© 2006 Thomson-Wadsworth The Lipids Triglycerides Phospholipids Sterols.

© 2006 Thomson-Wadsworth

The Lipids

TriglyceridesPhospholipids

Sterols

© 2006 Thomson-Wadsworth

Lipids

• Triglycerides– Fats and oils

• Phospholipids

• Sterols

© 2006 Thomson-Wadsworth

Fatty Acids and Triglycerides

• glycerol

© 2006 Thomson-Wadsworth

Fatty Acids and Triglycerides

• glycerol + 3 fatty acids triglyceride + H2O

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Fatty Acids

• Fatty acids– Length– Saturated vs. unsaturated

© 2006 Thomson-Wadsworth

Fatty Acids

• Organic acids– Example: acetic acid

© 2006 Thomson-Wadsworth

Fatty Acids

• Length of carbon chain

Stearic acid – 18-carbon, saturated

Simplified structure

© 2006 Thomson-Wadsworth

Fatty Acids

• Point of saturation

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

© 2006 Thomson-Wadsworth

An impossible chemical structure

Oleic acid – 18-carbon, monounsaturated

Linoleic acid – 18-carbon, polyunsaturated

© 2006 Thomson-Wadsworth

Fatty Acids

• Location of double bonds– Omega number

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

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Triglycerides

• Degree of unsaturation revisited– Firmness– Stability

•Oxidation–Antioxidants

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Triglycerides

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

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Phospholipids

© 2006 Thomson-Wadsworth

Phospholipids

• Phospholipids in foods

• Roles of phospholipids– Plasma

membrane– Emulsifiers

© 2006 Thomson-Wadsworth

Phospholipids

© 2006 Thomson-Wadsworth

Sterols

© 2006 Thomson-Wadsworth

Sterols

• Sterols in foods

© 2006 Thomson-Wadsworth

Sterols

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

© 2006 Thomson-Wadsworth

Sterols

• Cholesterol and atherosclerosis

© 2006 Thomson-Wadsworth

Lipids

• Hydrophobic vs. hydrophilic

© 2006 Thomson-Wadsworth

Fat Digestion

• Hydrolysis– Triglycerides monoglycerides, fatty

acids, glycerol

© 2006 Thomson-Wadsworth

Fat Digestion

© 2006 Thomson-Wadsworth

Fat Digestion

• Mouth– Melting– Lingual lipase

© 2006 Thomson-Wadsworth

Fat Digestion

• Stomach– Churning and mixing– Gastric lipase

© 2006 Thomson-Wadsworth

Fat Digestion

• Small intestine– CCK

•Bile and emulsification

© 2006 Thomson-Wadsworth

Fat Digestion

© 2006 Thomson-Wadsworth

Fat Digestion

© 2006 Thomson-Wadsworth

Fat Digestion

• Small intestine– Pancreatic lipases– Intestinal lipases

© 2006 Thomson-Wadsworth

Fat DigestionOverview

© 2006 Thomson-Wadsworth

Fat Digestion

• Enterohepatic circulation

© 2006 Thomson-Wadsworth

Lipid Transport

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

© 2006 Thomson-Wadsworth

Lipid Transport

• Lipoproteins and health– LDL vs. HDL

© 2006 Thomson-Wadsworth

Roles of Triglycerides

• Fat stores– Energy– Protection– insulation

© 2006 Thomson-Wadsworth

Essential Fatty Acids

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

© 2006 Thomson-Wadsworth

Essential Fatty Acids

© 2006 Thomson-Wadsworth

Essential Fatty Acids

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

© 2006 Thomson-Wadsworth

Essential Fatty Acids

• Eicosanoids– EPA derived vs. arachidonic acid

derived

• Fatty acid deficiencies

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Health Effects of Lipids

• Benefits from monounsaturated fats and polyunsaturated fats

© 2006 Thomson-Wadsworth

Health Effects of Lipids

• Benefits from omega-3 fats

• Balance omega-6 and omega-3 intakes

© 2006 Thomson-Wadsworth

Recommended Intakes of Fat

• DRI: 20% - 35% of energy intake

© 2006 Thomson-Wadsworth

Recommended Intakes of Fat

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

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

© 2006 Thomson-Wadsworth

Guidelines to Groceries

• Meats and meat alternatives

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Guidelines to Groceries

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

© 2006 Thomson-Wadsworth

© 2006 Thomson-Wadsworth

Guidelines to Groceries

• Fat replacers– Artificial fats

•Olestra

© 2006 Thomson-Wadsworth

High-Fat Foods• Changing guidelines for fat intake

© 2006 Thomson-Wadsworth

High-Fat Foods

• Cook with olive oil

• Nibble on nuts

• Feast on fish– But beware of mercury