New experiments, performed in vitro on bacterial cultures and in vivo in rats, show that coffee — regardless of caffeine content — inhibits gut microbiota and stimulates intestinal smooth muscle contractility.
Hegde et al, feeding rats coffee and also mixing it with gut bacteria in Petri dishes, found that coffee suppressed bacteria and increased muscle motility. Image credit: Free Photos.
“Coffee is one of the most popular beverages in the world,” said lead author Dr. Xuan-Zheng Shi from the University of Texas Medical Branch and colleagues.
“Consumption of coffee is inversely associated with the risk of constipation. We hypothesized that the benefit may be related to the effects of coffee on gut microbiota and smooth muscle contractility, two key contributors to normal motility.”
“We investigated the in vitro and in vivo effects of coffee on gut microbiota and smooth muscle contractility of the small intestine and colon in rats.”
The scientists examined changes to bacteria when 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 also documented changes to smooth muscles in the intestine and colon, and the response of those muscles when exposed directly to coffee.
They found that growth of bacteria and other microbes in fecal matter in a Petri dish was suppressed with a solution of 1.5% coffee, and growth of microbes was even lower with a 3% 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.
“More research is needed to determine whether these changes favor Firmicutes, considered ‘good’ bacteria, or enterobacteria, which are regarded as negative,” the researchers noted.
Muscles in the lower intestines and colons of the rats showed increased ability to contract after a period of coffee ingestion, and coffee stimulated contractions of the small intestine and colon when muscle tissues were exposed to coffee directly in the lab.
“When rats were treated with coffee for three days, the ability of the muscles in the small intestine to contract appeared to increase,” Dr. Shi said.
“Interestingly, these effects are caffeine-independent, because caffeine-free coffee had similar effects as regular coffee.”
“The results support the need for additional clinical research to determine whether coffee drinking might be an effective treatment for post-operative constipation, or ileus, in which the intestines quit working after abdominal surgery,” the study authors said.
They presented their results May 19 at the Digestive Disease Week 2019 in San Diego, CA.
_____
Shrilakshmi Hegde et al. 2019. In Vivo and in Vitro Effects of Coffee on Gut Microbiota and Smooth Muscle Contractility in Rats. Gastroenterology 156 (6): supplement 1, S-587; doi: 10.1016/S0016-5085(19)38364-7
