We measured the sum of serum 25-hydroxyvitamin D₂ and D₃ (25(OH)D) concentrations of thirty-five pastoral Maasai (34 (SD 10) years, 43 % male) and twenty-five Hadzabe hunter-gatherers (35 (SD 12) years, 84 % male) living in Tanzania. They have skin type VI, have a moderate degree of clothing, spend the major part of the day outdoors, but avoid direct exposure to sunlight when possible. Their 25(OH)D concentrations were measured by liquid chromatography-MS/MS. The mean serum 25(OH)D concentrations of Maasai and Hadzabe were 119 (range 58-167) and 109 (range 71-171) nmol/l, respectively. Br J Nutr
Friday, May 1, 2015
More Information on Vitamin D
This next quote I think is important. Our culture--in terms of politics, nutrition and other areas--thrives on promoting fear. You will hear dire warnings about too much Vitamin D (and other things). The following is a breath of sanity.
"The evidence is clear that vitamin D toxicity is one of the rarest medical conditions and is typically due to intentional or inadvertent intake of extremely high doses," writes Hollick, a professor of medicine, physiology and biophysics at Boston University School of Medicine.
ANd as far as what's a good level, some are recommending 20 as within the normal range. Bit when studies test levels of Vitamin D in the blood of peoples who live in the sun, we probably get a better idea of what's normal. So here are two.
Many of us have been waiting years for this data. To me, it means that the Vitamin D Council’s recommendation of 50 ng/ml is just about right, although I cannot argue with someone who recommends a level of 55 ng/ml. Remember, when errors in measuring vitamin D are made, they usually are overestimates. Thus, if mean natural levels are around 45 ng/ml, keeping your level around 50-55 ng/ml keeps you within what both the Maasai and the Hadzabe are telling us.
Also there is evidence that aging per se does not cause poorer conversion of sunlight to Vitamin D, but rather that as people spend less time in the sun they begin to lose the ability to convert sunlight to Vitamin D. Use it or lose it, apparently. A good question to ask is if that ability can be restored with more sun exposure. So far I can't find an answer.