Dietary fats include: triglycerides (TAG), phospholipids, and cholesterol

• most strongly influence the incidence of coronary heart disease (CHD)

• in causing disease, type of fat is more important than the total amount of fat consumes

Plasma Lipids and Coronary Heart Disease (CHD)

Plasma lipids may arise from:

• the diet

• endogenous biosynthesis

Low-density and high-density lipoprotein

• elevated levels of total cholesterol (hypercholesterolemia) = increased risk for CHD

• low-density lipoproteins (LDL-C) increases = CHD increases

• elevated high-density lipoprotein cholesterol (HDL-C) levels = decreased risk for heart disease

CHD Risk Factors

• abnormaln levels of plasma lipids (dyslipidemias)

• smoking

• obesity

• sedentary lifestyle

• insulin resistance

Benefits of Lowering Plasma Cholesterol

• decreasing LDL-C

• increasing HDL-C

• reducing risk for cardiovascular events

Dietary Fats and Plasma Lipids

• TAG most important class of dietary fats

Structural features that influence blood lipids:

• absence or presence and number of double bonds (saturated, mono- polyunsaturated)

• location of double bonds

• cis or trans configuration of unsaturated fatty acids

Saturated Fats

• do not contain double bonds

• typically solid at room temperature

• associated with:

  • high levels of total plasma cholesterol and LDL-C

  • increased risk of CHD

• main sources: dairy and meat products, some vegetable oils (e.g. coconut and palm oils)

• intake should be limited to less than 10% of total calories in diet

Monounsaturated Fats (MUFA)

• contain one double bond

• main sources: plant-based oils

• when substituted for saturated fatty acids in the diet:

  • lower total plasma cholesterol

  • lower LDL-C

  • maintain or increase HDL-C

• intake should constitue to more than 10% of total calories in diet

The Mediterranean Diet

• example of a diet rich in MUFA (from olive oil) and polyunsaturated fatty acids (PUFA) (from fish oils, plant oils, and some nuts)

• low in saturated fat

• contains:

  • seasonally fresh food

  • abdunacne of plant material

  • low amounts of red meat

  • olive oil (main source of fat)

• associated with:

  • decreased plasma total cholesterol

  • decreased LDL-C

  • increased HDL-C

Polyunsaturated Fats (PUFA)

• contain more than one double bond

• effects of PUFA on cardiovascular disease are influenced by location of double bonds

  • ω-6 fatty acids (n-6 fatty acids):

    • long chain PUFA

    • lower plasma cholesterol

    • LDL-C and HDL-C lowered

    • main sources: nuts, avocados, olives, soybeans

  • ω-3 fatty acids:

    • long chain PUFA

    • suppresses cardiac arrhythmia

    • reduce plasma TAG

    • decrease tendency for thrombosis

    • lower blood pressure

    • reduce risk of cardiovascular mortality

    • main sources: plant oils and some nuts

    • Docosahexaenoic acid (DHA) is an omega-3 fatty acid added in infant formulas to promote brain development

Trans Fatty Acids

• chemical classification: unsaturated fatty acids

  • behave more like saturated fatty acids

• elevate LDL-C

• lower HDL-C

• increase risk of CDH

• formed during hydrogenation of vegetable oils

Dietary Cholesterol

• only in animal products

• recommended amount: less than 200 mg/day

Plant Sterols

• main sources: plant sources (e.g. broccoli) and some margarines

• reduce LDL-C by interfering with the absorption of dietary cholesterol