Vitamin A
Gene expression
i.e. Whether genes are turned on/off
Immune Function
Contributes to formation of infection-fighting T-cells
Carotenoid form (plants) functions as an antioxidant
Promotes skin health by switching on the genes that cause immature skin cells to become mature and healthy
Many skin care products contain retinoids
Ex. Accutane, a retinoic acid product is used to treat acne
However, can have severe skin, gastrointestinal, nervous and cardiovascular side effects and increase risk of birth defects if taken by pregnant women
Sources of Vitamin A
Preformed vitamin A is found in animal products
Provitamin A is found in plant products
Vitamin A Deficiency and toxicity
Rare in North America, common in developing countries
Often linked with poverty, low diet variability
Can lead to xeropthalmia - abnormal dryness of the eye that affects the body’s ability to form tears
If untreated, can lead to breaks in cornea, even blindness
Night blindness is an early sign of xeropthalmia
Carotenoids may turn skin slightly orange, but otherwise have no toxicity symptoms
Preformed vitamin A toxicity can have serious side effects
Elevated pressure around the brain, dizziness, nausea, headaches and can be fatal
Typically due to over-supplementation
Has also been evidenced in arctic explorers who consume polar bear liver
=excessively high in provitamin A
Vitamin D
= generic name for a group of compounds including vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol)
Their main role is maintaining calcium homeostasis
Increase calcium, phosphorus and magnesium absorption
Also plays roles in cellular growth, immune function and the reduction of inflammation
Has also been studied for its role in cancer prevention
Establishing adequate vitamin D from food may have a role in cancer prevention, but supplementation has not been established to lower risk
sources: fish, cheese
Vitamin D Deficiency
Common; due to inadequate dietary consumption, limited sun exposure
Older adults, individuals with black skin, individuals with obesity, breastfed infants, people who have undergone gastric surgery are all at higher risk
In children, can promote rickets
In adults, can lead to osteomalacia
=softening of bones
Can progress to osteoporosis
Vitamin D Toxicity
Toxicity from food is rare, typically due to over-supplementation
Can promote anorexia, weight loss, increased urination, irregular heart rhythms
Can also increase blood calcium
Can harden blood vessels, eyes and negatively impact kidneys and heart
Vitamin E
generic term for eight vitamers
Alpha tocopherol = main one from diet
Vitamin E exerts its main functions through its antioxidant role
Also involved in immune function, cell signalling
Has also been studied for potential to decrease cancer, CVD, Alzheimer’s risk
However, supplementation has not been shown to decrease risk
Vitamin E Deficiency and Toxicity
Deficiency = rare; typically due to compromised fat absorption
Symptoms may include peripheral neuropathy, movement difficulties, muscle disorders and an impaired immune response
Toxicity is due to over-supplementation
Increases mortality rate
Has been linked to lung illnesses in those that vape
High levels of vitamin E were found in the blood of individuals with vaping-related lung issues such as difficulty breathing, chest pain, fatigue and vomiting
Vitamin K
Named for the Danish word for coagulation (blood clotting)
Prothrombin synthesis is dependent on a vitamin K coenzyme
Prothrombin is needed for the pathway that leads to the formation of sticky fibrin fibres – which help red blood cells clump together
Vitamin K Deficiency and Toxicity
Deficiency is rare
Except in newborns, those with compromised absorption, those who overuse antibiotics
Can lead to excessive bleeding, hemorrhaging
Newborns get a shot of vitamin K to prevent this
Toxicity has not been observed
An Indigenous Lens: Are Minerals Living Things?
