A new Irish study shows that metabolites produced by gut bacteria might help in reducing stress-related symptoms.

By Maria Arvaniti 

Stress is a mental state that can actually have great physical impact in our daily lives. Yet, not all stress is bad. In threatening situations, stress helped our prehistoric ancestors survive: by releasing chemicals and hormones in their bodies, stress urged them to either fight the enemy or run for their lives – a response known as fight-or-flight.

Nevertheless, chronic stress can be an overwhelming feeling, one that most of us are constantly figuring out how to control. According to a recent study published in The Journal of Physiology, a high-fiber diet may be just what we need1.

Bacteria can help us lower stress

Researchers from the APC Microbiome Ireland at University College Cork and Teagasc Food Research Centre in Ireland conducted a study that could have a great impact on how we deal with stress daily.

The scientists focused on short-chain fatty acids (SCFAs), such as acetate, propionate and butyrate. All these are nutrients that are produced by our gut bacteria when we eat dietary fibers – which cannot be digested by our own cells. Other recent studies have shown that increased amounts of these helpful compounds have positive effects in our brain2–4.

The results showed a reduction in their stress levels, as well as their depressive-like behaviour.

In this study, the researchers fed mice with a mix of SCFA for one week and gave them various behavioural tests. The results showed a reduction in their stress levels, as well as their depressive-like behaviour. They then investigated what biological effect this diet could have on the mice’s guts. They found that stress was causing their intestinal walls to be more permeable and that, in those fed SCFAs, this stress-related permeability was reduced. This increased permeability is also known as “leaky-gut” syndrome, a digestive problem commonly related to stress.

Linking “leaky-gut,” stress and diet

Leaky-gut” syndrome is a condition where numerous factors (including specific kinds of food or stress) are believed to cause increased permeability of the intestinal wall. In this way, harmful bacteria and other compounds can leak from the gut to our bloodstream, causing inflammation. The “good” bacteria in our gut can potentially act as crucial shields for our intestines, as their metabolites may protect us from this damage and keep our gut lining intact.

The scientists believe this research can help highlight the importance of nutrition-based strategies in the fight against stress. These results demonstrate that high-fiber diets have multiple benefits for our mental, as well as physical health. By eating various fruits and vegetables – rich in dietary fiber – we can ease our stress-related symptoms by boosting SCFA production from the bacteria in our gut. Think of it this way: you could have a potential stress-relieving shield on your side.


  1. van de Wouw, M. et al. Short-chain fatty acids: microbial metabolites that alleviate stress-induced brain-gut axis alterations. J. Physiol. 0, 1–22 (2018).
  2. Perry, R. J. et al. Acetate mediates a microbiome–brain–β-cell axis to promote metabolic syndrome. Nature 534, 213–217 (2016).
  3. Burokas, A. et al. Targeting the Microbiota-Gut-Brain Axis: Prebiotics Have Anxiolytic and Antidepressant-like Effects and Reverse the Impact of Chronic Stress in Mice. Biol. Psychiatry 82, 472–487 (2017).
  4. Hoyles, L. et al. Microbiome–host systems interactions: protective effects of propionate upon the blood–brain barrier. Microbiome 6, 55 (2018).