Nutrition Principles Lecture 36

Study Notes

Specific Objectives: Students will be able to identify acceptable macronutrient distribution ranges (AMDR) and differentiate between beneficial and harmful types of lipids.

AMDRs define the intake range of a macronutrient linked to a reduced risk of chronic disease while ensuring adequate essential nutrient intake.
For adults, the AMDRs are:
- 45-65% of daily calories from carbohydrates
- 20-35% of daily calories from fat
- 10-35% of daily calories from protein

Dietary fats influence the incidence of coronary heart disease (CHD), risk of cancer, and - to a lesser extent - obesity.
The type of fat consumed is more crucial than the total amount.

Blood LDL cholesterol levels strongly correlate with heart disease.
High HDL cholesterol levels are associated with a decreased risk of heart disease.
Elevated plasma triglycerides are also a risk factor for CHD, but the association is weaker than for LDL cholesterol.

Consuming saturated fats (triacylglycerols without double bonds) increases total plasma cholesterol and LDL levels, and the risk of CHD.
Primary sources of saturated fat are dairy and meat products, and some vegetable oils (e.g., coconut and palm oils).

These fats contain fatty acids with one double bond.
Primarily found in vegetables and fish.
They lower total plasma cholesterol and maintain or increase HDL cholesterol levels.
Oleic acid is an example of a monounsaturated fat.
They show a low incidence of CHD.

PUFAs are triacylglycerols with more than one double bond.
The effect of PUFAs on cardiovascular disease depends on the location of the double bonds.

An example is linoleic acid (18:2(9,12)).
Primarily found in vegetable oils.
Lowers plasma cholesterol and LDL.
Lowers HDL, which may pose a small detrimental effect on cholesterol.
Sources include nuts, avocados, olives, soybeans, and various oils (sesame, cottonseed, corn).

An example is linolenic acid (18:3(9,12,15)).
Found in plants.
Suppresses cardiac arrhythmias, reduces serum triglycerides, lowers blood pressure, decreases thrombosis tendencies, and significantly reduces cardiovascular mortality.
ω-3 fatty acids have little effect on LDL or HDL cholesterol levels.
Two fatty fish meals (e.g., salmon) per week are recommended.
Note: ω-3 long-chain PUFAs are often included in infant formulas to promote brain development.

Classified as unsaturated fatty acids, but behave like saturated fats.
Elevate serum LDL levels but do not impact HDL.
Increase the risk of CHD.
Formed during the hydrogenation of liquid vegetable oils (e.g., margarine production).
Found in commercial baked goods and deep-fried foods.