WASHINGTON - A study presented on Sunday at the on-going Digestive Disease Week 2019 in San Diego showed coffee could help keep the bowels moving and contribute to digestion because it suppressed bacteria and increased muscle movement.

Researchers from the University of Texas Medical Branch examined changes to bacteria when rats' fecal matter was exposed to coffee in a petri dish, and by studying the composition of feces after rats ingested differing concentrations of coffee over three days.

They found that growth of bacteria and other microbes in fecal matter in a petri dish was suppressed with a solution of 1.5 percent coffee, and growth of microbes was even lower with a three percent solution of coffee. Decaffeinated coffee had a similar effect on the microbiome.

After the rats were fed coffee for three days, the overall bacteria counts in their feces were decreased, but more research is needed to determine whether those changes favor "good" bacteria or negative ones, according to the researchers.

When rats were treated with coffee for three days, the ability of the muscles in the small intestine to contract appeared to increase. Also, muscles in the lower intestines and colons of the rats showed increased ability to contract after a period of coffee ingestion.

But the bowel movement effects have nothing to do with caffeine, because caffeine-free coffee had similar effects as regular coffee, according to the study.

The findings show coffee may be used in the future, after more clinical research, a therapy for post-operative constipation, in which the intestines quit working after abdominal surgery.