The Importance of Sunlight and Vitamin D
Krispin Sullivan
For the past number of years clinicians, physicians, national media and the National Institute of Health have been warning Americans to stay out of the sun. The purpose of this warning was intended to prevent melanoma, a serious form of skin cancer. In spite of the ever-increasing use of sunscreens and intentional reduction of sun exposure, incidence of this cancer is on the upswing. There is some evidence that the advice given regarding sunlight may have actually contributed to an increase in incidences of melanoma because of issues relating to genetics, UV-A radiation, UV-B radiation and extended exposure times due to reduction in sun-burning by sunscreen use.
One of the known protectors of skin cells from pre-cancerous changes is vitamin D. For most Americans the only source of vitamin D is sunlight. We have a national disaster in progress due to a misunderstanding of the nature of and need for UV-B and vitamin D.
Naked at Noon, Understanding the Importance of Sunlight and Vitamin D
The book explains how we get D from food, sunlight and supplements and how we have become so seriously D deficient by changes in location (immigration to genetically unfriendly climates), attitudes and lifestyles. There is a chapter on skin cancer and another on the importance of essential fats. It also covers information related to vitamin D's intimate relationship with calcium and magnesium.
"Ultraviolet (UV) light is divided into 3 bands or wavelength ranges, which are referred to as UV-C, UV-B and UV-A.6 UV-C is the most energetic and shortest of the UV bands. It will burn human skin rapidly in extremely small doses. Fortunately, it is completely absorbed by the ozone layer. However, UV-C is present in some lights. For this reason, fluorescent and halogen and other specialty lights may contribute to skin cancer.
UV-A, known as the “tanning ray,” is primarily responsible for darkening the pigment in our skin. Most tanning bulbs have a high UV-A output, with a small percentage of UV-B. UV-A is less energetic than UV-B, so exposure to UV-A will not result in a burn, unless the skin is photosensitive or excessive doses are used. UV-A penetrates more deeply into the skin than UV-B, due to its longer wavelength. Until recently, UV-A was not blocked by sunscreens. It is now considered to be a major contributor to the high incidence of non-melanoma skin cancers.7 Seventy-eight percent of UV-A penetrates glass so windows do not offer protection.
The ultraviolet wavelength that stimulates our bodies to produce vitamin D is UV-B. It is sometimes called the “burning ray” because it is the primary cause of sunburn (erythema). However, UV-B initiates beneficial responses, stimulating the production of vitamin D that the body uses in many important processes. Although UV-B causes sunburn, it also causes special skin cells called melanocytes to produce melanin, which is protective. UV-B also stimulates the production of Melanocyte Stimulating Hormone (MSH), an important hormone in weight loss and energy production.
The reason it is difficult to get adequate vitamin D from sunlight is that while UV-A is present throughout the day, the amount of UV-B present has to do with the angle of the sun’s rays. Thus, UV-B is present only during midday hours at higher latitudes, and only with significant intensity in temperate or tropical latitudes. Only 5 percent of the UV-B lig
ht range goes through glass and it does not penetrate clouds, smog or fog.
Sun exposure at higher latitudes before 10 am or after 2 pm will cause burning from UV-A before it will supply adequate vitamin D from UV-B. This finding may surprise you, as it did the researchers. It means that sunning must occur between the hours we have been told to avoid. Only sunning between 10 am and 2 pm during summer months (or winter months in southern latitudes) for 20-120 minutes, depending on skin type and color, will form adequate vitamin D before burning occurs." Krispin Sullivan.
http://sunlightandvitamind.com/
