Nutrition Exam Chapter 4 (Part one)

Primary role of carbohydrates

Provide energy (4 calories per gram); preferred fuel for brain and nervous system, extra stored as glycogen or fat.

Glycogen

Storage form of glucose in liver and muscle; serves as energy reserve.

Carbohydrates as raw materials

Serve as building blocks for other compounds and supply dietary fiber.

Monosaccharides

Single sugar units; include: Glucose (blood sugar, dextrose), Fructose (fruit sugar, levulose), Galactose (part of lactose)

Disaccharides

Two sugar units; include: Sucrose = glucose + fructose (table sugar), Lactose = glucose + galactose (milk sugar), Maltose = glucose + glucose (malt sugar)

Photosynthesis

Plants produce glucose from CO2 and H2O.

Starch

Polysaccharide of many glucose units; found in bread, rice, pasta, potatoes, beans, corn, peas, yams, lentils.

Whole Grains

Grain milled in entirety (all but husk), not refined; naturally high in fiber, vitamins, minerals, phytochemicals.

Refines Grains

Grains milled to remove husk, bran, and germ; only endosperm remains.

Enriched grains

Refined grains with B vitamins (thiamin, riboflavin, niacin, folic acid) and iron added back.

Fortified foods

Foods with added nutrients not originally present

insoluble fiber

Adds bulk, speeds transit through intestines, increases fullness; found in grains, brown rice, cabbage.

soluable fiber

Lowers cholesterol, slows glucose absorption, promotes healthy gut bacteria; found in oats, apples, berries, broccoli, carrots.

Fiber health benefits

Weight control, digestion, cholesterol regulation, glucose management; both soluble and insoluble fibers beneficial.

Too much fiber

Can cause dehydration, intestinal discomfort, and nutrient deficiencies.

Carbohydrate intake

45-65% of total daily calories.

Fiber intake

Men (38 g/day) Women (25 g/day)

Added sugar intake

Limit to <10% of total calories; WHO also recommends <10%.

MyPlate recommendations

Favor whole grains, vegetables, fruits; replace refined grains with whole grains; eat variety of vegetables, especially dark-green, red, and orange.

Whole-grain examples

Brown rice, oatmeal, whole oats, bulgur, popcorn, whole rye, graham flour, hulled barley, whole wheat, whole-grain corn.

Reading % Daily Value (fiber)

5% = low, 20% or more = high

Mouth Digestion

Saliva contains salivary amylase, starts breaking down starch into polysaccharides and maltose.

Stomach digestion

Carbohydrate digestion temporarily stops; food mixes with gastric juices to form chyme.

Small intestine digestion

Pancreatic amylase breaks polysaccharides into maltose; enzymes maltase, sucrase, lactase break disaccharides into monosaccharides (glucose, fructose, galactose).

Monosaccharide absorption

Glucose, fructose, and galactose absorbed into blood → liver; liver regulates glucose using insulin and glucagon.

Glucose usage in cells

Used for energy, stored as glycogen in liver/muscle, converted to fat if excess.