Exercise helps fight cancer. Wow! What a headline. But is it true?
Researchers studied exercise, and its effect on gut microbes and the molecules they produce in response to the exercise. They found that certain gut microbes produce a metabolite (formate) that is increased with exercise and which boosts the potency of CD8 T cells in the immune system – which are key to fighting cancer. The initial tests were done in mice, but then the researchers took their results and applied them to humans with melanoma.
They found that in humans with melanoma, high levels of formate had longer progression-free survival (they live with the cancer, but it doesn't get worse). This is big news! Of course, further studies are ongoing.
Bottom line: Exercise is beneficial for all sorts of reasons, but one may be its effects on cancer. Studies find that exercise is known to help prevent cancer and suppress the growth of existing tumors.
From New Scientist: Exercise helps fight cancer – and we may finally know why
Exercise seems to help prevent cancer and reduce the growth of tumours, and that protective effect may be due to the way working out changes the gut microbiome.
Exercise is known to help prevent cancer and suppress the growth of existing tumours. It is also associated with changes in the gut microbiome – and now researchers have shown how these changes could result in exercise’s cancer-fighting effect.
Marlies Meisel at the University of Pittsburgh in Pennsylvania and her colleagues gave an aggressive form of melanoma to two groups of mice. One group had been on a four-week exercise regimen, while the other group had been sedentary.
As expected, the mice who exercised had smaller tumours and better survival rates. However, a further test showed that in animals treated with antibiotics or kept completely germ-free, exercise showed no benefit. The evidence was clear: the magic was in the microbes, as well as the molecules they produce, called metabolites.
But the microbiome makes thousands of metabolites, so the researchers used machine learning to help sift through the candidate molecules and landed on formate. This is a metabolite of bacteria that is increased by exercise and boosts the potency of CD8 T cells in the immune system – which are key to fighting cancer.
Next, the team looked at 19 humans with advanced melanoma. Those with high levels of formate had longer progression-free survival – the length of a plateau when a person lives with cancer but it doesn’t get worse – than those with low levels.
“This research highlights the importance of assessing the metabolites the bacteria are producing, and not just which bacteria,” says Meisel.
Meisel and her team are now looking at whether exercise-induced changes to the gut microbiome could play a role in other conditions.