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Carbohydrates

Terms in this set (35)

Major Function
primary fuel source of the body
- used before other sources
- brain uses only carbs for energy if possible
In Relation to Lipids
carbohydrates allow lipids to be used slowly for energy
- slow use of lipids = more energy production
- rapid use of lipids leads to ketosis (raised levels of ketones in the blood; can cause nausea, headache, mental fatigue, and bad breath)
Chemical Makeup
2:1 ration of hydrogen:oxygen
- water is used to make them
- contain carbon (provides energy)
Important Carbohydrates
- dietary carb types: sugar, starch, fiber/resistant carbohydrates
- other important carbs: glycogen
Sugar: Monosaccharides
single carbohydrate molecules
- building blocks for larger carbohydrates
Sugar: Monosaccharides: Glucose
- main nutrient source of energy in the body
- fructose and galactose are converted to glucose
- found in all disaccharides and polysaccharides
- highly regulated in the body (controls energy for cells)
- insulin: hormone that promotes storage of glucose
- glucagon: hormone that releases glucose from storage (used when levels are low, between meals)
Sugar: Monosaccharides: Fructose
- sweetest sugar
- found in fruits, honey, sap
- found in many foods as high fructose corn syrup
Sugar: Monosaccharides: Galactose
- less common sugar
- part of lactose
High Fructose Corn Syrup
- a common sweetener
- cheaper and more stable that sucrose
- composition: glucose and fructose in roughly equal amounts
- health effects: availability is correlated with increased diabetes; similar effects to sucrose (chemically similar, metabolized similarly effect on satiety does not appear different, don't seem to cause more health problems)
Sugar: Disaccharides
two linked monosaccharides (glucose + glucose/fructose/galactose)
- broken down into monosaccharides during digestion
Sugar: Disaccharides: Maltose
malt sugar

glucose + glucose
produced during starch breakdown
Sugar: Disaccharides: Table Sugar
table sugar

glucose + fructose
naturally found in fruits and veggies
Sugar: Disaccharides: Milk Sugar
milk sugar

glucose + galactose
main carb in milk
ability to digest this can be lost after infancy (lactose intolerance)
Health Concerns of High Sugar
- micronutrient deficiency (if nutrient rich foods are replaced)
- tooth decay (supports bacterial growth)
- obesity (can contribute to excessive energy intake; excess sugar energy stored as fat)
Alternative Sweeteners
benefits: avoid promotion of tooth decay, may lower energy intake
Alternative Sweeteners: Sugar Alcohols
sugar-like carbohydrates

- have fewer kcal/g than normal carbs
- don't promote tooth decay
Alternative Sweeteners: Non-nutritive Sweeteners
non-carbohydrate sweeteners

- don't provide kcal
- don't promote tooth decay
Starch
the STORED form of carbohydrates in plants
- is a polysaccharide of glucose molecules
- the main carbohydrate in food (broken down to provide glucose)
- major sources: grains, legumes, root veggies
Fiber
the STRUCTURAL polysaccharides in plants
- human digestive enzymes cannot break bonds
- yield minimal energy
Sources of Fiber
found in all plant foods (veggies, fruit, legumes, whole grains)
- whole grains: contain all parts of the grain; fiber comes from the bran layer and germ layer
- not found in milk or meat
Health Effects of Fiber
can aid weight management
- foods are low in fats and sugars
- provide less energy/food
- promote feeling of fullness

can lower risk of heart disease and colon cancer
Soluble Fiber
fiber that dissolves in water
- generally in the pulp of plant foods
- tends to by gummy
- bacteria in the large intestine can digest this (provides some vitamin K and lipids)
- binds and removes cholesterol (results in lower cholesterol, may decrease cardiovascular disease)
- delays food transit out of stomach (slows glucose absorption, prevents glucose surge and rebound, reduces risk of developing diabetes)
- softens stool (draws water in => lowers constipation)
Insoluble Fiber
fiber that does not dissolve in water
- generally found in the skin of plant foods
- enlarges stool (lowers stress on intestinal muscles => prevents diverticulosis ; larger size makes it easier to pass stool => prevents constipation)
Excessive Intake of Fiber
- binds to minerals and carries them out of the body; isn't a problem with adequate mineral intake
- carries water out of the body; can cause dehydration
- requires water to soften stool (high fiber + low water = constipation)
Glycogen
polysaccharide that is the stored form of carbohydrates in animals
- long, branching chains of glucose
- not found in plants
- not a major dietary carb (found in minimal amounts in meat; breaks down quickly after slaughter)
Excess Glucose
...is stored as glycogen
- aids in regulation of blood glucose
- muscles store glycogen for physical activity
- liver stores glycogen to distribute to the body
Grains
- most are high in starch
- grains low in fat and sugar should be chosen
- half of grains should be whole grains
Veggies
- some are high in starch
- can be as high in carbs as grains
Fruits
- high in fructose
- vary in starch
Protein Foods
- almost no carbs
- exception: nuts and legumes (high in carbs)
Milk and Milk Products
- milk: only animal-derived food with significant carbs
- cream and butter contain no carbs and are low in other nutrients found in milk (NOT A GOOD SUBSTITUTE FOR MILK)
Relative Carb Content
more carbohydrates with...
- low water content
- more sweetness
- higher density
Glycemic Index
- a measure of how quickly carbohydrates in a food change blood glucose levels
- does not take serving sizes into account
- based on weight of carbohydrates in the food
Glycemic Load
blood glucose change due to single serving
Low Glycemic Index Diet
- unclear whether it has beneficial health effects for most people
- may prevent diabetes, obesity, and cardiovascular disease (research results are mixed)
- can aid blood sugar control in diabetes
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