Lack of sun produces adverse health outcomes

There's no question that chronic, excessive exposure to sunlight and sun burning incidents markedly increase your risk for skin cancer. But there's little evidence out there that if you practice safe sun exposure, it would increase your risk for skin cancer or wrinkling. Nurse Niki Patel ("Dermatology nurse sheds light on dangers of tanning," letters, Aug. 24) would have us cowering from the sun, which the human race evolved under for thousands of years living in harmony with its heat and light.

Little importance has been attached to the influence of nutrition in the genesis of skin cancer. Yet the limited amount of research carried out on the subject shows what you eat determines how your skin responds to sunlight. The proportion of healthy fats in your diet - together with vitamins (antioxidants) and mineral contents of your foods - could decide how likely you are to sustain skin damage from the sun.

Sunlight therapy was a medicine of the pre-antibiotic era, when infectious diseases were commonplace and the only defense against them was a strong immune system. Perhaps the most widely recognized benefit of exposing skin to the sun's ultraviolet rays is that this activates the production of vitamin D. Vitamin D appears to interact with virtually every tissue in the body. Moreover, the incidence of certain diseases seems to vary depending on sun exposure and vitamin D levels. For example, many cancers - most notably breast, colon, ovarian and prostate cancer - seem to increase the farther you get from the equator, where exposure to ultraviolet light from the sun is greatest.

While there could be many other explanations, the idea that vitamin D may help prevent malignancies has been buttressed by animal and laboratory studies indicating it can act as a brake on cell growth, preventing the uncontrolled cell division that is cancer. Similarly, vitamin D appears to damp down the immune system, and researchers have also found associations among sun exposure, vitamin D levels and the incidence of auto immune diseases such as multiple sclerosis, lupus and diabetes, in which the immune system attacks the body.

The sun is central to our well-being:

+ When vitamin D levels are low, the body cannot absorb sufficient calcium to stay healthy, no matter how much calcium is taken in.

+ Ultraviolet radiation can significantly reduce blood pressure.

+ Studies have shown exposure to sunlight (UV) increases the number of white blood cells.

+ Sadness and despair can be triggered by low light levels during winter months. The sun's daily cycle of light and dark regulates many of the body's most important hormonal and biochemical processes.

Health and economic burdens from insufficient solar UVB exposure and vitamin D greatly outweigh all known adverse health outcomes. These are the findings from a rigorous study published in the journal Photochemistry and Photobiology. Scientists investigated the annual number of cases and deaths due to cancer, multiple sclerosis, and osteoporotic hip fracture that likely could have been prevented with sufficient vitamin D as well as the number of cases and deaths from skin cancer and melanoma, and cases of cataracts that likely have been prevented by avoiding excess UV exposure. Economic burden values were then determined for these results.

It was estimated that about 50,000-63,000 annual cancer deaths in the United States (10 percent of all cancer deaths) could be prevented if all Americans had sufficient vitamin D. These findings are based on data in the Atlas of Cancer Mortality Rates for the United States, but are also supported by a number of recent reports that vitamin D plays a very important role in increasing survival once cancer is discovered. These deaths greatly outnumber the annual number of deaths from melanoma (8,000) and skin cancer (2,000).

Joe Vincze

North Brunswick