Sign in. It’s quick, free and it’s up to you.
An account is an optional way to support the work we do. Find out more.
LOOKING FOR A new way to kick the blues, quell the jitters or adjust your mood? Researchers in the ground-breaking field of psychobiotics, at University College Cork (UCC), advise that we need to learn how to nurture our microbiome.
Neuroscientist, Professor John F. Cryan is Vice President for Research and Innovation at UCC and principal investigator with the APC Microbiome Institute — world-renowned for research on the microbiome in health and disease, focusing on the gut microbiome and its influence on brain function and behaviour.
A recent paper in Cell Metabolism (2024) published by Cryan and a team of researchers at APC Microbiome uncovered the vital role that gut microbiota play in regulating the variations in stress hormones that happen throughout the day and night.
This research is just one of the most recent papers outlining the links between the gut bacteria and mental wellbeing. In 2017, Prof Cryan, along with psychiatrist and fellow principal investigator at APC Microbiome, Ted Dinan, joined with veteran science journalist Scott Anderson to publish The Psychobiotic Revolution – a fascinating account of the gut-brain axis, how gut bacteria matter to your mental health and critically, how to keep them thriving.
The first theories about the gut-brain connection go back to the 18th-century French anatomist Marie François Xavier Bichat, who discovered the gut had its own nervous system, independent of the central nervous system. It isn’t organised as a lump like the brain, but as an intricate double-layered lacework surrounding your entire gut like a tube sock. Later, another researcher, Michael Gershon, at the end of the 20th century dubbed the intestinal nervous system ‘the second brain.’
The two brains are in constant communication, and much of that comes from the gut microbiome, microbes that talk to both brains using a mishmash of chemicals that include neurotransmitters, cytokines and hormones. Each system is used differently by the microbes and act via your nervous, hormonal and immune systems in a way that can affect your mood.
Stress hormones are released as part of the fight-or-flight response. In The Psychobiotic Revoluton, Cryan and Dinan explain how this impacts the gut and immunity. That means that when you’re stressed, your defences are down.
‘People who are stressed are more susceptible to infection and inflammation. That in turn leads to greater stress, a vicious spiral that can leave people deeply anxious and depressed.
Stress can have an acute impact on your gut. ‘It can alter the levels of acids, mucus and other intestinal secretions, disturbing the cosy environment your microbes have grown accustomed to.’
Stress hormones can reduce your healthy microbes and increase unhealthy or pathogenic microbes. Strategies to dampen these vicious cycles are central to psychobiotic therapies under development, including the most recent research linking the role of the microbiome in controlling the diurnal variations in stress hormones.
The researchers at APC Microbiome are demonstrating how the microbiota is key to normal neurodevelopment and behaviour, raising the potential of targeting the microbiota-gut-brain axis in the development of novel psychobiotics.
‘The hope is that psychobiotics could eventually be used as easily as we now use Prozac (fluoxetine) to treat depression or Valium (diazepam) to treat anxiety, but with fewer side effects.’
Key to the use of psychobiotics is finding the correct dosage, combination and method of delivery.
In the interim, the best psychobiotic of them all is, of course, food. Professors Cryan and Dinan acknowledge that eating the right kind of foods has always been and still is the best way to achieve and maintain a healthy gut, reminding us of the old adage attributed to Hippocrates: ‘Let food be thy medicine and medicine be thy food.’
Eat more fibre.
Healthy gut bacteria, such as Bifido, consume the fibre moving through your intestine and produce butyric acid as a by-product. Butyric acid protects the cells lining your gut, as well as impacting the brain by encouraging the production of feel-good neurotransmitters.
Ultra-processed food is highly refined and lacking in fibre. What we give up in not eating fibre is ‘manna for healthy microbes.’
Foods rich in fibre include wholegrains, fruit, vegetables and legumes such as beans, peas and lentils.
Fermented foods have been used to preserve food for at least 5,000 years but have been largely displaced with the advent of the modern fridge. Foods such as kefir, kombucha and traditional Japanese bean based ferments such as tempeh, miso soy sauce and dozens more are part of the psychobiotic pantry.
Yogurt is probably the best known psychobiotic. Look for the ‘live and active culture’ label to ensure the product has living probiotics in it.
Other psychobiotic rules include stop eating junk food. Cryan and Dinan suggest this may be all it takes to make you feel better. A paper in the American Journal of Clinical Nutrition (2015) outlined how junk food, particularly when it’s high in sugar, affects your microbiome and your mood.
Minimise sugar, including alcohol, get plenty of omega 3s such as oily fish, olive oils and nuts and eat foods with lots of antioxidants or anti-inflammatory properties – coffee, green tea, turmeric as well as strawberries and blueberries – a paper in Annals of Neurology (2012) outlined the role of berries in reducing depression and cognitive decline.
Exercise. Research published in Gut Microbes (2015) outlined how exercise can improve cognition, treat diabetes, reduce irritable bowel syndrome and improve depression – all by improving our gut microbiome.
Antibiotics, possibly the most important medical breakthrough of all time after vaccines, if used too regularly, are like ‘dropping a bomb into your guts.’ Use them with care and only if absolutely necessary and advised by your doctor.
Cryan and Dinan finish the discussion of how to encourage a healthy gut microbiome on an optimistic note.
‘You now have the knowledge and tools to repair your gut, soothe your mind and lift your mood. You only have your microbes to outwit. You can do it.’
Dr Catherine Conlon is a public health doctor in Cork and a former director of human health and nutrition, safefood.
To embed this post, copy the code below on your site
have your say