Vitamin D supplementation is known to benefit conditions associated with the skeletal system such as rickets, fractures and falls, as well as a range of diseases including multiple sclerosis, autoimmune disorders, infections, cardiovascular diseases and certain cancers. Non-skeletal benefits of vitamin D supplementation are still currently being debated in many cases.
In a new meta-analysis published in the British Medical Journal (1), researchers analyzed the possible association between a higher blood level of vitamin D and a reduced risk of all- cause mortality. The review included 73 observational population studies that reported vitamin D serum levels and the cause of death among 849,412 men and women over a follow up period up to 29 years.
When comparing adults with the lowest one-third of vitamin D levels to those in the highest third, subjects had a 35% higher risk of mortality from cardiovascular disease or any cause over the follow-up period. Adults with the lowest levels also had a 30% greater risk of non-vascular, non-cancer death, and a 14% higher risk of death from cancer.
Evidence from these observational studies found significant inverse associations between serum vitamin D levels and risks of death from cardiovascular disease, lymphoma, upper digestive tract cancer, and respiratory diseases. In addition, when the form of vitamin D supplementation was taken into account, vitamin D3 significantly reduced all-cause mortality by 11%. Vitamin D2, on the other hand, did not appear to have any significant effect on mortality.
Researchers noted that further studies should be done to determine the optimal dose and duration of supplementation and to further confirm whether vitamin D3 affects the mortality risk differently than vitamin D2.
How you produce Vitamin D from Sunlight
First, it’s important to understand that vitamin D3 is an oil soluble steroid hormone. It’s formed when your skin is exposed to ultraviolet B (UVB) radiation from the sun (or a safe tanning bed). When UVB strikes the surface of your skin, your skin converts a cholesterol derivative in your skin into vitamin D3.
Not any sunlight will do though, it must be strong enough for the UVB rays to penetrate deep into the skin. An easy way to gauge the intensity of the sun is make sure that it is higher than 45 degrees in the sky. If you don’t remember your high school geometry, just stand out in the sun and look at the length your shadow (or any other object) if your shadow is shorter than you are tall, then the sun is strong enough to produce vitamin D. If it is longer then you can stand naked in the snow all day and you won’t produce any vitamin D.
Some times of they year the sun may be at that angle only mid day, in the middle of summer though it may be high enough in the sky for hours.
If you’re on statin drugs to reduce cholesterol or proton pump inhibitors like Prilosec or Prevocid, than will also lower the amount of cholesterol available to be converted into vitamin D.
Now that you’ve made Vitamin D, don’t wash it down the drain
However, the vitamin D3 that is formed is on the surface of your skin does not immediately penetrate into your bloodstream. It actually needs to be absorbed from the surface of your skin into your bloodstream.
The critical question then is: how long does it take the vitamin D3 to penetrate your skin and reach your bloodstream?
If you’re thinking about an hour or two, you’re wrong. Because new evidence shows it takes up to 48 hours before you absorb the majority of the vitamin D that was generated by exposing your skin to the sun!
Therefore, if you shower with soap, you will simply wash away much of the vitamin D3 your skin generated, and decrease the benefits of your sun exposure. So to optimize your vitamin D level, you need to delay washing your body with soap for about two full days after sun exposure.
Now not many people are not going to bathe for two full days.
However you really only need to use soap underneath your arms and your groin area. , so this is not a major hygiene issue. You’ll just want to avoid soaping up the larger areas of your body that were exposed to the sun.
Vitamin D Supplementation
For most people who work 9-5 indoors and especially in the winter the only other alternative to basking in the sun on a tropical island is to take vitamin D supplements. These are safe and inexpensive and reduce the dependance on sunlight and the avoidance of showers. Recommended amounts vary from a small amount up to 5,000 or 10,000 IU per day, but you need to have regular blood tests to monitor your blood vitamin D levels. You want at least 50 to 90 ng/ml
(1) Rajiv Chowdhury et al. Vitamin D and risk of cause specific death: systematic review and meta-analysis of observational cohort and randomised intervention studies. BMJ 2014;348:g1903 doi: 10.1136/bmj.g1903 (Published 1 April 2014).