Western science defines organic matter as that which contains carbon and comes from living things
the Indigenous world view thinks much more in terms of [things] being alive…If you talk about a rock in English, you are thinking about it being something static, something fixed…but in Ojibway, when you’re talking about asin or asiniig, you’re talking about something that is alive, something that has a spirit, something that is in motion
Overview of Minerals
Minerals are elements that form solid compounds and that are not bound to carbon = inorganic Divided into: Major minerals Required in higher amounts from diet Minor/trace minerals Required in lower amounts from diet
Mineral Bioavailability
Bioavailability = availability in food as well as its propensity to be absorbed and available for use within the body
Minerals are found in both plants and animals
Mineral content of plants depends on the soil
Mineral content of animals depends on what they eat
Animal products, especially from larger animals, are a better source of minerals than plant products
Plants Contain Compounds That Can Negatively Affect Bioavailability
Phytates Impair iron, zinc absorption Phytate effects can be reduced by: Soaking certain foods overnight Ex. Soaking beans Fermenting foods Ex. Making sourdough bread Oxalates Impair calcium, iron absorption Tannins Impair iron absorption May have disease-reducing effects Anti-cancer, antioxidant, antimicrobial and inti-inflammatory
Glucosinolates
Impair iron absorption
Calcium
Most abundant mineral in the human body
Also abundant in nature
Ex. Limestone, chalk, pearls
Key signalling mineral
Contributes to nerve signalling, key intracellular messenger
Required for muscle and heart contraction, gland secretion
99% of body calcium in stored in bones and teeth
Promotes their structural integrity
Calcium Homeostasis
Maintaining blood calcium is critically important
When levels drop, parathyroid hormone (PTH) is released
When levels are too high, calcitonin is release
Opposes actions of PTH
i.e. impairs osteoclast activity, promotes calcium excretion
Calcium Deficiency and toxicity
Minor increases are typically asymptomatic
Chronically elevated levels can lead to abdominal/bone pain, mental confusion
Can progress to the calcification, hardening, of tissues
Can lead to cardiac arrest
Rarely due to dietary excess, typically due to other chronic conditions
Phosphorus
Second most abundant mineral in body
Found within hydroxyapatite – crystal that contains both calcium, phosphorus
Phosphorus Deficiency and Toxicity
Since abundant in foods, deficiency is rare
Can lead to osteoporosis, seizures, coma, anorexia, muscle weakness, anemia and an increased risk of infection
Toxicity is rare
May lead to calcification of tissues
Sodium
A key electrolyte
It is the primary cation of the extracellular space
In water, electrolytes become positively/negatively charged ions
Their movement leads to the creation of an electrical current
Sodium also contributes to fluid balance
sources: processed foods,
Sodium Deficiency and Toxicity
Deficiency = hyponatremia
Typically caused by excessive vomiting, sweating, diarrhea
Symptoms include nausea, vomiting, irritability, fatigue, loss of appetite, confusion, muscle weakness and spasm
Can progress to loss of consciousness and coma.
Toxicity is typically due to excessive loss of body water, which concentrates sodium
Symptoms include thirst, weakness, nausea and loss of appetite
Can progress to confusion, muscle twitching, and brain hemorrhages
Hypertension, Sodium and the D.A.S.H Diet
Hypertension = high blood pressure
Increases risk for CVD mortality
Risk factors include:
Age, African heritage, family history, kidney disease, diabetes, obesity, physical inactivity, stress, alcohol use and tobacco smoke
Diet
D.A.S.H. = Dietary Approaches to Stop Hypertension
D.A.S.H. eating plan emphasizes:
whole foods, particularly fruits, vegetables, whole grains, low-fat dairy, poultry, fish and nuts and is high in fiber, potassium, magnesium, calcium and protein
D.A.S.H. eating plan limits:
red meat, sweets, total fat, saturated fat, cholesterol and sugar
D.A.S.H. eating plan + sodium reduction = significant reduction in blood pressure
Potassium
Main role is as an electrolyte
Main cation of the intracellular space
