Vitamin D deficiency and bone health in healthy adults in finland: Could this be a concern in other parts of Europe?

A low vitamin D status could be a concern not only in children and the elde rly in Europe, but also in adults. We do not know the effect of mild vitami n D deficiency on bone in this age group. The aim of this study was to dete ct the prevalence of low serum 25-hydroxyvitamin D [S-25(OH)D] and elevated serum intact parathyroid hormone (S-iPTH) concentrations in healthy young adults in the winter in northern Europe and to characterize the determinant s of these variables. In addition, we studied the association between vitam in D status and forearm bone mineral density (BMD) in this population group . Three hundred and twenty-eight healthy adults (202 women and 126 men, 31- 43 years) from southern Finland (60 degreesN) participated in this study co nducted in February through March 1998. Fasting overnight blood samples wer e collected in the morning. Forearm BMD was measured by dual-energy X-ray a bsorptiometry (DXA). The mean daily vitamin D intake met the recommendation s in the men (5.6 +/- 3.2 mug) and almost met it in the women (4.7 +/- 2.5 mug). The mean S-25(OH)D concentrations did not differ between genders (wom en, 47 +/- 34 nM; men, 45 +/- 35 nM; mean SD), but the women had significan tly higher mean S-iPTH levels than the men (women, 30 +/- 13 ng/liter; men, 24 +/- 12 ng/liter; p < 0.001). Low S-25(OH)D concentrations (< 25 nM) wer e found in 26.2% of the women (53 women) and 28.6% of the men (36 men), res pectively. Based on nonlinear regression analysis between S-25(OH)D and S-i PTH concentration, the S-iPTH concentration started to increase with S-25(O H)D concentrations lower than similar to 80 nM in the women and lower than similar to 40 nM in the men. Based on this relation between S-25(OH)D and S -iPTH concentrations, 86% of the women and 56% of the men had an insufficie nt vitamin D status. In linear regression analysis, the main positive deter minants of S-25(OH)D were dietary vitamin D intake (p < 0.02), the use of s upplements (p < 0.005), alcohol intake (p < 0.05), and age (p < 0.005). Smo king associated negatively with the S-25(OH)D concentration (p < 0.03). The main determinants of S-iPTH were S-25(OH)D (p < 0.01), dietary calcium int ake (p < 0.02), and body mass index (BMI; p < 0.01). In addition, female ge nder was associated with higher S-iPTH concentration. The mean daily dietar y calcium intake was 1037 +/- 489 mg and 962 +/- 423 mg, in the men and wom en, respectively. Significantly lower forearm BMd was found in the men (p = 0.01) but not in the women (p = 0.14) with higher S-iPTH concentrations. L ow vitamin D status was prevalent in these young adults in northern Europe in winter, although the vitamin D intake met the recommendation. This proba bly is not a local problem for northern Europe, because the natural sources of vitamin D are scarce and fortification is not very common in Europe, an d with the exception of the southern part of Europe, sunshine is not very a bundant in this part of the world. Thus, the results of this study indicate that more attention should be focused on vitamin D status and the sources of vitamin D in these countries.