Saturday, August 28, 2010

Prepare for the Winter: Get your Supply of Vitamin D Supplements

Figure 1: In Great Britain Vitamin D3
supplementation appears indicated
at least in the winter month
A recent study by researchers (Webb. 2010) from the School of Earth Atmospheric and Environmental Sciences at the University of Manchester highlight the importance of maintaining "late-summer 25-OH(D3) levels" throughout the winter month. In their investigation among 125 white Caucasians aged 20-60 years in Greater Manchester they found:
Dietary vitamin D remained low in all seasons (median 3.27 mug/day, range 2.76-4.15) while personal UV exposure levels were high in spring and summer, low in autumn and negligible in winter. Mean 25(OH)D levels were maximal in September (28.4 ng/mL; 28% optimal, zero deficient (< 5 ng/mL)), and minimal in February (18.3 ng/mL; 7% optimal, 5% deficient). A February 25(OH)D level of 20ng/mL was achieved following an average late summer level of 30.4 (25.6 to 35.2) and 34.9 (27.9 to 41.9) ng/mL in women and men, respectively, with 62% variance explained by gender and September levels.
With 50ng/ml 25(OH)D being what is currently considered an optimal vitamin D status by many, additional vitamin D supplementation would thus be warranted even in the summer month. This holds true in view of the results from another recent study (Michaƫlsson. 2010) reporting higher all-cause / cancer mortality for very low (<46 nmol/L) or very high (>98 nmol/L) levels of 25(OH)D in a community-based cohort of elderly men (mean age at baseline: 71 y; n = 1194) in Upsala.