6 The Role of Nutrition, Weight, and Exercise on the Aging Spine
Nutrition
Elderly populations are predisposed to malnutrition due to a variety of causes. The physiological changes associated with aging are altered glucose regulation and impaired hormonal homeostasis. There is decreased absorption of macronutrients (carbohydrates, proteins, and fatty acids) as well as micronutrients.1 The decreased absorption of micronutrients in the elderly population is significant for cobalamin, calcium, vitamin D, riboflavin, and niacin.
Calcium absorption declines in both sexes in the elderly, and is directly related to vitamin D metabolism. Cobalamin (vitamin B12) absorption decreases in the elderly and predisposes them to subacute combined degeneration of the spinal cord.2 Other vitamin B complexes may also have malabsorption, leading to neuropathies. The elderly have consistently lower levels of vitamin D. In a European study, vitamin D levels are lowest in winter in the elderly.3 This tendency of decreased sun exposure and decreased capacity of the aging kidney to convert vitamin D to active form may reduce endogenous levels of vitamin D. Western diets only supply 25% to 50% of the vitamin D daily requirement; hence, supplementation in the elderly is crucial.
Anorexia and decreased food intake is prevalent in the elderly population.4 Other than the previously noted causes of anorexia, elderly patients also suffer from psychological anorexia. It may originate from various life events such as loneliness, death of a spouse, lack of social life, estrangement from family, and loss of independence. It is important to recognize these major life events and provide the elderly population with counseling and support. Anorexia may also originate from the natural process of aging and changes within the central nervous centers for feeding and hydration. Although this change is inevitable and irreversible, it should not necessarily lead to undernourishment but merely readjust the food intake to the new levels. However, due to the complex interactions of aging, coexisting conditions, and life events occurring around aging, it may lead to malnutrition if not monitored.