Lecture 36: Principles of Nutrition (2) PDF

Lippincott’s illustrated reviews Chapter 27 – Page 355 Lecture 36 Principles of Nutrition (2) 1  Specific Objectives By the end of this lecture students can be able to: Know acceptable macronutrient distribution Ranges (AMDR). Differentiate between...

Lippincott’s illustrated reviews Chapter 27 – Page 355 Lecture 36 Principles of Nutrition (2) 1  Specific Objectives By the end of this lecture students can be able to: Know acceptable macronutrient distribution Ranges (AMDR). Differentiate between benefit and harmful types of lipids. 2 3  IV. Acceptable macronutrient distribution Ranges (AMDR) AMDR are defined as a range of intakes for a particular macronutrient that is associated with reduced risk of chronic disease while providing adequate amounts of essential nutrients. The AMDR for adults is: 45–65% of their total calories from carbohydrates, 20–35% from fat, and 10–35% from protein. 4  Dietary fats influence the incidence of: coronary heart disease (CHD); risk for cancer or obesity is much weaker. Type of fat is more important than the total amount of fat consumed. 5 Plasma lipids and CHD A much stronger correlation exists between the levels of blood LDL cholesterol and heart disease. high levels of HDL cholesterol have been associated with a decreased risk for heart disease. Elevated plasma triacylglycerols are also a risk factor for CHD, but the association is weaker than that of LDL cholesterol with CHD 6 Saturated fat: Consumption of saturated fats (Triacylglycerols fatty acid that not contain any double bond) increases: Levels of total plasma cholesterol and LDL Risk of CHD. The main sources are :dairy and meat products and some vegetable oils, such as coconut and palm oils. 7 Monounsaturated fats: Containing fatty acids with one double bond. Generally derived from vegetables and fish. Lower both total plasma cholesterol and LDL Maintain or increase HDL cholesterol. Show a low incidence of CHD Example: oleic acid 8 Polyunsaturated fats (PUFAs): Triacylglycerols containing fatty acids with more than one double bond. The effects of polyunsaturated fatty acids (PUFAs) on cardiovascular disease is influenced by the location of the double bonds within the molecule. 1. ω-6 Fatty acids: Example: linoleic acid, 18:2(9,12), Obtained from vegetable oils Lowers plasma cholesterol and LDL Lowers HDL, which protect against CHD. Sources :Nuts, avocados, olives, soybeans, and various oils, including sesame,cotton-seed, and corn oil. 9 2. ω-3 Fatty acids: Example : linolenic acid, 18:3(9,12,15), are found in plants. Suppress cardiac arrhythmias Reduce serum triacylglycerols Lower blood pressure Decrease the tendency for thrombosis Substantially reduce risk of cardiovascular mortality, They have little effect on LDL or HDL cholesterol levels. 10  Two fatty fish (for example, salmon) meals per week are recommended. [Note: The ω-3 long-chain PUFAs are included in infant formulas to promote brain development.] 11 Trans fatty acids: Classified as unsaturated fatty acids, but behave more like saturated fatty acids Elevate serum LDL (but not HDL) Increase the risk of CHD. Are formed during the hydrogenation of liquid vegetable oils(manufacture of margarine, hydrogenated vegetable oil). major component of commercial baked goods, such as cookies , cakes, and most deep-fried foods. 12 Reference Book: Champe, P. C., Harvey, R. A. and Ferrier, D. R., 2005. Biochemistry “Lippincott’s Illustrated Reviews”, 5th or 6th Edition 13