Vitamin A, D and E status in a Finnish population--a multivitamin study.

The serum concentrations of the three fat-soluble vitamins A, D and E, and the serum transport proteins for the first of these, were measured during the winter and summer in a healthy adult Finnish population. No statistically significant differences were found in the levels of vitamins A and E between the seasons. However, a marked seasonal variation was found in the levels of vitamin D metabolites, the serum concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D being higher in summer, and that of 1,25-dihydroxyvitamin D somewhat higher in winter, whereas the concentration of vitamin D-binding globulin remained constant throughout. The serum concentrations of vitamins A and E showed a marked interrelationship with a significant correlation (r = 0.512, P less than 0.001, n = 80). No outright deficiencies of the vitamins were found in this study, but the serum concentrations of 25-hydroxyvitamin D were rather low in winter. Supplementation with a moderate dose of vitamins A and E over a 2-month winter period did not affect the serum concentrations of these vitamins, whereas 250-500 i.u. of vitamin D daily markedly elevated the low 25-hydroxyvitamin D concentrations.