Serum concentrations of 25-hydroxyvitamin D and immunoglobulins in an older Swiss cohort: results of the Senior Labor Study.

Background: Vitamin D and the components of humoral immunity play important roles in human health. Older people have lower 25-hydroxyvitamin D (25(OH)D) serum levels than younger adults. We aimed to determine the levels of 25(OH)D serum concentrations in healthy senior citizens and to study their relationship to the levels of components of humoral immunity.