Episode 17: The Sun Vitamin

Sun exposure is responsible for life on this planet as we know it. Everything, from plants to most animals require some sun exposure. As far as our own biochemistry goes, sun exposure is responsible for regulating our sleep/ wake cycle, mood, cholesterol and Vitamin D levels. However, at northern latitudes in winter (from approximately September until May), there is not enough UVB wavelengths to stimulate Vitamin D production in our skin. In the popular media, there are countless supplemental regimes that are advocated, but one thing that should first be done are measurements.

This is where your doctor comes in. Typically, it is best to measure Vitamin D (via blood test) twice per year, in September and again in May. If you are low in September, supplementation is advisable during the winter. Then in May, another measurement will help to tell you whether or not the supplementation is working. The reference range that is considered normal from these tests is typically 75-250nmol/l (in Canada) or 30-100ng/ml (in the USA). There are 2 avenues that supplementation takes. The first is via oral supplement. Typical therapeutic doses for those without kidney disease, chrones disease or parathyroid disorders, range from 2-4000IU/day in winter. As Vitamin D is fat soluble, it can potentially build up to toxic doses if taken orally above this threshold.


If you opt to get your Vitamin D via tanning bed, 5 min of full body exposure (without sunscreen), twice per week is adequate. This exposure is not enough to cause you to burn, or even tan, but it stimulates your skin to produce Vitamin D, using the cholesterol in your system (which, incidentally, also lowers your cholesterol levels). Other benefits to this form of supplementation manifest as better moods and better sleeps (most likely due to the benefits of full spectrum light)


During summer, UVB is plentiful and oral supplementation is unnecessary so long as you generally get some daily, unblocked exposure on your arms, legs and torso for about 20 minutes.

Although only the oral supplementation can be done in less than 2 minutes, the exposure method only adds up to 10min per week in winter, which, if averaged over 7 days, also qualifies. Stay tuned next week where we’ll talk about Fomites.


Be Well and Be Zen


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