Today’s post takes on a promising area of research: probiotics and the brain. We often regard our guts and brains as separate systems despite their constant communication and cooperation.
Science dubs this alliance the gut-brain axis. However, some researchers have added a third term to the axis – microbiota-gut-brain axis in acknowledging how our trillions of gut microorganisms influence gut-brain interactions.
Healthy plant-based foods and probiotics benefit the microbiota by nourishing good gut bacteria. But what about probiotics and the brain? Let’s see where the research takes us!
Probiotics and the Brain: Cognitive Connections
In November 2020, the Journal of Neuropsychiatric Disease and Treatment published a randomized clinical trial from Kent State University’s Department of Psychological Sciences.
Researchers led by clinical psychology doctoral candidate Victoria Sanborn assessed probiotics’ benefits on the cognitive health of older people.
For three months, 77 of the study’s cognitively impaired enrollees took Lactobacillus rhamnosus GG twice each day. The other 68 took placebo capsules. Although both groups experienced improvements from their baseline cognitive test scores, the probiotics group had significantly better gains.
The placebo group’s average test scores at baseline and the trial’s end were:
- Before: 37.7
- After: 42.4
The probiotics group’s average test scores at baseline and the trial’s end were:
- Before: 38.7
- After: 47.6
In percentage terms, the probiotics group enjoyed a 23-percent gain in cognitive performance after 12 weeks, compared to 12.5 percent for the placebo capsule group. Or, as the research team concluded, the probiotics were responsible for a “significantly greater improvement in total cognition score.” Nearly twice as great, to be specific!
Probiotics and the Brain: Mood Mellowing
The Kent State study investigated the interactions between probiotics and the brain of older people. However, in 2015, 40 young Dutch adults took part in a study to determine if taking probiotics can improve mood. A team from Leiden University’s Institute for Psychological Research designed a study published in the peer-reviewed Journal of Brain, Behavior, and Immunity.
For four weeks, 20 of the participants consumed a daily 2-gram packet of powdered, multispecies probiotics. The other 20 took a placebo supplement. The researchers led by Assistant Professor Laura Steenbergen discussed earlier studies showing supplements with multiple probiotics strains were more beneficial than single-strain varieties. And their own study’s probiotics group enjoyed significant decreases in:
- Cognitive reactivity (negative thought patterns) resulting from sad moods
- Rumination (dwelling on negative past or present experiences)
- Aggressive thoughts
when compared to the placebo takers.
Probiotics and the Brain in Alzheimer’s Patients
Iranian researchers from the Kashan University of Medical Sciences conducted a double-blinded randomized controlled trial. Its goal was to examine probiotics’ effects on cognitive performance and body metabolism in Alzheimer’s patients. Led by Elmira Akbari, the study divided 60 patients into groups of 30. Every day for 12 weeks, the placebo group received regular milk, and the other had milk mixed with probiotics supplements.
After the trial’s end, all 60 underwent cognitive-function screening with the state Mini-mental examination. The probiotics group scored 22 percent higher than on their baseline test, whereas the placebo group’s scores declined 5 percent in the same period!
Although all three of these studies point to beneficial interactions between probiotics and the brain, this field of research is ripe for more attention. For example, the February 2021 edition of Nutrition Reviews published a systematic review led by researcher Jenifer F. Krüger from Brazil’s Federal University of Paraná Department of Nutrition. The researchers reviewed three trials that looked at the evidence supporting probiotics’ positive impacts on dementia. However, they termed the cumulative data “insufficient.”
The microbiota-gut-brain axis is a relatively new field of study. Some trials have shown that probiotics favorably affect our brains’ health, but we need more proof before drawing definitive conclusions about their impact. Yet, even as we tease out the exact ways probiotics benefit our brains, there’s little doubt that the microbiota-gut-brain axis exists, and what we put in our mouths has direct consequences on the health of our brains!