Vitamin D is a group of fat-soluble prohormones, which basically means that it is inert and that vitamin D obtained from sun and UV exposure, food, and supplements, must undergo two chemical reactions referred to as hydroxylation reactions to become beneficial to the body.

Calcitrol, the medical term for active vitamin D is important to organ health. Calcitrol’s most important benefit is boost calcium levels in the bloodstream. It does this by allowing the body to absorb calcium and phosphorus from food in the intestines more readily. It also aids the kidney’s by helping them reabsorb calcium which in turn promotes bone growth.

People who suffer from vitamin D deficiency are at risk for a number of bone disorders including thin and brittle bones in adults and Rickets in children. Vitamin D deficiency stems from a reduced intake of vitamin D containing foods and poor sunlight or UV exposure which is needed to create the active Calcitrol.

Vitamin D also plays other important roles in the body. It inhibits calcitonin release from the thyroid gland, which may result in the inhibition of bone and cartilage degeneration. It can inhibit parathyroid hormone secretion from the parathyroid gland, modulate neuromuscular and immune function and reduce inflammation.
 
Because vitamin D has no hormone activity itself, it has to be converted to an active hormone through a synthesis mechanism in the epidermal layer in the skin. In nature, this synthesis requires the presence of UVB light.

However, in winter months, adequate amounts of sunlight are not available to most humans. In addition to the lower UVB levels in the winter months, the need for exposure to a large area of the skin is impractical in colder weather.

There are only three ways for adults to insure adequate levels of vitamin D:

• regularly receive midday sun exposure in the late spring, summer, and early fall, exposing as much of the skin as possible being careful to never burn.
• regularly use a sun bed, avoiding sunburn, during the colder months.
  
• take vitamin D supplements.
  

Most people think of indoor tanning as purely cosmetic treatment, but there are studies that have shown the side-effect of UVB exposure in a tanning bed, aids the synthesis that promotes vitamin D development.

Using ultraviolet light for healing and health is not a new idea. In 1903, Dr. Niels Finsen received the Nobel Prize for Physiology/Medicine for his work treating the disease lupus vulgaris with ultraviolet light. Used in moderation, the ultraviolet lighting in most tanning salons can have the same effect.

The problem and negative press is mostly derived from studies of people that have been overexposed to the indoor tanning experience. Just as overexposure to the sun can cause many health problems, so does overexposure to indoor UVB rays.

Both exposure to sunlight or tanning UVB light sources, as it turns out, is necessary to health and normal metabolic activity. During the late spring, summer and early fall, sunlight is abundant and in moderate exposure amounts healthy. The same can be said about exposure to tanning facilities in the winter months when sunlight levels are not as productive to health.