Dietary Fats

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 (<strong>hypercholesterolemia</strong><strong>hypercholesterolemia</strong>) = 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

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CHD Risk Factors
  • abnormaln levels of plasma lipids (dyslipidemias)
  • smoking
  • obesity
  • sedentary lifestyle
  • insulin resistance

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Benefits of Lowering Plasma Cholesterol
  • decreasing LDL-C
  • increasing HDL-C
  • reducing risk for cardiovascular events

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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

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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

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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

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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

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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

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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

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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

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