Vitamin D - How Much to Take?

HOW MUCH VITAMIN D TO TAKE?
It’s the latest, greatest vitamin, but what’s the safe and effective dose?

New research on vitamin D, also called the sunshine vitamin, is showing that most Americans are deficient, and that a lack of it may be contributing to breast cancer, colon cancer, osteoporosis, multiple sclerosis, fibromyalgia and other autoimmune diseases. In fact, if you work inside and use sunscreen you’re probably vitamin D deficient. This applies even more if you live in a northern latitude.

You can get some vitamin D from food, and of course you can take supplements, but the very best, safest and most reliable source of vitamin D is sunshine. No doubt about it. But haven’t we been warned away from sun exposure? Won’t it cause cancer and wrinkles? Well, yes and no. Our national hysteria about sun damage is grossly exaggerated. It’s one of those myths that has been repeated so much that most everyone assumes it to be true. The sunscreen industry has done a great job selling its wares by scaring us about sun exposure. However, if you dig down and do some research it’s a different story.

Yes, if you repeatedly get sunburned you somewhat increase your risk of non-melanoma skin cancer. The fairer the skin, the more easily it is sunburned. By far the biggest risk for skin cancer is simply having fair skin—with or without sunscreen. There’s really no substantial evidence that using sunscreen protects you from skin cancer. There is a weak association between melanoma and sunburn, but there is no evidence that using sunscreen prevents melanoma. There is some research indicating that exposure to the sun as a child reduces the risk of melanoma.

The take-home lesson is to avoid getting sunburned. One way to avoid sunburn is to tan gradually. Start with five minutes a day in the sun and work up slowly. Being tan a lot will probably cause you to wrinkle sooner, but it’s unlikely to substantially increase your risk of skin cancer. If you have fair skin, wear protective clothing when you’re in the sun.

As I mentioned above, there is increasing evidence that avoiding the sun and becoming vitamin D deficient can increase your risk of many cancers as well as osteoporosis and autoimmune diseases. It just takes 15 to 20 minutes in the mid-day sun, three to four times a week, to provide you with adequate vitamin D. Now if you’re pale as a ghost, don’t go right out and sit in the sun for 20 minutes or you’ll get burned. Work up to it.

For those who live in colder, cloudier, northern climates or who just can’t get out in the sun enough, it’s probably a good idea to take a vitamin D supplement. The recommended daily allowance (RDA) of 400 IU is clearly too low. It was put in place before Americans became sun-phobic. Vitamin D is a fat soluble vitamin and as such can accumulate in the body and become toxic, so there has been justifiable concern about taking too much. Now that we have more research, it seems clear that we can safely take 2,000 IU daily in the D3 cholecalciferol form to maintain our vitamin D levels. If your doctor wants to ratchet up your vitamin D levels quickly with large doses, be sure to test levels regularly. Some doctors will recommend 10,000 IU for a few months to get vitamin D levels back to normal. Ask for the 25(OH)D test, which is not the most common, but is the most accurate.

ZRT Lab has an easy and accurate new vitamin D test available.

References

Berwick M, Armstrong BK et al, “Sun exposure and mortality from melanoma,” J Natl Cancer Inst 2005; 97:195–99.

Boscoe FP, Schymura MJ, “Solar ultraviolet-B exposure and cancer incidence and mortality in the United States, 1993-2002,” BMC Cancer 2006 Nov 10;6:264.

Dennis LK, Beane Freeman LE et al, “Sunscreen use and the risk for melanoma: a quantitative review,” Ann Intern Med
2003; 139: 966–78.

Ginanjar E, Sumariyono SS et al, “Vitamin d and autoimmune disease,” Acta Med Indones 2007 Oct-Dec;39(3):133-41.

Grant WB, “An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation,” Cancer 2002; 94:1867–75.

Holick MF, “Sunlight “D”ilemma: risk of skin cancer or bone disease and muscle weakness,” Lancet 2001; 357: 4–6.

Lin J, Manson JE et al, “Intakes of calcium and vitamin D and breast cancer risk in women,” Arch Intern Med 2007 May 28;167(10):1050-9.

Robien K, Cutler GJ et al, “Vitamin D intake and breast cancer risk in postmenopausal women: the Iowa Women's Health Study,” Cancer Causes Control 2007 Sep;18(7):775-82.

Solomon CC, White E et al “Melanoma and lifetime UV radiation,” Cancer Causes Control 2004 Nov;15(9):893-902.

Thieden E, Philipsen PA et al, “Sunscreen use related to UV exposure, age, sex, and occupation based on personal dosimeter readings and sun-exposure behavior diaries,” Arch Dermatol 2005; 141:967–73.

 


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