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
