Lecture Presentation Outline



Lecture Presentation Outline

I. Fat Intake and Health

❖ Instructor Resources: Unit 18 Nutrition Scoreboard transparency master; Unit 18 PowerPoint presentation on Multimedia Manager

A. Type of fat is more important than total fat

1. Some fats are better for you than others

B. Keep fat intake 20-35% of total caloric intake

C. Excessive caloric intakes cause weight gain

D. Total calories and physical activity are the components of weight management

E. Healthy diets depend on types of fat consumed and quality of diet

II. Facts about Fats

❖ Instructor Resources: Activity 18-7: Knowledge about Fats

A. Fats dissolve in fat and not in water

B. Fats are lipids

1. Lipids include all types of fats and oils

2. Fats are solid at room temperature

3. Oils are liquid at room temperature

4. Difference is due to chemical structures

C. Dietary Fats 

1. Fats in foods supply energy and fat-soluble nutrients

a. Essential fatty acids (linoleic acid and alpha-linolenic acid)

b. Fat-soluble vitamins D, E, K, and A

2. Fats increase the flavor and palatability of foods

a. Fats absorb and retain flavor so fats give flavors to food

3. Fats contribute to the sensation of feeling full

a. Fats stay in stomach longer

b. Are absorbed over a longer period of time

D. Fat Functions in Body

1. Fat is a component of cell membranes

a. Fats give cell membranes flexibility

b. Regulate the transfer of nutrients

2. Fat cushions kidneys and heart

3. Fat protects the organs and insulates them; cold-water swimmers build up body fat for the extra layer of insulation

4. Excess carbohydrate and protein is converted to some glycogen but most is changed to fat and stored in fat cells

❖ Instructor Resources: transparency #49: Fat Cells

E. Different Types of Fats

1. Triglycerides, saturated and unsaturated fats, cholesterol

2. Triglycerides are 98% of our dietary fat intake and majority of fat stores

3. Triglycerides are used by cells for energy formation and tissue maintenance

4. Many types of fatty acids in fats

a. Major ones are “saturated” or “unsaturated”

F. Saturated and Unsaturated

❖ Instructor Resources: transparency #50: Chemical Structures of Fatty Acids

1. Fatty acids have hydrogen attached to carbon

2. Saturated fatty acids have maximum hydrogen possible

a. Saturated fats are solid at room temperature

3. Fatty acids with less hydrogen are unsaturated

a. They are liquid at room temperature

b. Plant foods have most unsaturated fats

c. “Monounsaturated” if one bond is unsaturated

d. “Polyunsaturated” if two or more bonds unsaturated

G. Omega-6

1. Linoleic acid one of essential fatty acid family omega-6

2. Polyunsaturated, source of energy, stored in fat tissue

3. Linoleic acid is required for:

a. Growth

b. Maintenance of healthy skin

c. Water-barrier

d. Normal functioning of the reproductive system

e. Is a component of cell membranes and in high amounts in nerves and the brain

f. Blood pressure and blood clotting components are derived from linoleic acid

4. Food sources are sunflower, corn, and soybean oils

H. Omega-3

1. Linolenic acid one of essential fatty acid family omega-3

2. Alpha-linolenic acid, EPA and DHA are the primary members

a. Alpha-linolenic acid is essential but EPA and DHA are not

b. EPA and DHA are slowly produced from alpha-linolenic acid

3. Alpha-linolenic acid is

a. A structural component of all cell membranes

b. Found in high amounts in the brain and eyes

c. Precursor for compounds that regulate blood pressure and clotting, have opposite effect of linoleic acid derivatives

4. Found in walnuts, flaxseed, canola oil, and soybeans

5. Best sources are marine oils due to content of DHA and EPA

6. Fish Oils

a. DHA and EPA in fish oils have 4-6 double bonds, unsaturation makes these fluid at cold temperatures

b. Keep membranes and fat in fish flexible in cold water

c. DHA and EPA form biologically active compounds to reduce blood pressure and tendency of blood to clot

7. Regular consumption of omega-3 fatty acids:

a. Decreases risk of heart attack

b. Protects against irregular heart beat and sudden death

c. Decreases plaque formation in arteries

d. Lowers high blood pressure

e. Decreases the risk of stroke

8. Fish oil capsules are sources of EPA and DHA

9. Mercury in Fish

a. High levels of mercury may be in fish oil supplements

b. Pregnant and breastfeeding women and young infants are susceptible to harmful effects of mercury

c. Mercury-rich fish: shark, swordfish, king mackerel, and tilefish

d. Intake of these fish should be limited to 12 ounces or less per week

e. Other fish, shrimp and shellfish have low levels

10. DHA and EPA in eggs enriched with omega-3 fatty acids

11. AHA recommends 2 servings of fish per week

12. 0.65 grams of DHA and EPA daily

I. Ratio of Omega-6 and Omega-3

1. Ratio of omega-6 to omega-3 fatty acid intake is important

2. Functions of one adversely modified by high amounts of the other

3. People should consume omega 6 to omega 3 at 4 (or less) to 1

a. Americans ratio of omega-6 to omega-3 is over 9-to-1, we need to increase intake of omega-3 fatty acids