Also contributes to fluid balance
Diets higher in potassium associated with lower risk of hypertension
Potassium Deficiency and Toxicity
Deficiency typically has not symptoms
May promote tiredness, weakness, cramps
Can progress to irregular heart rhythm, cardiac arrest
Typically due to excessive vomiting, diarrhea
Toxicity = rare
Typically due to impaired kidney function
may promote muscle weakness, heart irregularities, paralysis
Chloride
Also functions as an electrolyte
In water, becomes the negatively charged ion chloride
Maintains water balance
Is part of hydrochloric acid (HCl)
Table salt, sodium chloride, is our main source
Chlorine Deficiency and Toxicity
Deficiency is rarely due to dietary insufficiency
Typically due to respiratory issues, vomiting, kidney malfunction
Can promote weakness, difficulty breathing, diarrhea, vomiting
Toxicity rarely due to dietary excess
Typically due to irregular fluid balance
Can promote tiredness, muscle weakness
Magnesium
Cofactor for more than 600 enzymes
Involved in energy metabolism, protein synthesis, DNA/RNA structure, brain development, heart health, bone density
Supports formation of hydroxyapatite crystals
special uses: Popular dietary supplement
Daily supplementation of 600 mg may help reduce migraine headaches
Has also been studied for role in promoting heart health, managing blood glucose
Prospective epidemiological studies support these claims
RCTs are lacking
Magnesium Deficiency and Toxicity
Deficiency = rare
Symptoms include loss of appetite, nausea, vomiting, fatigue, weakness
can progress to cramping, numbness, tingling or heart irregularities, and seizures
Toxicity = rare
Typically due to over-supplementation, laxative, antacid use
Symptoms include diarrhea, nausea and abdominal cramping
Sulfur
Third most abundant mineral in body
Critical for synthesis of amino acids methionine and cysteine, which contain sulfur and contribute to protein folding
Needed for formation of the antioxidant glutathione peroxidase
Sulfur Deficiency and Toxicity
Deficiency is rare in those that consume sufficient protein
May contribute to protein-energy malnutrition in those who are inadequate
Toxicity is rare
May promote diarrhea, colitis
Iron
Critical for formation of hemoglobin and myoglobin
Therefore vital for oxygen transport
Heme iron Found in animal products More bioavailable Non-heme iron Mainly found in plant products Less bioavailable Oxalates, phytates, tannins, caffeine and calcium negatively affect bioavailability Vitamin C promotes iron absorption, increases bioavailability
Iron Deficiency
One of the most common dietary deficiencies
Most serious outcome = iron-deficiency anemia
Symptoms include lethargy, tiredness, weakness, hair loss, pale skin
Can progress to an irregular heartbeat and delayed growth in infants and children
More common in vegetarians, women, athletes, pregnancy Stages Mild iron deficiency Low iron levels in blood, bone marrow Marginal iron deficiency Levels in liver, muscle spleen also depleted Iron-deficiency anemia Levels in red blood cells also deplete
Iron Toxicity
Very toxic at high levels
Hepcidin, the body’s iron-regulatory hormone, is responsible for keeping iron stores in balance
Suppresses the absorption of iron when levels are high
Over-supplementation can lead to nausea, vomiting, constipation, faintness, reduced zinc absorption and bioavailability
One-time megadose (>60 mg/kg) can lead to iron poisoning
Can lead to organ failure, coma, death
Typically occurs with children who mistake iron supplements for candy
Individuals with rare genetic condition called hemochromatosis have irregular iron absorption, increased risk of toxicity
Zinc
Cofactor for more than 100 enzymes
Has roles in gene expression, immune function, protein and DNA synthesis, wound healing, growth, development
Part of antioxidants superoxide dismutase and glutathione peroxidase
Abundant in diet
Phytates in plants can limit absorption
Zinc Deficiency and Toxicity
Deficiency rarely due to dietary insufficiency
Can promote slowed growth, erectile dysfunction, diarrhea, thinning hair and impaired
Toxicity typically due to over-supplementation
Can promote nausea, vomiting, a metallic taste in the mouth, loss of appetite, diarrhea, abdominal cramps and headaches
