1. Williams' Basic Nutrition & Diet Therapy
Chapter 3 Fats
Williams' Basic Nutrition & Diet Therapy 1

2. The Nature of Fats Dietary importance Classes of fats
Concentrated fuel for energy
Classes of fats
Lipids
Hyperlipidemia-elevated level of fat in blood
Composed of carbon, hydrogen, oxygen
Glycerides-majority of dietary fats
Triglycerides-3 fatty acids attached to glycerol base
Fatty acids-building blocks of triglycerides; classified by their length
Lipoproteins-vehicles for lipid transport-to be able to get the fat to and from cells in the body; LDL carry fat and cholesterol to cells and HDL carry free cholesterol from body tissues back to the liver for metabolism
Why is fat considered a backup fuel source for the body? (Carbohydrates are the primary fuel, followed by fat when needed.)
Explain that each class of fat serves a different purpose in the body and all are considered lipids.

3. Fatty Acids Saturated fatty acids
Filled or “saturated” with hydrogen-most are of animal origin; meat, dairy, and eggs
More heavy, more dense-solid at room temperature
Unsaturated fatty acids
Found in plant foods
Not completely filled with hydrogen
Less heavy, less dense-liquid at room temperature
Monounsaturated: one unfilled spot-examples olive, canola, peanut, avocados
Polyunsaturated: two or more unfilled spots-examples vegetable oils, corn, sunflower; safflower oil has the least amount of saturated fat
Saturated fats are heavier, denser, and more solid than unsaturated fats.
Unsaturated fats are usually in oil form.
What foods supply monounsaturated fats? (Olive and olive oil, peanuts and peanut oil, canola oil, almonds, pecans, and avocados)

4. Fatty Acids Essential fatty acids-
Only fatty acids essential for complete human nutrition are linoleic acid and alpha-linolenic acid
Linolenic acid is primarily found in soybean, canola, and flaxseed oil
serve important functions related to tissue strength, cholesterol  metabolism, muscle tone, blood clotting, and heart action
Must come from foods we eat
Can develop essential fatty acid deficiency
Nonessential fatty acids
-with adequate dietary supply of essential fatty acids body is capable of manufacturing saturated, monounsaturated, and other polyunsaturated fatty acids, as well as cholesterol
Saturated fats are heavier, denser, and more solid than unsaturated fats.
Unsaturated fats are usually in oil form.
What foods supply monounsaturated fats? (Olive and olive oil, peanuts and peanut oil, canola oil, almonds, pecans, and avocados)

5. Fatty Acids Trans-fatty acid Omega-3 and omega-6 fatty acids
Naturally occurring
Hydrogen atoms around carbon double bond are on opposite sides
Hydrogenation-when the hydrogen atoms on the carbon double bond are moved to opposite sides-for longer shelf life-tend to become more solid
Negative health consequences, cardiovascular disease
Omega-3 and omega-6 fatty acids
Determined by position of first carbon involved in double bond
What are some of the sources of unnecessary trans fats? (Restaurant foods, fast foods, packaged foods)

6. Fatty Acids Phospholipids Sterols
Lecithin-produced by the liver; key building block of cell membranes; ideal for transporting fats and cholesterol
Eicosanoids-hormones that exert control over multiple functions in the body; messengers for the CNS
Sterols
Cholesterol-synthesized in the liver; vital for membranes; precursor for some hormones; important in human metabolism; occurs naturally in foods of animal origin; found in egg yolks, organ meats, and other meats
What are some of the sources of unnecessary trans fats? (Restaurant foods, fast foods, packaged foods)

7. Functions of Fat in Foods
Fat in foods provides:
Energy-9 kcal/g (carbs 4 kcal/g)
Essential nutrients-linoleic and alpha-linolenic acid
Flavor and satisfaction
Fat substitutes are not absorbed and therefore do not provide energy or essential nutrients but may provide flavor and satisfaction
Fat provides 9 kcal/g versus 4 kcal/g for carbohydrates. Explain that this is an effective way to store energy.

8. Functions of Fat in the Body
Adipose tissue
Protects organs
Helps regulate temperature by acting as an insulator
Cell membrane structure
Forms part of cell membrane
Helps transport nutrients across cell membranes
Fat is stored in adipose tissue. What are some common sites of adipose tissue deposits?
Explain that a special fat covering protects nerve fibers and helps relay nerve impulses.

