Sunshine has gotten a bad rap. It is true that excessive ultraviolet light from sunshine can increase the risk of skin cancer and cataracts, but judicious amounts of sunshine can be extremely beneficial. For example, sunshine can play a critical role in helping to prevent osteoporosis. Sunlight, you will recall, is able to convert cholesterol into vitamin D, an essential factor in maintaining good bone health.72

In Chapter 7 that deals with protein, we saw that high intake of animal protein sources was also a significant factor in causing osteoporosis. In addition to sunshine and nutrition, however, other NEWSTART factors are important in dealing with osteoporosis. Exercise is vital to staving off age-related loss of bone mass. Recent research from Washington University School of Medicine in St. Louis has demonstrated that a woman can increase her bone mass by 2 to 3 percent per year by exercise alone.73

But what about skin cancer? Why not get our vitamin D from pills or supplemented foods, so we can avoid sunshine’s cancer risk? There’s no question about it: when many Americans think of sunshine, they think of an agent that increases the risk of cancer.

Sun Exposure in High Doses and Cancer
Sunlight in high doses increases skin cancer risk. About 95 percent of skin cancers are of two types: squamous cell and basal cell.74 Both of these types of cancer are increased by substantial cumulative lifetime exposure to the sun. Fortunately, however, they are slow growing and usually remain confined to the skin. Even though some 750,000 squamous and basal cell skin cancers are diagnosed each year in the United States, only about 2,100 fatalities (less than one percent) result.75 The fatalities occur mostly in those who fail to get prompt and complete removal of the cancer.

Melanoma, another type of skin cancer, provides a markedly different situation. This usually darkly pigmented cancer has a fearsome tendency to spread and kill the victim. Each year only about 34,000 cases of melanoma are diagnosed in our country; however, 7,200 (more than 20 percent) die annually from this dreaded skin cancer.76 Melanoma is currently on a rapid rise worldwide; in Europe, it increases by three to seven percent every year.77 Regarding this deadliest of skin cancers, it appears that the important factor is not so much the total amount of sunlight you are exposed to, but whether or not you get sunburned. Thus, overdoses of sunlight are to be avoided. More information on skin cancer is found in Chapter 2.

Sunlight in moderate amounts, however, is healthful, and may even be beneficial in cancer prevention. Research now suggests that judicious sun exposure and the production of vitamin D may also help to prevent certain types of cancer. Colon cancer is one of the malignancies that sunshine exposure may help to prevent. Researchers at the University of Washington studied cancer rates in nine different areas of the United States. They discovered that men from Southern states had much less colon cancer than Northerners.78 For example, when compared to men living in New Mexico, men in Michigan, Connecticut, and Washington had colon cancer rates 50 to 80 percent higher. The effect also seemed to hold true for women, although it was not as marked.

Another scientific article reviewed studies possibly linking cancer prevention with sunshine exposure. H.G. Ainsleigh, the author, pointed out that there is a long history of medical documentation suggesting that regular sun exposure substantially decreases the death rates from certain cancers.79 Like other researchers, Ainsleigh observed that the linkage between sun exposure and cancer prevention appears to be due to vitamin D. Vitamin D and related compounds appear able to suppress the abnormal growth of a variety of cancer cells. These include leukemia and lymphoma as well as cancers of the breast and colon.

Ainsleigh did not stop there. He went on to make some startling calculations; namely, that although frequent regular sun exposure statistically causes 2,000 U.S. cancer fatalities per year, it also acts to prevent another 138,000 U.S. annual cancer deaths—and could possibly prevent another 30,000 more if all Americans adopted the practice of regular, moderate sunning. He even raised the concern that blame for a 17 percent increase in breast cancer incidence during 1991 and 1992 may have been related to misplaced solar-phobia; with a “decade of pervasive anti-sun advisories from respected authorities, coinciding with effective sunscreen availability.” Sunscreen may induce otherwise cautious sunbathers to get overdoses of sun exposure.

Regarding sunshine and cancer, two facts clearly stand out. First, excessive, injudicious amounts of sunshine can increase skin cancer risk. Second, avoiding sunshine is not a good alternative. It is likely that sunshine and the vitamin D it produces may actually play a role in cancer prevention as well as in bone health.