Transcript Chapter 2

The 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
C
C
C
C
C
C
C
C
C
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
C
Acid
C
Monounsaturated
C
C
C
C
C
C
Acid
C
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
Polyunsaturated
C
Acid
C
liquid at room temperature
plant sources
– soy, safflower, corn oils, nuts
may decrease risk for heart disease
Omega-3, Omega-6 fatty acids
types of polyunsaturated fats
Essential fats need in diet
Ω
C
C
4
3
5
1
C
C
7…
6
2
Ω
1
2
3
4
5
6
C
7…
C
Acid
C
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 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
How much Omega-3?
For health benefits balance between omega3 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)
Hydrogenation
Adds Hydrogen
C
H
C
Acid
More saturated
H
H
H
H
C
C
C
C
H
H
C
C
H
H
C
C
C
C
C
H
H
Acid
C
H
H
Trans-fatty acids
Trans double bond
H
H
Cis double bond
H
H
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
More saturated
Beef fat
Stick margarine
Tropical oils (exception to the
rule)
Chicken fat (less solid)
Tub margarine
Squeeze margarine
Less saturated
Fish oils (exception to the
rule)
Vegetable oils
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?