© 2006 Thomson-Wadsworth The Lipids Triglycerides Phospholipids Sterols.

© 2006 Thomson-Wadsworth

The Lipids

TriglyceridesPhospholipids

Sterols


Lipids

• Triglycerides– Fats and oils

• Phospholipids

• Sterols


Fatty Acids and Triglycerides

• glycerol


Fatty Acids and Triglycerides

• glycerol + 3 fatty acids triglyceride + H2O



Fatty Acids

• Fatty acids– Length– Saturated vs. unsaturated


Fatty Acids

• Organic acids– Example: acetic acid


Fatty Acids

• Length of carbon chain

Stearic acid – 18-carbon, saturated

Simplified structure


Fatty Acids

• Point of saturation

• Degree of saturation– Saturated fatty acid– Monounsaturated fatty acid– Polyunsaturated fatty acid


An impossible chemical structure

Oleic acid – 18-carbon, monounsaturated

Linoleic acid – 18-carbon, polyunsaturated


Fatty Acids

• Location of double bonds– Omega number

•Omega-3 fatty acid•Omega-6 fatty acid



Triglycerides

• Degree of unsaturation revisited– Firmness– Stability

•Oxidation–Antioxidants



Triglycerides

• Degree of unsaturation revisited– Hydrogenation–Cis vs. trans-fatty acids




Phospholipids


Phospholipids

• Phospholipids in foods

• Roles of phospholipids– Plasma

membrane– Emulsifiers


Phospholipids


Sterols


Sterols

• Sterols in foods


Sterols

• Roles of sterols– Bile acids– Sex hormones– Adrenal hormones– Vitamin D


Sterols

• Cholesterol and atherosclerosis


Lipids

• Hydrophobic vs. hydrophilic


Fat Digestion

• Hydrolysis– Triglycerides monoglycerides, fatty

acids, glycerol


Fat Digestion


Fat Digestion

• Mouth– Melting– Lingual lipase


Fat Digestion

• Stomach– Churning and mixing– Gastric lipase


Fat Digestion

• Small intestine– CCK

•Bile and emulsification


Fat Digestion


Fat Digestion


Fat Digestion

• Small intestine– Pancreatic lipases– Intestinal lipases


Fat DigestionOverview


Fat Digestion

• Enterohepatic circulation


Lipid Transport

• Lipoproteins– Chylomicrons– VLDL = very-low-density lipoproteins– LDL = low-density lipoproteins– HDL = high-density lipoproteins


Lipid Transport

• Lipoproteins and health– LDL vs. HDL


Roles of Triglycerides

• Fat stores– Energy– Protection– insulation


Essential Fatty Acids

• Linoleic acid and the omega-6 family– Arachidonic acid





• Linolenic acid and the omega-3 family– EPA =eicosapentaenoic acid– DHA = docosahexaenoic acid



• Eicosanoids– EPA derived vs. arachidonic acid

derived

• Fatty acid deficiencies



Health Effects of Lipids

• Benefits from monounsaturated fats and polyunsaturated fats


Health Effects of Lipids

• Benefits from omega-3 fats

• Balance omega-6 and omega-3 intakes


Recommended Intakes of Fat

• DRI: 20% - 35% of energy intake


Recommended Intakes of Fat

• Linoleic acid AI– 5% - 10% of energy intake

• Linolenic acid AI– 0.6 - 1.2% of energy intake


Guidelines to Groceries

• Meats and meat alternatives




• Milk and milk products• Vegetables, fruits, and grains• Invisible fat




• Fat replacers– Artificial fats

•Olestra


High-Fat Foods• Changing guidelines for fat intake


High-Fat Foods

• Cook with olive oil

• Nibble on nuts

• Feast on fish– But beware of mercury

© 2006 Thomson-Wadsworth The Lipids Triglycerides Phospholipids Sterols.

Documents

fatty acidomega

monounsaturatedlinoleic

fat intakehighfat foodscook

fatsbalance omega

energy intakeguidelines

monounsaturated fats

lowdensity lipoproteinshdl

grainsinvisible fatguidelines