III. Modifying Fats

❖ Instructor Resources: Activities 18-2: Comparison of Butter, Spreads and Margarine & 18-4: Hydrogenation of Fats; Handout 18-1: Comparison of Butter, Spreads and Margarine

A. Unsaturated fats are unstable

1. Turn rancid with time, oxygen and heat

2. Solid fats better than oils in some cooking

B. The solution is “hydrogenation”

1. Hydrogen added to liquid unsaturated fats making them more saturated and solid

2. Shelf life, cooking properties, and taste improved

3. Hydrogenation has two drawbacks:

a. Hydrogenated vegetable oils have more saturated fat: corn oil contains 6% saturated fats, corn margarine has 17%

b. Hydrogenation changes structure of the unsaturated fatty acids, converts some fats into trans fats

C. Trans Fatty Acids

1. 30% of fatty acids may be converted from “cis” to the “trans” form as a result of hydrogenation

2. Trans fatty acids raise blood cholesterol levels more than dietary cholesterol, saturated fats or any other type of fat

3. Trans fat comes from hydrogenated vegetable oils

4. Trans fats are preferred for use in margarine, snack foods, bakery products, and fried foods; they are more stable and have longer shelf life

5. Americans should consume as little trans fats as possible

6. Nutrition Facts Panels must include the trans fat content of food products by January 1, 2006

a. Products labeled “trans fat-free” must contain less than 0.5 grams of both trans and saturated fats

b. Requirement to label the trans fat content of food products will increase the number of foods labeled “trans fat-free” and “no trans fat” and decrease use in foods

c. Food companies are developing other ways to produce foods without them

IV. Cholesterol

A. Cholesterol found only in animal products

1. Tasteless, odorless, clear liquid contained in lean and fat

2. Plants do not contain cholesterol because they can’t produce it and don’t need it

3. Cholesterol comes from two sources

a. Most (2/3) of cholesterol produced by liver

b. 1/3 comes from the diet

B. Cholesterol is not an essential nutrient

C. Cholesterol:

1. Is found in every cell in your body

2. Serves as the building block for estrogen, vitamin D and testosterone

3. Is a major component of nerves and the brain

4. Cannot be used for energy

5. The body has many uses for cholesterol

V. Fat Substitutes

A. Fat in foods can be replaced by substitutes

1. Fat substitutes imitate taste, texture, and cooking properties of fats with fewer calories

2. Success in imitating fat varies

3. Making perfect fat substitute is difficult

a. Few fat substitutes are consumer acceptable

B. Are Fat Substitutes Safe?

1. Fat substitutes from carbohydrates, protein, and vegetable oils are considered safe

2. Fat replacers from other substances must be tested for safety

a. Olean was tested extensively before being approved for use; it can cause diarrhea and oily stools if consumed in large amounts

C. Fat substitutes lower blood cholesterol

1. Foods containing fat substitutes reduce total fat

2. Fat substitutes may be part of solution to high fat intake health problems

VI. Fat Content of Food

• Not all of the fat in food is visible

• Vegetables, fruits and grains contain little fat

❖ Instructor Resources: Activities 18-1: Fats in Foods & 18-8: Fat Content of Fast Foods

A. Knowledge of the caloric and fat content of a food can be used to calculate the percentage of calories provided by fat

1. Pie slice has 350 calories and 15 gm of fat

2. Calculate percent of fat calories: multiply 15 gm by 9 cal/gm, divide the result by 350 cal, and multiply by 100

a. 15 gm fat x 9 cal/gm = 135 cal

b. 135 cal/350 cal = 0.39

c. 0.39 x 100 = 39% of total cal are from fat

B. Fat Labeling

❖ Instructor Resources: transparency #16: Nutrition Claims on Food Labels; Activity 18-3: Comparison of Snack Foods; Handout 18-2: Comparison of Snack Foods

1. Nutrition labeling regulations say standard definitions of “low fat,” “fat-free,” etc, must be used on food labels

2. Claims

a. Claims about cholesterol must comply with standards

b. If claim is about fat content, Nutrition Facts must specify food’s fat, saturated fat, trans fat, and cholesterol

c. If claim is about cholesterol content, Nutrition Facts must reveal product’s fat and saturated fat content

