Flashcards in Nutrition Chapter 5 Deck (43):
What are the 3 types of carbohydrate?
sugar, starch, fiber
What are the 4 forms of carbohydrate?
What are monosaccharides?
simple carbohydrate - one sugar, C6H12O6
galactose, glucose and fructose, sugar alcohols and pentoses (ribose, deoxyribose)
Foods - honey, fruits
What are the sugar alcohols?
xylitol, sorbitol, manitol
What are disaccharides?
simple carbohydrate, two sugars C12H24O12
maltose (2 glucose), sucrose (glucose and fructose), lactose (galactose and glucose)
Foods - table sugar, milk products
What are oligosaccharides?
complex carbohydrates, 3-10 sugar units
raffinose and stachyose
Foods - onions, beans, broccoli
What are polysaccharides?
complex carbohydrate, hundreds of sugars
starch and fiber
How is the digestibility of carbohydrates determined?
Whether they are linked by an alpha or beta bond. Alpha are easier to digest
What are starch and glycogen?
starch - storage form of glucose in plants
glycogen - storage form of glucose in animals
What are the 2 types of starch?
amylose and amylopectin
amylose - linear structure
amylopectin - high-branched structure
Foods - potatoes, beans, breads, pasta, rice
What is fiber?
composed of cellulose, hemicelluose, pectins, gums and mucilages
can be soluble or insoluble
provides no appreciable energy
metabolized by colonic bacteria
What are sources of soluble fiber?
fruits, oats, barley, beans
What are sources of insoluble fiber?
whole grains, vegetables
How is fiber classified?
by its physical and chemical properties
What occurs during CHO digestion in the mouth?
salivary amylase breaks down starch
digestion is not appreciable
What occurs during CHO digestion in the stomach?
no digestion occurs in the stomach
HCl neutralizes the enzymes
What occurs during CHO digestion in the SI?
enzymes breakdown starch and disaccharides into monosaccharides
*intestinal cells release disaccharidases
What role does the pancreas play in CHO digestion?
releases sodium bicarbonate to neutralize acid and allow digestion to occur
How are the monosaccharides absorbed?
via facilitated or active absorption
What occurs when monosaccharides are absorbed?
They are transported to the liver and converted to glucose for energy or stored as glycogen.
How is fiber digested?
mouth - mechanical actions break it down
stomach - no digestion, but it delays gastric emptying
SI - no digestion, delays absorption of nutrients
LI - bacteria enzymes digest fiber, covert to fatty acids or gas
What functions does fiber have in the LI?
holds water, regulates bowel activity, binds to bile, cholesterol and some minerals and carries them out of the body, enhances health of large intestinal cells
How does fiber effect cholesterol?
What is the recommended dietary fiber intake?
AI for women 25g
AI for men 38g
DV = 25g
How much fiber does the average American intake?
What are problems of excessive fiber intake (chronic)?
need extra fluid
binds to some minerals
fill the stomach of a young child quickly
energy - ATP from TCA cycle, ETC, glycolysis
stored - fat or glycogen
What are problems with lack of dietary carbohydrate?
glycogenolysis (glucose released from glycogen stores)
gluconeogenesis (protein used as source of glucose)
ketosis (incomplete metabolism of fats leads to ketone production)
What are the functions of carbohydrates?
How is glucose regulated (homeostasis)?
major organs: pancreas and liver
major hormones: insulin and glucagon
other hormones: epinephrine/norepinephrine, cortisol, growth hormone
What happens if glucose homeostasis isn't achieved?
What is insulin? What are its functions?
hormone released by the pancreas in response to high blood glucose
increases glucose uptake by the cells, promotes glycogen synthesis, reduces gluconeogenesis
net effect: lower blood glucose
What is glucagon? What are its functions?
hormone released by the pancreas in response to low blood glucose
breaks down glycogen, enhances gluconeogenesis
net effect: raises blood glucose
What is the function of epinephrine and norepinephrine?
raises blood glucose
fight or flight response
breaks down glycogen
What is the function of cortisol and growth hormone?
raises blood glucose
What is the glycemic response?
refers to how quickly and how high blood glucose levels rise after eating and how quickly the return to normal
What is the glycemic index?
blood glucose response of a given food compared to a reference food
What is the glycemic load?
amount of CHO in a food x the GI
What is the effect of a high glycemic load?
increases insulin output, insulin increases triglycerides, small LDL and fat synthesis
reduces satiety, muscles may become insulin resistant
What is the recommended CHO intake?
45-65% of calories
RDA is 130g
need 50-100g to prevent ketosis
current intake is about 50% of kcal
What is the recommend intake of added sugars?
DGA = less than 6% of kcal
WHO = less than 10% of kcal
What are the effects of a high sugar diet?
high glycemic index
indirectly related to dev. of diabetes
nutrient deficiencies (low nutrient density, empty and excess kcal, soda replacing milk)