Special Dietary Needs. Modifications for the Life Cycle

A. Vegetarian Diets. Some people adopt vegetarian diets, often out of philosophical or religious conviction. Forms of vegetarianism include lacto-ovo-vegetarian, lacto-vegetarian, ovo-vegetarian, and strict or pure vegetarian (vegan) (see Glossary). Vegetarians usually consume significantly less total fat, saturated fat, and cholesterol, and more polyunsaturated fat, carbohydrate, and dietary fiber than in the usual American diet. Meeting protein needs and consuming all the essential amino acids is increasingly difficult in the more restricted forms of vegetarianism.

The amino acids missing in any one grain or vegetable can be replaced by consuming several together in the same meal or adding dairy products (Table V). Vegan diets may be nutritionally inadequate if there is undue reliance on a single plant food source. Infants and children on vegan diets are particularly likely to develop symptomatic clinical nutritional deficiencies, with retarded growth and development. The four groups of plant foods relied on by vegans are legumes, cereal grains, fruits and vegetables, and nuts and seeds.

Other nutrients that may be deficient in vegan diets are vitamin B₁₂, vitamin D (for children not exposed to sunlight), riboflavin, calcium (especially for children and women), and iron (for women of childbearing age). Generous servings of green leafy vegetables, dried beans, sesame seeds, onions, and soybean milk will supply riboflavin and calcium, whereas beans, seeds, nuts, green leafy vegetables, dried fruits, and grains will supply iron.

B. The Athlete. Following the recommended dietary allowances will provide all necessary nutrients for a physical conditioning program. The diet that contributes to the best performance by the recreational or world-class athlete is that which is best for the nonathlete: a nutritionally balanced diet supplying appropriate quantities of water, energy, protein, fat, carbohydrate, vitamins, and minerals. Commercially promoted food supplements and drugs offer nothing to the healthy, well-nourished athlete and should be rejected.

Modifications for the Life Cycle . A. Pregnancy and Lactation. The critical period in which the developing fetus is influenced most by diet is between 17 and 56 days after conception. Many women do not know that they are pregnant until beyond this period; therefore the diet should be optimized prior to pregnancy. Any unhealthy eating practices or nutritional deficiencies should be corrected prior to conception. Guidelines for nutrition during pregnancy and lactation from the Institute of Medicine, National Academy of Science, were updated in 1992.

The pregnant woman should increase her food intake by about 300 calories per day, increase protein 20% and calcium 50%, and double the folic acid and iron intakes for optimal outcome. The normal-weight pregnant woman should gain 25-35 pounds, underweight and young adolescents up to 40 pounds, whereas the overweight woman should not gain more than 15-25 pounds.

Weight gain should begin in the second trimester. Additional calories are usually provided by complex carbohydrate (bread, vegetable, and fruit groups). The diet should include increased servings of the milk and meat group to provide extra protein. The calcium requirements are met by a higher intake of the milk group and foods rich in calcium. Iron supplementation is recommended, and many nutritionists recommend folate supplementation in order to achieve folate status that is adequate to prevent neural tube defects.

The lactating woman’s major increased needs are for calories, protein, and calcium, especially if lactation exceeds 3 months. These needs can be met by including 1 quart of whole milk per day in the diet.

B. Pediatric Needs. Infancy is the only time in life when a single food comprises the entire diet. Though commercial infant formulas meet nutritional needs, breastfeeding is recommended to nourish the healthy term infant, particularly for the first 6 months. Formula may be replaced with up to 1 quart per day of cow’s milk at about the first birthday. At that time the child will be consuming iron-rich foods such as fortified infant cereals or meats. Solid foods are added to the baby’s diet during the first half of the first year (4-5 months), with the first food usually being a single-grain cereal.

Strained fruits and yellow vegetables are then added, followed by green vegetables, meats, and egg yolks. Citrus, seafood, nut butters, chocolate, nitrate-containing vegetables, and egg whites are not introduced until the end of the first year. The older child should eat a variety of foods distributed according to the food pyramid. The adolescent requires increased calories, calcium, and iron. These needs are not met (except for calories) by a diet of soft drinks, French fries, candy, and potato chips.

C. Geriatric Needs. Caloric needs are less, depending on the level of activity, for the elderly. Inactive elderly persons should consume foods of increased nutrient density, such as lean meat, fish, eggs, milk, and vegetables, and curtail fats and carbohydrates. Intakes of calcium, iron, zinc, selenium, and vitamins D, B₆, folate, B₁₂, and C may be inadequate or marginal, especially in low-income elderly. Good sources of these nutrients include dark green vegetables, whole-grain and enriched cereals, pasta and bread, meat, fish, poultry, dried beans and peas, milk, and milk products. A multivitamin supplement that is formulated for the elderly may be appropriate when energy intake is less than 1500 kcal/day or when the diet is restricted.

Bibliography. Agricultural Research Service (1975). “Composition of Foods,” Agricultural Handbook No. 8'. U.S. Department of Agriculture, Washington, D.C.
Feldman, E. B. (1988). “Essentials of Clinical Nutrition.” F. A. Davis Co., Philadelphia.
National Academy Press (1989). “Diet and Health.” National Academy Press, Washington, D.C.
National Academy of Sciences (1989). “Recommended Dietary Allowances,” 10th Ed. National Academy of Sciences, Washington, D.C.
Pennington, J. A. T. (1994). “Bowes and Church’s Food Values of Portions Commonly Used,” 16th Ed. Lippincott, Philadelphia.