While scientists have long learned of the effects of the gut microbiome on physical health, more recent research shows that the gut may have an innate link to brain functions, known as the gut-brain axis. This means that in addition to their benefits on digestive health, prebiotics and probiotics may have benefits for mental health issues like depression and anxiety. Let’s take a look at the clinical evidence regarding the use of probiotics and prebiotics for anxiety.
The Gut-Brain Axis
A recent area of interest for scientists is the gut-brain axis, which describes an innate connection between the gut microbiome and the brain. This connection is believed to be bidirectional, meaning mental functions can affect gut health, while gut health can affect the brain. This link is complex, but it mainly involves signaling through neural, endocrine, and immune links. In clinical practice, the link between the gut and the brain have been apparent in cases of dysbiosis (imbalanced gut flora) associated with certain mood disorders.1
In a mouse study, researchers evaluated the groups of mice in different gut bacteria conditions. One group was germ-free, meaning they had no gut bacteria. The second group comprised germ-free mice colonized with gut bacteria later in life. The third group of mice had regular gut bacteria. The study showed that the mice bred in germ-free conditions were more likely to develop symptoms of anxiety.2
Which Probiotics Are the Best for Anxiety?
Research on the effects of probiotics on anxiety are still early, but they show promise. In a meta-study, researchers reviewed 21 studies (totaling 1,503 people collectively) to determine if changing intestinal microbiota had any effect on improving symptoms of anxiety. Overall, most (11 out of 21) studies showed that changing gut flora with probiotics or diet modifications improved anxiety symptoms.3
In one study, 380 pregnant women were randomized to either receive a placebo or a supplement containing Lactobacillus rhamnosus probiotic from early pregnancy through 6 months after delivery if breastfeeding. Mothers in the probiotic-treated group reported lower depression and anxiety scores than those treated with placebo in the postnatal period.4
In another study, researchers compared treatment using Lactobacillus rhamnosus GG with a prescription antidepressant (fluoxetine) in mice with obsessive-compulsive disorder (OCD) like behavior. Researchers found that Lactobacillus rhamnosus was comparable to prescription fluoxetine in reducing mouse OCD-like behaviors.5
In a placebo and probiotic comparison study, researchers evaluated the effects of Bifidobaterium longum probiotics on 22 participants and their response to stress, cognition, and brain activity patterns with and without probiotic. The participants were given a placebo for four weeks and then a probiotic for four weeks. They were tested after each course of treatment. Researchers found that probiotic usage reduced the release of stress hormones, reduced daily reported stress, and improved memory functions.6
How Do Prebiotics Help with Anxiety?
Prebiotics are nutrients that nourish the growth of existing probiotics in the gut. There are promising studies that show that anxiety can be reduced through the proper probioic-supporting diet.
Studies in rats showed that two common prebiotics, polydextrose and galactooligosaccharides, increased the number of Bifidobacterium and Lactobacillus probiotics in the gut. These strains are implicated in attenuating anxiety-like behavior and promoting resistance to stress and anxiety in rats.7
In another study, 45 healthy volunteers were given a placebo or one of two prebiotics daily for three weeks. Researchers measured salivary cortisol awakening response before and after administration, and the results showed that one of the prebiotic groups had significantly lower salivary cortisol awakening response. This suggests that prebiotics may decrease cortisol and stress.8
Additional Ways to Reduce Anxiety
Managing anxiety disorders often requires professional help, which may comprise therapy and/or medication. To further manage anxiety symptoms in your day to day, consider:
- Exercising, which can help you to relieve stress and improve your sleep quality
- Limit caffeine intake, a stimulant that is known to contribute to anxiety in high amounts9
- Practice meditation and deep breathing exercises
There are many natural ways to reduce anxiety. Probiotics and prebiotics show promising ways to change the gut microflora and to reduce anxiety in both human and animal models. These natural remedies for anxiety should be used in addition to lifestyle changes and traditional treatments that reduce anxiety.