High dietary intake also limit the absorption of copper and iron and promote their deficiency
Manganese
Cofactor for several enzymes
Facilitates energy metabolism, bone development, wound healing
Is also part of antioxidant superoxide dismutase
Abundant in shellfish, plants
Foods high in iron can slow its absorption
Deficiency, toxicity = rare
Copper
Involved in red blood cell synthesis, iron absorption
Cofactor for many enzymes
Facilitates energy metabolism, DNA/connective tissue synthesis,
special uses: Magnetic bracelets often contain copper
Are marketed as a treatment for arthritic pain
Not supported by quality evidence
May promote skin irritation
Also been studied for role in CVD, Alzheimer’s prevention
Evidence is insufficient to recommend supplementation
Copper Deficiency and Toxicity
~25% of Canadians are well below the RDA
Can negatively impact iron absorption, promoting iron-deficiency anemia
Deficiency symptoms may also include tremors, tingling sensations, awkward walking patterns, numbness and fatigue
Toxicity typically due to over-supplementation, genetic conditions
Can promote vomiting, diarrhea, yellowing of skin and muscle pain
Can progress to liver damage, heart failure, kidney failure and even death
Iodine
Essential component of thyroid hormones thyroxine (T4) and triiodothyronine (T3)
Have wide-spread metabolic effects
Regulation of fuel use, protein synthesis, heartbeat, body temperature regulation, muscle contraction, cell turnover
Main source is iodized salt
Iodine Deficiency
Affects ~ 2 billion people worldwide; 25% of which experience clinical symptoms
Compromises thyroid gland’s ability to make thyroid hormones
In adults, can lead to the formation of a goiter
In infants, can lead to congenital iodine deficiency syndrome
Increases risk of mental deficiencies, deaf mutism, difficulties with muscular control and slowed growth
Iodine Toxicity
Iodine poisoning typically due to over-supplementation
Can promote diarrhea, nausea, vomiting
More severe cases can lead to the swelling of airways, limiting breathing, a lowered heart rate and even coma
Can also lead to iodine-induced hyperthyroidism
Can promote accelerated heartrate, muscle weakness and unexplained weight loss, goiter
Selenium
Has roles in reproduction, the production and metabolism of the thyroid hormones, DNA synthesis
Essential component of the antioxidant glutathione peroxidase
special uses: Has been studied for potential to reduce CVD risk
Those with higher blood selenium levels have reduced risk of CVD
However, supplementation does not reduce risk
Has also been studied for potential to reduce cancer risk
Those with higher blood selenium levels have reduced risk of breast, lung, colon, prostate cancer
However, supplementation has not been established to reduce risk
sources: Content in plant foods varies significantly depending on soil quality
Selenium Deficiency
Rare in Canada, affects 1 billion+ people worldwide
Increases risk of male infertility, muscle weakness, fatigue, hair loss and a weakened immune system
Selenium deficiency + secondary stress (ex. Viral infection) are at higher risk for Keshan Disease
= potentially fatal heart disease
Climate change is predicted to decrease selenium content of soil by more than 50%
Selenium Toxicity
Increases risk of hair loss, nail discoloration, muscle and joint pain, headache and gastrointestinal symptoms
Early symptoms may include a metallic taste in the mouth and breath that smells like garlic
Selenium poisoning typically due to over-supplementation
Can promote neurological symptoms, breathing problems, kidney failure, heart attack and, though rare, even death
Ex. Outbreak of selenium poisoning in 2008 due to a dietary supplement that had 200X the stated amount of selenium
Molybdenum
Cofactor for enzymatic reactions
Helps to break down sulfites, which can promote allergic reactions, diarrhea, breathing difficulties
Content varies by soil quality
Deficiency is rare
Toxicity typically due to over-supplementation
May affect growth, promote kidney failure or promote the development of seizures and brain damage
Fluoride
ion of the mineral fluorine
Technically not essential since not required for growth or to sustain life
However, important for the formation of fluorapatite crystals
Mineralize teeth, strengthen enamel
