The link between gut and brain may extend to reducing stress, as data from animal and human studies show a reduction in anxiety following probiotic supplementation.
According to findings published in the British Journal of Nutrition, French scientists report that daily supplements of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 produced beneficial psychological effects in humans.
“These results provide further evidence that gut microflora play a role in stress, anxiety and depression, perhaps via the enteric nervous system as well as centrally,” wrote researchers led by Michael Messaoudi from contract research company ETAP-Ethologie Appliquee.
“Subject to the confirmation of these results, probiotics might offer a useful novel therapeutic approach to neuropathological disorders and/or as adjunct therapies in psychiatric disorders,” they added.
The probiotic formulation used in the study was Probio’Stick from Institut Rosell-Lallemand, and the study was sponsored by Rosell-Lallemand.
According to the FAO/WHO, probiotics are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host".
Messaoudi and his co-workers investigated the effects of probiotics on anxiety-type symptoms in rats, and also on anxiety, depression, and stress in healthy human volunteers.
For the rat study, animals were given daily supplements of probiotics for two weeks and then subjected to a defensive burying test, whereby an animal is subjected to a small electronic shock and defensively buries the probe with sawdust. Results showed that the probiotic-supplemented animals had lower stress and anxiety scores, compared with control animals. Animals receiving the pharmaceutical diazepam had the lowest scores, however.
For the human study, volunteers were randomly assigned to receive the probiotic supplements (1.5 gram of Probio’Stick) or placebo (xylitol, maltodextrin, plum flavour, malic acid) for 30 days, and then tested using a battery of stress and anxiety scales.
Results showed that levels of psychological distress, including measures of depression, anger-hostility, anxiety, and problem solving, were significantly improved in the probiotic group, compared with placebo.
“Other probiotics provide favourable results on behaviour. L. helveticus was demonstrated to favour sleep in elderly subjects. The Lactobacillus casei Shirota strain improved mood scores in normal subjects and decreased anxiety in patients with chronic fatigue syndrome,” wrote the researchers.
“The beneficial effects of probiotics on anxiety and depression may be explained by competitive exclusion of deleterious gut pathogens, decreases in pro-inflammatory cytokines and communication with the central nervous system via vagal sensory fibres, leading to changes in neurotransmitter levels or function,” they added.
“Though these data are preliminary, preclinical and clinical investigations should be extended to examine specific gut microbes and physiological markers associated with psychological distress,” concluded the researchers.
Source: British Journal of Nutrition
Published online ahead of print, FirstView Articles, doi:10.1017/S0007114510004319
“Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects”
Authors: M. Messaoudi, R. Lalonde, N. Violle, H. Javelot, D. Desor, et al.