Carbohydrates Flashcards
Monosaccharide Sugars
Fructose; Glucose; Galactose
Disaccharide Sugars
Sucrose (Fructose+Glucose);
Maltose (Glucose x 2);
Lactose (Glucose+Galactose)
Glucose as Starch in food
Branched & Unbranched
**Starch is the form of glucose in plants for humans
Glucose as Glycogen in muscle
HIGHLY BRANCHED
**allows for rapid, simultaneous breakdown and release
Glucose as Fiber in food
human enzymes can’t digest bonds
Fiber!
Indigestible polysaccharides in food.
Insoluble Fiber?
Still indigestible, but also can’t be dissolved in water
Soluble Fiber?
Still indigestible, but you can totally dissolve it in water it’s gummy and gel-like; and it’s broken down to some absorbable products in your colon microbiota
What’s sweeter fructose or glucose
fructose tastes better
Digestion role of mouth
enzymes in spit mix with food and break starch into maltose
Stomach?
stomach contributes nothing to carbohydrate digestion
Pancreatic enzymes
digest most of starch to disaccharides
intestinal enzymes
split disaccharides to monosaccharides
then monosaccharides enter capillary and get delivered to liver via portal vein
Liver?
liver converts galactose and fructose to glucose
COLON?
fiber travels unchanged to the colon (indigestible carb)
What does glucose do besides provide energy?
It builds some of the mucus that provides the protective coating in the intestinal tract; they create the carbon skeleton of non-essential amino acids, DNA & RNA
How does our body store glucose?
Blood glucose levels rise, and insulin is released to tell the cells to start taking up glucose, glucose is then stored as glycogen.
What body parts get glycogen?
2/3 muscle
1/3 liver
What happens in the absence of adequate carbohydrates?
- protein is broken down to supply glucose (breaks down muscles bc we don’t store protein)
- fat converted to ketones to provide brain with energy (leading to ketosis which disrupts acid-base balance in brain)
Carb daily requirements? [DRI]
Daily minimum of 130 grams/day (debatable)
~ 520 calories/day, 25% of 2000 calories.
USDA recommendations for carbs
300 grams, 60% of energy,
5-9 servings fruits and veggies, 6-11 servings grains
How are American’s doing at fiber-ing?
Current average fiber intake in US ~10-15 grams/day
1/4 - 1/2 of recommendation
Need for carbohydrates?
Nerve cells depend almost exclusively on GLUCOSE for energy.
Starchy foods, or complex carbohydrates are the preferred source of glucose in the diet.
Carbohydrate & body weight issues
gram for gram, carbohydrates provide fewer calories than fats.
important to differentiate refined sugar form complex carbs.
Soluble Fiber
barley, fruits, legumes, oats, veggies
lower blood cholesterol, slow glucose absorption
Insoluble Fiber
brown rice, fruits, legumes, seeds, veggies
increase fecal weight, regulate bowel movements
BENEFITS OF FIBER??
lower cholesterol and heart disease risk, blood glucose control, maintenance of digestive tract health, healthy weight management
Low Glycemic Effect
- Slow absorption of carbohydrate
- Modest rise in blood glucose
- Smooth return to normal blood glucose levels
High Glycemic Effect
- Fast absorption of carbohydrate
- Surge in blood glucose, leading to spike in insulin response
- Overreaction causing excess glucose to be removed
Glycemic Index
Ranking of foods according to the potential of 50 grams of carbohydrate from that food to raise blood glucose relative to 50 grams of glucose.
Glycemic Load
Glycemic index X grams of carbohydrate consumed.
More useful than Glycemic Index
What are the two problems with glycemic index?
- individually, many foods have a glycemic index that is counter intuitive (ice-cream vs. carrots)
- glycemic index of mixed foods isn’t effectively predicted by adding together the effect of individual foods.
Is the glycemic index useful to counsel individual patients?
Too many exceptions, counter-intuitive irregularities.
Who’s the most lactose intolerant?
Who’s the least lactose intolerant?
Asian Americans
Northern Europeans
Is lactose/malabsorption dichotomous?
No it’s more of a spectrum.
Shifts in dietary recommendations for diabetics?
- started with low-carb diet
- recommendation switched to a low-fat diet
- new dietary guidelines say that healthy diet for all is healthy diet for diabetes
now it’s high fat, low carb with fats from plant sources for low glycemic load
Refined grain
process by which the coarse parts of the food (bran, germ) are removed, leaving only the endosperm (starch, little protein)
Enriched/fortified grain
the addition of nutrients to a refined food product (iron, thiamin, riboflavin, niacin, folic acid)
Whole grain
a grain milled it its entirety, not refined
Does sugar cause obesity?
Difficult to separate out from calories due to sugar.
Does sugar increase risk of heart disease?
Not shown conclusively that moderate amounts of sugar affect the disease process in healthy humans. Causal link NOT proven.
Does sugar cause hyperactivity?
No.
Does sugar cause dental caries?
YES; causal link established.
Sugar Alcohols-Nutritive Sweeteners
Sorbitol, Isomalt, Mannitol, Xylitol.
dont contribute to dental caries, but do provide calories and are less sweet (could provide more calories to achieve same sweetness as sugar)
Are artificial sweeteners safe
approved by FDA
Are artificial sweeteners helpful for weightloss
as long as you don’t compensate
What does the American Heart Association recommend in regards to added sugars
REDUCTIONS IN ADDED SUGAR INTAKE
