Supplementation with a proprietary blend of four probiotic strains marketed by Probiotical as Bifizen was evidence to improve several measures of mood, minor depression, and anxiety, in 70 healthy men and women in a study published in Frontiers in Nutrition.
 
The study was focused on a population of people experiencing “subsyndromal” states of minor depression and anxiety. In the nine-week protocol, participants were either administered Bifizen or a placebo daily for six weeks, followed by a three-week washout period, in order to observe if effects would persist. Research-validated questionnaires were given to the participants, which are used to assess efficacy of drugs, counseling, and dietary supplements.
 
Among the 35 people in the Bifizen group, significant improvements were noted for measures of depression, anxiety, and cognitive reactivity to a sad mood, i.e. depression response. These improvements were noted at four and six weeks of supplementation, and endured for three weeks after treatment cessation.
 
On the contrary, no changes were observed in the placebo group. When compared directly with the placebo, the anxiety and mood response scores were significantly superior in the Bifizen group.
 
Serotonin Synthesis a Potential Marker
 
The intestinal tract is a major production site for serotonin, which is a metabolite of L-tryptophan. Blood concentrations in the Bifizen group were significantly higher than they were in the placebo group during treatment, and remained significantly elevated after the washout period.
 
While circulating serotonin doesn’t cross the blood-brain barrier, these increases “may be a surrogate signal of other metabolites being produced in the gut, or influence neural signals from the gut to the brain, and mediate the positive changes in mood that we observed,” said Chad Kerksick, PhD, lead author of the study and professor at Lindenwood University. “We are finishing a different manuscript from this study, which characterizes the effects of Bifizen on sleep dynamics. Our data, combined with other data, point towards a biologically real and measurable impact.”

Untangling the Gut-Brain Axis
 
The gut-brain axis is influenced by a myriad of emotional events and encounters, and untangling this complex network of interactions remains exciting and challenging, said Vera Mogna, CEO of Probitiotical SpA, the supplier of the test product.
 
The present study is a follow-up of a previous study which was conducted in the midst of the onset of the COVID-19 pandemic, which came with its own set of unique challenges, Kerksick noted. In that previous study, which was conducted with a population of 30 participants, supplementation with Bifizen was also linked to significant improvements in mood over four assessments with a reduction in depressive mood state, anger, and fatigue, as well as an improvement in sleep quality.
 
“We encountered significant challenges in the performance of this trial and appreciate the commitment of the subjects who completed the study,” said Kerksick. “What remains intriguing is the influence of a global pandemic on the psychosocial and mental health of our otherwise healthy subjects. Our findings offer an enticing suggestion that Bifizen could have effects in persons living with sub-clinical depression and anxiety, but this would need to be borne out in systematic clinical trials in appropriate populations.”
 
“We are inspired by these findings from Dr. Kerksick and his colleagues. Our 2019 study yielded promising results; this follow-up study extends the findings and includes the additional overlay of COVID-19. We are invigorated by these results and will continue to pursue the interface of the gut-brain axis and rationally designed probiotic formulations,” Mogna said.