Carbohydrates Flashcards
What atoms make up CHO?
Carbon, hydrogen and oxygen
How are carbs produced?
By plants via photosynthesis
What are complex carbs?
Oligo/polysaccharides such as starch, glycogen and fibre
Name 3 monosaccharides
Glucose
Fructose
Galactose
Name 3 disaccharides
Lactose
Maltose
Sucrose
What does lactose comprise of?
Glucose + Galactose
What does maltose comprise of?
Glucose + Glucose
What does sucrose comprise of?
Fructose + Glucose
What are sugar alcohols used for
Low calorie sweeteners
Name 3 sugar alcohols
xylitol
mannitol
sorbitol
What is the role of CHO?
Primary source of energy for the body
Exclusive energy source for RBCs
Maintaining blood glucose for homeostasis
What is the mechanism of glucose uptake
Insulin dependant via GLUT 4 transporter
What is the mechanism of fructose uptake
Non-insulin dependant
What is Galactosemia
An inborn error of metabolism in which galactose metabolism is inhibited due to galactokinase enzyme deficiency
Galactose build up results in bacterial infections, mental retardation and cataracts
What are pentose monosaccharides?
Ribose and deoxyribose (in RNA and DNA)
Made by the body in the pentose phosphate pathway
What bonds are found in maltose?
Alpha 1-4 glycosidic bond
what bonds are found in sucrose?
Alpha 1-4 glycosidic bond
What bonds are found in lactose?
Beta 1-4 glycosidic bonds
Explain a lactose intolerance
Primary: lack of lactase enzyme in adulthood as a result of weaning, which is the default for adults however many people develop lactase persistance
Secondary: in lactase persistence phenotypes, LI is
associated with damage of the lactase producing cells
What are oiligosaccharides?
Containing 3-10 saccharides
e.g. raffinose
What are polysaccharides?
containing >10 saccharides
e.g. starch and cellulose
Explain the structure of starch
Consists of amylose (alpha 1-4 bonds only) and amylopectin (alpha 1-4 and 1-6 bonds which cause branching)
What is the body’s glycogen storage capacity?
Up to 120g in the liver
~300g in muscles (depending on muscle mass and training status)
What is glycogen storage disease?
An inborn error of metabolism in which the body cannot convert glycogen to glucose due to various enzyme mutations
Causes poor growth, limited energy, risk of hypoglycaemia and liver enlargement
Where are GLUT 1 found?
red blood cells
brain
kidney
colon
Where are GLUT 2 found?
Small intestine
liver
kidneys
Where are GLUT 3 found?
Brain
Placenta
Kidney
Where are GLUT 4 found?
Skeletal muscle
Heart
Adipose tissue
INSULIN DEPENDANT
Where is GLUT 5?
Small intestine
What hormone promotes a decrease in blood glucose levels?
Insulin
Which hormones promote and increase in blood glucose levels?
Glucagon cortisol epinephrine/ norepinephrine noradrenaline/ adrenaline growth hormone
what is the AMDR for carbs?
45-65% of total energy intake
What is GI
GI ranks carbohydrate containing foods based on their
effect on blood sugar levels over two hours post-ingestion
Factors effecting the GI of a meal
• Amylose to amylopectin ratio
• Degree of processing. E.g. whole meal flour vs refined
flour; micronised starch versus whole grain
• Fat content of food /meal (e.g. lactose in whole fat milk
versus low fat milk)
• Acidity ( affects amylase activity and gastric emptying)
• Sugar content + type of sugar
• Other macronutrient contained in the food /meal
• Ripeness of fruit. Why?
• Fiber content. Why?
What is GL?
Based on the amount of carbohydrate (CHO) in the food serving consumed. Multiply the amount of CHO by the GI value of the food divide by 100
Give examples of soluble fibres
- oats
- nuts and seeds
- legumes
- beans and lentils
- apples, berries, pears
Give examples of insoluble fibre?
- whole wheat
- brown rice
- whole grain breads, cereals pastas
- carrots, cucumbers, celery
Functions of fibre
- Promoting bowel health
- Preventing obesity/ weight gain
- Blood glucose control
- Reducing plasma cholesterol
- Promoting gut health (microbiome)
What is gut dysbiosis
Pathogenic harmful microbes in the gut cause inflammation and an immune response in the body
what is the AI for fibre for men and women?
Men: 30g
Women: 25g
What are probiotics?
foods/ supplements providing the live micro-organisms to populate the GIT adequately
What are prebiotics?
dietary or supplemental constituents which provide substrate for bacterial fermentation and growth
What defines digestible and indigestible carbohydrates?
Digestible carbs are those which the body capable of digesting with correct enzymes
Indigestible carbs are those with dietary fibre which th body is unable to break down
What does amylase do?
Break alpha 1-4 glycosidic bonds
Why is fructose good for diabetics?
It does not acutely raise blood sugar levels and is lower GI than starch and glucose
What is the correlation between fructose and fatty liver disease?
Fructose overconsumption directly produces fatty liver, which in turn directly creates insulin resistance. Fructose is five to ten times more likely than glucose to cause fatty live
What factors increase fermentability?
RS2 and RS3
Beta glucans
Gums
Inulin
What decreases fermentability?
RS1
Cellulose
Lignin
How is yoghurt easier to digest for someone with a lactose intolerance?
fermentation to make yoghurt
“digests” some of the lactose, and the bacteria used in the fermentation also produce lactase
What is alpha diversity?
HEALTHY MICROBIOTA = ALPHA DIVERSITY
ALPHA DIVERSITY= RICHNESS & EVENNESS IN SPECIES
