Judith E. Brown

Prof. Albia Dugger • Miami-Dade College

www.cengage.com/nutrition/brown

Fats and Cholesterol in Health

Unit 18

Changing Views about Fat

• Type of fat is more important than total fat

• Excess calories cause weight gain, not fat

• Healthy diets provide 20-35% of calories from “healthy” fats

Facts about Fats

• Fats are a subcategory of lipids

• Lipids•Compounds that are insoluble in water and

soluble in fat• Includes triglycerides, saturated and unsaturated

fats, oils, cholesterol, and essential fatty acids

Key Terms

• Essential fatty acids•Components of fats required in the diet• Linoleic and alpha-linolenic acids

Functions of Dietary Fats

• Energy source• 9 calories/gram

• Carriers of fat-soluble nutrients• Essential fatty acids• Fat soluble vitamins (D,E,K,A)

Functions of Dietary Fats

• Energy stores• Excess calories are

converted to triglycerides• 1 pound body fat ~ 3500

calories

Functions of Dietary Fats

• Cushion and protect internal organs

• Provide insulation against cold

Functions of Dietary Fats

• Increase flavor and palatability of food

• Contribute to the sensation of feeling full

• Components of cell membranes, vitamin D, and sex hormones

Functions of Dietary Fats

Varieties of Fats

• There are many types of fat in food and in our bodies

Varieties of Fats

Triglycerides

• Make up 98% of our fat intake and most of our body’s fat store

• Transported in blood attached to protein carriers

• Used for energy and tissue maintenance

Saturated and Unsaturated Fats

• Saturated fats•Carbon chains saturated with the maximum

number of hydrogen atoms (all single bonds)• Solid at room temperature• Found in animal products

• Unsaturated fats•Monounsaturated: One double bond• Polyunsaturated: Two or more double bonds

Saturated and Unsaturated Fats

Fat Profiles of Foods

Essential Fatty Acids

• Linoleic acid •Omega-6 fatty acid•Component of all cell membranes, especially in

nerves and brain•Required for growth, skin, reproductive system• Factor in regulation of blood pressure, clotting• In sunflower, safflower, corn, and soybean oils

Essential Fatty Acids

• Alpha-linolenic acid •Omega-3 fatty acid•Component of all cell membranes, especially in

nerves and brain•Has opposite effects of linoleic acid on regulation

of blood pressure and clotting• In walnuts, dark green leafy vegetables, flaxseed,

canola, and soybean oils

Other Omega-3 Fatty Acids

• EPA (eicosapentaenoic acid)• Precursor of compounds used for blood clotting

and blood pressure regulation• Limits damage from inflammatory and oxidative

reactions

• DHA (docosahexaenoic acid)•Needed for brain and eye formation

EPA and DHA

• EPA and DHA are found in fish and shellfish• Adequate intake for adults: 500mg/day• 8 oz fatty fish (2 meals) per week•Reduces risk of heart disease and stroke• Improves fetal development• Limit fish oil supplements to 2 grams/day

EPA and DHA in Seafoods

EPA and DHA Fortified Foods

• Fish oils are now added to many foods and animal feeds• In juices, dairy, eggs, meat

• Confirm that foods contain EPA and DHA• Sources of omega-3s other than fish oils do not

contain EPA and DHA

Hydrogenated Fats

• Hydrogenation is used to transform unsaturated fats into saturated fats• Turns liquid oils into solid fats• Extends shelf life of processed foods

• Hydrogenation• Addition of hydrogen to unsaturated fatty acids•Converts natural cis form into trans fat

Cis Fatty Acids

• Cis fatty acids• The most common, naturally-occurring form of

unsaturated fatty acid•Contain hydrogens located on the same side of

doubly-bonded carbons

Trans Fatty Acids

• Trans fatty acids•Unsaturated fatty acids in fats that contain atoms

of hydrogen attached to opposite sides of carbon atoms joined by a double bond

• Trans fats• Fats containing fatty acids in the trans form

Trans and Cis Fatty Acids

Trans Fats

• Trans fats produced by hydrogenation:•Raise blood cholesterol levels more than any

other type of fat• Increase risk of heart disease, stroke, sudden

death from heart disease, type 2 diabetes• As little as 2.2 grams/day increases risk • Trans fat content required on labels

Trans Fats in Foods

Trans Fats on Labels

Checking Out Cholesterol

• Cholesterol is found only in animal products

Sources of Cholesterol

• 2/3 of cholesterol is produced by the liver

• The rest is obtained from the diet

Contributions of Cholesterol

• Cholesterol:• Is found in all cell membranes• Is a major component of nerves and brain• Is needed to produce estrogen, testosterone, and

vitamin D•Cannot be used for energy

Finding Fat Content of Food

• Where fat contents of foods are listed:• Food composition tables, Diet Analysis Plus

Program software, nutrition labels on foods

• To calculate % of calories from fat:•Grams fat x 9 calories/gram = fat calories• Fat calories/total calories x 100 = % of total

calories from fat

Fat Labeling

• Food labels must specify fat, saturated fat, trans fat, and cholesterol content

• Any claims must adhere to standard definitions for “low fat” or “fat-free”

Cholesterol Claims

Changes in Recommendations

• New recommendations have been developed for intakes of fat and cholesterol

• Diets relatively high in “good” fats reduce risk of heart disease, stroke, obesity

Mediterranean Diet

• High in “good” fats

• Reduces risk of stroke and heart disease

“Good” Fats, “Bad” Fats

• “Bad” fats• Include trans fats, saturated fats, cholesterol• Elevate total cholesterol and LDL levels• Solid at room temperature (fats)

• “Good” fats• Lower total cholesterol and LDL levels•Raise HDL levels• Liquid at room temperature (oils)

“Good” Fats, “Bad” Fats

Current Recommendations

• Adults: 20-35% of total calories from fat

• AIs• Linoleic acid: 5 g/day (men), 12 g/day (women)• Α-linolenic acid: 1.6 g/day (men), 1.1 g/day

(women)

Current Recommendations

• Trans fat and saturated fat intake: • As low as possible with a nutritious diet

• Cholesterol: < 200 mg/day

• EPA and DHA• Increase consumption by eating fish