Showing off a nice tan is not the only positive result that comes from being exposed to the sun. Our health can also benefit from it, even offsetting the risk of developing skin cancer. This is indicated by the latest research on vitamin D, a molecule that our skin synthesizes when it receives sunlight and which is accumulated during the summer, with prolonged exposures. It now seems that low levels of vitamin D in the body are linked to increased incidences of cancer, diabetes, respiratory infections and heart problems.
The direct relationship between low levels of vitamin D and cancer, regardless of where we live, was confirmed last spring by researchers at the University of California (USA). In an article published in PLOS ONE, they calculated the exact levels of this molecule that we need to have in the blood to dramatically reduce the risk of tumors. They concluded that women who reached concentrations of this vitamin of 40 nanograms or more per milliliter of blood were 67% less likely to suffer from cancer. Notably, this is twice the amount of vitamin D recommended by the US Institute of Medicine to ensure good bone health.
“In laboratory studies it has been shown that vitamin D inhibits cell proliferation, metastatic potential and angiogenesis –the formation of new blood vessels– as well as increasing cell suicide or apoptosis and providing anti-inflammatory properties,” explains Kimmie Ng, oncologist at Harvard University (USA) to OpenMind. “As many of these processes fail in cancer, a few years ago the hypothesis arose that vitamin D may be a good anti-cancer agent, and the clinical data appears to confirm this,” he adds. In fact, it was recently shown that the higher the latitude in which a person lives, the more likely they are to suffer from colorectal cancer or breast cancer. To this it can be added that the risk of leukemia also doubles among those living closer to the poles.
Insufficient vitamin D: lymphocytes are paralyzed
In addition, the immune system does not work very well with low vitamin D levels. In fact, the concentration of the molecule largely determines how our defense cells respond to inflammatory and infectious processes. If the quantity is insufficient, the T lymphocytes are paralyzed, unable to move to the site of the attack, and bacteria and viruses can take the upper hand. This seems to be especially true for microbes that attack the respiratory system, according to the latest scientific investigations.
On the other hand, the heart pays dearly when vitamin D is lacking. A study by American cardiologists last year revealed that coronary heart disease, strokes and heart attacks increase when the concentration of this molecule falls below 15 nanograms per milliliter of blood. Moreover, according to a study by Heidi May and her colleagues at Intermountain Medical Center Heart Institute (USA), measuring the vitamin D in the bloodstream can quite accurately predict the risk of heart failure.
Vitamin D reduces mortality
To this is added the fact that studies have shown that the lack of this vitamin doubles the risk of schizophrenia, increases erectile dysfunction, promotes allergies, hinders recovery in AIDS patients and increases the incidence of asthma and Parkinson’s disease. “More and more evidence exists that vitamin D prevents chronic diseases including cancer and heart disease, but also diabetes and autoimmune diseases,” says Dr. Ng. This would explain why a study printed in the Archives of Internal Medicine found that increasing vitamin D in the blood was enough to reduce mortality from any cause by 7%. Taking into account that it is estimated that at least one billion people worldwide have deficient levels of vitamin D, experts say we cannot sit idly by.
Does this mean we should all head out into the sun, even though experts have been warning us for years about the risk to the skin of excess ultraviolet rays? The data leaves no doubt – even despite the risk of melanoma, the overall number of cases of cancer of any kind is drastically reduced when we expose ourselves assiduously to the sun, thanks to the effect of the vitamin D. “As far as cancer is concerned, the sun has more positive than adverse effects on health,” concluded the Norwegian oncologist Johan Moan in the prestigious journal PNAS. However, although there is no doubt that type B ultraviolet rays are the most efficient in increasing the concentration of this molecule in blood, many researchers doubt whether this is enough to recommend a tan as a healthy habit. In fact, Kimmie Ng argues: “We shouldn’t encourage exposure to sunlight and, given that the vitamin D found in food is not sufficient, the best way to correct the deficit would be to take vitamin supplements, in consultation with a doctor”.