Prof. Edward Gorham from University of California, San Diego Dept. of Family & Preventive Medicine gives us some insights into the epidemic of vitamin D deficiency. He says that insufficient vitamin D affects all intercellular communications with myriad health consequences including cancers, MS, seasonal influenza, diabetes I and II, muscle pains and weakness, impaired wound healing and a number of pregnancy complications such as pre-eclampsia and pre-term birth.
Gorham cites various studies that support the importance of ensuring adequate vitamin D levels at all ages and life stages.
- Onset type I diabetes peaks annually in winter-spring season
- Bone loss study also shows flu symptoms are highest in winter
- Prostate cancer survival is highest in summer
- In USA, 74 percent of the population are below the clinical insufficiency level for vitamin D
- lower physical activity (i.e. sun exposure) associated with lower 25(OH)D
- lower physical activity associated with higher cancer risk
- women at x 2.25 elevated risk for vitamin D deficiency
- constitutive pigmentation is a risk factor for vitamin D deficiency
Prof. Gorham is an advocate for making the most of the original source of vitamin D, but explains how to use it appropriately. While the sun is the source of UVB photons used to make vitamin D, it’s just a tiny sliver of spectrum that initiates its formation. UVB at 280-319nm and is a long way from the visible light spectrum, it doesn’t penetrate atmosphere easily and perpendicular not oblique rays are required (compare the usefulness of the direct rays from a flashlight to the relatively useless diffuse ones). Pollution and cloud cover are UVB enemies, ditto high latitudes, ditto sunscreens!
Gorham says that we must re-evaluate our use of sunscreens. They have never been shown to prevent melanoma. However, they irrevocably change the relationship between our skin and the sun - a relationship refined over millenia. Gorham’s prescription for a continuing appropriate relationship between your skin and the sun as follows...
- Minimize UVA while allowing UVB
- 10-15 minutes exposure/day between 10:00 am and 2:00 pm
- Expose 40 percent of skin area
- Ensure it’s a clear day without pollution
- If this isn’t possible, use oral supplements of vitamin D3 to achieve 40-60ng/ml (100-150nMols/L)
RULE OF THUMB: For every 100IU ingested, there is increase of 1ng/ml
PREGNANCY DOSE: 4,000IU/day
BREASTFEEDING DOSE: 6,000IU/day