Probiotics may not be healthy for everyone
A study published in the Proceedings of the National Academy of Sciences (PNAS) in the United States has shown that probiotics are only beneficial for people with healthy intestinal barriers.
Probiotics are living micro-organisms (bacteria and yeasts), which, if taken in sufficient quantities, are thought to have a positive effect on health.
"Good bacteria" are present in large quantities in our bodies (in intestinal, vaginal, and oral flora). Probiotics, often sold in the form of food supplements containing cultures such as lactobacillus and bifidobacterium, are intended to reinforce the action of these beneficial bacteria, which are not always present in sufficient numbers for our immune systems to function properly.
In this study, researchers from the Cockrell School of Engineering at the University of Texas at Austin sought to learn more about the functioning of the intestine and the efficacy of probiotics.
The intestine is lined with an epithelium: a delicate single-cell layer that protects the body against potentially harmful bacteria in the gut. Assistant professor in biomedical engineering Hyun Jung Kim and PhD student Woojung Shin used an organ-on-a-chip, a special micro-chip with a layer of human cells to model the functioning of this intestinal barrier.
The study found that damage to this barrier results in inflammation, which deprives probiotics of any positive effect.
In a healthy digestive system, probiotics can be very useful. However, if the digestive barrier is compromised, they may be harmful, just like any other bacteria that can spread through the body if not contained within the intestine.
The study will pave the way for further research on the real causes of intestinal and digestive disorders and more personalised diagnoses. The hope is that doctors will soon be able to identify the reasons for damage to the intestinal barrier that are specific to each patient, and to provide better adapted treatments.
Going forward, Shin plans to develop more customised human intestinal disease models for inflammatory bowel disease and colorectal cancer, with a view to exploring how the gut microbiome controls inflammation, cancer metastasis, and the efficacy of cancer immunotherapy.