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• What are some things you have heard about fat that you would like to know more about?

What you need to know…•The functions of fat

• (what fat does for/in your body)•The food sources of fat•The effects of having fat and not having fat in your diet.

Basic Functions of Fat

• Store and provide energy• Provide insulation• Help manufacture steroids and bile• Play a role in transporting fat-soluble nutrients in the blood• Used to manufacture major sex hormones• Key to the structure of cell membranes

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Saturation of Fatty Acids

• The degree of saturation of a fatty acid is determined by whether the carbons are held together by a double or single bond.

• Saturated Fatty Acids• All the carbons on the fatty acid are bound to hydrogen.• There are no double bonds.• Solid at room temperature• Higher melting point

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Saturation of Fatty Acids (Cont'd)

• Unsaturated Fatty Acids• Some carbons on fatty acid form a double bond with each other instead of

binding to hydrogen.• Monounsaturated fatty acid (MUFA)

• Has one double bond• Polyunsaturated fatty acid (PUFA)

• Has two or more double bonds• Liquid at room temperature• Lower melting point

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Saturated and Unsaturated Fatty Acids Help Shape Foods

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Reduce Foods that Contain Trans Fat and Cholesterol• Saturated fats from animal and plant sources were used in home

cooking and commercial food preparation to• Provide a rich flaky texture to baked goods• Decrease the incidence of rancidity

• Later, the technique of hydrogenation of oils and the use of trans fat performed a similar function without adding cholesterol to the diet.

• Hydrogenation: Replacing saturated fat with hydrogenated fat

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Read Food Labels to Lower Saturated and Trans Fat Intake

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Foods with Trans Fats

• During the hydrogenation process some of the double bonds are reconfigured.

• The unstable cis fatty acids in the double bond form trans fatty acids.

• Some trans fats are naturally occurring.• Trans fat may actually be worse for heart health than are saturated

fats.• Raise LDL cholesterol• Lower HDL cholesterol

• The FDA requires trans fat to be listed on food labels.

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Replacing Trans Fats in Foods

• The food industry is working to find replacements for trans fats in foods.

• The objective is to produce oil that has the characteristics of trans fatty acids without compromising health.

• Interesterification: The process of rearranging the fatty acids on the triglyceride molecule to improve the consistency and usefulness of processed food

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Rancidity

• Rancidity: Spoiling of fats through oxidation• Leads to rancid taste and smell; spoiled food

• Double bonds are less stable than single bonds.• Foods with unsaturated fats become rancid faster than foods with

saturated fats.

PUFA > MUFA > Saturated fatty acids

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Three Types of Lipids

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Structure of a Chylomicron

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Lipoproteins

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Lipoproteins Transport Fat

• HDL and LDL biomarkers are used to determine the health of arteries.• LDLs

• Carry cholesterol fromthe liver to the tissues

• "Bad cholesterol"• "Lousy" DLs

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• HDLs• Carry cholesterol from the

cells to the liver• "Good cholesterol"• "Healthy" DLs

How Does the Body Use Fat and Cholesterol?They serve several critical roles in the body: • Used as a source of energy • To form body structures (including cell membranes) • Regulate metabolism • Enhance the absorption of fat-soluble vitamins• Provide a layer of insulation to help regulate body temperature• Help cushion the major organs

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Fat Is Used as Energy

• Provides concentrated source of kilocalories • 9 kilocalories per gram

• Readily available when the body needs energy• Body's main source of energy throughout the day• Excess fat is stored

• The body has an unlimited ability to store excess energy as fat in adipocytes.• Fat cells can grow up to 1,000 times their original size.• Additional fat cells are made when fat stores are filled.

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Fat Is Used as Energy (Cont'd)

• Fat as a fuel source• Preferred by the heart, liver, and resting muscle• Spares glucose so it is only used by the central nervous system and red blood

cells• Provides a backup source of energy between meals• Cannot sustain life during prolonged starvation

• Glucose is needed to metabolize fat.• The glycerol portion of fat can make small amounts of glucose.

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Fat Helps Insulate the Body and Protect Vital Organs• Fat in subcutaneous tissue

• Insulates body• Maintains body temperature

• Fat protects bones and vital organs from trauma.• Too much stored fat can be detrimental to health.

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Cholesterol Is Used to Make Bile, Hormones, and Vitamin D• The body needs cholesterol as

• A structural part of the cell membrane• A precursor to vitamin D• A precursor to bile acid• A precursor to sex hormones such as estrogen and testosterone

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Think Pair Share

Compare and contrast carbohydrates, proteins, and lipids: what do they have in common and how are they different?

How Much Fat Do We Need Each Day?• Overall intake of fat in the United States is higher than it should be.• Acceptable Macronutrient Distribution Range (AMDR)

recommendation:• 20 to 35 percent of daily kilocalories should come from fat.

• For heart health• Consume no more than 10 percent of total kilocalories from saturated fat.• Limit trans fats to < 1 percent.

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Dietary Cholesterol Is Not Essential

• The liver synthesizes cholesterol needed by the body.• ~900 mg/d• The liver decreases synthesis based on dietary intake.

• To reduce the risk of cardiovascular disease, dietary cholesterol should be limited to < 300 mg/d.

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The Best Food Sources Are Low in Saturated Fat• Unsaturated fats are abundant in vegetable oils, such as soybean,

corn, and canola oils, as well as in soybeans, walnuts, flaxseeds, and wheat germ.

• These foods are also good sources of linoleic acid. • Walnuts, flaxseeds, and canola oil also contain alpha-linolenic acid.

• Fish are generally good sources of omega-3 fatty acids, and all fish contain EPA and DHA.

• Avoid cod-liver oil, as it is very high in vitamin A, which can be detrimental.

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The Best Food Sources Are Low in Saturated Fat (Cont'd)• Most saturated fat comes from animal foods, such as fatty cuts of

meat, whole-milk dairy products, and the skin on poultry. • Coconut, palm, and palm kernel oils are also very high in saturated fat.

• Consume lower fat versions of fat-containing foods to obtain healthy nutrients while avoiding unhealthy fats.

• Read the Nutrition Facts panel to help you choose foods that are low in fat.

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Food Sources of the Essential Fatty Acids

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Food Sources of Omega-3 Fatty Acids

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Time to research your questions!

DOL—In Tues/Thurs Box!!!

1. Describe 2 functions of fat in your body2. Which of the following would be the BEST source of fat?

a) Whole milkb) margarinec) fish

3. Name one way eating fat can be good for you and one way it can be bad for you.