Water fluoridation = “greatest public health achievements of the 20th century” – Center for Disease Control and Prevention
Reduces risk of tooth decay by 35%
However, many people are against it due to:
Cost
Ability to get fluoride from toothpaste, treatments
Not wanting to tamper with water supply
Increased risk of fluorosis
However, levels in water are limited to prevent fluorosis
Overview of Energy Balance
Energy = ability to do work
Energy intake = total energy consumed from food
Energy expenditure = energy used to fuel basal metabolism, physical activity, processing food
Energy balance = when energy intake = energy expenditure
Energy Intake
Carbohydrates, lipids, proteins = the three energy-yielding nutrients
Alcohol (7 kcal/g) also provides energy, but not a nutrient
Energy Expenditure
We burn energy for three main purposes:
Basal metabolic rate (~60-75%)
Diet-induced thermogenesis(~10%)
Physical activity (~15-30%)
Basal Metabolic Rate (BMR
BMR = the amount of energy the body needs to perform its most basic, life-sustaining functions over a period of time
Ex. Breathing, heart beat, nerve signalling
When we say someone has a fast metabolism, we typically mean that they burn a lot of calories to sustain their body, even before physical activity is factored in
They may therefore be less likely to gain fat mass
factor that determines: Main controllable factor = lean body mass
Diet-Induced Thermogenesis
AKA specific dynamic action, thermic effect of food
= energy that is used and dissipated as heat following food intake
More energy is required to process protein compared to other nutrients
However, at most, DIT accounts for 15% of energy expenditure
Energy Retrieval
An energy deficit occurs when energy intake is less than energy expenditure
When a consistent energy deficit is maintained, lipids are removed from adipocytes, decreasing fat mass and weight
obesity Energy Storage
When energy intake is higher than energy expenditure, excess energy is mainly stored as lipid within our adipocytes, found within adipose tissue
As adipocytes grow in size and number, fat mass and total weight increase
Adipocytes and Adipokines
Adipocytes secrete adipokines = messengers that communicate with other body tissues
Ex. leptin
Below a certain level of fat mass, adipokine secretion has a health-promoting maintaining effect
Above a certain level of fat mass (obesity), adipokines are more likely to promote low-grade inflammation and disease
Leptin: The Fullness Hormone
Leptin is an adipokine that acts on the brain’s hypothalamus to promote satiety (fullness)
When our fat cells get larger, more leptin is released – this decreases appetite, promoting an energy deficit
If leptin production is genetically compromised (extremely rare), obesity results quickly
Many individuals with obesity are leptin resistant
obesity food consumption
Appetite = drive to consume food
Hunger = physiological need to consume food
Satiety = sense of fullness that makes us stop eating and keeps us feeling full until the next meal
Our appetite and satiety centers are found within the brain’s hypothalamus
Receives constant cues that affect appetite
obesity food production
The abundance of food and food cues in our environment promote a constant stream of signals to provoke high energy consumption
= obesogenic environment
Our thoughts interpret what we see, connect it with memory and emotion, and a message may then be sent to our appetite centre about it
Also, many food offerings are energy-dense and nutrient-poor
obesity Individual Psychology
Stress, mental health status and the way we think about ourselves and our bodies can affect both how much we eat and how much we exercise
Recall: our emotional brain communicates with our appetite center
Sometimes we are not hungry but want to eat in order to cope with something else that is going on
Food has a rewarding effect on the brain
Social Psychology
psychology of our social surroundings
Can affect food preferences, body size acceptance, physical activity….
Our perceived lack of time may compromise our ability to eat healthy and be active
obesity Individual Physical Activity
= main controllable factor that affects energy expenditure
Our childhood experiences, physical capacities and perceptions of physical activity can increase/decrease desire to be active.
