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Chapter 070. Nutritional Requirements and Dietary Assessment (Part 1)

Harrison's Internal Medicine Chapter 70. Nutritional Requirements and Dietary Assessment Nutritional Requirements and Dietary Assessment: Introduction Nutrients are substances that must be supplied by the diet because they are not synthesized in the body in sufficient amounts. Nutrient requirements for groups of healthy persons have been determined experimentally. For good health we require energy-providing nutrients (protein, fat, and carbohydrate), vitamins, minerals, and water. Specific nutrient requirements include 9 essential amino acids, several fatty acids, 4 fat-soluble vitamins, 10 water-soluble vitamins, and choline. Several inorganic substances, including 4 minerals, 7 trace minerals, 3 electrolytes, and the ultratrace elements, also must. | Chapter 070. Nutritional Requirements and Dietary Assessment Part 1 Harrison s Internal Medicine Chapter 70. Nutritional Requirements and Dietary Assessment Nutritional Requirements and Dietary Assessment Introduction Nutrients are substances that must be supplied by the diet because they are not synthesized in the body in sufficient amounts. Nutrient requirements for groups of healthy persons have been determined experimentally. For good health we require energy-providing nutrients protein fat and carbohydrate vitamins minerals and water. Specific nutrient requirements include 9 essential amino acids several fatty acids 4 fat-soluble vitamins 10 water-soluble vitamins and choline. Several inorganic substances including 4 minerals 7 trace minerals 3 electrolytes and the ultratrace elements also must be supplied in the diet. The required amounts of the essential nutrients differ by age and physiologic state. Conditionally essential nutrients are not required in the diet but must be supplied to individuals who do not synthesize them in adequate amounts such as those with genetic defects those having pathologic states with nutritional implications and developmentally immature infants. Many organic phytochemicals and zoochemicals present in foods have health effects. For example dietary fiber has beneficial effects on gastrointestinal function. Other bioactive food constituents or contaminants such as lead may have negative health effects. Essential Nutrient Requirements Energy For weight to remain stable energy intake must match energy output. The major components of energy output are resting energy expenditure REE and physical activity minor sources include the energy cost of metabolizing food thermic effect of food or specific dynamic action and shivering thermogenesis e.g. cold-induced thermogenesis . The average energy intake is about 2800 kcal d for American men and about 1800 kcal d for American women although these estimates vary with body size and activity .