As interest grows around how gut health might impact mental health, researchers have discovered that probiotics could be the next breakthrough supplement to fight negative emotions.

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. The randomized, double-blind, placebo-controlled design in 88 healthy volunteers reported their mood daily, and saw improved mood after two weeks of taking probiotics.

Probiotics—endorsed by recently confirmed Medicaid and Medicare head Dr. Mehmet Oz—are the “good” bacteria in your gut, found in fermented foods like yogurt, kimchi, kefir, and kombucha. Within your gut lies the gut microbiome, made up of trillions of microorganisms including bacteria, viruses, and fungi. To keep your gut healthy, that bacteria needs to be fed and maintained—which is where probiotic-rich foods and supplements can help.

For the study, participants were split into two groups, with one group taking a probiotic containing nine bacterial strains over the course of 28 days and the other given a placebo. Subjects then completed psychological questionnaires, a daily mood report, and computer tasks testing how they were processing their emotions.

Once they hit the two-week mark, researchers observed that the probiotic group’s negative mood significantly reduced, while there was no impact on positive mood.

“It is striking that by simply asking participants how they were feeling each day, we could detect the beneficial effects of probiotics on mood,” said study co-author Laura Steenbergen.

The gut-brain connection

There is mounting evidence that your gut health impacts your mental health.

“The gut-brain connection provides various routes through which bacteria in the gut can influence how we feel and behave, including via the vagus nerve, immune system and hormones,” said study co-author Katerina Johnson. That means that our gut directly communicates with our brain, impacting our mental wellbeing.

Inflammation in your gut can also lead to mood disruption, studies show, including anxiety-related mental health issues.

In this new study, researchers found that the group taking probiotics had not only an overall reduction in negative emotions, but lower feelings of anxiety, stress, worry, and rumination. Researchers also noted that those who had the greatest effect from the probiotics on their mood were those who self-described as risk-avoidant.

“Perhaps in the future probiotics could be used in a targeted way as an early intervention to reduce the chances of negative feelings progressing to mental health conditions such as depression, though more research would be needed to confirm that,” says Steenbergen.

3 more potential benefits of probiotics

While not everyone agrees that probiotics have benefits, they are a heavily studied supplement—with over 1,000 clinical trials and counting—that could potentially support your health in myriad ways in addition to mood. According to the National Institutes of Health (NIH) Office of Dietary Supplements, well-researched benefits of probiotics may include:

1. Easing stomach issues

Probiotics have been shown to reduce the risk of antibiotic-associated diarrhea, which can happen as a result of antibiotics disrupting the gut microbiome, specifically when patients started taking probiotics within two days of the first antibiotic dose. The NIH also points out that some evidence links single- and multi-strain probiotics to alleviating the symptoms and duration of acute infectious diarrhea in children.

Inflammatory bowel disease (IBD) is a chronic inflammatory disease that includes ulcerative colitis and Crohn’s disease. While there is no cure for it, research reflects that probiotics can help manage symptoms, although the NIH notes that clinical guidelines do not specifically recommend probiotics for IBD.

Irritable bowel syndrome (IBS), which presents similarly to IBD and causes disruption to the digestive system, is not considered a disease and does not lead to inflamed or damaged intestines. However, its symptoms can be just as disruptive—and according to the NIH, certain probiotic products have the potential to restore some microbiome functionality and help manage the symptoms of this condition.

2. Lowering cholesterol

Taking combinations of certain probiotic strains could help improve lipid profiles, research indicates—specifically reducing total and LDL (bad) cholesterol. However, more research is still needed to understand the full extent of probiotics and cholesterol.

3. Supporting weight management and obesity

Since the microbes of the intestinal tract help extract nutrients and energy from food—therefore impacting calorie expenditure and storage—the NIH reports that probiotics could be a tool used in weight management. Some clinical trials on probiotics and obesity have reported potentially positive results, but more research is still needed.