Cancer / Sunlight provides the body with vitamin D that works to prevent the development of malignant tumors
By "New York Times" and Tamara Traubman
In recent years, the sun has been declared the number one cause of skin cancer. However, recently some scientists have begun to investigate the possibility that sunlight may also play a positive role in maintaining health, and in fact it helps protect against some types of cancer.
The idea was first proposed by epidemiologists 22 years ago. The theory holds that vitamin D, which the skin produces in response to sun exposure, works to prevent the development of malignant tumors. According to the theory, people living in less sunny and high altitude areas do not produce large amounts of the vitamin, and thus may be more susceptible to the development of tumors.
At first the scientists despised the whole idea. But two decades later, the possibility that the vitamin might be a significant factor in the fight against cancer doesn't seem so unlikely. While the hypothesis linking vitamin D deficiency and cancer is controversial, researchers are testing vitamin D as a possible agent for cancer treatment. In human trials, the possibility is tested that the vitamin or similar compounds can treat cancer or strengthen the action of chemotherapy drugs.
Sunlight provides the body with about 90% of its vitamin D. The ultraviolet rays encourage the skin to produce a biologically-natural form of the vitamin, which then turns into an active form of a hormone called calcitrol. Dr. Cedric Garland and Dr. Frank Garland from the USA, two epidemiologist brothers and pioneers of the theory, hypothesized that the development of some types of cancer is related to a lack of sun exposure and vitamin D. They noticed that according to the maps published by the "National Cancer Institute" of the USA , the highest death rates are clustered in less sunny countries, whose residents are more likely to stay indoors.
Later, other scientists raised the possibility that low levels of vitamin D could also lead to prostate cancer, noting that it was twice as common in black men as in white men. "Black people are less prone to skin cancer because their dark skin acts as a shield from the sun's rays," says Dr. Gary Schwartz, an epidemiologist at Wake Forest University. "But dark skin may explain the high death rates from prostate cancer." According to him, men in Maine are 50% more likely to die of prostate cancer than men in Florida.
The research of the Garland brothers showed that people in areas where there is a relatively low amount of sunlight, or people with low levels of vitamin D, are at a higher risk of suffering from a variety of other types of cancer as well. In April, researchers from the National Cancer Institute reported that the chance of dying from breast, colon, ovarian and prostate cancers was reduced by 10% among about 27% of people in sunny areas. This, based on death certificates from 24 countries.
However, it does not appear from the findings that the more a person exposes himself to the sun, the less likely he is to get cancer. "The relationship between the metabolism of vitamin D and bowel cancer is already quite well known; There are also old theories that say that the farther you get from the equator, the more the incidence of breast cancer increases," says Prof. Tamar Peretz, director of the Sharett Oncology Institute at the Hadassah Medical Center in Jerusalem. According to her, "there are some loopholes in the theory. For example, in Israel, which is a country with a lot of sunshine, the incidence of breast cancer should have been low, according to the theory. We know it is higher than many countries." According to her, there are many reasons for the development of different types of cancer, "and in this case, as in many other things, neither too little nor too much is good".
"The theory is getting more and more proof," says Dr. Cedric Garland. He believes that the recommended daily amount of vitamin D is 10 mg for adults, and recommends avoiding prolonged exposure to the sun without protection. At the same time, pharmaceutical companies are testing how to produce compounds similar to vitamin D that will help prevent diseases.
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