Geriatrics

Elderly people may have highly variable nutritional needs depending on their state of health. Metabolic changes have slowed the digestive rate, increased the fat-to-muscle ratio, and decreased liver and renal functions; all of these events have an impact on digestion, absorption, and excretion of vitamins and minerals. Use of medication also can have a significant impact on absorption and utilization of nutrients.

Dietary deficiencies in the elderly can occur for many reasons—for example, because older persons may not eat sufficient food, may not eat the correct foods, or may not eat an adequate variety of foods. Vitamin B₁₂ deficiency may result from decreased acidity of the stomach. The signs of vitamin deficiency may be subtle but always should be considered; for example, thiamine deficiency (associated with alcohol abuse) can cause Wernicke’s encephalopathy or organic amnestic syndrome, folic acid deficiency is associated with dementia, and vitamin B₁₂ deficiency can result in psychologic changes and peripheral neuropathy. Vitamin D deficiency is not uncommon among the elderly, especially in nursing home residents or others who do not get out in the sun. A vitamin D deficiency can contribute to osteoporosis.

Pediatrics

Pediatric RDAs for various vitamins and minerals vary widely; age and body weight are significant factors, and careful attention should be paid to children’s diets throughout the growing years. Nutrient deficiency states are always quickly seen and often are more devastating in children than in adults. Some deficiencies can have lifelong effects as well; for example, vitamin D deficiency causes abnormalities in bone ossification, causing bones to become soft and bend in a disease called rickets. Vitamin D therapy will stop further damage but will not correct many existing bone deformities.

As children grow, their need for supplementation changes. Breastfed infants get almost all the nutrients they need from their mother. The only supplements these babies may need are fluoride (which is present in only small amounts in breast milk) and an iron supplement after 4 to 6 months of age. Bottle-fed infants receiving infant formula are receiving the RDA through the formula. Consider the use of iron-fortified formula after age 4 months.

As they start to eat solid foods, however, many children develop strong food preferences, and parents can struggle to maintain a balanced diet. Balance over time is the important point to remember. Not every meal has to include every nutrient; ensuring a balance for the day is sufficient. Caution parents to avoid food conflicts by frequently offering small portions of foods from many sources. Vitamin supplementation is not necessary for a child who is willing to eat from many food groups, but it may be helpful in the child who eats only a small variety of foods.

A study published online by the Journal of Endocrinology and Metabolism revealed that children who followed a diet with limited fat content and high levels of dietary fiber had better fasting blood glucose levels and lower blood pressure and very low-density lipoprotein levels at ages 25 to 29 compared with those in the control group. Metabolic syndrome also was uncommon in the dietary-intervention group, the researchers found.

Pregnancy and Lactation

In general, almost all vitamin and mineral RDAs increase during pregnancy, to support the increase in metabolic rate and the demands of a growing fetus. These nutritional needs, with the exception of iron, can be met by most women through diet. Iron requirements during pregnancy are nearly impossible to meet by diet alone, and iron deficiency anemia may result. Folic acid supplementation is being recognized increasingly as an essential pregnancy nutrient, and many physicians are recommending the use of iron and folic acid supplements by all pregnant women.

One potential problem in pregnancy is vitamin and/or mineral toxicity. Nutrients that are particularly harmful to a developing fetus if provided in excess (10 or more times the RDA) include iron, zinc, selenium, and vitamins A, B₆, C, and D. Although some vitamins taken in excess just pass through the system and are excreted in the urine, other vitamins may be stored in tissues, and toxicity may develop. When megadoses of vitamins such as A and C are consistently taken, the body develops a tolerance for the higher doses.

Gender

Men’s nutritional needs remain relatively stable from late adolescence into old age. With aging, illness, and injury, dietary needs must be reassessed, and supplementation might be considered. Elderly men (>80 years) are at relative risk for osteoporosis. Adequate calcium intake is essential in elderly men and women.

Women’s needs vary widely throughout their lifetime. Until adolescence, children’s needs are essentially the same, and a gradual increase in RDA is noted for most nutrients. During adolescence, however, women’s dietary needs undergo striking changes.

