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Originally Posted by
Yeah but you've had melanoma.
Dora
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That's an important point, and Bill, you should really discuss this with your doctor. However, there is increasing evidence that many people have gone too far the other way with sun exposure, and consequently, many people, particularly in temperate climates or as you point out, who wear completely enveloping garments, are seriously deficient in vitamin D and that this is higher in people who use sunscreen carefully (a recent paper found that dermatologists in Australia were almost all grossly deficient). The current recommendations in the UK are to expose one fifth of the body for 20 minutes each day, but there are concerns that in northern climates, this is sufficient only in summer - far greater exposure and/or supplementation is needed in winter.
Quote:
Originally Posted by
More isn't always better with vitamins. Too much vitamin D can
calcify your blood vessels and contributes to the formation of kidney
stones. So you have to be careful with supplements. But most people
don't need them.
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This is true to an extent. However, there is considerable debate as to how much vitamin D is 'enough'. Current recommendations are 200-400 IU, increasing to 700IU in people aged 70 years, with an upper limit of 1000 IU. Many experts now consider that this is too low, and recommend a minimum of 1500 IU, particularly for women, as insufficient vit D prevents calcium absorption, leading to increase likelihood of osteoporosis. A risk assessment carried out in 2007 (Hathcock JN, Shao A, Vieth R, Heaney R. Risk assessment for vitamin D. Am J Clin Nutr 2007;85:6-18), analysing a number of studies, found that doses as high as 10,000 IU were not associated with significant harm.
The consensus also seems to be that 'natural' sources of vitamin D such as cod liver oil are better than 'synthetic' sources, because the latter are usually part of a multivitamin formulation, and thus if you try to increase your level of vit D, you may well exceed the toxic doses of other components, particularly vit A. A teaspoon of cod liver oil contains around 450 IU of vitamin D.
Everyone really should be increasing their intake of oily fish, not just for vit D, and you are unlikely to do yourself any harm taking up to 2 teaspoons of cod liver oil (around the equivalent of a high-dose 800 microgram capsule). BUT please see your doctor first, and ask to have your vitamin D level measured.