Nutrient intake and immune function of elderly subjects

Food intake, aging, and immune function share complex influences. Therefore, the purpose of this study was to examine relationships between nutrient intakes from food and dietary supplements and a biomarker of immune function.

Data were collected from participants in a cross-sectional study as well as baseline data from a longitudinal study (n=89). Subjects completed 24-hour food recalls, including supplement intake. Polyclonal mitogen phytohemmagluttin (PHA) was the immune function stimulator used. Height and weight were used to calculate body mass index.

Descriptive, bivariate correlation, Spearman's rho for nonparametric data, t tests, and stepwise regression with nutrient intakes as independent variables and T-cell proliferation as dependent variables.

Significant positive correlations (P< or =0.05) were found between PHA-induced proliferation and intake of docosahexaenoic acid (DHA), eicosahexaenoic acid (EPA), sodium, and selenium, although intakes of DHA plus EPA were inadequate when compared to recommended intakes. A significant negative correlation with total vitamin A, with many vitamin A levels being above the upper limit of safety. Regression analyses found these nutrients to be variables significant in explaining the variance in PHA (P=0.005).

Selenium, sodium, DHA, EPA, and vitamin A intake from diet and supplements were associated with PHA-induced proliferative responses. Clients may be counseled to have adequate selenium, EPA, DHA intake, and vitamin A, but avoid excess vitamin A.