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Nutritional Requirements


Adrienne Youdim

, MD, David Geffen School of Medicine at UCLA

Last full review/revision May 2019| Content last modified May 2019
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Good nutrition aims to achieve and maintain a desirable body composition and high potential for physical and mental work. Balancing energy intake with energy expenditure is necessary for a desirable body weight. Energy expenditure depends on age, sex, weight (see table Recommended Dietary Reference Intakes Recommended Dietary Reference Intakes* for Some Macronutrients, Food and Nutrition Board, Institute of Medicine of the National Academies Nutrition is the science of food and its relationship to health. Nutrients are chemicals in foods that are used by the body for growth, maintenance, and energy. Nutrients that cannot be synthesized... read more ), and metabolic and physical activity. If energy intake exceeds expenditure, weight is gained. If energy intake is less than expenditure, weight is lost.

The USDA publishes MyPlate, which helps people develop a healthy eating style and make healthy food choices that suit their individual needs. The recommendations are individualized based on age, sex, and physical activity.\


Generally, the recommended intake decreases with aging because physical activity tends to decrease, resulting in less energy expended.

The the following general guidelines are emphasized for adults and children:

  • Increasing consumption of whole grains

  • Increasing consumption of vegetables and fruits

  • Substituting fat-free or low-fat milk products (or equivalents) for whole-fat milk products

  • Reducing consumption of saturated fats

  • Reducing or eliminating consumption of trans fatty acids

  • Exercising regularly

Adequate fluid intake is also important.

Fats should constitute ≤ 28% of total calories, and saturated and trans fatty acids should constitute < 8%. Excess intake of saturated fats contributes to atherosclerosis. Substituting polyunsaturated fatty acids for saturated fats can decrease the risk of atherosclerosis.

Routine use of nutritional supplements is not necessary or beneficial; some supplements can be harmful. For example, excess vitamin A can lead to hypervitaminosis A, with headaches, osteoporosis, and rash.

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Nutritional Requirements
Which of the following is the general recommended dietary intake of protein (in ounces) for 40-year-old men who participate in 30 to 60 minutes of moderate physical activity on a daily basis?
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