The Microbiome and Everyday Brain Health - Probiotics

The Microbiome and Everyday Brain Health

Over the past few years, a number of studies have linked the gut microbiome to the risk of cognitive conditions like Alzheimer’s disease and Parkinson’s disease.1,2 But it turns out that those microscopic bugs in your belly can also influence how your brain works on a day-to-day basis. In fact, research shows that the bacteria in your gut produces neurotransmitters, such as serotonin and dopamine, that can affect mood and cognition.3 Additionally, your gut microbiome can influence your immune system and spark inflammation, both of which have been connected to cognitive function.4

Bugs in the Brain?

Here’s how these factors influence cognition and mood: Your gut microbiome produces metabolites that travel to the brain via the vagus nerve and cross the blood-brain barrier. Activity along this bi-directional internal highway, technically known as the gut-brain axis, can then directly affect how your brain functions.13 This explains why bacterial imbalances in your gut (dysbiosis) may cause conditions such as periodic bouts of anxiety or occasional brain fog.5,6 Some studies suggest that dysbiosis might also impact your emotional responses and decision-making capabilities.14

For instance, a recent study that appeared in the journal PNAS Nexus found that changes in the gut microbiota can influence a person’s sensitivity to fairness and how they treat others. During the study, 101 adults were divided into two groups—one who took a daily synbiotic supplement (probiotics plus prebiotics) and one who took a placebo. Over the next seven weeks, both groups took part in behavioral tests, including an “ultimatum game” in which one player is given a sum of money he must split (fairly or unfairly) with a second player, who is free to decline the offer if they deem it insufficient. In that case, neither player receives any money. At the end of the study, the researchers found that those receiving the synbiotic were more inclined to reject unequal offers—a reaction that showed a greater sensitivity to fairness during the tests—than those taking the placebo. These findings suggest that improving your gut microbiome beneficially influences the way you make daily decisions, especially in a social context.7 While more research is needed before you can give your gut bacteria credit for all those good decisions you’ve made, optimizing your microbiome just might give your brain the boost it needs to live better—and wiser—every day!

Balance Your Bacteria, Balance Your Brain

Fortunately you can make favorable changes to the makeup of your gut microbiome, shifting it away from dysbiosis and closer to better bacterial balance and improved brain health. Not surprisingly, those changes often start with your diet. Research that appeared in Food Research International noted that routinely consuming ultra-processed food high in unhealthy fats, sugar, and food additives negatively changes the composition of bacteria in the gut, sparks intestinal inflammation, and affects the brain via the gut-brain axis.8 Earlier findings out of the University of Southern California reports that eating the typical standard Western diet filled with ultra-processed food not only alters the composition of the microbiome, it also damages the intestinal barrier and the blood-brain barrier.9 However, swapping out a poor diet for meals based on high-quality protein, antioxidant-rich fruits and vegetables, healthy fats, and fiber-rich beans and grains not only helps balance your microbiome, it can also help to improve your day-to-day brain function—including your mood and decision-making capabilities.10

The Synbiotic Solution

Adding a synbiotic provides both probiotic and prebiotic support to both the gut and the brain. In addition to the PNAS Nexus findings on decision-making, Australian research reports that supplementing with a synbiotic can improve working memory, a benefit with daily brain applications.11 Your working memory is a cognitive system that allows you to temporarily hold and manipulate information in your mind, enabling you to perform tasks like following instructions, solving problems, and learning—things we do every day in a variety of situations. Think of it as a mental workspace where you can juggle information to complete tasks.

A comprehensive synbiotic can also help smooth the rough edges of everyday life.

A small new study published in the journal npj Mental Health Research found that daily probiotic supplements were associated with significantly reduced anxiety, stress, and fatigue in healthy adults. During the randomized, double-blind, placebo-controlled trial, 88 healthy volunteers reported their mood daily. By the end of the study, those taking the probiotics reported an improvement in their mood after just two weeks of supplementation.12

These studies provide compelling evidence that the human microbiome plays a significant role in regulating day-to-day cognition and mood, highlighting the importance of maintaining a healthy gut microbiota for overall cognitive health. This research also provides an empowering path toward improving the gut-brain axis and, as a result, better brain function every day.

References

  1. Zhang R, Ding N, Feng X, et al. The gut microbiome, immune modulation, and cognitive decline: insights on the gut-brain axis. Frontiers in Immunology. 2025;16:1529958.
  2. Chen Q, Shi J, Yu G, et al. Gut microbiota dysbiosis in patients with Alzheimer’s disease and correlation with multiple cognitive domains. Frontiers in Aging Neuroscience. 2024;16:1478557.
  3. Loh JS, Mak WQ, Tan LKS, et al. Microbiota–gut–brain axis and its therapeutic applications in neurodegenerative diseases.Signal Transduction and Target Therapy. 2024;9:
  4. Carabotti M, Scirocco A, Maselli MA, et al. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of Gastroenterology. 2015;28(2):203-9.
  5. Dinan TG, Cryan JF. Gut instincts: microbiota as a key regulator of brain development, ageing and neurodegeneration. Journal of Physiology. 2017;595(2):489-503.
  6. Fröhlich EE, Farzi A, Mayerhofer R, et al. Cognitive impairment by antibiotic-induced gut dysbiosis: Analysis of gut microbiota-brain communication. Brain, Behavior, & Immunity. 2016;56:140-55.
  7. Falkenstein M, Simon MC, Mantri A, et al. Impact of the gut microbiome composition on social decision-making. PNAS Nexus. 2024;3(5):166.
  8. Song Z, Song R, Liu Y, et al. Effects of ultra-processed foods on the microbiota-gut-brain axis: The bread-and-butter issue. Food Research International. 2023;167:112730.
  9. Noble EE, Hsu TM, Kanoski SE. Gut to brain dysbiosis: Mechanisms linking Western diet consumption, the microbiome, and cognitive impairment. Frontiers in Behavioral Neuroscience. 2017;11:9.
  10. Ribeiro G, Ferri A, Clarke G, et al. Diet and the microbiota – gut – brain-axis: a primer for clinical nutrition. Current Opinions in Clinical Nutrition and Metabolic Care. 2022;25(6):443-50.
  11. Freijy TM, Cribb L, Oliver G, et al. The impact of a prebiotic-rich diet and/or probiotic supplements on human cognition: Secondary outcomes from the ‘Gut Feelings’ randomised controlled trial. Nutritional Neuroscience. 2024;1-11.
  12. Johnson KVA, Steenbergen L. Probiotics reduce negative mood over time: the value of daily self-reports in detecting effects.npj Mental Health Research. 2025;4:
  13. Bonaz B, Bazin T, Pellissier S. The Vagus nerve at the interface of the Microbiota-Gut-Brain Axis. Frontiers in Neuroscience. 2018;12:49.
  14. Toledo M, Martínez-Martínez S, Van Hul M, et al. Rapid modulation of gut microbiota composition by hypothalamic circuits in mice.Nature Metabolism. 2025;7:1123–35.

This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice.