A high-fiber diet has been linked to a range of health benefits, including protective effects against heart disease, cancer and obesity. Now we can add lower rates of depression to the list, at least if the right gut bacteria are hanging around.

A study involving more than 5,800 women of various ages found that premenopausal women with higher intakes of dietary fiber were less likely to experience depression than premenopausal women with lower fiber intake. The same association was not found among postmenopausal women. The researchers, who reported their findings in Menopause, theorized that the difference between the groups may be due to estrogen levels affecting the balance of gut microorganisms in pre- and postmenopausal women.

The link between dietary fiber and mental health in women, and likely men as well, might be partially explained by gut-brain interactions: Positive changes in gut-microbiota composition brought on by higher fiber consumption could positively affect neurotransmission. Future research will need to determine whether estrogen depletion during menopause does indeed make the microbiome less responsive to a dietary change like eating more fiber—and, if so, how the effects can be ameliorated.

See also: Feeling Blue? Eating More Fiber Could Help