Bacteria to give you a lift

Probiotic bacteria may lessen anxiety and depression-related disorders, according to the latest research, writes SUZANNE CAMPBELL

WHAT WE EAT can promote feelings of wellness and pleasure, and according to recent research conducted at University College Cork, foods containing probiotic bacteria may have potential in treating anxiety and depression- related disorders.

The research, which was carried out by Dr Javier Bravo, Prof John Cryan and their colleagues at the Alimentary Pharmabiotic Centre in UCC, found that probiotic bacteria can influence neurotransmitters and potentially ease feelings of anxiety or depression.

The study, which was published in Proceedings of the National Academy of Sciences USA, centred on the "gut-brain axis" or how the intestines communicate to the brain.

“There hasn’t been a lot of research done on probiotics and depression,” says Prof Ted Dinan, a psychiatrist who was involved in the study. “We had done some previous work on probiotics and behaviour, but what makes the current study so different is that we discovered how probiotics affect a very important neurotransmitter, and act on feelings of anxiety.”

Probiotics are described as a “functional food” and are defined by the Food Safety Authority of Ireland (FSAI) as “foods that in addition to providing nutrition, possess characteristics that can help to achieve or maintain good health”.

Dairy products such as yoghurt drinks with added “good” bacteria are the most common probiotic products available to Irish consumers. Many people purchase probiotic products believing them to reduce bloating, diarrhoea, and to improve general health. But some probiotics have been found to have little effect on general intestinal health.

The UCC study dealt with a specific probiotic, the bacteria lactobacillus rhamnosus JB-1, showing that ingesting the bacteria resulted in significantly lower levels of the stress hormone, corticosterone. The research, which was conducted on mice, revealed that the animals who were fed probiotics showed significantly less stress, anxiety and depression-related behaviour than those fed with a simple broth.

The study highlights the important role of bacteria in how the gut and brain communicate with each other. Regular feeding with the lactobacillus bacteria caused changes in the brain neurotransmitter known as GABA, demonstrating that probiotics can affect the brain in normal situations – reducing feelings of stress and anxiety.

The relationship between the gut, probiotics and depression is not a new one. Sufferers of irritable bowel syndrome (IBS) frequently also suffer from depression. “In our hospital, 50 per cent of patients with IBS have anxiety and depression,” says Dinan.

“We don’t completely know why this is, but the general view is that it’s essentially a disorder in communication between the brain and gut.”

For those looking to enhance their mental health, the study offers interesting insights, but the specific lactobacillusbacteria used in this research may not be present in many off-the-shelf probiotic foods.

The UCC team is also uncertain as to whether more general lactobacillus bacteria could have the same effect on mood and behaviour as the specific one used in their experiments.

However slight the hope, probiotics could provide a future remedy for sufferers of depression, many of whom are prescribed SSRIs, or selective serotonin re-uptake inhibitors.

“As a psychiatrist, I would like to see something other than conventional treatments for anxiety and depression. Most patients who take SSRIs would be delighted to try something else,” says Dinan. “But without large scale placebo- based studies, we don’t know as yet just how effective probiotics can be.”

The APC unit in Cork may be able take this research further but, for now, the less glamorous claims made by many probiotic foods in terms of their role in gut function may be running into trouble with the European Food Safety Authority (EFSA).

“Out of over 180 health claims made by probiotics that were examined by the EFSA’s panel of experts, none have sufficient evidence to back them up,” says Dr Mary Flynn of the FSAI.

Some of the bacteria in their products were not evaluated properly and the bacteria also change with every tiny alteration of temperature or pH level.

“Probiotics are a positive development in food and there’s definitely a story there, but in terms of consumers, the claims they make about their affects on health have so far simply failed to be valid,” says Flynn.

More research is needed if probiotics are to prove to consumers exactly how they improve general health. Is it a step too far to say they could also have a role in mental health?

If the findings from UCC are replicated in human trials, probiotic foods could yet become useful tools for the brain, not just the bowel.