3. Standard serving sizes must be used on food labels.

VII. Revised Thinking

A. People lose weight on low- or high-fat diets, low- or high-carbohydrate diets, and low- or high-protein diets

1. Weight depends on dietary changes, not relative proportions of fat, carbohydrate, and protein

2. Fat consumption for Americans decreased from 43% of total calories in 1970 to 33% of calories now

3. But overweight and obesity increased since 1970

a. Fat intake decreased, carbohydrate intake increased

b. High carbohydrate may be related to rising obesity

c. Consumption of high carbohydrate diets by obese people may hasten development of type 2 diabetes

B. Mediterranean Diet

❖ Instructor Resources: transparency #20: Mediterranean and Asian Diet Pyramids

1. Groups who consume high fat diets can have average or below average rates of heart and other chronic diseases

2. The traditional Mediterranean diet is based on whole grain products, vegetables, fruits, nuts, olive oil, dried beans, wine, fish, and poultry

3. 40% of calories come from fat, mostly monounsaturated

4. People eating the Mediterranean diet are physically active and normal weight or lean

5. Despite high fat content, people on that diet and lifestyle have low rates of heart disease and cancer, and long life expectancy

C. The Fulani

1. Fat intake and health relationships must be in context of the overall diet and lifestyles

2. Fulani pastoralists of Northern Nigeria subsist on a diet of animal blood, meat, and dairy products

3. Very high in fat and saturated fat, yet Fulani have normal levels of blood lipids and are not at increased risk for heart disease

4. Fulani are highly physically active, lean, and tend not to smoke

D. Heart disease, cancer, type 2 diabetes, and obesity increase in people who move from traditional diets and high levels of physical activity to Western diets and sedentary lifestyles

❖ Instructor Resources: transparency #12: Diabetes in Japanese Immigrants

1. High fat diets in U.S. and Canada are high in calories and saturated fat and low in vegetables, fruits, and whole grains

2. Levels of physical activity are low, rates of obesity high

3. High fat and saturated fat in these circumstances relate to increased blood cholesterol levels and risk of heart disease

E. New recommendations include effects of different sources and amounts of dietary fat, and influence of low fat diets on carbohydrate in populations that are inactive and obese

F. Recommendations for fat intake are changing because some types of fat are better for health than others

❖ Instructor Resources: transparency #51: Healthy and Unhealthy Fats

1. Good Fats

a. Fats provide energy and essential functions in the body

b. Good fats lower cholesterol and LDL, and raise HDL

c. Monounsaturated fats, polyunsaturated fats, alpha-linolenic acid, DHA, and EPA are healthy fats and present in oils

2. Bad Fats

a. Bad fats elevate cholesterol and LDL levels

b. Trans fats, saturated fats, and cholesterol are unhealthy

c. Bad fats solid at room temperature, found in meat and dairy products, hard margarines, shortening, snack foods

G. Low Fat Foods

1. Contain less fat than regular version

a. Products may not contain good fat

b. Fish oils, unsaturated fat, and trans fat-free products provide healthy fats

2. Healthy diets are not based on individual foods, but overall diets

3. Emphasize foods providing healthy fats

H. Fat Intake

❖ Instructor Resources: Activities 18-5: Recipe Improvement & 18-6: Fat Reduction of a Diet

1. Current recommendations call for 20-35% of total calories from fat

2. AIs for linoleic acid 17 gm/day for men, and 12 gm/day for women

3. AIs for alpha-linolenic acid 1.6 gm/day for men, 1.1 gm for women

4. Intake of trans fats and saturated fats should be low

5. Most Americans consume enough linoleic acid, but intakes of alpha-linolenic acid tend to be low

a. Americans encouraged to increase consumption of EPA and DHA by eating fish more often

6. Saturated fat intake averages 11-12% of calories, and increases risk of heart disease

I. Cholesterol Intake

1. No recommended level of cholesterol intake

a. No evidence that cholesterol required in diet

b. Body produces enough cholesterol

c. People do not develop cholesterol deficiency

2. Blood cholesterol levels increase as consumption increases, so intake should be minimal

3. Cholesterol intake is 250 mg per day in U.S., a better intake would be less than 200 mg a day

VIII. Progress

A. Recent recommendations for fat intake are a change in dietary intake guidance

B. Change developing for years as research results supported new recommendations

C. We need to learn about dietary fats and health, as components of diet and lifestyle modify relationships between fat intake and health

D. The new recommendations mean that nutrient and health relationships are getting more study

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