Lipids: Fats and Oils All Food Fats Were Not Created Equal!

Classification of Lipids b Triglycerides-A glycerol and 3 fatty acids Saturated Fatty acids-carries maximum number of hydrogen atomsSaturated Fatty acids-carries maximum number of hydrogen atoms Unsaturated Fatty Acids-one or more points of unsaturation occurUnsaturated Fatty Acids-one or more points of unsaturation occur –Monounsaturated (MUFA)-contains one point of unsaturation –Polyunsaturated (PUFA)-contains two or more points of unsaturation –Omega 6 (linoleic)-leafy veggies, seeds, nuts, grains, oils –Omega 3 (linolenic)- oils, nuts, seeds, soybeans

Classification (con’t) b Phospholipids-similar to a triglyceride, but having a phosphorus-containing acid in place of one of the fatty acids (lecithin) b Sterols-most common is, which is a soft waxy substance made by the liver and found in animal foods, but not an essential nutrient b Sterols-most common is cholesterol, which is a soft waxy substance made by the liver and found in animal foods, but not an essential nutrient

Lipid Structures

The Fatty Acids

Fatty Acid Structure (Fig. 5-1-A) omega endalpha end degree of saturation H H H H H H H H H H H H H H H H H O H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

Saturated Fatty Acid Structure (Fig. 5-1-A) omega endalpha end degree of saturation: single carbon bond H H H H H H H H H H H H H H H H H O H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

Monounsaturated Fatty Acid Structure (Fig. 5-1-B) omega endalpha end One double bond H H H H H H H H H H H H H H H O H-C--C--C--C--C--C--C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

Polyunsaturated Fatty Acid Structure (Fig. 5-1-C) omega endalpha end > 2 double bonds H H H H H H H H H H H H H O H-C--C--C--C--C--C=C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

Carbon Chain Length of Fatty Acids b Long chain FA > 12 Carbons> 12 Carbons b Medium chain FA Carbons Carbons b Short chain FA < 6 Carbons< 6 Carbons

Comparing Dietary Fats

Healthful Oils

Fat in the USDA Pyramid

Processed Fats and Hydrogenation b Hydrogenation is adding hydrogen atoms under pressure to solidify an oil b Forms trans fatty acids b Try to avoid hydrogenated and partially hydrogenated fats in foods Increases blood cholesterol levelsIncreases blood cholesterol levels Decrease HDL’s and increases LDL’sDecrease HDL’s and increases LDL’s b Check labels (i.e.margarines)

Minimize Intake of Trans Fatty Acid b Limit use of hydrogenated fats b Limit deep-fried foods b Limit high fat baked goods b Limit use of non-dairy creamers

Rancidity b Decomposed oils b Breakdown of the C=C double bonds by ultraviolet rays, O 2 b Yields unpleasant odor and flavor b PUFA more susceptible b Limits shelf life

Prevention of Rancidity b Hydrogenation (Not recommended) b Addition of vitamin E b Addition of Butylated hydroxyanisol (BHA) and Butylated hydroxytolune (BHT) b Refrigerate b Consume in a reasonable time

Digestion and Absorption of Fats b Digestion Liver makes bileLiver makes bile Gallbladder stores bile, then releases into small intestineGallbladder stores bile, then releases into small intestine Bile Emulsifies fatBile Emulsifies fat Pancreas releases enzyme splitting triglycerides into Monoglycerides, Glycerol, and FAPancreas releases enzyme Lipase splitting triglycerides into Monoglycerides, Glycerol, and FA b Absorption Monoglycerides, Glycerol, and FA absorbed through wall of small intestine Smaller fats absorbed into blood and carried as lipoproteins Larger fats absorbed into lymphatic system as chylomicrons

Fat Digestion and Absorption

Functions of Fat b Stores energy b Cushion vital organs b Insulates the body and maintain body temperature b Transports essential fatty acids and fat soluble vitamins b Part of cell membrane structure b Offers satiety in meals b Enhances food flavor and aroma

Metabolism of Lipids z zChylomicrons y yTransport dietary fat z zVLDL y yTransport lipids made by the liver

Metabolism of Lipids b Lipoprotein Carriers High-density LipoproteinsHigh-density Lipoproteins –Contains a large percentage of protein –Returns cholesterol from storage places to the liver for dismantling and disposal –“Good cholesterol” Low-density LipoproteinsLow-density Lipoproteins –Contains a large percentage of cholesterol –Transfers lipids from liver to tissues –“Bad cholesterol”