9. Food Sources of Fat Animal fats Plant fats
most concentrated of which include meat fats (e.g., bacon, sausage), dairy fats (e.g., cream, ice cream, butter, cheese), and egg yolks
lean portions do not have the same hypercholesterolemic effects as their full-fat counterparts when they are consumed with diets that are high in fiber
Plant fats
mostly monounsaturated and polyunsaturated fats, including the essential fatty acids. Food sources for unsaturated fats include vegetable oils (e.g., safflower, corn, cottonseed, soybean, peanut, olive.
How much of a daily dietary intake needs to be from fat to supply adequate amounts of essential fatty acids? (10%)

10. Characteristics of Food Fat Sources
Visible fats
 include butter, margarine, separate cream, salad oils and dressings, lard, shortening, fatty meats (e.g., bacon, sausage, salt pork), and the visible fat of any meat
Easier to control
Invisible fats
include cheese, the cream portion of homogenized milk, nuts, seeds, olives, avocados, and lean meat
Basically those that you cannot cut out of food
Ask students to name some of the obvious fats.
Ask students to identify some of the sources of invisible fats. Are any of the students surprised by these sources of fats?

11. Food Label Information
Calories from fat
Calories from saturated fat
Total fat
Saturated fat
Polyunsaturated fat
Monounsaturated fat
Cholesterol
Voluntary information
The FDA regulates food labeling. Explain how and why it does so.
Do the students think that food manufacturers would add the voluntary information if it showed an amount of a nutrient the consumer would see as “bad”?

12. Digestion of Fats Mouth Stomach Small intestine
Bile produced diluted in the liver
Bile from the gallbladder concentrated- stimulated to be released by cholecistokinin
Bile is an emulsifier
Bile breaks down fat into smaller particles to be able to be used in the body
Enzymes from the pancreas
Enzymes from the small intestine
Absorption
The primary digestion action occurring in the mouth is mechanical. Foods are broken up into smaller particles through chewing and are moistened for passage into the stomach.
Little, if any, chemical fat digestion takes place in the stomach. Why do you think this is? (Prompt the students to remember the principle of “like attracts like”; stomach acid is more attracted to hydrophilic compounds than hydrophobic compounds.)

13. The primary digestion action occurring in the mouth is mechanical
The primary digestion action occurring in the mouth is mechanical. Foods are broken up into smaller particles through chewing and are moistened for passage into the stomach.
Little, if any, chemical fat digestion takes place in the stomach. Why do you think this is? (Prompt the students to remember the principle of “like attracts like”; stomach acid is more attracted to hydrophilic compounds than hydrophobic compounds.)

14. Dietary Fat and Health The American diet is high in fat.
Increases risk for obesity, elevated blood fats, diabetes, arteriosclerosis, among other complications
Excess calories are stored as fat.
Animal food sources contribute to excess cholesterol and saturated fat in the diet such as lard
A decrease in saturated fat reduces serum total cholesterol.
Monounsaturated fats reduce LDL cholesterol when substituted for saturated fat.
Why are excess calories stored as fat and not carbohydrate or protein? (Explain that storing excess energy as fat is the way the body is supposed to work. It is a machine meant to store the most energy in the least amount of space.)
Heart disease continues to be one of the leading causes of death in developed countries. Much attention is focused on reducing risk factors leading to this disease.

15. Dietary Guidelines for Americans
Control saturated fat and cholesterol
Use only lean cuts of all meats; use more poultry and seafood
Limit eggs to two or three per week
Use low-fat or fat-free milk and milk products
Avoid adding too much fat in food preparation
Remember that end products of fat metabolism will be fatty acids, glycerols, or diglycerides
By using these tips, people can significantly reduce their fat intake.
Ask students to describe some other tips that can help reduce fat in the diet.

16. FDA Health Claims
A diet low in total fat may reduce the risk of some cancers
Diets low in saturated fat and cholesterol may reduce the risk of coronary heart disease
Other claims are pending
How could an individual follow some of the FDA’s recommendations contained in its pending claims?

17. Dietary Fat Requirements
Healthy diet guidelines:
Stress the health benefits of a diet low in fat, saturated fat, and cholesterol
Recommend that the fat content should not exceed 20% to 35% of total kilocalories
Less than 10% of kilocalories should be from saturated fat
Dietary cholesterol should be limited to 300 mg/day
Example: calorie= 300 calories to 525 calories of fat
Tell the class how much cholesterol is in one egg. According to these guidelines, can one egg be eaten every day?