Unit 18

Fats and Cholesterol in Health

Facts about fats

• Lipids can dissolve in fat, not water• Fats- solid at room temperature• Oils- liquid at room temperature

Contributions of dietary fats

• Supply energy• We need essential fatty acids (about 1

teaspoon per day)• Deliver fat-soluble vitamins to the body• Increase flavor and palatability of foods• Contribute to the feeling of being full• A component of cell membranes

Excess calories are stored as fat• Regardless of their source, all extra

calories (carbs, protein, fat) are stored as fat.

• Layer of fat under skin- subcutaneous fat- insulation

• Fats surround the organs- visceral fat- cushion them

• Excess fat- visceral fat contributes the most to heart disease (apple vs pear)

Different types of fat

• Triglycerides• Diglycerides• Monoglycerides• Saturated• Monounsaturated• Polyunsaturated• Cholesterol• glycerol

Triglycerides

• Glycerol + 3- fatty acids = triglyceride

fatty acidGlycerol + fatty acid

fatty acid

Diglycerides

• Glycerol + 2 fatty acids = diglyceride

fatty acidGlycerol + fatty acid

monoglycerides

• Glycerol + 1 fatty acid = monoglyceride

Glycerol fatty acid

Digestion of Triglycerides

• Glycerol + 3- fatty acids = triglyceride

fatty acid

Glycerol + fatty acid = monoglyceride

fatty acid

Saturated vs unsaturated fats

• Saturated- solid at room temperature

• Unsaturated- liquid at room temperature

• Unsaturated fat + hydrogenation = saturated fat– Saturated fat has a longer shelf life

because it is less likely to oxidize

Cholesterol

• A fat-soluble, colorless liquid found in animals but not plants

• Hormones- testosterone and estrogen• Component of cell membranes in

animals• “turns sunlight into Vitamin D”• Cannot be used for energy- no

calories• Major component of nerves and brain

Omega-3 fatty acids

• Found in fish oils, flax seed, some other foods

• Lower risk of heart disease

hydrogenation

• Saturate fats by pumping hydrogen thru them

Trans fatty acids

• Mirror images of fatty acids found in nature

• Created during hydrogenation process

• Associated with an increased risk of heart disease

Which is better for you?

• Butter- saturated fat, contains cholesterol

• Stick Margarine- hydrogenated- contains trans fatty acids but no cholesterol

• Tub margarine- partially hydrogenated- contains some trans fatty acids but no cholesterol

Taking the fat out of foods

• Adding less fat to foods to processed foods

• Trimming fat from meats• Removing skin from chicken• Adding less fat to ground beef

• Adding water to ham and other meats (cheating)

Fat substitutes

• Are they safe?• Do they replace saturated fats in

the diet?• What are they made from?

– Carbohydrate-based– Protein-based– Fat-based– combinations

Other ways to replace fat in the diet• Smaller serving size

– Hamburger instead of a Big Mac– Small fries instead of large fries

• Use different ingredients– Veggie pizza instead of pepperoni

• Use a low-fat or non-fat version– 1% or skim milk instead of whole or 2%

• Have something else instead– Fruit instead of ice cream

How much fat is in the foods you eat?

• Read the label• Look for key words in the name

– With gravy– Cream sauce– Au gratin– With cheese– Fried – Alfredo