INTRODUCTION

• Nutrients are the constituents of food necessary to sustain the normal functions of the body.

• Nutrients needed in larger amounts such as those energy-rich molecules e.g., carbohydrate, fats and protein are called macronutrients.

• Those nutrients needed in lesser amounts such as vitamins and minerals are called micronutrients.

DIETARY FATS

• The incidence of a number of chronic diseases are significantly influenced by the kinds and amounts of nutrients consumed.

• Dietary fats have been linked to coronary heart disease.

• A. plasma cholesterol and coronary heart disease: plasma cholesterol may arise from the diet or from endogenous biosynthesis

• 1. LDL (low density lipoproteins) and HDL (high density lipoproteins): 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 coronary heart disease.

• Abnormal levels of plasma lipids (dyslipidemias) act in combination with smoking, obesity, sedentary lifestyle all increase the risk for coronary heart disease.

DIETARY FATS AND PLASMA LIPIDS

• TRIACYLGLYCEROLS: is the most important class of dietary fats. Their biologic properties are determined by:

• 1. the presence or absence of double bonds.• 2. the number and location of double bonds.• 3. the cis-trans configuration of the unsaturated

fatty acids.

• A. saturated fats: these are triacylglycerols that do not contain any double bonds.

• Consumption of saturated fats Is strongly associated with high levels of total plasma cholesterol and LDL cholesterol and an increased risk of coronary heart disease.

• SOURCES OF SATURATED FATS: coconut and palm oils, diary and meat products.

• B. monounsaturated fats: these are fatty acids with one double bond

• SOURCES: vegetables and fish.• Monounsaturated fats lower both plasma

cholesterol and LDL cholesterol but increase HDLs and thus a decrease in heart disease

• C. Polyunsaturated fatty acids: triacylglycerols containing primarily fatty acids with more than one double bonds.

• The effects of polyunsaturated fatty acids on cardiovascular disease is influenced by the location of the double bonds within the molecule e.g.,

• 1. n-6 fatty acids: these are polyunsaturated fatty acids with the first double bond beginning at the sixth carbon atom when counting from the methyl end of the fatty acid molecule e.g., linoleic acid

• They are also called the omega-6 (ω-6) fatty acids.• These fatty acids decrease cholesterol levels, LDL and

also HDL levels.• Sources: nuts, avocado, olives, soybeans, sesame,

cotton seeds and corn oils.

• 2. n-3 fatty acids: are polyunsaturated fatty acids with the first double bond beginning at the third carbon atom when counting from the methyl end of the fatty acid molecules e.g., linolenic acid

• These fatty acids decrease triacylglycerols but have little effect on LDL or HDL levels.

• Sources: plants and fish oils• 3. dietary cholesterol: is found only in animal products.

Increased levels of cholesterol have been associated with heart disease.

• 4. trans fatty fats: are chemically classified as unsaturated fatty acids but behave more like saturated fatty acids in the body.

• They elevate LDL levels but not HDL and they increase the risk of heart disease.

BENEFICIAL EFFECTS OF LOWERING PLASMA CHOLESTEROL

• Dietary or drug treatment of hypercholesterolemia is effective in decreasing LDLs, increasing HDLs and reducing the risk for cardiovascular heart disease.

• Treatment with “statin” drugs decreases plasma cholesterol.

DIETARY CARBOHYDRATES

• The primary role of dietary carbohydrate is to provide energy.

• CLASSIFICATION OF CARBOHYDRATES• 1. monosaccharides: glucose and fructose• 2. disaccharides: sucrose, lactose and maltose• 3. polysaccharides: starch• 4. fibers: is defined as the nondigestible

carbohydrates present in plants

FUNCTIONS OF FIBERS

• 1. Adds bulk to the diet.• 2. increases bowel motility• 3.delays gastric emptying and can result in

sensation of fullness.• 4. decrease the risk for constipation,

hemorrhoids, and colon cancer.• Recommended daily allowance of fiber:

25g/day for women and 38g/day for men.

DIETARY PROTEIN

• SOURCES:• 1. animal sources: meat, poultry, milk, fish• 2. plant sources: wheat, corn, rice and beans.

PROTEIN-CALORIE MALNUTRITION• There are two forms of malnutrition:

kwashiorkor and marasmus.

• Affected individuals show a variety of symptoms including a depressed immune system with a reduced ability to fight infections.

KWARSHIORKOR• Occurs when protein deprivation is greater than the

reduction in carbohydrates.• Kwarshiorkor is frequently seen in children after weaning

at about one year of age, when their diet consists predominantly of carbohydrates.

• Symptoms include: stunted growth, edema, skin lesions, depigmented hair, anorexia, enlarged fatty liver and decreased plasma albumin concentration.

• Edema results from the lack of adequate plasma proteins to maintain the redistribution of water between tissues and blood.

• A child with kwarshiorkor frequently shows a deceptively plump belly as a result of edema.

MARASMUS

• Occurs when there is insufficient calorie intake

• Symptoms: arrested growth, extreme muscle wasting, weakness and anemia.

• There is absence of edema.