A review of breast cancer data by scientists in the US has established a causal link between the disease and vitamin D deficiency.
Epidemiological and laboratory studies have long established that high vitamin D levels can reduce the risk of breast cancer.
However, a previous study of 67,721 French women, led by Pierre Engel, epidemiology manager at Quintiles-Outcome, showed the importance of a minimum vitamin D level in preventing breast cancer.
That poses a particularly problem for women at northern latitudes because exposure to sunlight is insufficient to produce enough vitamin D, especially in the dark winter months.
Although even short periods of UV exposure is enough for vitamin D production, the busy lifestyles of many western women mean they spend too little time in the sun.
“High vitamin D levels reduce the risk of breast cancer and also offer protection against many other diseases,” Ad Brand of the Sunlight Research Forum (SRF) said.
“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.”