Module 6 Flashcards
What are the main types of carbohydrates?
Sugars, starches and fibres
All three are made up of monosaccharides, or sugars
What are intrinsic sugars?
Sugars that are found naturally in foods like fruit and milk
What are extrinsic sugars?
Sugars that are added to food to enhance the flavour of processed foods
What are the three main monosaccharides?
- Glucose
- Fructose
- Galactose
What is Glucose?
Blood sugar
most common monosaccharide and can be metabolized into ATP, main energy currency
What is Fructose?
Fruit sugar
found mainly in fruits, vegetables and honey and is sweeter then glucose
What is Galactose?
Milk sugar
found in milk and similar sweetness to glucose
What are the three main disaccharides?
Sugars with two monosaccharide units
- Sucrose
- Maltose
- Lactose
What is Sucrose?
Table sugar, used in coffee and baking
made up of glucose and fructose
What is the enzyme Sucrase?
breaks down sucrose into its respective two sugars (glucose and sucrose)
absorbed at the villi of the small intestine
What is Maltose?
Malt sugar, makes bread sweater
made up of two glucose
What is the enzyme Maltase?
breaks down maltose into glucose molecules
absorbed in the small intestine
What is Lactose?
Milk sugar
made up of glucose and galactose
What is the enzyme Lactase?
breaks down lactose into glucose and galactose
some people lack this enzyme causing lactose intolerance
What are Oligosaccharides?
Few sugars, have between 3-10 monosaccharides in their chain
considered fibres because humans lack enzyme to digest
Are Oligosaccharides prebiotics?
Yes because digestive bacteria can use it for food
What are Polysaccharides?
Many sugars, have more than 10 monosaccharides in their chain and composed of long glucose chains
starch, fibre
What type of carbohydrate does not have an enzyme that can break it down?
Fibre
What is Starch?
Composed of long chains of glucose either straight (amylose) or branched (amylopectin)
we get starch from eating plants
What is the most common carb in the human diet?
Amylopectin
What is the digestion process of starch?
broken down into oligosaccharides, then into disaccharides and then into monosaccharide glucose
What is Fibre?
- Composed of long chains of glucose molecules
- Cellulose, dextrin, inulin
- Lack enzymes to break bonds
What is Soluble Fibre?
- Dissolves in water
- Found in apples, beans, peas, citrus, fruits
- Bacteria in large intestine can ferment to produce short-chain fatty acid
- 1 gram = 2-3 kcal of energy
What is Insoluble Fibre?
- Does not dissolve in water
- Wheat, beans, potatoes
- Passes through digestive tract mostly unchanged
What is Glycogen?
- large unbranched chain of glucose
- stored in our muscles and around our liver
- long-term energy storage
How is Glycogen made?
synthesizing chains of glucose molecules with the aim of storing them 0.5-2kg
What are Refined Carbohydrates?
Part of the grain is removed, the bran and germ layer
lowers the nutrient density of that plant
What are Unrefined Carbohydrates?
Carbs that are consumed in their entire form ex: whole grain wheat
more nutrient dense, high in fibre and phytochemical
What is contained in the bran layer?
High in fibre, calcium, iron, B vitamins
What is contained in the germ layer?
High in protein, B and E vitamins
How are Carbohydrates digested?
- Mouth - salivary amylase begins digestion
- Stomach - HCL acid inactivates salivary amylase
- Pancreatic amylase is secreted into the small intestine to continue digestion
- Microvilli also secretes various carb digesting enzymes
- Undigested carbs pass to the large intestine, broken down by bacteria
- Any remaining carbs are excreted
Why is there no chemical digestion in the stomach?
because amylase is sensitive to high acidity
Where are carbohydrates mainly digested?
small intestine
What are brush borders?
contains carb-digesting enzymes that are released to finish off digestion
Which carbs are metabolized?
Fructose, galactose at the liver
glucose is not metabolized but stored is glycogen
What is lactose intolerance?
