Dietary intake of vitamin D in premenopausal, healthy vegans was insufficient to maintain concentrations of serum 25-hydroxyvitamin D and intact parathyroid hormone within normal ranges during the winter in Finland

Objective To study vitamin D status and bone metabolism of premenopausal vegetarians and omnivores during a 1-year period. Design Longitudinal, observational study. Bone mineral density was measured, blood samples from fasting subjects were obtained, and 24-hour urinary samples were collected in February 1994, August 1994, and January 1995. Serum 25-hydroxyvitamin D [S-25(OH)D] and intact parathyroid hormone (S-iPTH) concentrations were measured and intestinal calcium absorption was estimated. Dietary intakes of vitamin D and calcium were calculated. Subjects/setting Six vegans, 6 lactovegetarians, and 16 omnivores living in Helsinki, Finland. Statistical analyses performed Student-Newman-Keuls test; unbalanced, repeated-measures multiple analysis of variance; analysis of covariance; Pearson correlation test; and linear regression analysis. Results Dietary intake of vitamin D was significantly lower in vegans (P < .05, yearly mean standard deviation=0.09 +/- 0.06 mug/day) and in lactovegetarians (P < .05, 0.7 +/- 0.4 mug/ day) compared with omnivores (4.0 +/- 2.1 mug/day). Throughout the year S-25(OH)D (P=.01) concentrations were lower and S-iPTH (P=.01) concentrations were higher in vegans than in omnivores and lactovegetarians. Bone mineral density in the lumbar region of the spine was lower in vegans (yearly mean standard deviation=1.034 +/- 0.174 g/ cm(2)) than in omnivores (P=.05, 1.177 +/- 0.099 g/cm(2)) and tended to be lower than that in lactovegetarians (P=.17, 1.138 +/- 0.06 g/cm(2)). Bone mineral density in the neck of the femur tended to be lower in vegans (0.843 +/- 0.116 g/cm(2)) than in omnivores (P=.07, 0.999 +/- 0.138 g/cm(2)) and lactovegetarians (P=.15, 0.961 +/- 0.059 g/cm(2)). No seasonal variation was found in bone mineral density in the study groups. Conclusions At northern latitudes, dietary intake of vitamin D in vegans was insufficient to maintain S-25(OH)D and S-iPTH concentrations within normal ranges in the winter, which seems to have negative effects on bone mineral density in the long run. Applications An Increase in vitamin D intake should generally be recommended for vegans at least during, winter, or selections of foodstuffs fortified with,vitamin D should be broadened in northern latitudes.