The aging gut. Nutritional issues.

With improvements in health care, living standards, and socioeconomic status, more adults are living to old age. As the population ages, it is increasingly important to understand the factors that affect the nutritional status and thus the health status of older adults. Many factors contribute to inadequate nutrition, including health status, financial capacities, mobility, exercise, and physiologic needs. This article considered only the potential changes in nutritional needs because of alterations in the gastrointestinal tract owing to aging. One of the most remarkable changes with aging is the frequent development of atrophic gastritis and the inability to secrete gastric acid. This process affects approximately a third of older adults in the United States and only recently was recognized to be due to infection by H. pylori in the majority of cases. The lack of gastric acid in atrophic gastritis may lead to small intestinal bacterial overgrowth and influences the absorption of a variety of micronutrients, including iron, folate, calcium, vitamin K, and vitamin B12. Lactose maldigestion is a frequent condition in older adults and is extremely common worldwide. The intolerance of dairy products leads to avoidance of these foods and likely contributes to the development of osteopenia. Overall, the small intestine and pancreas undergo astonishingly few clinically significant changes with aging. The relative preservation of overall gastrointestinal function with aging is likely due to the large reserve capacity of this multiorgan system. Further research is needed to define the precise nutritional needs for older adults because simple extrapolation of values from younger adults is now recognized to be insufficient. In addition, it is no longer acceptable to define adequate nutriture in terms of amounts of vitamins needed to maintain serum levels of a nutrient. Further RDAs must consider the functional implications of adequate nutrition. Nutrients in the elderly will be measured as to whether they result in improvements in markers of chronic disease such as homocysteine or, most importantly, in the prevention of chronic disease such as osteoporosis and cardiovascular disease.