The Good, the FAT, & the UglyThe Good, the FAT, & the Ugly

Pauline Williams, MPA, RD, CD

Nutrition and Food Science Workshop 2008

The body needs fat

Insulation

Protection

Energy Storage

Muscle fuel

Hormone Synthesis

Nerves

Cell Membranes

Fats look and act different in the body

Number of carbons in chain

– Short, medium, or long

Placement and number or double bonds

Structure – chain, round, bent

Fatty Acids

Saturated versus Unsaturated Fatty Acids

Saturated fatty acid – filled to capacity with hydrogen atoms

Unsaturated fatty acid – missing hydrogen

– Monounsaturated – one point of unsaturation

– Polyunsaturated – two or more points of unsaturation (PUFA)

Saturated Fats

solid at room temperature

– Exception: coconut and palm oil

Usually from animal sources

– lard, butter, bacon, fatty red meat, cream, chocolate, cream cheese, sour cream

high intake

– increase risk for heart disease

Acid

CC

CC

CCCC

CC

C

Monounsaturated

liquid at room temperature, cloudy in fridge

Food sources

– Avocado

– Nuts (almonds, cashews, hazelnuts, peanuts, pecans, pistachios)

– Oil (olive, canola, peanut, sesame)

– Olive

may be protective against heart disease

Acid

CC

CC

CCC

C

C C

C

C

Polyunsaturated

liquid at room temperature

plant sources

– soy, safflower, corn oils, nuts

may decrease risk for heart disease

C C

Acid

CC

C

CC

C C

CC

Omega-3, Omega-6 fatty acidstypes of polyunsaturated fats

Ω

1 2 3 4 56

Ω

Acid

CC

CC

CCC

C

1 2

3 4

5 6 7…C C

C

C

Acid

C

CC

C

C

C

C CC

CC

7…

Essential fats need in diet

Omega 6 fats

Linoleic acid omega-6

– Margarine

– Mayonnaise, salad dressing

– Nuts (walnuts)

– Oils (corn, safflower, soybean)

– Seeds (pumpkin, sunflower)

Omega 3 fats

Linolenic acid omega-3

– Fatty fish (salmon, tuna)

– Flax seed

– nuts

– Linolenic acid can be converted to EPA and DHA

EPA (eicosapentaenoic acid) and

DHA (docosahexaenoic acid)

– lower blood pressure

– prevent blood clot formation (large amounts may cause bleeding, bruising)

– protect against irregular heartbeats

– may reduce inflammation

– essential for normal infant growth and development

– may support immune system

– may inhibit cancers

EPA and DHA

How much Omega-3?

For health benefits balance between omega-3 and omega-6 fatty acids

– Americans get mostly omega-6 from

• vegetable oils, salad dressings, and margarine and

– Americans need more omega-3

• Fish 2 times a week

• Average U.S. intake of EPA and DHA is 150 mg/day

• Recommended is 500 mg/day (about 2 fatty fish meals per week)

C

Hydrogenation

Adds Hydrogen

More saturated

C C

Acid

CC

C

CC

C C

CCH

H

HH

H

C Acid

CC

CC

CCCC

CC

CH

H

H

H

H

H

H

H

Trans-fatty acids

Acid

C

CC

C

C

C

C CC

CC

AcidC

CC

CC

CC

C

C

C

C

H

H

HH

Trans double bond

Cis double bond

Trans fatty acids

Affects blood cholesterol similar to saturated fat

Soft or solid at room temperature

Created when oils are hydrogenated

What foods have them? (Processed)

– Baked goods (cookies, pie, cakes)

– Fried foods (especially fast food)

– Margarine

– Processed snacks, crackers, chips, microwave popcorn

Looking at the label

One serving crackers

No trans fat

30% daily limit saturated fat

Why Hydrogenate?

Reduce rancidity and increase shelf life

Change to more solid texture

– spreads more easily

– makes baked goods flaky and tender

Butter or Margarine

Soft or liquid margarines

– made from unhydrogenated oils

– mostly unsaturated

Solid margarine

– Hydrogenated oils

Butter

– Saturated fat

Choose any sparingly

Types of fat in oils

Saturation continuum

Beef fat

Stick margarine

Tropical oils (exception to the rule)

Chicken fat (less solid)

Tub margarine

Squeeze margarine

Fish oils (exception to the rule)

Vegetable oils

More saturated

Less saturated

Cholesterol/Lipid Transport Lipoproteins

Chylomicrons (mostly fat; neutral for risk CVD)

VLDL=very low density lipoprotein

LDL =low density lipoprotein

HDL=high density lipoprotein

Good and Bad Cholesterol

LDL

– “lousy”

– Higher LDL increase risk for heart disease

HDL

– “Healthy”

– Higher HDL protective against heart disease

Cholesterol effect Diet

Saturated fat and Trans fat

– Increases LDL, decreases HDL

Polyunsaturated fat

– Decreases LDL, decreases HDL

Monounsaturated fat

– Decreases LDL, keeps HDL same

Cholesterol intake (very little impact)

Cholesterol effect other

Genetics

Health behaviors

– Smoking

– Exercise can help lower LDL and raise HDL

Fats and Healthy Eating

20-35% calories from fat

Limit saturated and trans-fat

– Less solid fat

Choose oils not solids fat

– Monounsaturated fat

– omega-3 fats (good sources 2-3 times/weei)

Minimize cholesterol intake

– Not a large effect on heart disease

How many grams/day?

20-35% of total kcals = fat kcals

2000 kcals x .20 = 400 fat kcals

2000 kcals x .35 = 700 fat kcals

Fat kcals / 9 = fat grams

400 kcals / 9 = 44 g fat

700 kcals / 9 = 78 g fat

Fat Replacers

Olestra – most common

– Not digested

– Sucrose polyester (fatty acid bonded to a sugar)

– Mimics texture and quality of fat

Whip air or water into product to decrease fat

Use less fat

– May add carbohydrate to get texture

Pros and Cons of Olestra

Questions?