Immunity in frail elderly: a randomized controlled trial of exercise and enriched foods

To examine the effects of 17-wk physical exercise and enriched foods on cellular immune response (CIR) in frail elderly.

A total of 112 independently living, frail elderly men and women (mean age 79.2 +/- 5.9) received: twice weekly comprehensive, moderate intensity, progressive group exercise (group A, N = 26); daily enriched foods (group B, N = 31); both (group C, N = 29); or neither (group D, N = 26). Exercises focused on skills training. Foods were enriched with micronutrients with a high prevalence of deficiency in older people (at 25-100% the RDA). A social program and identical regular foods were offered as a control. CIR was measured by delayed-type hypersensitivity skin test response (DTH) against seven recall antigens expressed as the total number of positive responses and sum of diameters of all positive responses.

No independent or interactive effect of enriched foods was observed. Therefore, exercise (groups A + C) was compared with no exercise (groups B + D). Nonexercising subjects showed an average decline of 0.5 responses compared with an unchanged responsiveness among exercising subjects (difference = 0.5, 95% CI: 0.04-0.89, P = 0.03 adjusted for baseline DTH, activity level, and micronutrient status). Nonexercising subjects had a larger decline in the sum of diameters of all positive responses than exercising subjects but the difference did not reach significance (adjusted difference = 2.1 mm, 95% CI:-1.0-4.8).

Exercise may prevent or slow the age-related decline in immune response. Micronutrient enriched foods showed no effect. As infectious diseases can have debilitating or even fatal consequences for the elderly, prevention of the age-related decline in CIR could significantly improve their quality of life.