With the onset of menses, dietary iron needs increase. Many women do not take in adequate amounts of dietary iron to compensate for monthly blood loss. This need decreases with the use of hormonal contraception. Adolescents and young women lower their relative risk of iron deficiency anemia when they use hormonal contraception.

It is certainly possible for an individual’s diet to provide sufficient iron, but because many women diet to keep their weight down and men may engage in excessive exercise, and because many individuals do not develop good food habits (or do not learn them during adolescence), many American diets are inadequate, and iron supplementation should be considered.

Folic acid supplementation (400 mcg) should be taken by all women of reproductive age. A deficiency in this B vitamin has been shown to be related to an increase in neural tube defects in the developing fetus.

Appropriate calcium intake is a significant problem for American women. Chronic calcium deficiency often starts in young women and worsens with age. As adolescence begins, many women stop drinking milk. Many women become deficient in calcium just when they need it most for pregnancy, lactation, and menopause. Bone loss accelerates during the first 5 to 10 years after menopause and if not stopped can lead to devastating consequences. In a study on white women, it was estimated that 25% of women older than age 70 and 50% of those over age 80 will show evidence of vertebral fracture. By the age of 90, 33% of all white women will have sustained a hip fracture, and many of these women will die as a direct result of complications related to the fracture. Comparable data are not available for women of other races. Initiation of calcium supplementation by age 35 has been proposed by many scientists; it should continue through menopause and should be added as an adjunct to bisphosphonate treatment for osteopenia or osteoporosis (see Chapter 39).

Vitamin D is another critical bone-building nutrient that many women lack when they need it most—as they age. Vitamin D promotes calcium absorption, and one without the other is useless. Taking a calcium supplement without paying attention to vitamin D does not help bones. Many women become deficient in vitamin D because they stop drinking fortified milk and do not spend sufficient time outside to absorb UV radiation to make vitamin D. Many women, because they are worried about the relative risks of skin cancer, cover all exposed skin if they do go outside, again blocking vitamin D absorption. Many research studies have suggested clinical problems linked to low Vitamin D levels but the quality of many studies is problematic at this time.

Controversy Over Antioxidants

The hypothesis that antioxidant vitamins might reduce the relative risk of many degenerative diseases is based on a large body of basic and human epidemiologic research. However this hypothesis is unsupported by randomized, placebo-controlled trials. One of the most consistent findings in dietary research is that those who consume larger quantities of fruits and vegetables have lower rates of heart disease, stroke, and cancer. Attention has been focused recently on the antioxidant content of fruits and vegetables as a possible explanation for their apparent protective effects.

Increasing evidence suggests that free radical reactions are involved in early or later stages of development of human disease; it is therefore of particular importance for researchers to explore whether vitamin E and other antioxidants found in the human diet may be capable of lowering the incidence of disease. Low levels of antioxidants, which increase free radical activity, are clearly associated with an increased relative risk of these diseases. Put simply, the proposition is that if human diets are improved by an increase in the quantity of antioxidants included in them, it might be possible to use this approach to reduce the incidence of numerous degenerative diseases.

Antioxidant vitamins, which include beta carotene (provitamin A), vitamin E, and vitamin C, are hypothesized to decrease cancer relative risk by preventing tissue damage by trapping organic free radicals and/or deactivating excited oxygen molecules—a byproduct of many metabolic functions. These micronutrients may be reduced by smoking and passive smoking.

Over the past decade, extensive studies on the health effects of antioxidants have been conducted, many with inconclusive findings. The largest analysis of data on antioxidant vitamins ever conducted, which was published by Bjelakovic et al in 2007, shows that on the whole, antioxidant vitamins confer no health benefits. In fact, beta carotene, vitamin A, and vitamin E may actually increase mortality. More recent studies suggest there may be some utility in antioxidants. In a 2011 study of 2264 U.S. women diagnosed with early-stage breast cancer, those who took supplements of vitamin C or vitamin E at least 6 days a week had a lower relative risk of cancer recurrence; however, the reduction in absolute risk was very low. More studies should be undertaken to evaluate the use of excessive exogenous antioxidants. It appears they may actually impair endogenous antioxidant reserves, thus impairing natural processes, and actually contribute to harm.