In the last few years it has become evident that the benefits of vitamin D in creating health go far beyond those of promoting strong bones. It is true that a major deficiency in vitamin D will interfere with calcium absorption and bone growth. But it has only recently become obvious that long-term vitamin D deficiency is associated with other conditions. These include certain cancers, auto-immune disorders, type-one diabetes, infertility, obesity, and seasonal affective disorders and depression.
Long-term deficiencies develop because vitamin D has two major functions in the body. The first is to maintain blood calcium levels, which is vital to the function of all the cells in the body. It is only when there is sufficient vitamin D in the body to maintain blood calcium, that the second function, that of turning genes off and on, is met. This affects genes that are making proteins that fight cancer and those that promote cancer
Sources of Vitamin D
The major source of vitamin D is from the sun. Studies show that if you go out in the summer sun in your bathing suit and without sun-block until your skin just begins to turn pink, you make an average of 20,000 units of cholecalciferol – the form of vitamin D produced by the skin. Once this level is reached the skin begins to degrade any further vitamin D build-up, thus preventing an overdose. As a tan develops, the skin also makes less vitamin D. So to receive the benefits of vitamin D , dark-skinned people need longer in the sun than those with light skin.
Without adequate exposure to sunlight it is extremely difficult to get enough vitamin D to maintain health, because vitamin D is found naturally in relatively few foods, and then only in small amounts.. The major vitamin-D -containing foods are oily fish such as salmon. mackerel and sardines, but you would need to eat far more of these than is feasible in order to get an adequate dose of Vitamin D. The same is true for fortified foods such as milk
How To Know If You Are Getting Enough Sun
Because the summer sun is so important in building vitamin D stores in the body, it is important to spend time in the sun without sun-block if you are to get the benefits of vitamin D. There are three kinds of ultra-violet rays remitted by the sun, UV-A, UV-B and UV-C, but the body only produces vitamin-D when the UV-B rays shine directly onto your skin. UV-B is decreased :
- at latitudes above 35 latitude north or below 35 latitude south, especially between autumn and spring;
- at low altitudes; and
- in cloudy or polluted air conditions.
In these situations you need to supplement with vitamin B3 during the winter months. Those above the age of 70 should also use vitamin D food sources or supplementation as their ability to make vitamin D in the skin is two-thirds lower than that of a 20-year-old.
Those concerned about their vitamin D levels can request a vitamin D test from their Doctor. The 25 hydroxy D level should be at least 30 ng/ml (75 nmol/l), but optimally in the 50 to 60 ng/ml range. Numerous studies show strong relationships between these levels and reduced risk of a wide variety of chronic diseases , and an increased lifespan.
The current evidence appears to be clear that the benefits of vitamin D include creating health by lowering the chances of cancer and many other conditions.