A double-blind, randomized, placebo-controlled trial of Lactobacillus helveticus and Bifidobacterium longum for the symptoms of depression

Abstract

Objectives:This trial investigated whether probiotics improved mood, stress and anxiety in a sample selected for low mood. We also tested whether the presence or severity of irritable bowel syndrome symptoms, and levels of proinflammatory cytokines, brain-derived neurotrophic factor and other blood markers, would predict or impact treatment response.Method:Seventy-nine participants (10 dropouts) not currently taking psychotropic medications with at least moderate scores on self-report mood measures were randomly allocated to receive either a probiotic preparation (containing Lactobacillus helveticus and Bifidobacterium longum) or a matched placebo, in a double-blind trial for 8 weeks. Data were analysed as intent-to-treat.Results:No significant difference was found between the probiotic and placebo groups on any psychological outcome measure (Cohen’s d range = 0.07–0.16) or any blood-based biomarker. At end-point, 9 (23%) of those in the probiotic group showed a ⩾60% change on the Montgomery–Åsberg Depression Rating Scale (responders), compared to 10 (26%) of those in the placebo group (χ12=0.107, p = ns). Baseline vitamin D level was found to moderate treatment effect on several outcome measures. Dry mouth and sleep disruption were reported more frequently in the placebo group.Conclusions:This study found no evidence that the probiotic formulation is effective in treating low mood, or in moderating the levels of inflammatory and other biomarkers. The lack of observed effect on mood symptoms may be due to the severity, chronicity or treatment resistance of the sample; recruiting an antidepressant-naive sample experiencing mild, acute symptoms of low mood, may well yield a different result. Future studies taking a preventative approach or using probiotics as an adjuvant treatment may also be more effective. Vitamin D levels should be monitored in future studies in the area. The results of this trial are preliminary; future studies in the area should not be discouraged.

Effect of probiotic interventions on depressive symptoms: A narrative review evaluating systematic reviews

“…Supplementary Table S1 shows characteristics of all the individual trials that have assessed probiotic interventions on depressive symptoms included in the systematic reviews . All individual studies were randomized controlled trials.…”

Efficacy of probiotics on anxiety-A meta-analysis of randomized controlled trials

“…As illustrated in some previous publications(McFarland, 2014;Romijn et al, 2017), probiotics may have a beneficial effect on mood or psychological symptoms in healthy subjects but no significant effect in subjects with mental or physical illness. As illustrated in some previous publications(McFarland, 2014;Romijn et al, 2017), probiotics may have a beneficial effect on mood or psychological symptoms in healthy subjects but no significant effect in subjects with mental or physical illness.…”

“…The remaining 12(Begtrup et al, 2013;Feher et al, 2014;Guyonnet et al, 2007;Kato-Kataoka et al, 2016;Lorenzo-Zuniga et al, 2014;Lyra et al, 2016;Marcos et al, 2004;Ostlund-Lagerstrom et al, 2016;Pinto-Sanchez et al, 2017;Romijn, Rucklidge, Kuijer, & Frampton, 2017;Steenbergen, Sellaro, van Hemert, Bosch, & Colzato, 2015;Stevenson et al, 2014) studies were included in the quantitative meta-analyses. After removing duplicate results, there remained 1,050 studies, of which 1,010 were subsequently excluded in the title and abstract screening step.…”

Eating Disorders and the Intestinal Microbiota: Mechanisms of Energy Homeostasis and Behavioral Influence

“…While the popular media tend to focus on psychobiotic clinical trials that achieve positive results, negative results are also quite common. For example, a recent double-blind, placebo-controlled RCT investigating the efficacy of probiotics in the treatment of depression found no marked difference in outcomes between the placebo and probiotic groups [71]. A meta-analysis of RCTs investigating the efficacy of psychobiotics in treating anxiety and depression revealed that many RCTs report different results, with overall preliminary evidence existing to tentatively support the use of psychobiotics in treating these disorders [72].…”