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Evidence answer · Gut & microbiome

What are the signs that your gut microbiome is out of balance?

Uncertain · Moderate evidence

A disrupted gut microbiome manifests as reduced bacterial diversity, mood complaints, skin problems, and a leaky gut wall, but most associations are still correlational. If you recognise multiple signs, it is worthwhile to discuss with your doctor whether lifestyle or medication use may be affecting your microbiome.

The full answer

One of the clearest signs of a disrupted gut microbiome is reduced diversity of gut bacteria. People with cognitive decline or Alzheimer's disease have, on average, fewer different bacterial species in their gut than healthy people, as shown by an analysis of 17 studies. Less diversity means that the ecosystem in your gut is less resilient.

Your gut and your mood are closely connected. A disrupted microbiome interferes with the production of neurotransmitters and causes low-grade inflammation. This is associated with depressive symptoms and anxiety. In people with liver cirrhosis, cognitive problems have even been found that run through this gut-brain connection.

A less visible but measurable sign is the altered composition of your bacterial population. In obese individuals, a particular bacterial species was significantly reduced in abundance, which coincided with higher glutamate levels in the blood. After bariatric surgery, that bacterium partially recovered. Another change is that the gut produces fewer short-chain fatty acids; these are the nutrients that feed the gut wall itself. When the gut wall receives too little nourishment, it can become 'leaky' and allow substances through that should not pass.

A leaky gut wall is itself also a sign of dysbiosis. Harmful bacterial waste products then leak through the gut wall into the bloodstream. This is associated with liver disease and chronic inflammation. Skin conditions such as atopic eczema and autoimmune diseases are also linked to a disrupted microbiome, through the influence of bacteria on the immune system.

Factors that can disrupt your gut microbiome include a monotonous diet, antibiotic use, and unhealthy lifestyle habits. Concrete signs to watch for are therefore: persistent mood complaints without a clear cause, recurring gut problems, skin complaints, or a noticeably poor response after taking antibiotics. Note, however, that all of these associations are correlational; researchers observed these patterns occurring together, but a direct cause-and-effect relationship has not always been proven in humans.

The evidence
7 studies · 1 meta-analyses · ≈ 1,311 participants

All claims are based on associative research (observational studies, meta-analyses, and animal models). No RCT evidence is available in the source that directly proves dysbiosis as the cause of the conditions mentioned.

Last reviewed: July 2026
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