Eating fiber alters the microbiome. It may boost cancer treatment, too.

Cancer researchers think they have found an explanation for why some cancer drugs don’t always work. The answer — and a possible solution — may be found in the gut microbiome.

The composition of a person’s gut microbiome — which consists of trillions of bacteria and other microbes — appears to influence whether a ground-breaking cancer treatment called immunotherapy is successful in some patients. Scientists have found that patients who harbor certain gut bacteria have better responses to immunotherapy than patients who lack them.