Furthermore, how much we move our body at work and in our leisure time all contribute to our total energy expenditure.
obesity Physiology
We all handle energy differently
Ex. Different BMRs, hormonal activity, genetics
Also, differences in microbiome and appetite regulation can have significant effects on energy balance
Microbiome and Energy Balance
Individuals with obesity are more likely to have more Firmicutes in their colon
These bacteria are better at harvesting energy from food, increasing energy intake
There is also mounting evidence of a gut-brain axis that increases obesity risk
=communication between microbiota and brain
May affect appetite etc
Body Composition
proportion of fat mass vs. lean mass on body
A body that has more lean mass and less fat mass is associated with health
Weight and Percent Body Fat
Weight cannot fully capture body composition
Body Mass Index (BMI) considers body height and weight, but still does not capture body composition
Percent body fat expresses fat mass as a percentage of total mass
Better at determining body composition
Measuring Body Composition
DEXA/ dual X-ray absorptiometry = low dose X-ray that scans the body in two planes
Gives image of the body used to determine body composition
Can also indicate bone density
Air/Water Displacement
Psychological Aspects of Weight Loss and Maintenance
Our psychological health impacts appetite, desire to be active
Self-efficacy = belief in our ability to achieve a certain task
Setting small, achievable goals, celebrating victories, affirming thoughts can help build it
Emotional eating may be used to cope with negative emotions, feelings
Positive coping, psychology mechanisms may help decrease it
Ex. Talking to others, spending time in nature, journaling, crying, speaking to a counsellor
Mindfulness may also help
= practice of being aware of and experiencing the present moment with a judgement-free, curious approach
ex. Mindful eating, mindfulness meditation
Pharmaceutical Interventions for Obesity
Orlistat Blocks the activity of lipase in small intestine Fat absorption, caloric intake decrease Liraglutide Increases the activity of GLP-1 Promotes satiety Naltrexone/Bupropion Reduces food cravings by altering the reward circuit in the brain that drives food-seeking behaviour
Risk Factors for Eating Disorders (EDs)
EDs are multifactorial Contributing factors may include: Genetics Female gender Socio-cultural factors Ex. Pressure to be thin Personality Ex. Perfectionism, sensitivity towards reward and punishment History of sexual/physical abuse
Binge Eating
Occurs in bulimia and binge eating disorder and sometimes in anorexia
Main symptom = loss of control eating
A bingeing episode:
Occurs in a specific amount of time (ex. 2 hours)
Typically occurs in the absence of hunger, is typically at a fast rate, occurs while the person is alone, and is associated with feelings of guilt and shame
Bulimia Nervosa
Involves binge eating episode + compensation
Ex. Vomiting, excessive exercise, laxatives
Risk Factors:
Preoccupation with food
Distorted perceptions around body weight
Depression
Frequent dieting increase risk
Vomiting can damage teeth, cause electrolyte imbalances
Binge Eating Disorder
Most common eating disorder
Binge eating without compensation
Promotes obesity and its related complications
Risk factors include:
Frequent dieting
Inability to interpret hunger/satiety signals
Anorexia Nervosa
= significant restriction in energy intake leading to a unhealthfully low body weight
Individuals with anorexia often:
Have an intense fear of weight gain
Feel disturbed by their weight/shape
Struggle with self-worth and acceptance
Experience amenorrhea
It is the psychiatric disorder with the highest mortality rate
Orthorexia Nervosa
= an obsession with eating healthy that has negative psychological implications
it is the obsession and negative mental health implications of these restrictions that may cause it to be a disordered eating pattern
Also, increases risk for micronutrient deficiencies
Believed to be promoted by societal pressure toward ‘clean eating’
Signs:
Compulsively checking nutrition labels
Cutting out foods, nutrients, etc.
