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Go ahead, get some sun! January 28, 2010

Posted by Gretchen Giannelli in Health Communications & Marketing, Mental Health, Prevention.
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During the past few decades health officials have waged a campaign urging us to avoid excessive sun exposure in order to prevent skin cancer. We’ve been told to slather on the sunscreen– the higher the SPF, the better– and stay indoors during the middle of the day when the sun’s rays are strongest. Statistics have shown increasing rates of melanoma, the most serious type of skin cancer.  While it makes sense to prevent skin cancer, the advice to avoid the sun may have swung the pendulum too far in the other direction and created a new problem. People have followed the advice so well that many of us are now deficient in vitamin D. This important vitamin is also called the “Sunshine Vitamin” because our main source  is through exposure to sunshine. Vitamin D is made when the sun’s photons convert cholesterol in our exposed skin.  But clothing and sunscreen can prevent the conversion. Importantly, most food does not provide adequate amounts of Vitamin D, unless fortified.

Last year researchers analyzed two National Health and Nutrition Examination Survey studies. (NHANES studies provide valuable data to researchers on risks, trends and emerging public health issues.) When they compared serum vitamin D levels from the 1988-1994 survey and the 2001-2004 survey they saw “a growing epidemic of vitamin D deficiency ” and racial differences were prominent with levels in blacks decreasing even more than in whites. Indeed, many researchers have cited this epidemic, but are frustrated that the policymakers are slow to follow the science and make new recommendations to increase our vitamin D intake. This disconnect between science  and policy is called circular epidemiology, something that the new FDA Deputy Commissioner, Joshua Sharfstein vowed to address in his recent lecture at GWU.

Why is vitamin D so important? Back in 1822 doctors understood the importance of vitamin D in preventing rickets—think rickety bones in children—and more recently in osteoporosis, but new research has illuminated the critical role of vitamin D in non-skeletal functions; it has anti-microbial, anti-inflammatory, anti-coagulant, and immune protective properties. Dozens of studies show its role in prevention of cardiovascular disease, autoimmune diseases such as lupus erythematosus and multiple sclerosis, asthma, diabetes, depression, schizophrenia, and cancer.

As revealed by the NHANES analysis, vitamin D is tied to racial disparities. Because higher levels of melanocytes in darker skin are protective against the sun and more exposure time is needed to make vitamin D some researchers hypothesize that the greater deficiency in blacks may explain the increased rates of cardiovascular disease in that population. An article in the June 2009 issue of the Journal of Nutrition indicated that “[v]itamin D deficiency is associated with bacterial vaginosis (BV), and this link may contribute to the strong racial disparity in the prevalence of BV.  Bacterial vaginosis is linked to adverse birth outcomes.”

To determine whether a deficiency exists, ideally, you should get your blood levels checked by a physician, but you can also order a test kit online from The Vitamin D Council or go with general recommendations.

If you want to obtain your vitamin D from the sun here’s the smart way to get your exposure as recommended by the Vitamin D Council:

[J]udiciously expose as much skin as possible to direct midday sunlight for 1/4 the time it takes for one’s skin to turn red during those months when the proper ultraviolet light occurs at one’s latitude (usually late spring, summer and early fall). Do not get sunburned. Vitamin D production is already maximized before your skin turns pink and further exposure does not increase levels of vitamin D but may increase your risk of skin cancer. Black patients may need 5–10 times longer in the sun than white patients, depending on skin type.

It is important to note that showering and washing should be avoided for at least some time after sun exposure to allow the vitamin D to penetrate; otherwise, it could wash off. There are conflicting reports on how long this should be, however, and the Vitamin D Council reports more research is needed.

The supplement doses are where it gets confusing. The 1997 report from the Food and Nutrition Board made recommendations for doses between 200 international units (IU) in children to 600 IU in older adults. However, these doses are now considered way too low by some of the same expert researchers who prepared the 1997 report and who went on to form The Vitamin D Council. The Vitamin D Council recommendations are:

purchase the 1000 IU/day vitamin D3 cholecalciferol* pills that are available over-the-counter… or a 5,000 IU capsule. Take an average of 5,000 IU a day, year-round, if you have some sun exposure. If you have little, or no, sun exposure you will need to take at least 5,000 IU per day. How much more depends on your latitude of residence, skin pigmentation, and body weight. Generally speaking, the further you live away from the equator, the darker your skin, and/or the more you weigh, the more you will have to take to maintain healthy blood levels.

*Note that the council recommends D3 (chlolecalciferol), which is more bioavailable than D2 (ergocalciferol), another form sometimes seen as a supplement.

Other conflicting messages come from two popular doctors with their own health and nutrition websites, Dr. Andrew Weil and Dr. Joseph Mercola. They make new recommendations for 2000 IU and 5000 IU, respectively.

Clearly, there is a need for more consistent information so people can choose the proper dose of Vitamin D.  Importantly, The Institute of Medicine of the National Academies of Science has “named a committee to undertake a study to assess current relevant data and update as appropriate the DRIs for vitamin D and calcium.” Their report is expected to be completed in May 2010 and it is likely that the recommendations will be increased based on the newest research on this topic.  Also, lots of folks remain unaware of possible deficiencies and this is a critical public health message which should be communicated as part of the new recommendations.

In the meantime, go ahead and get some sun where you can find it. With sun exposure (and most things) it pays to heed the sage advice:  Moderation in all things is the best policy.

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Comments»

1. Ashraf Faden - February 1, 2010

This was really interesting. I didn’t realize that Vit. D affects so many conditions. Here is an article in MedlinePlus about vitamin D and asthma I came across in one of my RSS feeds: http://www.nlm.nih.gov/medlineplus/news/fullstory_94661.html

2. Gretchen Giannelli - February 1, 2010

Thanks Ashraf, one of our fellow students is now living in Qatar and doing her CE based on findings from the public health dept on low Vit D levels in its citizens. There is plenty of sun, but the cultural practices of dress mean that there is not enough exposure and thus they are deficient.

3. Osteoporosis Free - February 10, 2010

Dear friend,

I found very helpful articels in here.
Thanks for the sharing and keep posting. OK

BR
Auliandri
Moderator of emiratesosteoporosissociety.com

4. Nanotechnology-what are the implications for public health? « Target Population - March 1, 2010

[…] shampoo to make hair feel silky and smooth, in oral vitamin D spray to make it more bioavailable (see my previous blog on importance of vitamin D) and in chocolate shakes to make cocoa blend […]


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