HE325 Nutrition

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Carbohydrates.pptx

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Carbohydrates

4 kcal per gram

Carbohydrates

Simple Sugars

Glucose (also known as dextrose, or blood sugar)

Four functions

Gives flavor and sweetness to foods

Spares protein from being used as an energy source

Energy (esp. the brain)

Preventing ketosis

Simple Sugars

Fructose (fruit sugar)

Tastes the sweetest of all sugars

Naturally occurring in fruits and vegetables

High fructose corn syrup used as an additive in many foods (although fructose only about 50% in the sweetener)

Simple Sugars

Galactose (bond glucose with this to form lactose)

Simple Sugars

Sucrose (combo. of glucose and fructose)

Common table sugar

Provides some of natural sweetness of honey, maple syrup, fruits, and vegetables

Manufactures use refining process to extract sucrose from sugar cane or sugar beets

On food label, sugar is synonymous with sucrose

Simple Sugars

Lactose (glucose and galactose)

Milk sugar

Found in milk of most mammals (human milk has higher concentration than cows milk)

Simple Sugars

Maltose (glucose bonded with glucose)

Breakdown of starches

Happens when digestive enzymes and small intestines break down starch

Fermented in the production of beer

Carbohydrates

Complex Carbohydrates

Complex carbohydrates

Starch

Plants store energy as starch for growth and reproduction

Food sources rich in: grains (wheat, rice, corn, oats, barley); legumes (peas, beans, lentils); tubers (potatoes, yams)

Gives food a moist, thick texture (think of inside of baked potato or using flour to make gravy thicken)

Complex carbohydrates

Glycogen

Stored form of carbohydrates

Provides glucose when blood glucose levels low

Stored in skeletal muscle and the liver

In muscles glycogen provides glucose for strenuous muscular activity

Liver uses glycogen to regulate blood glucose levels

Normally body can only store about 200 to 500 grams of glycogen at a time

Athletes “load” carbohydrates to try to increase stored glycogen; can increase amount of stored glycogen by about 50%

Carbohydrates

Do carbohydrates (especially sugar) make you fat?

Sugar is a carbohydrate (remember 4 kcal per gram)

Do carbohydrates (especially sugar) make you fat?

High fat intake associated with greater risk of obesity (fat has 9 kcal) per gram)

Many foods high in sugar also high in fat (doughnuts, cookies)

Do carbohydrates (especially sugar) make you fat?

Excess energy (calories) from any source can cause obesity

Increased availability of low-fat and fat-free foods has not decreased obesity rates (obesity rates actually climbing)

Speculation that people think low-fat or fat-free means calorie free, not realizing that many foods have removed fat, but added sugar, which doesn’t always make it lower in calories, depending on how much sugar they add

Foods high in sugar are low in nutrients and become “extras” in the diet

Carbohydrates

Artificial Sweeteners

Saccharin

Banned in 1977

Protests by consumer and industry groups caused a freeze of ban

Products containing saccharin had to have warning label about cancer risk

In 2000 convincing evidence about the safety released and Congress repealed warning label rule

Still banned in Canada

Artificial Sweeteners

Aspartame

Combo of 2 amino acids (phenylalanine and aspartic acid)

Found in drinks, gelatin desserts (jello), gums, and fruit spreads

Heating destroys sweet of Aspartame so cannot be used in cooking

Some safety concerns raised, although high-protein foods like meat contain more phenylalanine than aspartame sweetened foods

Some people report headaches, dizziness, seizures, nausea but scientific studies have failed to confirm these effects

Maximal daily amount of aspartame would equate into sixteen 12-oz. diet sodas a day for adults and eight for children

Artificial Sweeteners

Acesulfame K

Brand name Sunette

Approved for use in 1988

Found in chewing gum, powdered beverage mixes, nondairy creamers, gelatins, and puddings

Heat does not affect sweetness

Artificial Sweeteners

Sucralose

Brand name is Splenda

Approved for use in 1998

Made from sucrose

Found in baked goods, beverages, gelatin desserts, frozen dairy desserts

Carbohydrates

Alternative Sweeteners

Sugar alcohols

Xylitol, sorbitol, mannitol

Not as sweet as table sugar

Body does not fully digest and absorb so contain about 2 to 3 kcal per gram as opposed to regular 4 kcal per gram for table sugar

Do not affect blood sugar levels so often found in foods targeted for diabetics

May have laxative effect if consume too much

Alternative Sweeteners

Stevia

Derived from stevia plant found in South America

FDA has not approved as an additive so cannot be used in food in the US

May be sold as a dietary supplement

Brand name Truvia

Alternative Sweeteners

Natural Sweeteners

Honey

Maple syrup

Agave nectar

Carbohydrates

Fiber

Functions

Supplies mass to the feces – makes elimination easier

Fiber

Too little fiber

Constipation

Diverticula

pouches that protrude through the exterior wall of the lg.intestine – caused by high pressure

Hemorroids

pronounced swelling of a lg. vein, particularly the veins found in the anal region – results from high pressure

Fiber

Health benefits

Aids in weight control – fills us up without yielding much energy

Reduces risk of obesity

Decrease chances for colon cancer

Slows glucose absorption – may be helpful for diabetes

Inhibits absorption of cholesterol

May help reduce gallstones – inhibits absorption of bile acid

Fiber

How much do we need?

For 2000 kcal diet, goal is 20 to 25 grams

For 1000 kcal diet, goal is 10 to 15 grams

Average intake in US is less than one serving per day

Fiber

Problems with high fiber diets

Requires high fluid intake

Can contribute to intestinal gas

May contribute to blockages when fiber intake is high and fluid intake is low

Fiber

Insoluble fiber

Dietary fiber that does not dissolve in water

Fiber

Soluble fiber

Dietary fiber that does dissolve in water

Fiber

Foods rich in fiber

Fiber

Fruits

Apples Grapefruit

Bananas Mango

Berries Cherries

Pears Cranberries

Oranges

Fiber

Vegetables

Asparagus Green peppers

Broccoli Red cabbage

Brussels sprouts Spinach

Carrots Sprouts

Fiber

Nuts and seeds

Almonds Sesame seeds

Hazelnuts Sunflower seeds

Pecans Walnuts

Fiber

Legumes

Most legumes

Fiber

Grains

Brown rice Wheat-bran cereals

Oat bran Whole-wheat breads

Oatmeal

Fiber

Other

Psyllium seed husk

found in laxative drinks such as Metamucil