Breast cancer is the most frequent type of cancer affecting women worldwide. Although the chances of recovery are around 90%, this only applies if the cancer is detected early. Surgery, chemotherapy, hair loss or even a mastectomy - women suffering from breast cancer have to contend with all of these possible consequences. There is therefore virtually no other illness which frightens women more.

Since breast-cancer rates increase every year, the diagnosis and treatment options are of particular interest to scientists. It has long been known that high vitamin D levels can reduce the risk of breast cancer. This has been demonstrated in numerous epidemiological and laboratory studies.

With their study involving 67,721 French women, scientists led by Pierre Engel have shown that a minimum vitamin D level is necessary in order to prevent breast cancer. However, this is particularly difficult to achieve at northern latitudes because exposure to sunlight is insufficient to produce enough vitamin D, especially in the winter months. Whether this link is strong enough to meet the Hill criteria¹ had not hitherto been studied.

A group of scientists in the United States led by Sharif B. Mohr has now reviewed the available scientific data relating to breast cancer and vitamin D on the basis of the Hill criteria. After evaluating the findings, they found that the inverse correlation between vitamin D and breast cancer does indeed meet the Hill criteria. This means that there is now scientific proof that vitamin D reduces the risk of breast cancer.

"Modern lifestyles ensure that many women in the west spend too little time in the sun. Although even short UV exposure is enough for vitamin D production, many women in the west nevertheless suffer from a pronounced vitamin D deficiency. High vitamin D levels reduce the risk of breast cancer and also offer protection against many other diseases. In the Northern Hemisphere, the level of sunlight from September to May is often insufficient for the body to produce enough essential vitamin D. It might therefore be sensible to undergo moderate artificial UV exposure on a regular basis", explains Ad Brand of the Sunlight Research Forum (SRF).

The Sunlight Research Forum (SRF) is a not-for-profit organisation based in The Netherlands. SRF's aim is to help promote, the latest medical and scientific information on the effects of moderate UV exposure on man.

1 Hill criteria: The Hill criteria are a medically recognised series of criteria by which a causal link between a specific factor (environmental impact, socio-economic factors, etc.) and the occurrence of a disease pattern can be verified.