Too much vitamin D is damaging to the body.
http://www.sciencedaily.com/releases/2010/01/100122002340.htm
ScienceDaily (Jan. 22, 2010) — High blood levels of vitamin D are associated with a lower risk of colon cancer, finds a large European study published online in the British Medical Journal. The risk was cut by as much as 40% in people with the highest levels compared with those in the lowest.
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Participants with the highest levels of blood vitamin D concentration had a nearly 40% decrease in colorectal cancer risk when compared to those with the lowest levels.
However, some recent publications have suggested maintenance of blood vitamin D levels at 50 nmol/l or higher for colorectal cancer prevention. Thus, the authors also compared low and high levels of blood vitamin D concentration to a mid-level of 50-75 nmol/l. This comparison showed that while levels below the mid-level were associated with increased risk, those above 75 nmol/l were not associated with any additional reduction in colon cancer risk compared to the mid-level.
Although the results support a role for vitamin D in the etiology of colorectal cancer, the authors caution that very little is known about the association of vitamin D with other cancers and that the long term health effects of very high circulating vitamin D concentrations, potentially obtained by taking supplements and/or widespread fortification of some food products, have not been well studied.
With respect to colorectal cancer protection, it is still unclear whether inducing higher blood vitamin D concentration by supplementation is better than average levels that can be achieved with a balanced diet combined with regular and moderate exposure to outdoor sunlight, they say.
2 comments:
While of course sun exposure is the natural and free source of Vitamin D3 there has been work done in Belgium showing women (age 50~80) getting regular sun exposure gardening in towns although they got more UVB exposure had lower vitamin D levels than women gardening in country locations.
It depends on upper atmospheric pollution so unless you have a UVB meter or regularly get your 25(OH)D3 level checked (grassrootshealth D Action) it's worth taking an effective strenth capsule to make sure.
Up to 10,000iu/daily is absolutely safe, even in sunny countries.
1000iu required for each 25lbs you weigh.
Only 10% of daily requirement can be met from diet assuming you eat oily fish once every day. Even in Iceland they only eat 4 portions of oily fish a week.
Circulating 25-Hydroxyvitamin D Levels in Fully Breastfed Infants on Oral Vitamin D Supplementation Shows that to enable babies to be born vitamin D replete and able to obtain Vitamin D natural from mothers milk 6400iu/daily was required at latitude 32n.
Human skin naturally makes 10,000iu/daily Vitamin D3 biologically identical to the over the counter form. It is inconcievable that the natural levels human bodies naturally achieve given full body outdoor exposure are harmful, (we would not have survived the evolutionary process if so) Therefore anyone suggesting unnaturally low vitamin D levels at which higher levels of chronic illness is found must be able to show that these lower levels are indeed safer.
At present the higher your vitamin D3 level the longer you life, the less pain you feel, the better cognitive performance and for men the more testosterone you have circulating. I'm for
Thank you.
People whose ancestors lived in areas with more sunlight have more pigment in their skin. Of course, this lowers their chance of getting skin cancer. It also decreases the amount of vitamin D they can make for a given amount of light. A light-skinned person might not be in danger of getting too much vitamin D from the sun, in sunny areas, but it is not inconceivable it could be so. I don't know if any studies have been done in this area.
Because my father has had a bunch of skin cancers, and other reasons, I avoid direct sun exposure. But I take a vitamin D capsule.
I tried a form of vitamin D in a liquid form. I kept feeling bad, with symptoms of possible liver or gall bladder problems. I experimented, and verified it was being caused by the liquid vitamin D. I don't know if was a matter of the stuff having more vitamine D than it was supposed to, or I absorbed it better and thus got more than I got from a capsule, or some problem with the oil in was in.
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