What does a disrupted gut barrier do to the rest of your body?
A leaky gut barrier is associated with chronic inflammation and a range of diseases, from diabetes and joint complaints to kidney and liver conditions. The association has been broadly demonstrated, but whether the gut is the true cause or is itself suffering alongside the disease has not yet been definitively established for most conditions.
When the gut barrier no longer seals properly, bacterial toxins can slip through the gut wall and enter the bloodstream. The best-known culprit is lipopolysaccharide, a substance found in the cell wall of certain bacteria. Once in the blood, this substance continuously stimulates the immune system, leading to chronic low-grade inflammation throughout the body. That inflammation is the common denominator behind many of the consequences.
For people with diabetes the connection is particularly clear: a disrupted gut microbiome leads to reduced production of short-chain fatty acids that protect the gut wall, greater toxin leakage and reduced sensitivity to insulin. In chronic kidney disease the relationship works in reverse: damaged kidneys disrupt the gut bacteria, the gut leaks more, and the toxins damage the kidneys further still, a vicious cycle. In liver patients this has been studied most extensively: a smaller randomised trial (38 patients) showed that an antibiotic targeting the leakage considerably improved the cognitive problems associated with serious liver disease.
Consistent associations have also been found with joint inflammation (in rheumatoid arthritis and related conditions), autoimmune diseases such as lupus, type 1 diabetes and multiple sclerosis, and bone loss after menopause. Whether the leaky gut is the cause or instead the consequence of the disease remains unclear in most of these cases. The association has been demonstrated time and again, but proving that the gut barrier is the true driver will require larger clinical trials. There are still too few of those.
In skin conditions such as psoriasis the evidence is thinnest. There are indications that psoriasis patients more often have a leaky gut, but that observation is largely based on a single review with a pronounced point of view and has not yet been independently confirmed. Treatments aimed at restoring the gut barrier through probiotics, prebiotics or diet sound logical, but clinical evidence that they genuinely help in most of these conditions is not yet available.
Claims are based on review studies, observational human studies, animal research and one small RCT (n=38) in liver cirrhosis. For most associations the following applies: the association is consistent, causality is plausible but has not yet been definitively established in large-scale trials.