PSYCHOBIOTICS: CAN YOUR GUT AFFECT YOUR BRAIN?

EVER had a ‘gut feeling’ about something? It turns out the connection between our gut and our brain might be stronger than we think. Research led by John F Cryan and Ted Dinan at APC Microbiome Ireland has literally turned our concept of brain health upside down.

The last decade has seen the microbiome — the collective genes of the trillions of microbes that inhabit our gut — emerge as one of the hottest research areas in science and medicine. Indeed, there is a growing realisation that these gut critters play a fundamental role in shaping all aspects of physiology, including brain function and mediating the stress response.

Using animal models Dinan, Cryan and their team have demonstrated that in the absence of gut bacteria, brain structure and function are altered, leading to deficits in memory, social behaviour and emotional states. They also confirmed that a healthy gut microbiota in early life is essential for normal neurodevelopment and that changes in the gut microbiota may be a susceptibility factor for a variety of brain disorders. They have shown that stress can affect the composition of gut microbes and that diet is crucial in supporting the development of the microbiota. For example, older people suffering from very ill health tend to show less microbial diversity. Recently, the gut microbiota has been implicated in a variety of conditions including obesity, autism, multiple sclerosis, schizophrenia, even Alzheimer’s disease and Parkinson’s disease. We can improve cognitive function by changing the gut microbiome but questions remain as to whether we can lower the risk of developing Alzheimer’s or dementia per se. However, animal studies have shown that extreme manipulations of the microbiome prevent the toxic build-up of plaques in the brain. These findings lend credibility to targeting the microbiome for mental health benefits — an area of study known as ‘psychobiotics’. This can be done by probiotics, prebiotics or via diet. Although the field of psychobiotics is in its infancy, there are already promising signs. First, in animal models and subsequently in healthy volunteers, the Cork team have shown that specific strains of bacteria can dampen down the stress response, and affect cognitive function and the brain’s electrical activity.

So what is the best way to nurture the microbiome for the brain? “We’re still figuring this out but there are clear things we should do and things we should avoid,” says Cryan.

Increase your intake of:

Prebiotics, which feed good bacteria such as Bifido and Lactobaccillus strains, with foods containing a fibre called inulin, with vegetables such as Jerusalem artichokes, potatoes, leeks, onions, garlic and bananas.

Omega 3 fatty acids found in oily fish, seeds and nuts.

Polyphenols found in nuts, seeds, coffee, dark chocolate, red wine, olive oil and berries.

Yoghurt and fermented milk (Kefir), fermented foods such as sauerkraut, kimchee, miso and kombucha.

Decrease your intake of:

Trans fats (found in processed food and many comfort foods, biscuits, cakes), emulsifiers, and sweeteners.

Exercise

Studies show the beneficial effects of aerobic exercise on microbiome diversity.

Avoid

Stress and sleep disturbances/jetlag C-Section, if possible, and support breastfeeding

Minimise antibiotic usage as much as possible

Have a pet — it will increase your microbiome diversity John Cryan and Ted Dinan are professors and heads of the departments of Anatomy and Neuroscience and Psychiatry and Neurobehavioural Science respectively, and principal investigators at APC Microbiome Ireland in University College Cork. They are co-authors of the bestselling book, ‘The Psychobiotic Revolution: Mood, Food, and the New Science of the Gut-Brain Connection’.