20 Oct 2015
Can probiotics help depression, anxiety, memory, or mood? This area of research into probiotics is certainly hotting up as the interest between the gut microbiome, brain and behaviour is becoming of increasing interest to scientists and the public. The most recent study, performed at the APC Microbiome Institute at the University College Cork, and covered in numerous media outlets this week, reported that the strain Bifidobacterium longum (see Probiotics Learning Lab for more glossary definitions) 1714 reduced daily stress.
The research1 took 22 healthy male volunteers who were given a capsule of 1 billion probiotics for one month, and then took a placebo for another month, although they had no knowledge of what they were taking when. The participants were tested for daily stress and memory throughout using various tests and methods including the Cohen Perceived Stress Scale, socially evaluated cold pressor test and neurocognitive performance. The consumption of the probiotic strain Bifidobacterium longum 1714 lowered reported daily stress with lower levels of salivary cortisol in participants who were taking the probiotic compared to those taking the placebo. As well as this, subtle enhancements in visuospatial memory were reported. Dinan, who led the study, said more research is required and it is still unclear as how exactly the B. longum strain might have an effect on the brain, but one possibility is that the bacteria release substances that activate the vagus nerve, which connects the gut to the brain. Alternatively, the chemicals they release may enter the blood stream and reach the brain that way. The fascinating fact remains that “When [participants] were given these bacteria they were less anxious and their capacity to memorise material seemed to be enhanced,” said Dinan, who led the study at the Society for Neuroscience meeting in Chicago, where the findings were released.
Another study2 published in the British Journal of Nutrition in 2011 tested two strains Lactobacillus acidophilus Rosell-52 and Bifidobacterium longum Rosell-175 for their effect on stress levels. 55 volunteers were administered with either the two probiotic strains, or a placebo, every day for 30 days, and then tested for stress and anxiety levels. The group taking the probiotic showed significant improvement in psychological distress, depression, anger-hostility and anxiety. L. acidophilus Rosell-52 was also shown to help improve sleep in elderly subjects. Again, a tentative but promising result.
An eight-year study3, led by gastroenterologist Stephen Collins at McMaster University in Hamilton, Canada, is another example of where research can’t really avoid the relationship that the microbiome appears to have with psychology. Researchers of this study noticed that psychological issues such as depression and anxiety seemed to be a risk factor when suffering from persisent IBS. Historically we have probably generally assumed that the uncomfortable symptoms of constant IBS may have understandably led the person to ‘feel down’. However, Premysl Bercik, also a Mac Master gastroenterologist, says that this interplay begged interesting questions. Could psychiatric symptoms be driven by lingering inflammation, or perhaps by a microbiome thrown out of balance?
The Gut Brain Axis
So what are 'psychobiotics'? As nutritional therapist Kathy recently describes in a fascinating blog post ‘Are Psychobiotics a fad, or here to stay’ over in the Probiotics Learning Lab, this new term is defined as a ‘live organism that, when ingested in adequate amounts, produces a health benefit in patients suffering from psychiatric illness’. She also goes on to explain the physiology of how gut bacteria can affect the brain.
A recent write up in last week’s ‘Nature’ talks about the funding that is now being given to this new interest in gut bacteria. In the last two years, the US National Institute of Mental Health in Maryland has funded 7 pilot studies of up to 1 million US dollars to examine what it calls the ‘microbiome – gut – brain axis'. The EU has just put 9 million Euros towards a five year project called MyNewGut, the main objectives being to target brain development and disorders. We certainly look forward to the results of that. Watch this space!
For further reading, take a look at the following:
2.Mr Messaoudi et al., Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. British Journal of Nutrition, 10.1017/S0007114510004319
3.Marshall JK et al (2010) Eight year prognosis of postinfectious irritable bowel syndrome following waterborne bacterial dysentery. Gut May, 59 (5) 605-11
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