Can a probiotic supplement improve symptoms of ADHD? Original paper

Some research suggests that bacteria in the gastrointestinal tract can influence the function of the brain as part of a phenomenon termed the gut-brain axis. Based on this research, a number of trials have looked at whether supplementing with probiotics can improve depression, stress, and anxiety. However, there has been much less research on whether probiotics can improve symptoms of attention deficit hyperactivity disorder (ADHD).

In this noncontrolled trial, 30 children (ages 4 to 16) with ADHD were assigned to supplement with the probiotic Bifidobacterium bifidum (strain Bf-688) at a dose of 5 × 10⁹ colony-forming units (CFUs). The participants took the supplement for 8 weeks. The outcomes assessed were symptoms of ADHD — specifically, inattention and hyperactivity/impulsivity — as well as body weight, BMI, and fecal microbiota composition.

After both 4 and 8 weeks of taking the probiotic, participants experienced a decrease in inattention and hyperactivity/impulsivity and an increase in body weight and BMI.

After 8 weeks of taking the probiotic, participants experienced changes in their microbiota composition, including a decrease in their Firmicutes to Bacteroidetes ratio, which is associated with a number of conditions.

Given the lack of a control group, these results should be viewed with caution. However, it’s interesting to note that the observed increase in body weight following probiotic supplementation does seem consistent with previous research. A 2017 meta-analysis of randomized controlled trials found that probiotic supplements led to an increase in body weight among children (although these studies primarily used Lactobacillus strains).^[1]