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Monday, July 31, 2006

How much sunlight do we need to keep vitamin D levels healthy?

This follows on from my previous posting about vitamin D and sunlight.
In this article, I tell you how to boost vitamin D with sunlight.
My niece, Jasmine, and my son, Alama, have very different skin types and therefore have differing tolerances to sun and differing rates of vitamin D production; so they dress appropriately when playing in the sun.

The single most important fact anyone needs to know about vitamin D is how much nature supplies if we behave naturally, e.g., go into the sun. Fair-skined people make about 20,000 units of vitamin D within 30 minutes of full body exposure to the sun (only sufficient to make the skin slightly pink - no more). Vitamin D production in the skin occurs within minutes and is already maximized before your skin turns pink. Furthermore, if one stays in the sun long enough, the sun starts destroying excess vitamin D, a natural safeguard against toxicity which one does not have if taking pharmaceutical doses of vitamin D.
20,000 units of vitamin D in one exposure is enormous and is for good reasons: our bodies need vitamin D and huge amounts to be healthy and it is stored in the body to be available during times of low production such as during winter. It can take several months to build body stores to optimum. Diet is very much a supplementary source that can not replace skin production of vitamin D.
Get your head around this: One would have to take over 200 cod liver oil capsules to equal the vitamin D produced during one exposure to the sun!
Tanning may actually reduce your ability to produce vitamin D because longer and longer exposures to the sun are required to produce a given amount of vitamin D and overdoing single exposures causes destruction of vitamin D.

Fear of the fatal form of skin cancer, malignant melanoma, keeps many people out of the sun. The problem with the theory is that the incidence of melanoma continues to increase dramatically although many people have been completely avoiding the sun for years. I am not saying sunburns are safe, they are defintely not. Brief full body sun exposure may slightly increase your risk of non-melanoma skin cancer but it is a much smarter thing to do than suffering from vitamin D deficiency which has many health risks, including increased risk of many forms of cancer.
At the last of my regular skin checks with my dermatologist, I asked him about skin cancer rates among Maori and Pacific Islands people in New Zealand. He advised that it was negligible - about 1/50th that of NZ Europeans. This is further confirmation that health and safety policies that deny our darker skinned children the benefit of sunlight are misguided and are, in fact, doing our children harm.

Fair-skinned people like myself only need to expose as much skin as possible to direct midday sunlight for a few minutes three times a week during summer. This, with a healthy diet, should maintain healthy vitamin D levels throughout the year. Darker skinned people, like my partner, Alofa, and our children will need five to ten times longer in the sun. After several months of sun exposure, a 25(OH)D level should be between 35 and 55 ng/ml. It takes time if the body's vitamin D levels are low.
As I have previously explained, especially if you already have any kind of chronic health issues, you must ask your doctor to test your 25(OH)D levels (your Dr might look sideways at you, but insist on the test). If the results are below 50 ng, then start the sunbathing carefully and regulalry and have your levels tested again every few months until you hit the 50 ng mark!

1 comment:

Wayne said...

vitamin D is made from modifying cholesterol in natural body skin oils, think twice before you wash and scrub away the natural oils with 'cleansing" chemicals from your skin, doing so is also more likely to dry your skin out since its been robbed of its natural water proofing from the oil.