Researchers at McGill University have uncovered a molecular mechanism underlying the cancer-preventive effects of vitamin D, demonstrating that its active form effectively shuts down cancer cells. Studies show that individuals with higher blood levels of vitamin D have significantly longer lifespans compared to those with lower levels of the vitamin. The findings were published on April 10, 2024, in the Proceedings of the National Academy of Sciences.

The research team, led by Professors John White and David Goltzman from McGill's Faculty of Medicine’s Department of Physiology, discovered that the active form of vitamin D works through several mechanisms to inhibit the production and function of cMYC, a protein that drives cell division. Elevated cMYC levels are active in more than half of all cancers.

This new discovery adds to the growing body of research on the role of vitamin D in improving health and preventing disease. Previous studies have established a direct connection between low vitamin D levels and various cancers, as well as cardiovascular diseases. Dr. Stephen B. Kritchevsky, a Professor of Internal Medicine and Transitional Science at Wake Forest School of Medicine, found a significant correlation between low vitamin D levels and increased health risks.

Dr. Kritchevsky’s research revealed that vitamin D insufficiency (defined as blood levels <20 ng/ml) was present in a third of study participants. This deficiency was associated with nearly a 50% increase in mortality rates among older adults. He noted, “Our findings suggest that low levels of vitamin D may be a substantial public health concern for older adults in the U.S.”

While vitamin D can be obtained from limited dietary sources and direct sun exposure during the warmer months, poor dietary intake and sun avoidance have led to widespread vitamin D deficiency in many populations around the world. It is well-established that vitamin D has a broad range of physiological effects, and a lack of it is linked to higher incidences of certain cancers, especially those of the digestive tract like colon cancer, as well as some types of leukemia.

Professor White explained, “For years, my lab has been dedicated to studying the molecular mechanisms of vitamin D in human cancer cells, particularly its role in halting their proliferation.” The team found that vitamin D regulates both the production and degradation of cMYC. More importantly, they discovered that vitamin D promotes the production of MXD1, a natural antagonist of cMYC, which essentially shuts down cMYC's function.

In their experiment, the researchers applied vitamin D topically to mice and observed a reduction in cMYC levels, with evidence showing decreased cMYC activity. Interestingly, when they studied mice lacking the specific vitamin D receptor, they found significantly elevated levels of cMYC in various tissues, including skin and the lining of the colon. This suggests that topical application of vitamin D could be just as effective as oral intake in preventing cancer.

These findings shed light on the powerful potential of vitamin D as a preventive tool against cancer, emphasizing its importance in health and disease prevention.