Principle of Nutrition Wassim Y. Almawi , Ph.D. September 2016

1. Principle of Nutrition Wassim Y. Almawi, Ph.D. September 2016

2. Nutrition • Nutrients: food constituents needed for sustaining and driving normal body functions. • Nutrients provide: • Energy • Essential molecules which: • Cannot be synthesized by the body (henceessential) or, • Can not be synthesized at a rate sufficient to meet the needs for growth and maintenance.

3. Essential Nutrients • Proteins/Amino Acids • Fatty acids • Vitamins: • Both water- and fat-soluble vitamins • Minerals: • Including: calcium, phosphorous, sodium, potassium, and iron.

4. Dietary Reference Intakes

5. Recommended Dietary Allowance (RDA) • An estimate of the amount of a nutrient needed to meet the needs of 95% of the population. • Does not indicate the minimal requirement for healthy individuals;it recommends/provides a margin of safety for most individuals. • Is designed to prevent nutrition-deficiency syndromes (rickets and scurvy). • Maintenance of optimal health, and prevention of some diseases may require provision of a number of nutrients in amounts exceeding those of RDA.

6. RDA & Adequate Intake (AI)

7. Personal RDA & AI

8. Factors Affecting RDA • Age: • Adults requirements: 0.8 g of protein/kg body weight • Infants: more than 2.0 g of protein/kg body weight. • Gender/Sex: • Males: RDA for males 20% greater than those for women • Females: increased RDA allowance for iron to compensate for the periodic iron loss during menstruation. • Physiological and pathological: • Pregnant and lactating women: 20% to 30% increased RDA for most nutrients. • Increased requirement of some nutrients in patients with injury and illnesses.

9. Energy Requirements • Recommended energy intake: • Adult 70 kg man: 2900 kcal (12,142 kJ) • Adult 50 kg woman: 2100 kcal (8,800 kJ). • The energy intake depends on the type of food: • Energy content of fat is more than twice that of protein or carbohydrate. • Energy content of ethanol is intermediate between fat and carbohydrate.

10. Total Energy Requirements Total energy requirement = the sum of three energy-dependent processes: • Basal Metabolic Rate (BMR): • Energy expended in resting, post absorptive state for normal body functions (respiration, blood flow). • Thermic Effect of Food: • Increased heat production (30%) during food digestion and absorption. • Physical Activity: • Provides for the greatest variation in energy requirements.

11. Essential Nutrients • Proteins/Amino Acids • Fatty acids • Vitamins: • Both water- and fat-soluble vitamins • Minerals: • Including: calcium, phosphorous, sodium, potassium, and iron.

12. Fats & Oils • Triacylglycerol constitute the majority (90%) of dietary lipids. • Lipids (triacylglycerols) are needed for: • Providing essential fatty acids. • absorption of dietary fat soluble-vitamins.

13. Carbohydrates • Monosaccharides: The principal monosaccharides are: • Glucose (fruits, sweet corn, corn syrup and honey) • Fructose (honey and fruits). • Disaccharides: The most abundant disaccharides are sucrose, lactose and maltose. • Polysaccharides: Complex sugars, including starch found in plants, wheat, and vegetables. • Dietary fiber: • Non-digestible carbohydrates (cellulose, lignin and pectin). • Increases the bowel motility, and thus reduces the exposure to carcinogens, and thus the risk of cancer, constipation, and hemorrhoids.

14. Proteins • Provide essential amino acids for protein synthesis. Sources: • Animal: contain all essential amino acids. • Plants: do not contain all essential amino acids, thus have lower biologic value than animal proteins. • Healthy adults have a normal nitrogen balance, which occurs when the amount of nitrogen consumed equals that of excreted nitrogen (urine, sweat, feces).

15. Nitrogen Balance • Nitrogen Balance: Difference between nitrogen consumed and excreted nitrogen • Positive Nitrogen Balance: • Consumed nitrogen exceeds excreted nitrogen. • Typically seen in : • Children & pregnancy • Recovery from a severe illness, • Some pathological conditions, such as tissue growth. • Negative Nitrogen Balance: • Excreted nitrogen exceeds consumed nitrogen. • Associated with: • Inadequate dietary protein intake, • Lack of an essential amino acid • Physiologic stresses: trauma, burns, illness or surgery.

16. Minerals • As they cannot be made by living systems, minerals which originate in the earth, must be provided for adequate physiological processes. • Since plants obtain minerals directly from soil, dietary minerals come directly from plants, or indirectly from animal sources. • Minerals are also present in drinking water in variable proportions depending on the geographical location.