Lipid Transport Lipoproteins –Chylomicrons –VLDL = very-low-density lipoproteins –LDL = low-density lipoproteins –HDL = high-density lipoproteins Copyright 2005 Wadsworth Group, a division of Thomson Learning

Lipid Transport Animation

Lipid Transport Lipoproteins and health –LDL vs. HDL Copyright 2005 Wadsworth Group, a division of Thomson Learning

Roles of Triglycerides Fat stores –Energy –Protection Cushioning (e.g. fat pads on foot) –Insulation Fat is a poor conductor of heat Copyright 2005 Wadsworth Group, a division of Thomson Learning

Essential Fatty Acids Remember that an essential nutrient is a nutrient which the body cannot make or make in sufficient quantities Our cells cannot make omega-3 or omega-6 from scratch or convert one to another. They can only elongate 16 carbon omega- 3 or omega-6 and make longer chain fatty acids Linoleic acid and the omega-6 family –Arachidonic acid Copyright 2005 Wadsworth Group, a division of Thomson Learning

Essential Fatty Acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

Essential Fatty Acids Linolenic acid and the omega- 3 family –EPA =eicosapentaenoic acid (20 carbons) –DHA = docosahexaenoic acid (22 carbons) –Important for normal growth and development esp. eyes and brain –Maybe important for prevention and treatment of heart disease Copyright 2005 Wadsworth Group, a division of Thomson Learning

Essential Fatty Acids Eicosanoids –prostaglandins, thromboxanes, prostacyclin and the leukotrienes. –Both Arachidonic acid and EPA are used to make different types of eicosanoids –EPA derived vs. arachidonic acid derived –EPA derived ones are more protective –EPA derived eicosanoids help to protect against heart disease Copyright 2005 Wadsworth Group, a division of Thomson Learning Arachidonic acid EPA

Essential Fatty Acids Fatty acid deficiencies –Not very common –Usually only in infants and children who are fed fat free milk or low-fat diets or long term lack of polyunsaturated fatty acids in their diet –A deficiency of omega-3 fatty acids may be associated with depression

Essential Fatty Acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

Lipid Metabolism Storage as fat –Adipose tissue –LPL = lipoprotein lipase Copyright 2005 Wadsworth Group, a division of Thomson Learning