Limiting food intake to narrow range of foods
Physical Activity
PA recommendation:
150 min of mod-vig PA/ week accumulated 10 min at a time
+ two days per week of resistance training
Fuel Use During Physical Activity
Which fuel (energy source) is preferentially used depends on:
Duration of PA
Intensity of PA
i.e. whether PA is aerobic or anaerobic
PA Duration vs. Fuel Use
The first ~two minutes of exercise are anaerobic Relies on ATP (used up in ~2 s) ATP-CP system (used up in ~10 sec) Anaerobic glycolysis At a moderate intensity, after two minutes, aerobic metabolism dominated Relies on Aerobic glycolysis Aerobic fatty acid metabolism
Creatine Phosphate-ATP System
Creatine phosphate helps to replenish ATP by donating its phosphate group
Helps fuel anaerobic activities
Anaerobic Glycolysis is the Main Fuel for Anaerobic Activities
Glycolysis = break down of glucose
Glucose is the only dietary fuel that can be used for anaerobic activities
Fuels high intensity activities and the first 11-120 seconds of exercise
Aerobic Fuel Use Following the First Two Minutes of Exercise
Glucose use decreases over time Comes from: Muscle glycogen Blood glucose Lipid metabolism is the main fuel source following the first 20 minutes of exercise Comes from: Muscle triglycerides Adipose tissue lipid stores
Fuel Use vs. Exercise Intensity
Low-moderate intensity activities = aerobic zone
Can use all fuels
Preferential use of lipids
High intensity activities = anaerobic zone
Can only use glucose, ATP-CP for anaerobic processes
However, some aerobic metabolism will still take place – can use aerobic lipid metabolism as well
Carbohydrate Intake
Glucose is a fuel for both aerobic and anerobic activities
However, we store a limited amount as glycogen
Consuming sufficient carbohydrates can maximize glycogen stores
Pre-Exercise
Pre-exercise meal should be properly timed and have the right balance of nutrients to promote performance and minimize digestive issued
A pre-exercise meal that contains carbohydrate is the best established way to maximize time to exhaustion
Recommendations: 1-4 g/kg body weight of carbs 1-4 hours before exercising for more than 60 minutes
Favour easily digestible carb sources that are low in fibre and fat
Minimizes digestive distress
Fluid intake is also important
Glycogen Supercompensation
Aka carbo-loading
= maximizing glycogen stores before a long bout of endurance exercise (ex. Half-marathon)
Method: in the two days before event, consume 10-12 g/kg/body weight per day
Maximizes time to exhaustion during event
During Exercise
Water is the most important nutrient to consume during exercise
Can weigh yourself before/after exercise to see how much water was lost, replenish the same amount next time
i.e. lose 1 kilogram of weight = 1 litre of lost water
For longer bouts of activity, electrolytes also need to be replenished
These both help stave off the effects of dehydration
Fuels During Exercise
If exercising for less than an hour, no extra fuel is needed during exercise
Endurance activities lasting 60+ minutes may require extra fuel
Recommendation = 30-60 g/hour of easily digested carbohydrate
Ultra-endurance athletes (2.5+ hr) may require up to 90 g/hr
Post-Exercise
We have three nutritional priorities following exercise:
Promote muscle growth and repair (protein)
Protein sensitivity is highest in two-hours following exercise
Recommendation: 0.25-0.3 g/kg body weight with 10 g of essential amino acid
Refill glycogen stores (carbohydrates)
Glucose transport into muscle cells increases in 30-40 minutes following exercise
Replenish lost fluids and electrolytes
Hydroxymethylbutyrate (HMB)
Compound produced by the breakdown of essential amino acid leucine
Decreases protein breakdown while increasing protein synthesis
May improve muscle recovery by decreasing muscular damage
Other Ergogenic Aids
Vitamin and mineral supplements
Can only fix a deficiency
Anabolic steroids
Similar to testosterone
Serious side effects include severe acnes, tendon issues, aggressive behaviours, CVD risks, depression, shrunken testes
Cannabis
Currently no evidence base to recommend it as ergogenic aid
Also, may cause chest pain, reduction in strength
