It is well established science that our bodies manufacture Vitamin D when exposed to sunlight and that Vitamin D serves many important health functions with our cells and organs. It is becoming well established science that supplementing with Vitamin D has numerous benefits. It is not yet established science (but I believe that it someday will be) that receiving sunlight is far superior to taking Vitamin D supplements.
First some background: Vitamin D does not meet the technical definition of a vitamin as something that is essential to human health but that cannot be produced by the body. Vitamin D is essential to our health (used in calcium and phosphorous metabolism, a strong role in the immune system, anti-cancer properties, and much more); however it can be produced by our bodies when we are exposed to the UVB rays of the sun. This role of sunlight was not known when the substance was first discovered and named. Once something is named, the name usually sticks, so Vitamin D it is and will remain.
Cholecalciferol or Vitamin D3, is the natural form of vitamin D for humans. Vitamin D3 is produced in the skin with sunlight exposure. Vitamin D2, known as ergocalciferol, is a compound produced by irradiating yeast with ultraviolet light. As a supplement, Vitamin D3 is much easier to metabolize than the D2 form.
There is some controversy over the optimal amounts of Vitamin D. The 400 IU amounts of Vitamin D found in many multiple vitamins are usually sufficient to prevent severe deficiencies but are usually not enough to provide optimal amounts. 2000 IU is usually taken as a safe optimal daily dose when supplementing; the only way to know for sure is have your Vitamin D levels tested. Blood levels of Vitamin D less than 20 ng/ml (nanograms per milliliter) is considered deficient while somewhere between 40 ng/ml and 70 ng/ml is considered optimal
Now for sunlight: 30 minutes of summer sunlight can produce up to 20,000 IU of Vitamin D for someone exposed to the mid-day sun while wearing a bathing suit without sunscreen. However, at our latitude, little or no Vitamin D will be produced by sunlight exposure from November through March. I had my Vitamin D levels tested in early April which should be somewhere near the annual low—mine was at 17 ng/ml which is just below the minimum recommended 20 ng/ml. Now it is May, and sunlight is abundant so I expect my levels by the fall will be quite high again. I think I’ll get retested then just to see…
The latest research shows that the dangers of too little sunshine exposure with subsequent low Vitamin D levels far exceed the dangers of too much sunlight exposure. (Don’t get sunburned though!) This leads to the following question: Why not simply supplement with vitamin D3 and not worry about getting sunshine? To me, this is similar to the question of why not just supplement with vitamins and ignore what we eat. I think that just as we are discovering that there are many previously unknown micro-nutrients that our bodies need in foods, we will discover that sunshine helps our bodies produce far more than simple Vitamin D.
Science is beginning to show this. Here’s a link about a study showing that the effects of sunlight were greater than the effects of Vitamin D in reducing the incidence of multiple sclerosis symptoms: http://www.eurekalert.org/pub_releases/2010-03/uow-sel032210.php
Over time, I think that many other studies of this nature will be performed. In the meantime, heliotherapy (therapy with sunshine) has a long and successful history of promoting wellness and curing disease. Sunshine is cheap and abundant this time of year, so get out in the sun! Start with 15 or 20 minutes at a time with no sunscreen, but don’t let yourself get sunburned. For most of you, 90 to 150 minutes per week of direct mid-day sun should be sufficient. You will feel so much more relaxed! In October, when the sun starts to get lower in the sky, I’ll recommend some vitamin D3 supplementation for many of you.