In the fight against breast cancer, we can use all the help we can get, and according to a new study, there may be one ally that has been seriously underestimated: the sun. New research suggests that high levels of vitamin D, a nutrient our skin makes after sunlight exposure, can help women better survive breast cancer by stopping the reproduction of cancer cells.

The research found that high levels of vitamin D were associated with lower overall mortality among breast cancer patients, raising their chances of survival by about 30 percent. This benefit was particularly useful in pre-menopausal women, The Daily Mail reported.

“Our findings provide compelling observational evidence for inverse associations between vitamin D levels and risk of breast cancer progression and death, said study co-author Dr. Song Yao in a statement.

For the study, researchers looked at the prognosis and overall outcomes of 1,666 women with breast cancer and found that the higher the concentration of a blood biomarker for Vitamin D, called 25-hydroxyvitamin D (250HD), the better the overall survival.

While the results are exciting, the researchers emphasized that the study was not designed to establish causality, meaning that women with cancer should not be flocking to the beachside based on this research alone. However, extra vitamin D can’t hurt, as it’s been proven to be essential for bone health. If you want to get more in your diet, reported that in addition to sunlight exposure, you can eat more fatty fish, such as salmon and tuna, drink fortified milk, or add more eggs to your diet — just make sure to have the whole egg as the vitamin D is found in the yolk.

Breast cancer is not the only illness that vitamin D has been shown to fight. A study released earlier this year suggested that vitamin D supplements improved heart function in people with heart muscle weakness and could be especially beneficial to heart failure patients. On the other hand, vitamin D deficiency has also been linked to chronic heart failure. According to research, vitamin D may be so beneficial to heart failure patients that it may even prevent some from needing an implantable cardioverter defibrillator, a device that can detect irregular heart rhythms and shock the heart to restore normality.

Source: Yao S, Kwan ML, Ergas IJ. Association of Serum Level of Vitamin D at Diagnosis With Breast Cancer Survival A Case-Cohort Analysis in the Pathways Study. JAMA Oncology. 2016

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