Plasma Levels of Vitamin D Metabolites in Elderly Subjects and Effects of Single Oral Administration of Multivitamin Tablets

Abstract

To clarify the nutritional status of vitamin D in elderly subjects, the plasma levels of 25-hydroxyvitamin D (25-OH-D) and 1α, 25-dihydroxyvitamin D (1, 25-(OH)_2D) and the effects of single oral administration of multivitamin tablets (200 IU/day of vitamin D_2) on plasma levels were compared with those in young adults. Separative assay on the vitamins D_2 and D_3 compounds of 25-OH-D and 1, 25(OH)_2D was performed. When the concentrations of these compounds in the plasma were assayed before administration of multivitamin tablets, the plasma levels of total 25-OH-D (25-OH-D_2^+25-OH-D_3) and total 1, 25(OH)_2D(1, 25(OH)_2D_2^+1, 25(OH)_2D_3) in elderly subjects were significantly lower than those in young adults. No significant difference was found between those in male and female of elderly subjects. When the concentrations of 25-OH-D and 1, 25(OH)_2D in the plasma were assayed after single oral administration of 200 IU of vitamin D_2 in multivitamin tablets, neither 25-OH-D_2 nor 1, 25(OH)_2D_2 plasma levels was increased.