Study: High Blood Levels Of Vitamin D May Protect Women From Breast Cancer

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For some time, a connection between vitamin D levels and the risk of developing breast cancer has been implicated, but its clinical relevance had not yet been proven—until now. Sascha Abbas and colleagues from the working group headed by Jenny Chang-Claude at the German Cancer Research Center, collaborating with researchers of the University Hospitals in Hamburg-Eppendorf, have now obtained clear results.

While previous studies had concentrated chiefly on nutritional vitamin D, the researchers focused on complete vitamin D status, studying 25-hydroxyvitamin D—25(OH)D—as a marker for both endogenous vitamin D and vitamin D from food intake.

The study involved 1,394 breast-cancer patients and an equal number of healthy women after menopause. Results showed that women with a very low blood level of 25(OH)D have a considerably increased risk of breast cancer. The effect was found to be strongest in women who were not taking hormones for relief of menopausal symptoms. However, the study authors note that diagnosis-related factors such as chemotherapy or lack of sunlight after prolonged hospital stays might have contributed to low vitamin levels of breast cancer patients.

In addition, the researchers looked at the vitamin D receptor. The gene of this receptor is found in several variants known as polymorphisms; the research team investigated the effect of four of these polymorphisms regarding the risk of breast cancer development. They found out that carriers of the Taql polymorphism have a slightly increased risk of breast tumors that carry receptors for the female sex hormone estrogen on their surface. No effects on the overall breast cancer risk were found. A possible explanation offered by the authors is that vitamin D can exert its cancer-preventing effect by counteracting the growth-promoting effect of estrogens.

Besides its cancer-preventing influence with effects on cell growth, cell differentiation and programmed cell death (apoptosis), vitamin D regulates, the calcium metabolism in the human body. Foods that are particularly rich in vitamin D include certain oily fish, eggs and dairy products. However, the largest portion of vitamin D is produced by the body with the aid of sunlight.

Source: Science Daily