The role of microbes, probiotics, fiber, and diet on mental health

Mental health issues are part of my life, and I am not alone. I first began to have problems with my mood when I started puberty. My mother had depression. My aunt had schizophrenia. I have also struggled with sleep since adolescence. The number of people with anxiety and/or depression continues to climb. Millions of people have mental health issues, likely you or someone you love.

Do you wish you had a simple intervention that could improve your mental health?

There are more studies examining the role of microbes, probiotics, fiber, and diet on mental health.

This paper (PMID 36815026) examined the impact of probiotics and prebiotics (fiber) on mental health, sleep, and well-being. The study was an 8-week, 2 × 2 factorial randomized controlled trial. This kind of study allows the scientists to understand how much each part of the intervention contributes to the overall outcome. In this study, the interventions were a high-fiber diet, a prebiotic supplement, and a probiotic supplement.

They enrolled adults (n=119) with moderate psychological distress and low fiber intake. They had 3 treatment arms: (1) probiotic supplement and usual diet (probiotic group); (2) high-prebiotic (fiber) diet and placebo supplement (prebiotic diet group); (3) probiotic supplement and high-prebiotic diet (synbiotic group); and (4) placebo supplement and diet-as-usual (placebo group).

The primary outcomes were change from baseline to end of study (8 weeks) in mood, as measured by two questionnaires: total mood disturbance and Profile of Mood States Short Form. Secondary outcomes included changes in anxiety, depression, stress, sleep, and well-being.

The results revealed that all the interventions were well tolerated. The prebiotic diet reduced total mood disturbance compared to placebo at 8 weeks [Cohen’s d = -0.60, 95% confidence interval (CI) = -1.18, -0.03; p = 0.039]. Improved anxiety, stress, and sleep were noted in response to the prebiotic (high fiber) diet, while the probiotic tentatively improved well-being relative to placebo. Interestingly, there was no evidence of symptom improvement from the probiotic (d = -0.19, 95% CI = -0.75, 0.38; p = 0.51) or synbiotic treatments (d = -0.03, 95% CI = -0.59, 0.53; p = 0.92). The inability to detect benefits from the synbiotic group may be due to the small sample size.

The conclusion I draw from this study is that we must begin with adding more fiber and fermented foods to our diet. Then add probiotics. If you have any issues with constipation, add more fiber. And pay attention to how your mood responds to the addition of fiber, fermented foods, and probiotics.

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