A diet with adequate amounts of vitamin D may alter gut bacteria, offering better immunity to cancer, according to a new study with a Greek lead researcher.
With more cases of cancer emerging at younger and younger ages, the scientific community's research into ways of prevention and treatment is endless. This includes a newer experimental research effort by researchers at the Francis Crick Institute, the National Cancer Institute (NCI) of the US National Institutes of Health (NIH), and Aalborg University in Denmark.
In their recent research, published in Science, they found that vitamin D encourages the growth of a type of gut bacteria in mice, improving immunity to cancer. Specifically, they observed that laboratory mice fed a diet rich in vitamin D had better immune resistance to experimentally transplanted cancers and improved response to immunotherapy.
This result was verified when gene editing was used to remove a protein that binds vitamin D in the blood and keeps it out of the tissues.
Vitamin D, also known as the sunshine vitamin since sunlight enhances its production, is found in foods such as fatty fish, eggs and fortified foods.
The role of the microbiome
Surprisingly, the research team found that vitamin D acts on the intestinal epithelial cells, which in turn increases the amount of a bacteria called Bacteroides fragilis. The particular microbe gave the test animals better immunity to cancer, as the transplanted tumours did not grow much, but the researchers are unsure how.
Expanding their study and aiming to test whether the bacteria alone could provide better immunity to cancer, they gave mice on a normal diet Bacteroides fragilis. These mice were also better able to resist tumour growth, but not when the mice were fed a vitamin D-deficient diet.
Previous studies have suggested some association between vitamin D deficiency and cancer risk in humans, although the evidence was inconclusive. Furthermore, although the bacterium Bacteroides fragilis is also found in the human microbiome, more studies will be needed to fully understand the effect of vitamin D on immune resistance to cancer through the same mechanism.
Evangelos Giampazolias, former postdoctoral researcher at the Crick and now Group Leader of the Cancer Immunosurveillance Group at the Cancer Research UK Manchester Institute, said:
“Pinpointing the factors that distinguish a ‘good’ from a ‘bad’ microbiome is a major challenge. We found that vitamin D helps gut bacteria to elicit cancer immunity improving the response to immunotherapy in mice.
“A key question we are currently trying to answer is how exactly vitamin D supports a ‘good’ microbiome. If we can answer this, we might uncover new ways in which the microbiome influences the immune system, potentially offering exciting possibilities in preventing or treating cancer.”
Maria Kotopouli is a columnist for Ygeia Mou. Translated by Paul Antonopoulos.
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