The Role of Sunshine and Vitamin D On Our Health Print
Sunday, July 19, 2009
If you're the type of person who avoids the sun on your skin at all costs, you may be depriving yourself of one of the sun's life-sustaining benefits, which are actually very significant. Although for years we have been told to stay out of the sun to avoid wrinkles and skin cancer, we may be courting other more serious health dangers. Research is showing that getting the right amount of sun on our skin is a delicate balancing act.

Lack of sunlight leads to vitamin D deficiency, which in turn creates a cascade of diseases including some life-threatening cancers. According to a study from the Harvard Medical School, "Vitamin D deficiency is the single most important dietary deficiency in the world today. It has already been linked to prostrate cancer, colon cancer and breast cancer. After almost 35 years of increases in allergic and autoimmune disease, we are beginning to understand the causes of the epidemic."

Before its skin-cancer effect was fully known, the sun's light-visible and ultraviolet (UV)-had quite a favorable reputation. In the decades preceding antibiotics, tuberculosis was a major health problem. Treatment centers sprang up around the world, all offering a similar treatment. These centers were generally located in sunny, but cool areas of the world and offered a high cure rate for tuberculosis and other chronic illnesses by exposing patients to natural sunlight for specified periods. In 1903, Danish scientist Niels Finsen won the Nobel prize in medicine for his therapeutic use of ultraviolet light from he sun, which gave rise to the field of Heliotherapy, or sun treatment ("helio" is Greek for "sun").

In the mid-20th century a link between the sun and skin problems became apparent, which led to the demise of unprotected sunbathing. We now use sunscreen lotion with high SPF numbers and cover up as much as possible. We have been warned to stay out of the sun in order to protect our health, specifically to prevent skin cancer. However, studies now show that staying out of the sun is a recipe for disaster - Vitamin D deficiency is now thought to be widespread - up to 70% of the population according to some studies. Ironically, much of the Vitamin D research shows that this deficiency is actually contributing to the rise many diseases and cancers, including the skin cancers that it is supposed to prevent.

A Potent Hormone

Vitamin D is not just a vitamin, but it is actually a potent hormone that regulates at least 600 different genes associated with key body functions. One definition of a hormone is "a chemical substance produced in the body that controls and regulates the activity of certain cells or organs." Vitamin D fits this definition because we actually create it in our bodies. It is produced when UVB sunlight rays react with a cholesterol layer in our skin. The vitamin then enters the blood, travels to the liver to be synthesized to 25-hydroxyvitamin D, then to the kidneys, which converts it to an active form called 1,25-dihydroxyvitamin D. Finally, it winds up in the intestine, where it helps the body to absorb dietary calcium.

And it definitely regulates the activity of other cells in the body. Vitamin D is a powerful immune system controller. It acts on the immune system through nuclear receptors called Vitamin D Receptors or VDR's. Nuclear Receptors are substances that attach to genes and affect their expression of that particular gene depending upon environmental inputs. Only VDR's are specific to Vitamin D, but there are thousands of different nuclear receptors that gather information from the environment and tell genes what to do. Most cells, if not all cells in the body have VDR receptors - making the influence of Vitamin D widespread. VDR's have been linked to the genes that control inflammation - which is present in all chronic diseases.

VDR's do many things depending upon where they are located and what is currently needed in the body, but one of their major functions is regulation of many antimicrobials that the body produces. This is perhaps why vitamin D research has led the journal Science News to call it "The Antibiotic Vitamin."

Vitamin D is also the hormone that regulates calcium. Vitamin D activates the parathyroid glands, that actually control the calcium levels in the body, and tell them what to do.
Lack of Vitamin D in the diet can prevent the absorption of calcium from the digestive system - no matter how much you take. But the benefits of this nutrient are more than bone-deep. Vitamin D deficiency has recently been associated with a host of chronic illnesses that seem to have nothing to do with each other, including heart disease, diabetes, infertility, high blood pressure, acne, multiple sclerosis, chronic muscle pain, inflammatory bowel disease, autoimmune diseases and many cancers.

Sources of Vitamin D

Ninety to 95 percent of our vitamin D is made in the skin and transformed into a useable form in our bodies. Therefore, the sun, more than food or supplementation, is the body's best source for obtaining vitamin D.

How much vitamin D you get from the sun depends on where you live, how intense the sun is, how much cloud cover, time of year, how dark your skin is and how much skin you actually expose.

Sun exposure to the arms and legs for 10-15 minutes per day should provide between 3000-20,000 IU's of Vitamin D for those with light skin.

The Dept. of Laboratory Medicine and Pathobiology, University of Toronto, Mount Sinai Hospital, Ontario, Canada states, "Total-body sun exposure easily provides the equivalent of (10,000 IU) vitamin D." If you have dark skin, you'll need between 5 to 20 times more exposure for the same amount of Vitamin D.

An optimal daily amount of vitamin D is between 3,800 IU and 5,000 IU per day. Taking supplements is not an optimal way to get vitamin D, because you can actually get too much and it can become toxic. The beauty of getting it from the sun is that you can never overdose on Vitamin D. With longer exposure to UVB rays, an equilibrium is achieved in the skin, and the vitamin simply degrades as fast as it is generated.

Vitamin D food sources exist, however it is very difficult to get all of your Vitamin D requirements through foods. The main sources are fatty fish, cod liver oil, egg yolks and wild mushrooms. These few sources are really the only significant sources of foods with Vitamin D. There are a others, such as sweet potatoes, dandelion greens, and some herbs, but they have so little Vitamin D that that they cannot be used for the purpose of getting adequate amounts of vitamin D.