Far from just a medical buzzword, psychobiotics have the potential to build up the brain, and even lead to reduced stress and anxiety levels. In the second installment of RTÉ's documentary Stressed, presenter Jennifer O'Connell replicated a study of Professor John Cryan's where she took a probiotic for 4 weeks, with clear results and benefits. Below, Professor Cryan outlines exactly what a 'psychobiotic' is, and why they should factor more in your diet. 

What is a psychobiotic?

Psychobiotics are any bacteria, or support for bacteria, which benefit the brain. This includes probiotics, live microorganisms that have a beneficial effect on the prevention and treatment of diseases; prebiotics, often dietary fibres, which support the growth of beneficial microorganisms in the intestine; as well as any intervention that targets the microbiome (the collective genes of the microorganisms that reside in environments such as the human gut) to support brain health.

Probiotics and prebiotics may be found in foods, and are often consumed as part of a healthy, varied diet. Probiotics can be found in fermented foods while prebiotics can be found in fruits, vegetables and whole grains. However, not all probiotics and prebiotics are psychobiotics, ie. not all probiotics and prebiotics have brain health benefits.

What have studies to date shown regarding the effectiveness of different psychobiotics in reducing conditions like stress and anxiety?

A growing number of scientific studies has now shown that brain health can be positively impacted by targeting the microbiome. Probiotic strains which have been most promising include Bifidobacterium and Lactobacillus species. Reductions in stress responses due to probiotic supplementation have been described in a number of international studies. Benefits of stress-reduction for prebiotic supplements have also been described (galactooligosaccharides, GOS).

What were the results of the psychobiotic study that featured in RTE’s ‘Stressed’ documentary?

The psychobiotic experiment involving presenter Jennifer O’Connell was based on a previous study conducted by researchers from the Science Foundation Ireland Research Centre APC Microbiome Ireland, based at University College Cork.

This study showed that the bacterial strain Bifidobacterium longum 1714 reduces stress and improves memory in study of healthy men. The scientists, led by Prof John Cryan, Prof Ted Dinan and Dr Gerard Clarke, had previously determined that the bacterial strain Bifidobacterium longum 1714 reduced stress, anxiety, and depressive-like behaviours and improved memory in laboratory-based studies.

To check whether the strain would have similar effects in people, 22 healthy male volunteers took the probiotic strain daily for four weeks and a placebo for another four weeks. At the start of the study and after each of the four-week conditions, researchers measured the participants’ acute stress, memory, and brain activity. The participants also rated their daily stress on a questionnaire throughout the study.

The researchers found that both perceived daily stress and physiological reaction to an acute stressor were reduced in the probiotic condition. Participants also performed better on a visual memory task after receiving the probiotic. These findings suggest this psychobiotic strain may prove to be useful for alleviating stress-related conditions, although additional studies with more participants are needed. This research was published in the journal Translational Psychiatry.

I am stressed. Should I now go out and buy probiotic and prebiotic supplements?

Not all probiotic or prebiotic supplements will necessarily have brain-health benefits when people consume them. A different study done by APC Microbiome Ireland scientists, of an equally-promising potential psychobiotic, Lactobacillus rhamnosis (JB-1), failed to show any mental health benefits in healthy people. So caution is required; scientific evidence is needed to support any health claims.

If you are feeling stressed and under pressure, the first course of action is to seek advice from your GP. Improvements in diet and exercise have significant and well-proven brain-health benefits, so these are also good places to start. Anti-anxiety and anti-depressant medications, where required, play a vital role in treatment of patients suffering from mental health issues.

Psychobiotics are an exciting new development, which could play an important supportive role in the prevention and treatment of mental health conditions in the future. Psychobiotic research is in its infancy, but the future is bright.

Further information about psychobiotics is contained in this recent book from the APC scientists who featured in the ‘Stressed’ documentary, Prof John Cryan and Prof Ted Dinan: The Psychobiotic Revolution: Mood, Food, and the New Science of the Gut-Brain Connection. It’s available in all good bookshops and also online.