Do you have Vitamin D deficiency? Of course you do! There seems to be a major fad in medicine in the last four or five years to screen for Vitamin D. In my practice, nearly every patient reports a deficiency of Vitamin D; and only three have reported normal levels! What is happening? And what should be done?
Are the normal values are accurate? Historically, lab values were designed to detect 25-hydroxyvitamin D3, the biologically active form, in people at risk for calcium deficiency due to malnutrition and/or aging. Vitamin D3 is well-known as a necessary factor in metabolism of calcium and phosphorus. Severe deficiency, particularly in elderly nursing home dwellers, can lead to osteoporosis and potentially fatal bone fractures.
Recommended lab values range between 20 and 30 ng/ml, and some studies recommend 31 to 51 ng/ml. These values were established on a relatively small number of mostly women (because osteoporosis is more common after menopause), and only in a particular high-risk group. Whether these numbers apply in both genders, at all ages, and across ethic lines is not well-established.
It has long been known that not all Vitamin D forms are equal. Dietary sources such as fish oil are practically useless, and pills are only about 10% as effective as Vitamin D3 created in skin by sun exposure.
Think about this evolutionarily! Vitamin D3 levels are best at the equator, where mankind evolved for a very long time. Extremes of latitude, both north and south, show lower Vitamin D3 levels because the sun’s UV B rays are at more of an angle, especially in the Winter. Vitamin D3 levels are famously lower in Winter everywhere — and in crowded (shady) and polluted cities, at all times. Moreover, darker skinned peoples need more time in the sun to activate effective Vitamin D3 production because melanin (dark pigment) blocks UV B rays.
Getting back to laboratory screening, a major Task Force (not corporate funded) in 2011 evaluated the literature and recommended that screening continue for high-risk populations. However, they concluded “At the present time, there is not sufficient evidence to recommend screening individuals who are not at risk for deficiency or to prescribe vitamin D to attain the noncalcemic benefit for cardiovascular protection.” So, the popular fad of screening healthy people and prescribing pills is not valid.
[Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline.
Holick MF1, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM; Endocrine Society.
J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30. doi: 10.1210/jc.2011-0385. Epub 2011 Jun 6.]
What is the health benefit of Vitamin D3 anyway?
Even if lab values are not particularly accurate for the average person, is it nevertheless important that we get biologically active Vitamin D3 by sun exposure? Actually, more and more research suggests that it is valuable beyond mere calcium/phosphorus metabolism. D3 has been shown to be important for cardiac health, immune system strength, helping to prevent multiple sclerosis, and has been implicated in lessening 18 different cancers, particularly breast, prostate, and colon cancers!
Ironically, a narrow focus in medicine for decades has led to near-paranoia about skin cancer. As a result, the sun block industry has blossomed! It turns out that the effort to avoid skin cancer so carefully has actually INCREASED susceptibility to 18 other types of cancer, as well as heart disease, immune dysfunction, and even increased depression!
How much sun is actually needed?
Lots of research exist on the amounts of sun needed to get the benefits of Vitamin D3. To keep it simple, follow the advice of Andrew Weil MD. Just figure out the time it takes in the sun to make your skin a little pink, then expose as much of your body as you can at 25-50% of that time around three times a week in Spring and Summer. Such exposure should build up enough stores of Vitamin D3 to gain benefits through the Winter. The advantage of this strategy is that it corrects for seasonal variations, latitude and urban differences, and ethnic pigmentation variations.
Dr Weil has a friend, Michael Holick MD PhD, who wrote a very detailed book on how much sun is needed in various countries at different latitudes. He publishes elaborate tables for various ages and ethnicities all over the world. You can find it on Amazon at http://www.amazon.com/The-Vitamin-Solution-Strategy-Problems/dp/0452296889.
Essentially, Caucasians in moderate latitudes away from the equator need approximately 10 min of sun, between 11 AM and 3 PM at the height of the sun, three times a week in Spring and Summer — say, wearing tank top and shorts or so. Most Asians and Hispanics with moderate pigmentation need 20-30 min three times a week. And Blacks need about 60 min three times a week. Moreover, people in their 60s convert Vitamin D in the skin at a slower rate, and those of us older than 70 do it even slower. So older people need to add 50% to these numbers.
Allow me to harp on my universal theme — getting back to our caveman-origin genes. The closer our lifestyle fits genes that have evolved over eons, the more our bodies can maintain optimal health. To the extent that we deviate from this, the more we develop all kinds of degenerative diseases. So get enough sleep, exercise regularly, eat as close to the earth as possible, and do outdoor activities like hiking, golf, gardening, or just sunbathing.
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Sun exposure between 11 and 3 is extremely difficult for me because I’m still working 5 days a week inside a building. Will extra time later in the day work?
Thanks for the question. Sure, it is the total UV B exposure that counts. Even more time on weekends to cover weekdays is fine. Even more in summer to cover winter is fine. Thanks for chiming in!