London, England – Vitamin D has been found to play a crucial role in enhancing the immunity of mice to cancer by promoting the growth of specific gut bacteria. A recent study conducted by researchers at the Francis Crick Institute, the National Cancer Institute (NCI) of the U.S. National Institutes of Health (NIH), and Aalborg University in Denmark, revealed that mice with higher levels of vitamin D exhibited stronger resistance to tumor growth and responded more effectively to immunotherapy.
The study indicated that an increase in Bacteroides fragilis, a type of gut bacteria, was observed in mice fed with vitamin D, leading to improved immune response to cancer. This finding raises the question of whether a similar effect could be seen in humans, as previous studies have hinted at a possible correlation between vitamin D levels and cancer risk.
Researchers noted that further investigation is needed to explore how vitamin D could potentially be utilized to enhance the beneficial gut microbiome, potentially opening up new pathways for cancer treatment and prevention. The study, published in Science, demonstrated that vitamin D not only boosted the immune resistance of mice to experimentally transplanted cancers but also improved their responses to immunotherapy treatment.
Surprisingly, the research team discovered that vitamin D targeted epithelial cells in the intestine, leading to an increase in the abundance of Bacteroides fragilis. This specific microbe contributed to better immunity to cancer in mice, as evidenced by reduced tumor growth. However, the mechanism behind this phenomenon remains unclear and requires further investigation.
To test the individual impact of the bacteria on cancer immunity, mice on a normal diet were administered Bacteroides fragilis. These mice also showed enhanced resistance to tumor growth, but this effect was not observed in mice placed on a vitamin D-deficient diet. While previous studies have suggested a link between vitamin D deficiency and cancer risk in humans, evidence supporting this connection has been inconclusive.
The researchers conducted an analysis of data from 1.5 million individuals in Denmark, which highlighted a potential association between lower vitamin D levels and an increased risk of cancer. Additionally, an analysis of a population of cancer patients suggested that individuals with higher levels of vitamin D were more likely to respond positively to immune-based cancer treatments.
Although Bacteroides fragilis is also present in the human microbiome, further research is needed to determine whether vitamin D can provide similar immune resistance to cancer in humans through the modulation of gut bacteria. The study’s authors emphasized the need for more in-depth research before conclusively establishing the benefits of correcting a vitamin D deficiency for cancer prevention or treatment.