Low body mass index (BMI) and micronutrient deficiencies are associated with increased morbidity and mortality rates in old age. Whether adverse patterns of dietary variety predict both low BMI and low micronutrient intakes in older adults was investigated.
A cross-sectional analysis of national survey data was conducted in 1174 healthy adult men and women (ages 21 to 90 years) who provided physiologically plausible dietary data in the 1994-1996 Continuing Survey of Food Intakes by Individuals. Measurements included reported energy intake, protein intake (percentage meeting Recommended Dietary Allowance), micronutrient intakes (percentage meeting Estimated Average Requirements for 14 micronutrients), and BMI.
Adults who were 61 years or older consumed a greater total variety of foods, chose foods from a wider range of food groups, had a greater variety of micronutrient-dense foods and energy-weak foods, and had a lower variety of micronutrient-weak foods compared with adults ages 21 to 60 years (p < .05 to.001). However, older adults with low BMIs (< 22 kg/m2) consumed a lower variety of energy-dense foods compared with older adults with higher BMIs (p < .05). The variety of energy-dense foods predicted both energy intake and BMI at all ages in multiple regression models controlling for confounding variables (R2 = .124 for energy, R2 = .574 for BMI, p < .001). A higher percentage of older persons had inadequate micronutrient intakes compared with younger persons (p < .05), especially vitamin E, calcium, and magnesium, but consumption of a particularly wide variety of micronutrient-rich foods helped counterbalance these trends (p < .05). Older adults who had a low BMI and consumed a low variety of micronutrient-dense foods were particularly at nutritional risk, with only 65.4% consuming the Recommended Dietary Allowance for protein and none meeting the Estimated Average Requirements for all 14 micronutrients.
In contrast to previous suggestions that older persons consume a monotonous diet, this study showed that adults who were 61 years or older consumed a greater total food variety, and a greater variety of micronutrient-dense and energy-weak foods, compared with adults who were 60 years or younger. Although consumption of a low variety of energy-dense foods may contribute to reduced energy intake and body weight at any age, the variety of micronutrient-dense foods consumed needs to increase in old age to prevent micronutrient deficiencies. These findings suggest that all adults need advice on the changing needs for dietary variety with aging to maintain health, and that older persons with low BMI are particularly vulnerable to dietary shortfalls.