Lecture 13 Flashcards
What are the 3x functions of Carbohydrates?
- Supplies energy (glucose main source for cells)
- glucose key energy source of brain (can also use ketones) - Protein sparing - enough glucose to avoid metabolism/starvation/states of illness, use up carb stores and then start breaking down protein to provide energy - clinically important as not great re long term health/longterm health
- Prevents ketosis
Staple food- Carbs
Asian: Rice Pacifica: Cassava(Taro) African: Cassava European: Wheat/Potatoes Euro-American: Wheat/Potatoes Native American: Corn/Maize Andean: Potatoes/Rice -most cultures have carbs as main staple food source
Starches
(a complex carb) Potatoes Bread Rice ---> Glucose
Dietary Fibres
(a complex carb) Insoluble: Bran + Bran flakes Soluble: Lentils, Beans, Oatmeal, Psyllium
Complex Carbs
Starches + Dietary Fibre
Simple Carbohydrates
Sugars
Sugars
Disaccharides: 1. Sucrose (simple sugars) 2. Maltose (barley) 3. Lactose (milk) Monosaccharides 1. Glucose 2. Fructose 3. Galactose ---> all form after digestion glucose
Sugars- Monosaccharides
- Glucose-used in body
- Fructose-fruit + honey
- Galactose-milk
- all contain ketone + aldehyde group
Sugars- Disaccharides/Polysaccharides
- all contain glucose
- occur more often in food > monosaccharides
- sucrose: glucose + fructose= table sugar (cooking and baking)
- Lactose: glucose + glaactose = milk products
- Maltose: glucose + glucose = fermentation/alcohol production (beer and barley’s sugar)
What are carbs?
Oligosaccharides and polysaccharides - glucose units
- Glycogen:
- storage form (mainly in liver + skeletal muscles. 12-14hrs worth of glycogen energy in body-not that much. Therefore vital to replenish (otherwise revert to protein if insufficient)
- liver glycogen- for blood glucose regulation
- SM glycogen- contraction
- provides a rapid release of energy when needed - Starches:
- storage form of glucose in plants
- found in cereal grains, root veges(grow below ground, larger carb storage), and legumes
Chemical configuration of Glycogen and Starch (amylopectin and amylose)
- Glycogen:
-100s of glucose units. Highly branched chains.
-each new glucose molecule needs a special protein (for the attachment of the first glucose) - Starch (Amylopectin/Amylose)
-100s of glucose molecules.
either:
-Amylopectin: occasionally branched chains
-amylose: unbranched chains
Absorption of Carbohydrates
Primarily takes place in the SI small intestine
Glucose and galactose are absorbed by active transport
Fructose is absorbed by facilitated diffusion- passive (over concentration gradient)
villi –> venule –> hepatic vein –> liver (galactose and fructose converted to glucose)
-glucose doesn’t need to be converted. so is readily available for blood glucose control + glycogen storage
Large fructose consumption
Fatty liver
- metabolic syndromes/disease
- potentially caused by excess lactose intake
Lactose carb malabsoprtion
1 Primary -familial condition- inherit or genetically predisposed. Particularly asian descent. (therefore increased likelihood of lactose malabsorption
2 Secondary - caused by e.g. bacteria which has caused gastroenteritis and have damaged villi in SI, or Autoimmune celiac disease which destroys SI villi
Symptoms: bloating, abdominal discomfort and diarrhoea
-creates osmotic load, draws in water, secretory diarrhoea
-When in LI. large bowel’s bacteria like/live off carbohydrates, ferment, greating gas (methane + Hydrogen) –> bloated and gassy
Lactase deficiency
Management:
-Remove milk products
-increase consumption of milk products gradually (secondary condition)
-spreading dairy intake throughout the day
-use of enzymes (Primary deficiency. microencapsulated inactive enzyme capsule - put into milk essentially lactase- and digest’s milk’s lactose)
Good carbs for health
-less processed. more fibre and nutrients.
