Nutrition in the elderly.

Nutritional modulation is one approach to successful aging. In animals, dietary restriction increases life span. Alterations in the macronutrient and micronutrient constituent of the diet can modulate gene expression. Anorexia is common in elderly persons. The results of studies in animals suggest that aging is associated with a decrease in the opioid feeding drive and an increase in the satiating effect of cholecystokinin. Unrecognized depression is a common, treatable cause of anorexia and weight loss in elderly persons. Protein synthesis decreases in elderly persons; nevertheless, nitrogen balance can be maintained in patients with fairly low intakes of protein. Carbohydrate intolerance is common and may be modulated by nutritional intervention and physical activity. The role of cholesterol in the development of heart disease in very old persons is controversial. Homebound and institutionalized elderly persons often do not expose their skin to sunlight; because the skin of older persons has a decreased ability to form vitamin D, the vitamin D status in these persons is precarious and they are at risk for osteopenia. Vitamins are often abused by elderly persons. Drug administration alters the vitamin requirements of persons. Borderline zinc state has been associated with deteriorating immune function, especially in persons who have diabetes mellitus or who abuse alcohol. Zinc administration appears to protect against the deteriorating vision associated with age-related macular degeneration. Selenium deficiency seems to be associated with an increased prevalence of cancer.