It is the physiological changes that occur with aging that alter nutrient needs. Gradual loss of lean body mass and reduced energy expenditure lower caloric needs. However, nutrient needs remain the same or in some cases increase. As a result, packing more nutrition into fewer calories becomes a challenge for older adults. For this reason, focusing on quality food choices becomes paramount.
While adults are not easily categorized, certain nutrients require greater attention as people age. Which vitamins and minerals are critical depends on the health status of the individual. Specific dietary recommendations are set for two age groups: adults 51-70 years old and those 70 and older. Adult Dietary Reference Intakes (DRIs) increase with age for vitamins C, D, K and B6, as well as calcium. Additionally, Dietary Guidelines for Americans 2005, published jointly by the U.S. Department of Health & Human Services (USDHHS) and the U.S. Department of Agriculture (USDA), highlights special key issues for older adults. “Nutrients are interactive; many nutrients are needed within each system of the body for that system to run efficiently,” says Adele Huls, PhD, RD, LMNT, chair elect of the American Dietetic Association’s (ADA) Healthy Aging Dietetic Practice Group. “Those needs continue as we age. So, in essence, all nutrients have benefits in aging.” Let’s review some of the most important.
Calcium. As it ages, the body does not absorb calcium as easily as it used to. Increased calcium excretion accompanies decreased absorption. Age-associated loss of bone density increases risk for fractures and osteoporosis. Losses of skeletal calcium in postmenopausal women can reach more than 40% (Tucker 2003). Because bone fractures are a significant contributor to morbidity and mortality in older people, achieving daily calcium needs is critical; yet only 5% of older women and 10% of older men consume the DRI recommendation (Tucker 2003).
Vitamin D. Evidence suggests that vitamin D, best known for its role in bone health, may have a function in preventing a number of diseases. A recent meta-analysis concluded that adequate vitamin D intake is associated with lower death rates from all causes (Autier & Gandini 2007). According to the Dietary Guidelines, the need for the “sunshine vitamin” increases from 10 to 15 mcg after age 50 as blood levels of vitamin D decline. For the elderly, higher amounts (25 mcg, or 1,000 IU) from both fortified foods and supplements have been recommended.
Vitamin B12 and Folate. Most individuals over age 50 have a reduced ability to absorb naturally occurring vitamin B12 and must therefore consume it in its crystalline form (fortified foods or supplements). Vitamin B12 deficiency can cause cognitive dysfunction and neurological problems in older people (Carmel 1997).
Sodium. Since many people will develop hypertension at some point during their lifetime—and typically the higher their salt intake, the higher their blood pressure will be—older adults should aim to consume no more than 1,500 milligrams (mg) of sodium per day (about ¾ teaspoon of salt). Older adults as a group tend to be more salt sensitive.
Fiber. Since constipation may affect up to 20% of people over age 65, foods rich in dietary fiber become increasingly important for older adults (USDHHS 2005). Additional causes of constipation among this age group may include side effects of medications and lack of appropriate hydration. Low fiber intake may also contribute to other gastrointestinal diseases common among older adults, including diverticulosis.
Adequate fluid intake not only eases constipation; it also helps avert dehydration, a serious threat to the elderly. Causes of impaired fluid and electrolyte balance include physiologic impairments in renal function and thirst perception, reduced body fluid and blunted medication effects (Ritz 2001). Severe dehydration in the elderly can lead to cognitive impairment and functional decline.
Other Nutrients. The role of antioxidants in the aging process is worth mentioning. Zinc, along with vitamins C and E, and the phytochemicals lutein, zeaxanthin and beta carotene from food sources, may help prevent or slow the onset of age-related macular degeneration, the leading cause of blindness in people over age 55. Evidence suggests that low dietary intake of these nutrients may also increase cataract risk (ADA 2005).