食品营养学脂质（英文版） Lipid

食品营养学脂质（英文版） Lipid思维导图：包含classification，definition: 1.necessary, absence(<10%) creates specific disease 2.body cannotmanufacture it or not sufficient, must obtain from diet

Lipid

• classification
  • Triglycerides(95%): 3 units of FA & 1 unit of glycerol
  • Diglycerides
  • Monoglyceride
  • Phospholipids: 2 FA & 1 phosphorus & glycerol
    • eg. Lecithin
    • hydrophobic & hydrophilic characteristic
    • response to hormones and generate signals inside the cells
  • Sterol
    • eg. cholesterol: making emulsifiers in Bile
    • eg. Vitamin D
    • eg. familiar steroid hormones (sex)
  • Lipoproteins: noncovalent complexes of fat with pro
    • chylomicrons (lowest): formed in the intestine wall and carrying a high ratio of fat (90%) with a small amount of protein
    • VLDL (very low density)：carry triglycerides and other lipids made in liver to the body cells for their use
    • LDL (low density)：transport cholesterol and other lipids to the tissues; LDL are made from VLDL after they have donated many of their TG to body cells
    • HDL (high density)：carry cholesterol away from body cells to the liver for disposal
    • function:
      • transport: major carriers of lipids on the plasma
• FA
  • EFA: Essential Fatty Acid
    • definition: 1.necessary, absence(<10%) creates specific disease 2.body cannot manufacture it or not sufficient, must obtain from diet
    • Linoleic acid (LA) & Linolenic acid（LNA）
    • Function
      • Membrane structure
        • LA strengthens cell membrane, prevent damaging increase in skin and membrane permeability
        • LA deficiency--breakdown in skin integrity: eczema, skin lesions, scales disease
      • Cholesterol transport and metabolism
        • transport: like other FA, LA combines with cholesterol to cholesterol esters to transport in blood
        • metabolism: like other unsaturated FA, LA lower serum cholesterol level
      • Prolong blood clotting time
        • increase fibrinolytic activity
        • why?--cholesterol forms major part of plaques that narrow the arteries in atherosclerosis--underlying cause of heart disease and stroke
      • Local hormone-like effects
        • major metabolic precursor of prostaglandins
    • recommendation
      • LA：4% EER
      • LNA: 0.6%EER
      • n-3:n-6: 1:4-1.6
  • Chain length: 2-6short\ 8-12medium\ >14long
  • degree of saturation
    • saturated FA: do not have double bonds
    • unsaturated FA
      • cis configuration
      • trans configuration
    • from FA to fats
      • Saturated Fats: Food fats composed of such saturated fatty acids are called saturated fats.
      • Monounsaturated Fats: Food fats composed of unsaturated fatty acids with one less hydrogen atom creating one double bond.
      • Polyunsaturated Fats: Food fats composed mainly of unsaturated fatty acids with two or more places unfilled with hydrogen creating double bonds.
        • ω-3: α-linolenic acid (ALA), EPA, DHA
        • ω-6: linoleic acid
• Healthy concerns
  • saturated fats > trans FA > cholesterol
  • saturated fats
    • increase the cholesterol content in blood
    • dietary saturated fat and trans fat can trigger a rise in LDL cholesterol in the blood
    • recommendation: trimming the saturated fat and trans fat from foods and replacing them with monounsaturated and polyunsaturated fats, within a reasonable calorie intake, is associated with lower LDL levels.
  • cholesterol
    • It travels in the blood stream attached to long-chain fatty acid, forming cholesterol esters
    • vital:
      • be distributed in all cells（cell membrane）, large amounts in brain and nerve tissue
      • is a precursor to all steroid hormones
    • concerns--cholesterol forms major part of plaques that narrow the arteries in atherosclerosis--underlying cause of heart disease and stroke