Coffee Really Does Make You Go and the Science Shows

But it isn’t the caffeine content that sends espresso hounds to the bathroom

Ruth Schuster
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FILE Photo: A drip coffee maker is exhibited by Bubble Lab at the Irisbond exhibit at CES in Las Vegas, Nevada, January 10, 2018.
FILE Photo: A drip coffee maker is exhibited by Bubble Lab at the Irisbond exhibit at CES in Las Vegas, Nevada, January 10, 2018.Credit: AFP
Ruth Schuster

Coffee, boon or bane? Its effect seems to be highly individual. The latest wrinkles in coffee science are that its polyphenol content can reduce the risk of cardiovascular disease and — as any coffee hound will tell you — drinking it helps them move their bowels. Now science has ratified that anecdotal evidence, but it hardly shed light on how the effect happens.

Counterintuitively perhaps, it isn’t the caffeine in the bean that is boosting the muscular motility of the intestines. Caffeinated and decaf coffee have the same effect on our relief, reveals research published in the journal Digestive Disease Week. What it is, we do not know — but the scientists also found that coffee affects the bacterial population of the rat gut, which might be involved.

It is true that the poo-boosting effect was tested in rats, not Texans, though the study was led by Dr. Xuan-Zheng Shi, lead author of the study and associate professor in internal medicine at the University of Texas’ Medical Branch in Galveston. People will believe what they will believe, but not one single rat has hung his bowel movements on their morning coffee fix, so there’s that bias eliminated.

The researchers did two basic things: They fed coffee to rats and they also fed it to gut bacteria cultured in petri dishes in the lab. What they found was that the coffee suppressed bacterial growth and increased intestinal muscle motility, and the caffeine content involved was not a factor.

“When rats were treated with coffee for three days, the ability of the muscles in the small intestine to contract appeared to increase,” said Xuan-Zheng.

Not only in vivo: coffee stimulated muscular contractions when dripped onto intestinal muscle issue in the lab.

A lot of unknowns remain. While the coffee affected the rats’ bowel movements, its effect on the bacterial biome remains to be elucidated. We all, and rats, have a vast population of bacteria in our guts; some are beneficial, some are not, and some are neutral to us. Which of these populations the coffee affects remains to be seen.

As for the biome, the more concentrated the coffee, the sadder the bacteria became — whether the coffee was caffeinated or not. Moreover, the bacteria counts in the leavings of the rats fed coffee were diminished.

As for the cardiovascular effect, about two months ago scientists at the Institute for Scientific Information on Coffee looked at polyphenols in coffee and association with cardiovascular disease — in a few words, drinking coffee is good for your heart, at least from this narrow perspective, the fact that caffeine can raise one’s blood pressure temporarily notwithstanding.

Prof. Kjeld Hermansen of the Aarhus University Hospital in Denmark found indication that there really is an association between consuming polyphenols and reduced probability of CVD — yet again, how that works is a mystery.

It is known that polyphenols have antioxidant properties and some also modulate the activity of a wide range of enzymes and cell receptors. Consuming polyphenols may help prevent a range of diseases associated with oxidative stress, including cancer, neurodegenerative conditions such as Parkinson’s and Alzheimer’s, and CVD.

We can get polyphenols from a vast range of plant sources, from the expensive spice called star anise to cocoa, berries, apples and mainly coffee. Their production in the plant can be mightily affected by environmental conditions and whether the source is raw or cooked; also, note that a food or drink containing these micronutrients doesn’t mean they are bio-available — which means they may be there, but you won’t get any benefit from it.

But is coffee associated with cancer, as some scares would have it? In the cases of some rare cancers, there isn’t much data, but the general word is: No. 

At the end of the day, coffee has an enormously complex chemical composition and some parts of it may be good for you, some bad, and all too soon this may become academic. Some species may be able to adapt as global warming intensifies, but many are expected to disappear because the rate of change is outstripping their ability to adapt.

A study published in Science Advances this January says that 60 percent of the 124 existing coffee species are already endangered, and predicts that most species of coffee will go extinct