1. Chapter Four The Lipids: Fats & Oils
NUT SCI 242 Food & Nutritional Health
© Karen Lacey, MS ,RD, CD

2. What are Lipids? A family of compounds that includes
Triglycerides (fats & oils)
Fats: lipids that are solid at room temperature
Oils: lipids that are liquid at room temperature
Phospholipids
Sterols (cholesterol).

4. I. A Primer on Fats The Functions of Fat in the Body
Energy source esp. for muscles
Serves as an energy reserve
1# body fat contains 3500 kcal
30-50# of stored fat

5. Cont’d Major component of cell membranes Nourishes skin & hair
Insulates the body from temperature extremes
Cushion the vital organs to protect them from shock

8. B. The Functions of Fat in Food
Provide calories (9 per gram)
Provide satiety
Carry fat-soluble vitamins & essential fatty acids
Contribute aroma & flavor

10. Lipid Terminology
Triglycerides: the major class of dietary lipids, including fats & oils
Made up of 3 units known as fatty acids and 1 unit called glycerol (backbone)
Comprise about 95% of lipids in food and the human body

13. Cont’d Phospholipids: Sterols 2nd of three main classes of lipids
similar to a triglyceride, but contains phosphorous
Sterols
3rd of three main classes of lipids;
Cholesterol
one of the sterols
manufactured in the body for a variety of purposes

14. Cont’d
Fatty acids:
basic units of fat composed of chains of carbon atoms
an acid group at one end and hydrogen atoms attached all along their length

16. II. A Closer View of Fats
Chain Length (number of carbons linked together)
Shorter = more soluble in water
Saturated vs. Unsaturated (number of hydrogens the chain is holding)
Maximum = saturated
Unsaturated = one or more is missing
Point of unsaturation = site where hydrogen is missing

18. Cont’d
Saturated fatty acid: a fatty acid carrying the maximum possible number of hydrogen atoms
Animal foods such as meat, poultry and full-fat dairy products
Tropical oils such as palm and coconut

20. Cont’d
Unsaturated fatty acid: a fatty acid with one or more points of unsaturation.
Found in foods from both plants & animal sources
Monounsaturated fatty acids (one double bond)
Polyunsaturated fatty acids (two or more)

22. Cont’d
Monounsaturated fatty acid: also called a MUFA; a fatty acid containing one point of unsaturation
Found mostly in vegetable oils such as olive, canola & peanut

23. Cont’d
Polyunsaturated fatty acids: also called a PUFA; a fatty acid in which two or more point of unsaturation occur
Found in nuts, vegetable oils such as safflower, sunflower and soybean, and in fatty fish

24. B. Essential Fatty Acids
The body can synthesize all of the fatty acids it needs from carbohydrates, fat or protein except for two:
Linoleic acid
Linolenic acid
PUFAs
Found in plant & fish oils

26. Omega - 6 versus Omega - 3 Omega – 6 Linoleic Omega – 3 Linolenic
Cold water fish
Help dissolve blood clots
Lower blood pressure
Dilate the arteries

28. Characteristics of Fats in Foods
Liquid vs Solid
More saturated a fat is, the more solid it is at room temperature
More unsaturated a fat is, the more liquid it is at room temperature

30. III. Characteristics of Fats in Foods
Hydrogenation
The process of adding hydrogen to unsaturated fat to make it more solid and more resistant to chemical changes such as spoiling
Increasing a fat’s saturation can cause a fat to lose its unsaturated health benefits

32. C. Trans-Fatty Acids Formed when margarine is processed
Hydrogen molecules are on opposite sides of point of unsaturation
“Partially hydrogenated vegetable oil”
Link between trans fatty acids and heart disease
Table 4-3, page 107
Keep to minimum

35. V. Phospholipids
A lipid consisting of a water-soluble head and a fat-soluble tail
Contain phosphorous
Component of cell membranes
Serve as emulsifiers (allow fats and water to mix and travel in and out of cells into watery fluid on both sides)

37. Cont’d Lecithin is a common phospholipid
Often used as an emulsifier in foods such as margarine, chocolate & salad dressings

38. V. Cholesterol – a Sterol
Found only in animal products
Also made & used in the body:
Structure of cell membranes
Used to make bile for digestion
Bile: a mixture of compounds, made by the liver, stored in the gallbladder, & secreted into the small intestine
Emulsifies lipids to prepare them for enzymatic digestion & helps transport them into the intestinal wall cells

39. Cont’d Used to make the sex hormones estrogen & testosterone
Made into vitamin D with the help of sunlight
Deposited in the artery walls leading to plaque buildup & heart disease

42. VI. How the Body Handles Fat
Digestion
Emulsification
Absorption

51. VII. Lipids & Health Good vs. Bad Cholesterol

54. B. Lowering Blood Cholesterol Levels
Eat no more than 30% of calories from fat
Eat no more than 8-10% of calories from saturated fat
Eat no more than 10% of calories from PUFAs
MUFAs should make up 10-15% of total calories
Limit daily cholesterol intake to no more than 300 milligrams

55. VIII. Fat in the Diet Food Guide Pyramid
3 groups traditionally account for nine-tenths of the fat in the U.S. diet
Fats, oils & sweets group
Meat, poultry, fish, dry beans, eggs & nut group
Milk, yogurt & cheese group
Most of the fat in our diets comes from animal products

57. B. Fat Substitutes Carbohydrate-based Protein-based
Help retain moisture to maintain the juiciness or creaminess that is lost with fat reduction
Carrageenan, fruit purees, gelatin, gums, starches & products made from fiber
Protein-based
Proteins are cooked & blended to form tiny round particles that trap water to maintain the mouth feel of fat
Whey protein concentrate (Dairy-Lo), or milk & egg white protein (Simplesse)

58. Cont’d
Fat-based
Are either only partially digestible or completely undigestible to prevent absorption of fat
Caprenin (substitute for cocoa butter in candy), Salatrim (found in low fat baking chips), and olestra (often found in fat free potato chips)

59. C. At the Grocery Store
Read labels to determine both the amounts & types of fat contained in foods

61. D. In the Kitchen Use canola & olive oil for baking & cooking
Prepare lean cuts of meat
Bake, broil & steam instead of frying
Use low-fat or fat-free dairy products & dressings
Season with herbs & spices rather than with fats
Incorporate plant-based protein sources such as soy & legumes

62. E. At the Table Eat more fresh fruits & vegetables
Use jam instead of butter
Limit use of high-fat condiments including mayo, butter & sour cream or use low-fat varieties
Use mostly monounsaturated vegetable oils such as olive or canola
Eat fewer high-fat desserts

63. F. Recipe Modification Egg whites Fat-free evaporated milk
Fat-free sour cream
Fruit purees
Fat-free cream cheese
Oils

64. IX. Diet & Heart Disease Risk Factors High cholesterol
High blood pressure
Smoking
Diabetes
Lack of exercise
Stress
Obesity
Unhealthy diet
Age
Gender
Genetics

65. Cont’d Ways to Reduce Risk Limit intake of cholesterol & saturated fat
Quit smoking
Maintain a healthy weight
Eat high fiber foods
Increase physical activity
Increase fruit & vegetable consumption
Limit alcohol consumption