The amount of healthy bacteria in the gut during early life influences how happy we are as children and adults. [Photo: Bigstock]

Healthy gut bacteria regulates happiness, emotional stability

14 June, 2012

Natural Health News — Brain levels of serotonin, the ‘happy hormone’ depend on the amount of healthy bacteria in the gut during early life.

Their research published in the journal, Molecular Psychiatry shows that normal adult brain function are regulated by the presence of gut microbes during development.

Serotonin, the major chemical involved in the regulation of mood and emotion, is altered in times of stress, anxiety and depression and most clinically effective antidepressant drugs work by targeting this neurochemical.

Scientists at the University College Cork, in the Republic of Ireland  used an animal model to determine that that the absence of bacteria during early life significantly affected serotonin concentrations in the brain in adulthood.

Although not directly applicable to humans the study did turn up some interesting findings.  It highlighted for instance that the influence of gut bacteria (microbiota) is sex dependent, with more marked effects in male compared with female animals.

Whatismore many of the central nervous system changes related to gut bacteria that take place in infancy, especially those related to serotonin, could not be reversed later. This suggests a permanent imprinting of the effects of absence of gut flora on brain function.

“We’re really excited by these findings” said lead author Dr Gerard Clarke. “Although we always believed that the microbiota was essential for our general health, our results also highlight how important our tiny friends are for our mental wellbeing.”

This study builds on earlier work, from the Cork group and others, showing that a healthy gut flora is essential  in maintaining communication between brain and the gut, sometimes called the ‘second brain’.

The best way to ensure healthy gut bacteria in infants is to breastfeed for at least the first six months of life.

The findings of the Irish team also echo those of another recent small study, the findings of which were presented at the recent Digestive Disease Week 2012 conference in San Diego, California .

In it researchers at the University of California, Los Angeles (UCLA) assigned 45 women to receive either a daily probiotic yoghurt (containing B. lactis CNCM I-2494, yoghurt symbiosis L. bulgaricus, S. thermophilus, and L. lactis), a non-probiotic yoghurt or no yoghurt at all. After just 4 weeks there was evidence that the women in the probiotic yoghurt group had a more stable emotional response when exposed to a stressful situation.

As with the Cork study, Kirsten Tillisch who led the Californian researchers noted, “By changing the environment in the gut, we can actually change what happens in the brain”. This study was sponsored by Danone, manufacturers of probiotics products.