The Sun and Human Health

Jacobs Liberman, O.D., Ph.D., challenges the modem myth that the sun is dangerous to our well-being. The sun was once used as a general tonic to heal almost everything and man has run nacked on this planet under the sun for centuries. The sun provides the basis for all life on earth. The sun is the source of energy for all plants, and indirectly, for all animals. If the sun causes cancer, man wouldn't be here today. Contrary to popular belief, sunbathing actually helps heal cancer of the skin while sunblock increases cancer risk.

 Sunlight helps the body heal wounds and injuries and overcome virtually any illness. Dr. Carl Hoffminster wrote that soldiers in World War II healed and survived much better when their open wounds and broken bones were exposed to sunlight. It's the great cancer cover-up. Panicked into avoiding sunlight by health experts, we are now dying in our thousands from diseases linked to deficiencies of vitamin D. But still the exaggerated warnings come.

 According to the National Cancer Institute, lifetime exposure to sunlight may ...reduce your risk of some of the most common types of cancer. In an analysis of death certificates from 24 states over an 11-year period, the NCI researchers found that people who lived in the sunniest parts of the country, and those exposed to the most sunlight through their jobs, had significantly lower rates of breast and colon cancer than matched controls. The scientists identified cases through a database maintained by the NCI, the National Institute for Occupational Safety and Health, and the National Center for Health Statistics. The data was collected from 24 states from 1984 through 1995, and includes information on occupation, state of residence at birth and at death, and cause of death. The researchers took significant measures to ensure the accuracy of their data. They only included people who were born and died in states in the same solar radiation range. And they classified farmers in their own occupational category, separate from other outdoor jobs, as they have been shown to have higher overall rates of certain types of cancer. They also narrowed down the cases substantially with a long list of exclusions.

 Even after all those adjustments, the results were compelling. Overall, people who lived in the highest solar radiation range (in states like Arizona, Hawaii, Florida, and Texas) had less risk of dying of breast, ovarian, prostate, or colon cancer than those who lived in the lowest range (states like Maine, New Hampshire, Ohio, and Washington). The occupational difference was most significant in relation to cases breast and colon cancer; across all levels of solar radiation, people who worked outside had 20 to 25 percent less risk of these two types of cancer. And the benefits of outside work weren't attributable to the amount of hard labor. Even after the researchers adjusted for level of physical activity, the reduction in risk remained. In their discussion, the NCI researchers theorize that sunlight offers cancer protection through its contribution of vitamin D. Recent laboratory tests have shown that vitamin D can slow or halt the proliferation of breast and colon cancer cells.

Benefits of sunlight for human health

 While it is wise to avoid burning [Kennedy et al., 2003] or excess tanning from solar or indoor ultraviolet radiation (UVR), it should be realized that solar UVB radiation (290-315 nm) is the primary source of vitamin D for most Americans and Europeans. Dietary sources are inadequate and supplements have to be used carefully.

 Mid-day summer sun is the best source of UVB, since minimal exposure times are required, and the UVB to UVA (315-400 nm) ratio is highest. If using sunscreen, it might be advisable to go into the sun for 10-15 minutes without sunscreen to generate a day's worth of vitamin D.

 As for melanoma and other skin cancer, several points should be made. First, while UVR generates free radicals that can do some of the damage, dietary antioxidants and skin pigmentation are nature's way of fighting free radicals. A recent paper by Millen et al. [2004] reported that diets high in antioxidants and low in fats and alcohol can reduce the risk of melanoma by about 50%. Smoking is also a risk factor for non-melanoma skin cancer. Second, occupational exposure to UVR is associated with reduced risk of melanoma [Kennedy et al., 2003].

 The health benefits of UVB through production of vitamin D are considerable, with more benefits being recognized at a rapid pace. My work indicates that over 20,000 Americans die prematurely annually from insufficient UVB/vitamin D [Grant, 2002]. I also estimate that half of those with multiple sclerosis in the U.S. would not have MS if they had as much UVB exposure as those living in the southern states.

 Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease

  ABSTRACT

 Most humans depend on sun exposure to satisfy their requirements for vitamin D. Solar ultraviolet B photons are absorbed by 7-dehydrocholesterol in the skin, leading to its transformation to previtamin D3, which is rapidly converted to vitamin D3. Season, latitude, time of day, skin pigmentation, aging, sunscreen use, and glass all influence the cutaneous production of vitamin D3. Once formed, vitamin D3 is metabolized in the liver to 25-hydroxyvitamin D3 and then in the kidney to its biologically active form, 1,25-dihydroxyvitamin D3. Vitamin D deficiency is an unrecognized epidemic among both children and adults in the United States. Vitamin D deficiency not only causes rickets among children but also precipitates and exacerbates osteoporosis among adults and causes the painful bone disease osteomalacia. Vitamin D deficiency has been associated with increased risks of deadly cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes mellitus. Maintaining blood concentrations of 25-hydroxyvitamin D above 80 nmol/L ( 30 ng/mL) not only is important for maximizing intestinal calcium absorption but also may be important for providing the extrarenal 1 -hydroxylase that is present in most tissues to produce 1,25-dihydroxyvitamin D3. Although chronic excessive exposure to sunlight increases the risk of nonmelanoma skin cancer, the avoidance of all direct sun exposure increases the risk of vitamin D deficiency, which can have serious consequences. Monitoring serum 25-hydroxyvitamin D concentrations yearly should help reveal vitamin D deficiencies. Sensible sun exposure (usually 5–10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.

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