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Nutritional Requirements

By Adrienne Youdim, MD, Associate Professor of Medicine; Associate Professor of Medicine, David Geffen School of Medicine at UCLA; Cedars Sinai Medical Center

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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* for Some Macronutrients, Food and Nutrition Board, Institute of Medicine of the National Academies), and metabolic and physical activity. If energy intake exceeds expenditure, weight is gained. If energy intake is less than expenditure, weight is lost.

Daily dietary requirements for essential nutrients also depend on age, sex, weight, and metabolic and physical activity. Every 5 yr, the Food and Nutrition Board of the National Academy of Sciences/National Research Council and the US Department of Agriculture (USDA) issues the dietary reference intakes (DRIs) for protein, energy, and some vitamins and minerals (see Table: Recommended Dietary Reference Intakes* for Some Macronutrients, Food and Nutrition Board, Institute of Medicine of the National Academies, Recommended Daily Intakes for Vitamins, and Guidelines for Daily Intake of Minerals). For vitamins and minerals about which less is known, safe and adequate daily dietary intakes are estimated.

Pregnant women and infants have special nutritional needs.

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 (see Table: General Recommended Dietary Intakea for 40-Yr-Olds With Moderate Physical Activityb*). The web site provides a tool (SuperTracker) that helps people plan, analyze, track, and manage their diet and physical activity.

General Recommended Dietary Intakea for 40-Yr-Olds With Moderate Physical Activityb*

Food Groups





7 oz

6 oz


3.5 cups

2.5 cups


2 cups

1.5 cups


3 cups

3 cups


6 oz

5 oz


6 tsp

5 tsp

Estimated daily intakeh

2600 calories

2000 calories

aActual needed intake varies based on height and weight and is determined most accurately be monitoring how body weight changes in response to changes in dietary intake. The amounts for men are based on a height of 5 ft 10 in and a weight of 150 lb. The amounts for women are based on a height of 5 ft 6 in and a weight of 130 lb.

bAbout 30 to 60 min of moderate or vigorous activity (eg, brisk walking, jogging, biking, aerobic exercise, yard work) daily.

cAt least half should be whole grains. Generally, 1-ounce equivalents from the grains group = 1 slice of bread, 1 cup of ready-to-eat cereal, or 0.5 cup of cooked rice, cooked pasta, or cooked cereal.

dPeople should vary the vegetables they eat and include beans and peas, dark green vegetables (eg, broccoli, greens, lettuce, spinach), orange vegetables (eg, carrots, sweet potatoes, winter squash), starchy vegetables (eg, corn, potatoes), and other vegetables (eg, asparagus, cauliflower, mushrooms, tomatoes). Generally, 1 cup from the vegetable group = 1 cup of raw or cooked vegetables or vegetable juice or 2 cups of raw leafy greens.

eGenerally, 1 cup from the fruit group = 1 cup of fruit or 0.5 cup of dried fruit.

fOne cup from the dairy group = 1 cup of milk, yogurt, or soy milk (soy beverage), 1.5 ounces of natural cheese, or 2 ounces of processed cheese.

gThe protein foods group includes meat, poultry, seafood, beans, peas, eggs, processed soy products, nuts, and seeds. Generally, 1-ounce equivalents from the protein foods group = 1 ounce of meat, poultry or fish; 0.25 cup of cooked beans; 1 egg; 1 tablespoon of peanut butter; or 0.5 ounce of nuts or seeds.

hThese values are general estimates; daily caloric intake varies greatly from person to person.

Note: Individualized recommendations can be obtained by entering the relevant information at the USDA web site (MyPlate) using the SuperTracker tool.

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:

  • 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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