Structures of Lipoproteins

How much Fat Do We Need? b Requirements 3% of Calories from linoleic acid3% of Calories from linoleic acid.3% of Calories from linolenic acid.3% of Calories from linolenic acid b Recommendations Govt. Recs. –No more than 30% total fat, < 65 grams/day –No more than 10% saturated fat –Less than 300mg from cholesterol WHO Recs.- lower limit 0% McDougall, Ornish, Pritikin Recs. –10-15% total fat

Essential Fatty Acids b Body can’t make it b Needed for immune function, vision, cell membrane, and production of hormone-like compounds

Essential Fatty Acid- Omega-3 (alpha- linolenic acid) omega endalpha end 1st double bond is located on the 3rd carbon from the omega end H H H H H H H H H H H H H H H H H O H-C--C--C=C--C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H

Omega-3 Fatty Acid b Primarily from fish, canola, and soybean oil b Found also in flax seeds and walnuts b Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are related b Metabolized to form eicosanoids b Recommended to eat fish 1-2 x per week or consume the plant sources given b Decreases blood clot formation b Lowers risk of heart disease

Essential Fatty Acid- Omega-6 (alpha-linoleic acid) omega endalpha end 1st double bond is located on the 6th carbon from the omega end H H H H H H H H H H H H H O H-C--C--C--C-- C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH H H H H H H H H H H H H H H H H H

Omega-6 Fatty Acid b Found in vegetable oils b Only need ~ 1 tablespoon a day b Increase blood clot b Increase inflammatory responses

Signs and Symptoms of Essential Fatty Acids Deficiency b flaky, itchy skin b diarrhea b infections b retarded growth and wound healing b anemia

Heart Disease b Symptoms take years to develop b Plaque build-up can begin in childhood b Myocardial infarction (heart attack) b Stroke

Risk Factors for Heart Disease b Age, Family History, Sex b Smoking, Stress b High blood pressure b High blood cholesterol (hyperlipidemia) >200 mg/dl of total cholesterol>200 mg/dl of total cholesterol HDL < 35 mg/dlHDL < 35 mg/dl Cholesterol/HDL Ratio >4.5 Female, >5.0 MaleCholesterol/HDL Ratio >4.5 Female, >5.0 Male b Diabetes b Lack of regular exercise and obesity

The National Cholesterol Education Program b Reduce fat intake to 7% of total energy intake from saturated fat if elevated LDL does not respond to previous reduction b PUFA up to 10% of Calories b MUFA 10-15% of Total Calories b Limit cholesterol to ~300 mg/day b Reduce cholesterol to 200 mg/day if LDL remains high b Increase Soluble Fiber to grams/daily

American Heart Association’s Recommendations b No RDA for fat b Eliminate smoking b < 30% of total energy intake (TEI) from all fats b 8% -10% of TEI from saturated fat b < 10% of TEI from PUFA b < 15% of TEI from MUFA b < 300 mg cholesterol/day b < 2400 mg sodium/day b Not recommended for children under 2 years old

Dr. Dean Ornish’s Program for Reversing Heart Disease b 10% of Total Fat Calories b Almost no Saturated Fat b Half of Fat Intake Each MUFA and PUFA b 5mg/day of Cholesterol b 70-75% Carbohydrate b 10-15% Protein

Dr. Nathaniel Pritikin’s Program b 10% of Total Fat Calories b Almost no Saturated Fat b Low MUFA and PUFA b <100mg/day of Cholesterol b 75-85% Carbohydrate b 10-15% Protein b >35 grams/daily Fiber b <1600 mg/daily Sodium

The Mediterranean Diet b Abundant in plant foods b Olive oil and nuts are the most abundant sources of fat b Saturated fat <7% of total calories b Wine consumed in low to moderate amounts b Physical activity encouraged b Heart disease rates are low

Review of Lifestyle Habits to Reduce Risk of Heart Disease   Fat may  Heart Disease   Saturated Fat may  Heart Disease   Hydrogenated Fats may  Heart Disease   Phytochemicals may Heart Disease   Omega 3’s and MUFA may Heart Disease   Fiber Intake   Physical Activity

Avoid a Heart Attack