Wholemeal bread, crumpets, muffins
Wholegrain breakfast cereals
Rice, pasta, noodles, couscous
Starchy vegetables - potato, corn, sweet potato (complex, eat in moderation)
Legumes -beans, lentils (nutrient and protein rich)
Fruit- fresh, tinned, dried (dont juice, as faster as more fructose. Not good if pre-diabteic or losing weight)
-contains fibre, and vit c, polypheniles (powerful anti-ox and good for overall health)
Dairy foods- milk, yoghurt
Carbs bad for health
-more processed/refined. less fibre and nutrients Chocolate Cake, muffins Cookies/biscuits Sweet pastries Candies/Lollies Sweet/Savoury sauces Fruit juices
Recommended Serves of carb
Pre-schoolers: 4x servings of carbs Children: 5x servings Adults: 6x servings 1 Medium slice of bread 26g 1 roll 50g 1 small pita pocket/tortilla 50g 2x breakfast wheat biscuits 34g 1/2 cup muesli 55g 1/2 porridge 130g 1 cup cooked pasta/rice 150g 4 grainy crackers 40g 1 cup plain popcorn
Soluble Dietary fibres features
Forms gel in gut (mucin and pectin)
Binds with fatty acids (e.g. fibre sterol)(to reduce cholestrol uptake)
Prolongs stomach emptying time + movement through dig tract (fuller for longer)
Lowers total cholesterol and LDL cholesterol
Fermented by bacteria - SFA (short chian fatty acid e.g. butaric acid /proponate, whcih feed gut enterocytes to keep health, ensure DNa methylation is appropriate (reduced risk of large bowel cancer)
Regulates blood sugar
Insoluble Dietary fibres features
Softens stools (draws water in/sponge like)-prevent contribution
-but therefore MUST consume enough fluid, so can have swelling action of fibre in bowel
-important for patients (especially as they age)
Increases transit time
Rich Sources of Soluble dietary fibre
Lentils Rolled Oats Strawberries Apples (also insoluble) Oranges
Rich Sources of Insoluble dietary fibre
Wholemead Bread Skin of Kumara Skin of zuchinni Skin of potato Grainy cereal/bran
Dietary fibres
Both soluble and insoluble dietary fibre:
- provided by complex carbs
- cannot be digested and absorbed by Small Intestine
- can only be absorbed/digested in large intestine
- large bowel microbiota thrive of carbs and dietary fibre - their only source of energy which they can utilise to proliferate
- microbiota is very individual between people. born with it - vaginal delivery contamination of microbiota + through breast feeding (stays with you)
- live with us synergistically. Therefore important to keep healthy, as effect immune system, bowel health, and regulates enterocyte turn over and DNA methylation of enterocyte (both in large bowel)
- microbiota can change during:
- poor diet
- illness (gastroenteritis)
- during antibiotics/radiation therapy
- but then reverts back to original form. Dietary fibre really important for keeping it health
Large Intestine microbiota
Dietary fibre really important for keeping microbiota healthy
-large bowel microbiota thrive of carbs and dietary fibre - their only source of energy which they can utilise to proliferate
-microbiota is very individual between people. born with it - vaginal delivery contamination of microbiota + through breast feeding (stays with you)
-live with us synergistically. Therefore important to keep healthy, as effect immune system, bowel health, and regulates enterocyte turn over and DNA methylation of enterocyte (both in large bowel)
-microbiota can change during:
-poor diet
-illness (gastroenteritis)
-during antibiotics/radiation therapy
But then reverts back to original form
Dental care
Younger children + Certain areas have higher risk
No fluoridation in areas such as northland and BOP
children under 5 without teeth
-cannot eat well- therefore risk factor for poo nutrition
Recommended intakes of sugar
45-65% Energy
15% simple sugars –>5% WHO 2013 (responding to global obestiy epidemic)
-NZ 10% = 25g sugar = 6 tsp
Added sugars, syrups, juices
Amount of sugar in products
Coke can = 10 tsp sugar Mars bar = 8tsp Creamed tomato soup = 5tsp STACK.com -issue with terms of health- hidden sugar and increased consumption of these products
Artificial sweetners
good for people with sweet tooth (pre-diabetic or diabetic or trying to loose weight)
- used to be sweetened with sacrin - pot. link to pancreatic cancer
- no aspartain + stevia (plant sugar basis)
High sugar diet
High glycemic index categorisation of GI -how much carb food will raise Blood glucose by, relative to glucose -Glucose has GI level of 100 (max) -other food ranked relative
High Glycemic index food
break down carb and absorb glucose quickly
-(spikes) high peak of blood glucose
-(spikes) high insulin response to decrease blood glucose
high peaks and troughs in blood glucose and insulin
-tend to create hunger as blood glucose and insulin drops
=Hyperglycaemic effect (feel hungry again and snack (cycle))
Why eat foods with lower glycemic index?
Avoid high peaks of blood glucose and insulin/Hyperglycaemic effect (hungry and want to snack during trough)
More of a plateau effect- longer to digest, break down carbs and absorb glucose
-no high peak in blood glucose
-Lower insulin response to blood glucose
-plateau of blood glucose + sustains for longer
-fuller for longer and dont get so hungry so quickly
-Exercise has same effect on insulin
What has a similar sustained effect of insulin as Lower Glycemic index foods?
Exercise
-Avoid high peaks of blood glucose and insulin/Hyperglycaemic effect (hungry and want to snack during trough)
More of a plateau effect- longer to digest, break down carbs and absorb glucose
-no high peak in blood glucose
-Lower insulin response to blood glucose
-plateau of blood glucose + sustains for longer
-fuller for longer and dont get so hungry so quickly
Summary
Carbs are:
Important staple food
Important source of energy
Mono, Di and Polysaccharides - absorbed as mono in small intestine
Food sources have different health effects
Dietary fibre important in the maintenance of bowel health
Excessive intakes of simple sugars int he diet may have adverse effects on health
