Consuming a high-fiber diet could make some cancer therapies more effective and halt the growth of tumors, said researchers at the American Association for Cancer Research.

According to Christine Spencer, a research scientist at the Parker Institute for Cancer Immunotherapy in San Francisco, high-fiber diets seem to foster a more diverse collection of gut microbes in cancer patients, thus boosting immunotherapy.

However, researchers found that probiotic supplements reduce the diversity of microbes in cancer patients’ guts, while they were long believed to be doing the opposite.

“A lot of people have perceptions that probiotics will have health benefits, but that might not be the case for cancer patients,” Spencer said.

Cynthia Sears, an infectious diseases specialist at Johns Hopkins University School of Medicine, said that many studies have linked high-fiber diets to diminished cancer risk and other health developments.