Probiotic supplementation- beneficial or not?

Olivia Kahn-Boesel, BA

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​Patients often wonder if there are any holistic remedies or natural supplements they can take to support their health. One of the most often asked about supplements are probiotics, or “good” bacteria (lactobacilli strains specifically), which are found naturally in fermented foods, such as yogurts, or in beverages like Kombucha. Probiotics are hypothesized to be beneficial for gut microbiota, GI symptoms, removing toxins, improving mood/cognitive function, and even reducing cholesterol levels and improving hypertension. One of the most important questions is, however, is there any benefit to probiotic supplementation in otherwise healthy individuals?

​Probiotics are well studied for gut health, specifically in terms of microbiome alterations and improving GI symptoms. Studies show that probiotic supplementation accelerates the transition of premature infant microbiome into mature microbiome and helps reduce inflammation. However, a review of seven randomized control trials (RCTs) studying the influence of probiotic supplementation found that probiotics actually did little to alter the microbiome- only one study found probiotics to significantly modify the overall diversity of the gut bacterial community. Various GI symptoms have been shown to improve with probiotic supplementation, including an RCT that demonstrated improved bloating, burping, and flatulence with 6 weeks of probiotic supplementation, and a review that GI symptoms improved in those with IBS and chronic constipation in those who took probiotics, though the exact mechanism of improved symptoms remains unclear.
 
There are also claims that probiotics improve mood/ cognitive function. A study of university badminton players found that six weeks of supplementation with probiotics led to decreased anxiety and stress levels and improved aerobic capacity. An RCT of older adults found that those assigned to the probiotic intervention group had improved mental flexibility and less stress after 12 weeks of supplementation. In another RCT, 30 adults with Alzheimer’s disease showed improved cognitive status via higher mini-mental status examination scores after 12 weeks of probiotic supplementation as compared to the control group. However, a meta-analysis of 10 studies of elderly adults found no significant overall alteration in cognition with probiotic supplementation. While the results are intriguing, more research is needed into the effects of probiotics on cognitive function, specifically the mechanism by which probiotics are theorized to improved mood and brain function.

In healthy adults, probiotics can be beneficial in improving gut microbiota concentration, immune system mediators, stool consistency and vaginal lactobacilli concentration, according to one review of 45 studies. They found there is not sufficient evidence to link probiotics to cardiovascular health or reduced lipid levels. The review concludes that if increasing bacterial concentrations is necessary for an individual to improve their health, then probiotic supplementation is likely helpful for them. The study does mention that bacteria levels are likely to return to what they were previously after supplementation is stopped.
 
Overall, my takeaway is that if you have GI distress or diarrhea, a probiotic may improve symptoms. If your gut microbiota is damaged, either from heavy antibiotic use, being elderly or a premature infant, probiotics are likely helpful for rebuilding the microbiome. Otherwise, if you are a healthy kid or adult, probiotics will probably not have adverse effects, but likely will not cause major positive effects either. More research is needed into the effect of probiotics on cognitive health, especially in terms of the mechanism by which memory and mood might be affected by probiotics. But if you don’t mind taking an additional pill every day, or even just eating more yogurt, why not?

About the Author:

​Olivia Kahn-Boesel is a fourth year medical student at Harvard Medical School. She is currently applying into internal medicine residencies and is interested in a career in gastroenterology. She previously attended Tufts University, where she studied biology and community health. She has interests in health equity, improving health outcomes for underserved populations, and medical education. In her free time she enjoys dancing, playing soccer, and exploring cities.