Mid-term Study Guide

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Fats/ Lipids

Lipids

Term applies to variety of substances, including triglycerides

Fats/ Lipids

Triglyceride

Most abundant lipid

In the body, fat cells store triglycerides in adipose tissue

In foods, we call triglycerides “fats and oils” – fats solids at room temp. – oils liquid at room temp

Term “triglyceride” is used interchangeably with the word “fat”

Fats/ Lipids

Functions of triglycerides (fat / lipids):

Provide energy for the body

Store energy for later use

Insulate and protect the body

Transport fat-soluble vitamins

Add flavor and texture to foods and increases satiety after meals

Chain Length

The number of carbons in the chain

Long chain (12 or more carbons) – solid at room temp

Medium chain (6 to 10) - produce liquid oils at room temp. - coconut milk

Short chain (less than 6) – form liquid oils at room temp – dairy fat sources -The shorter the carbon chain, the more liquid the fatty acid becomes and the lower its melting point

Chain Length

Shorter fatty acids are also more water-soluble (think of milk)

Fats containing primarily polyunsaturated or monounsaturated fats are usually liquid at room temp – not affected by chain length

Saturated Fat

Saturation

Saturated – bonds between carbons are a single connection, carbons filled with hydrogen are saturated (think of a sponge full or saturated with water)

Triglycerides that contain primarily saturated fat are solid at room temp

Saturated Fat

Most fats high in saturated fatty acids, such as animal fats, remain solid at room temp. A good example is the solid fat surrounding a piece of uncooked steak at room temp. Chicken fat is semisolid at room temp, contains less saturated fat

In some foods, such as whole milk, saturated fats are suspended in liquid so solid nature of these fats at room temp is less apparent.

Milk actually contains a combination of liquid and solid fats

Saturated Fat

Saturated fatty acids increase total cholesterol levels and LDL cholesterol levels

Saturated Fat

Sources of Saturated Fat:

Animal products (including dairy products, yes, cheese), palm and coconut oils, and cocoa butter

Unsaturated Fat

Dietary fats high in unsaturated fat melt at a lower temperature

Unsaturated Fat

Monounsaturated fatty acids

Sources:

Most nuts and olive, canola, peanut, and safflower oils

Unsaturated Fat

Polyunsaturated fatty acids

Sources:

Sunflower, corn, soybean, and cottonseed oils

Unsaturated Fat

Replacing saturated fats with monounsaturated or polyunsaturated fats lowers LDL (bad) cholesterol and total cholesterol but does not lower HDL (good) cholesterol

Essential Fatty Acids

Fatty acids the body can not make

Omega-3 – mostly unsaturated

In foods, Alpha-Linolenic Acid is the major Omega-3 fatty acid

Omega-6 – mostly unsaturated

In foods, Linoleic Acid is the major Omega-6 fatty acid

Essential Fatty Acids

Functions of Omega 3’s and Omega 6’s

Perform important roles in immune system function and vision

Help form cell membranes

Essential Fatty Acids

Benefits of Omega-3 Fatty Acids

Reduce blood clotting

Favorable effect on heart rhythm

Helpful in managing the pain of inflammation associated with arthritis

Can help depression

Essential Fatty Acids

Some studies show that people who eat fish about twice a week (total weekly intake 8 oz.) run a lower risk for heart attacks than people who rarely eat fish – probably due to omega-3’s reducing blood clotting

Studies have also shown that large amounts of omega-3 fatty acids from fish (3 to 4g/day, one 3oz. serving has about 1.6g) can lower blood triglycerides in people with high triglyceride concentrations

Essential Fatty Acids

Food Sources of Omega-3 Fatty Acids

Fish such as: mackerel, tuna, salmon, herring, trout, sardines

Canola oil, soybeans, olive oil, walnuts, peanuts, hazelnuts, pistachios, pecans, almonds, flax seeds

Essential Fatty Acids

Food sources of Omega-6 Fatty Acids

Flax seeds, soybean and canola oil

Cholesterol

A waxy lipid found in all body cells

Is found only in foods that contain animal products

Cholesterol

Functions of Cholesterol:

Precursor to bile acids, which are needed for fat digestion

Essential structural component of cell membranes and particles that transport lipids in the blood

2/3 made by body cells (hereditary), 1/3 is consumed in the diet (lifestyle)

Cholesterol

LDL (Low Density Lipoprotein) also known as the “bad cholesterol”

The lipoprotein that deposits in the blood (Couch Potato)

Elevated LDL cholesterol is strongly linked to cardiovascular disease risk

Cholesterol

HDL (High Density Lipoprotein) also known as the “good cholesterol”

Picks up cholesterol from arterial plaques, reducing their accumulation (Sweeper)

Hydrogenated Oils

Hydrogenation

Adds hydrogen to an unsaturated fatty acid, making it more saturated

Body ends up treating the same as a saturated fatty acid

Increases hardness, turning liquid oils into more solid fats (margarine, shortening)

Creates trans fatty acids

Trans Fatty Acids

A form of an unsaturated fatty acid

Lowers HDL, raises LDL

Trans Fatty Acids

Look at ingredients list – if partially hydrogenated vegetable oil is listed in ingredients, then there are some trans fats

On food labels if there is less than one gram per serving, it can state that there are zero grams – watch those portions!

Recommended less than 1% of calories should come from trans fats (typical in U.S. 2.7%)