Chapter 4 - Lipids

Nutrition for Health and Health Care, 5th Edition
DeBruyne ■ Pinna © Cengage Learning 2014
LipidsChapter 4

Introduction
• Fat
– Dietary intake
• Health risks associated with too much and too little
– Member of lipids class of compounds
• Triglycerides (fats and oils)
• Phospholipids
• Sterols

Roles of Body Fat
• Lipids: provide energy
• Adipose tissue
– Fat-storing cells; also secretes hormones
– Fat stored in fat cells
• Supplies 60 percent of the body’s ongoing energy
needs during rest
– Fat embedded in muscle
• Along with glycogen, provides energy to muscle

The Chemist’s View of Lipids
• Triglycerides
– Predominant form of lipids
– Three fatty acids attached to a glycerol
“backbone”
• Fatty acids
– Differ in chain length and degree of saturation
– What is the difference between a saturated
fatty acid and an unsaturated fatty acid?

(cont’d.)
• Comparison of three fats
– Lard (from pork): most saturated ► hardest
– Chicken fat: less saturated ► somewhat soft
– Safflower oil: most unsaturated ► liquid
• Stability
– Why are polyunsaturated fatty acids most
susceptible to becoming rancid?

(cont’d.)
• Stability
– Methods manufacturers protect fat-containing
products from rancidity
1. Seal products airtight and refrigerate
2. Add antioxidants, e.g., BHA and BHT
3. Hydrogenate products

(cont’d.)
• Hydrogenation
– Advantages: protects against oxidation and
alters texture
– What are the disadvantages?
• Essential fatty acids
– Linoleic acid: omega-6 fatty acid
– Linolenic acid: omega-3 fatty acid

(cont’d.)
• Phospholipids: class of lipids
– Food sources: eggs, soybeans, peanuts, etc.
– Lecithin and other phospholipids
• Constituents of cell membranes
• Emulsifiers in the body
• Some generate signals in cells

(cont’d.)
• Sterols
– Large, complex molecules
• Interconnected rings of carbon
• Cholesterol, vitamin D, and sex hormones
– Cholesterol
• Obtained in foods as well as made by the liver

(cont’d.)
• Cholesterol
– Leaves liver by two routes:
1. Incorporated into bile, stored in the gallbladder,
and delivered to the intestine
2. Via the bloodstream to all the body’s cells

Digestion and Absorption of Lipids
• Goal of fat digestion
– Break triglyceries into monoglycerides, fatty
acids, and glycerol (Table 4-3)

Health Effects and Recommended
Intakes of Fats
• Diet high in saturated fats or trans fats
– Increased risk of cardiovascular disease
– Greater-than-average chances of some
cancers
– An increasing waistline often increases blood
triglycerides

Intakes of Fats (cont’d.)
• Fats and heart health
– High LDL: increased likelihood of fatal heart
attack or stroke
• Promotes cholesterol uptake in the blood vessel
walls
– High HDL: lower disease risk
– Trans fats: raise LDL and lower HDL

• Dietary Guidelines for dietary cholesterol
– Healthy people: less than 300/day
– People with or at high risk of heart disease:
less than 200 mg/day
• Monosaturated fat (olive oil)
– May prevent heart disease
• Omega-6 and omega-3 fats
– Lower total cholesterol and LDL

• EPA and DHA heart health benefits
– Lower blood triglycerides
– Prevent blood clots
– Protect against irregular heartbeats
– Lower blood pressure
– Defend against inflammation
• Food sources of omega-3 and omega-6
Fatty Acids (Table 4-4)

• What concerns are associated with taking
omega-3 supplements?
• Recommendations for fat intake
– Dietary Guidelines
• Diet low in saturated fat, trans fat, and cholesterol
• 20 to 35 percent of daily energy
– FDA Daily Values
• 30 percent of daily energy

Fats in Foods

Fats in Foods (cont’d.)
• Foods with five grams (45 kcal) pure fat:
– 1 tsp. oil or shortening, 1 ½ tsp. butter, 1
Tbsp. salad dressing, 1 ½ Tbsp. of sour
cream, etc.
• Invisible fats
– Majority of solid fats in U.S. diet
• Milk and yogurt
– Varying fat content
– Rich in calcium and protein

• Meat categories by fat content
– Very lean, lean, medium-fat, and high-fat
• USDA Food Patterns protein
recommendation for adults
– Five to seven ounces per day
• Most vegetables and fruits
– Little or no fat

• Most grains have small amounts of fat
• Dietary Guidelines regarding fat intake
1. Select the most nutrient-dense foods from all
food groups
2. Consume fewer and smaller portions of
foods and beverages containing solid fats

• Dietary Guidelines regarding fat intake
3. Replace solid fats with liquid oils
4. Check Nutrition Facts labels and select
foods with little saturated fat and no trans fat
• Solid fat ingredients
– Butter, coconut oil, palm oil, shortening, etc.
– Solid fat ingredients listed on food labels
(Table 4-6)

• Do not overdo fat restriction
– Include a teaspoon of fat in every meal
• Fat-reduced products
– Fat replacers
– Artificial fats
– Preparation methods
• Whipping air into foods, baking foods vs. frying,
adding fat-free milk, etc.

• Alternatives to fat in supporting weight loss
– Must actually replace fat and energy in the
diet
• Food labels
– List total fat, saturated fat, trans fat,
cholesterol, and fat kcalories per serving
– Easy to compare similar products

Chapter 4 - Lipids

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