- Drinking coffee may help protect against the development of irritable bowel syndrome or relieve its symptoms for some people, according to a new meta-analysis.
- The meta-analysis included data from 432,022 participants across eight studies.
- In five of them, coffee was protective against the condition, while three suggested the opposite.
- Irritable bowel syndrome affects women more frequently than men.
A recent meta-analysis examining data from several studies of the same subject to determine overall trends found that consuming coffee may help prevent and relieve irritable bowel syndrome (IBS). The meta-analysis hopes to make sense of conflicting reports, and, indeed, it suggests that coffee’s protection against IBS may not apply to everyone.
According to the meta-analysis, coffee drinkers are 16% less likely to develop IBS than people who do not drink coffee. This applies to people who drink any amount of coffee regularly.
The analysis was based on eight studies that met the researchers’ standards for analysis, selected from an initial group of 187 studies identified in the EMBASE, PubMed, and the Cochrane Library databases up to March 31, 2023.
To qualify, the studies had to be randomized, controlled studies, or cross-sectional studies that focused on the correlation between coffee drinking and IBS. They also had to be in English.
The final eight studies included 432,022 individuals.
The meta-analysis posits that the contradictory findings of previous studies may have to do with coffee’s complexity. It contains over a hundred compounds, which can vary considerably based on their source, how they were roasted, types of ground, and their method of preparation. These details are not always delineated in studies.
Many of the studies also relied on self-reporting questionnaires regarding both coffee and IBS, and that this could cause misclassification and confounding issues.
The meta-analysis appears in the journal Nutrients.
The authors of the meta-analysis suggest that the connection between the two has to do with coffee’s bioactive molecules.
The study’s senior investigator, Dr. Qin Xiang Ng, from the National University of Singapore, explained to Medical News Today:
“Coffee is a polyphenol-rich beverage. Coffee contains several bioactive compounds, such as polyphenols, diterpenes, trigonelline, and melanoidins.”
Gastroenterologist Dr. Babak Firoozi, not involved in this research, also emphasized that compounds found in coffee “have antioxidant, anti-fibrotic, and anti-inflammatory properties, as well as an influence on gut microbiota, bile acids, motility of the intestines, and intestinal permeability.”
“These properties can potentially have a beneficial impact on IBS,” said Dr. Firoozi.
Dr. Ng said that of the eight studies included in the meta-analysis, three actually found that coffee promoted IBS.
“It is important to note, however, that all three studies were cross-sectional in design, may contain several biases, and cannot establish causation between coffee consumption and the risk of IBS,” he cautioned.
Cross-sectional studies only detect associations and cannot prove a causal relationship between them.
Dr. Firoozi explained that the results of these three studies may not be so surprising, given that coffee can sometimes upset digestion.
“Coffee can also be a potent cathartic through many of these bioactive compounds. Not only can caffeine in coffee stimulate motility, but other molecules in coffee promote bowel movements through increased intestinal transit,” he explained.
“Therefore, coffee in some with diarrhea predominant IBS may not be of benefit and could actually make symptoms worse,” said Dr. Firoozi.
As a result, he said, “I don’t recommend regular coffee intake solely for IBS.”
He added that the story is different for patients with fatty liver disease. For them, he recommends at least one cup of coffee each day, including decaffeinated coffee. Coffee, he said, “has been known to reduce fibrosis in the liver. It also helps prevent gallstones.”
“This is a very interesting study, which lays out the potential benefits of coffee and its positive impact on IBS. That positive impact includes altering the gut microbiota, improving motility and permeability of the intestines, and reducing the sensitivity of the intestines,” said Dr. Firoozi about the meta-analysis.
“However, meta-analysis results can be incomplete and may be difficult to interpret with confidence,” he noted.
“I hope that this study will lead to a more robust, long-term longitudinal study that looks at the effects of coffee consumption not only on preventing IBS, but also as an intervention to help those people with the symptoms of IBS,” added Dr. Firoozi.
Reflecting on the importance of this meta-analysis and future research directions, Dr. Ng told MNT:
“On the whole, the current evidence suggests a potential protective effect of coffee against IBS. We know that drinking coffee is safe at expected human consumption levels, and coffee may have health benefits for the gut that should be further studied in large prospective cohort studies.”
IBS is a common gastrointestinal disorder. It causes the gastrointestinal tract to become hypersensitized and may cause bowel muscles to contract.
The result is pain in the abdomen, bloating, cramping, constipation, and/or diarrhea. IBS is also frequently accompanied by excessive gas.
However, IBS does not increase a person’s risk of developing colorectal cancer.
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