- caused by insufficient secretion of enzyme lactase
- cannot be digested in small intestine but rather by bacteria in the larger intestine –> produces methane gas
What are the symptoms of lactose intolerance?
cramps, bloating, diarrhea, abdominal pain
What is the glycemic response?
spike in blood glucose once glucose enters circulation
diets that produce a lower GR have lower risk of type 2 diabetes, CVD and obesity
What is the glycemic index?
ranking of a food’s potential to spike blood sugar on a 100-point scale
low GI <55
medium GI 56-69
high GI >70
What is glycemic load?
a more accurate assessment of how much blood glucose will spike because it also takes into account how much carbs are in the food
What is the role of Insulin and Glucagon?
- blood glucose-regulating hormones
- secreted by the pancreas
What is hypoglycemia?
low blood glucose, can affect energy levels
What is hyperglycemia?
high blood glucose, can lead to diabetes if chronic
What is the endocrine function of the pancreas?
pancreas secretes insulin and glucagon into the blood in order to regulate blood glucose
What is the exocrine function of the pancreas?
pancreas secretes pancreatic juice into the digestive tract to facilitate digestion
What is the process of insulin regulating blood glucose levels?
- Normal blood glucose
- Following a meal, blood glucose concentration increases
- The pancreas secretes insulin into the blood
- Insulin binds to its receptors on cells
- Brings glucose channels to the cell’s surface
- Glucose leaves the blood and enters the cells
- Blood glucose returns to normal
What happens when blood glucose levels drop?
pancreas releases glucagon
What are the three main processes of glucagon?
- Glycogenolysis - conversion of glycogen to glucose
- Gluconeogenesis - conversion of amino acids into glucose
- Lipolysis - breakdown of stored lipids
What is the main role of Carbohydrates?
provide energy in the form of ATP, mainly from glucose
What are the functions of Carbohydrates?
- Energy provision
- Protein sparing
- Fat burns in a carbohydrate flame
What happens when the body doesn’t have enough carbohydrates?
- amino acids will be used to make glucose through gluconeogenesis, breakdown of body proteins
- lipid metabolism cannot enter citric acid cycle and will instead form ketones
What is diabetes?
chronically elevated blood glucose levels
Acute diabetes symptoms?
increased thirst, weight loss, tiredness, frequent urination
Chronic diabetes symptoms?
cardiovascular disease, blindness, kidney disease, numbness
What is type 1 diabetes?
immune cells damage the insulin-secreting cells of the pancreas
10% of cases
What is type 2 diabetes?
pancreas still secretes insulin but the cells become resistant to insulin
90% of cases
Is it more common for Indigenous people to get type 2 diabetes?
Yes, 2-3 times more common
What is gestational diabetes?
- elevated blood glucose and impaired glucose management during pregnancy
- type 2 diabetes
What are the risk factors for diabetes?
type 1 - unknown
type 2 - obesity, genetics, physical inactivity, diet
How can we prevent diabetes?
type 1 - unknown
type 2 - medication, lifestyle changes
How can we manage type 1 diabetes?
insulin injections, lifestyle changes
What is reactive hypoglycemia?
low blood glucose due to excessively high dose of insulin
What is non-reactive hypoglycemia?
various causes such as fasting, medications, pregnancy, disorders
Is sugar bad?
- sugar is not inherently bad or good
- however modern diets tend to be high in extrinsic sugars –> higher risk of CVD, diabetes, obesity
How can we minimize extrinsic sugars?
focus on consuming more whole foods and replacing sugary drinks with water
What are non-nutritive sweeteners?
- sugar substitutes or artificial sweeteners
- negligible calories and a sweet-tasting flavour
What causes a higher CVD risk?
diets high in sugars, refined carbs
What causes a lower CVD risk?
diets high in fibre
What do refined carbs promote?
higher glycemic response
Why do fibres decrease CVD risk?
- soluble fibre lowers LDL cholesterol
- soluble fibre regulates blood sugar
What are the recommendations for consuming carbs?
- consume carbs from whole, unprocessed foods like fruits and whole grains
- limit added sugars to no more then 10% total energy intake
- consume fibre rich foods (more for men)
