Fat Dietary fats:

Polyunsaturated fatty acids Monounsaturated fatty acids Saturated fatty acids

Cholesterol It is recommended that dietary saturated

fat intake be <7% of energy to reduce CHD risk

Fat Dietary fats and cholesterol play a major

role in CHD development Saturated fatty acids: contain no double

bonds and generally vary in chain length from 12 to 18 carbons.

Major sources of saturated fat in diet: dairy, beef, pork, poultry, and lamb products

Saturated Fatty Acids Saturated fatty acids increase LDL-

cholesterol concentrations by decreasing LDL receptor–mediated catabolism

This effect is mediated both by decreased LDL receptor messenger RNA (mRNA) expression and decreased membrane fluidity

This latter effect causes less receptor recycling across the cell membrane.

It is recommended that dietary saturated fat intake be <7% of energy to reduce CHD risk

Monounsaturated fatty acids

The major monounsaturated fatty acid in the diet is oleic acid, which contains one double bond at the number 9 carbon

Monounsaturated fatty acids, as compared with dietary carbohydrates, were neutral with respect to their effects on plasma total cholesterol concentrations

When substituted for dietary saturated fatty acids, monounsaturated fatty acids have a hypocholesterolemic effect

Monounsaturated fatty acids

Monounsaturated fats do not lower LDL or HDL cholesterol relative to saturated fat as much as does polyunsaturated fat

Food sources: olive oil, peanut oil, margarine, chicken fat

Trans Fatty Acids Trans Fatty acids are formed during the

hydrogenation process, a process that converts vegetable oils to a semisolid state

Major sources: baked products, processed foods, and margarines

Increases plasma concentrations of lipoprotein(a), an independent risk factor for CHD

Polyunsaturated fatty acids

Subclassified: n−6 and n−3 The major n−6 fatty acid in the diet is α-

linoleic acid, the precursor for arachidonic acid (20:4n−6)

α-Linoleic acid is not synthesized by the body and is therefore an essential fatty acid.

Food sources: vegetables and vegetable oils (corn, soybean, safflower, and sunflower), with the exception of coconut and palm oils

Ω-3 fatty acid linolenic acid (18:3n−3) hypocholesterolemic effect: reducing both LDL-

and HDL-cholesterol concentrations, lower platelet aggregation, lower immune response, and lower blood pressure

fish oil, especially eicosapentaenoic acid, lower triacylglycerol concentrations significantly

recommended that the polyunsaturated fat intake be <10% of energy

An optimal ratio of n−6 to n−3 fatty acids in the diet is believed to be ≈4:1.

Cholesterol 1.3 egg yolks/d containing 272 mg

cholesterol increases LDL cholesterol Cholesterol with saturated fat, should be

restricted in the diet to ≤200 mg/d to decrease CHD risk

National Cholesterol Education Program coronary heart disease (CHD) risk factors- NCEP in addition to diabetes and elevated LDL cholesterol1

1Subtract one risk factor for HDL cholesterol ≥ 1.6 mmol/L (60 mg/dL). Diabetes has been defined as a CHD risk equivalent.2Defined as CHD in a male first-degree relative aged <55 y or a female first-degree relative aged <65 y.

1) Male ≥45 y

2) Female ≥55 y

3) Family history of premature CHD2

4) Hypertension

5) Cigarette smoking

6) HDL cholesterol <1.0 mmol/L (40 mg/dL)

National Cholesterol Education Program guidelines on dietary therapy(Am J Clin Nutr February 2002 vol. 75 no. 2 191-212)

Nutrient Average US diet2

Therapeutic lifestyle changes

Saturated fat (% of energy) 12 <7

Monounsaturated fat (% of energy) 13 <20

Polyunsaturated fat (% of energy) 7 <10

Cholesterol (mg/d) 270 <200

Total energy —To achieve and maintain a desirable body weight

Carbohydrate (% of energy) 51 50–60

Protein (% of energy) 15 15

Hypertension Calcium, potassium, magnesium,

phosphorus, and fiber that would be included in a diet containing adequate amounts of dairy products and fruit and vegetables.

Reduce salt intake (< 5 g/day) Maintenance body weight