7 Best Probiotics for Anxiety & Depression

A growing body of research has been unveiling the best probiotics for anxiety and depression. This may be one of the easier interventions that can have a significant impact on your mental health.

Prevalence and Impact of Anxiety and Depression

Anxiety and depression are more common than you may realize. According to public health surveys from 2021, roughly 4 in 10 adults report symtoms of anxiety and depression. Furthermore, a 2022 survey found 90% of Americans believe there is a mental health crisis in the U.S.

From living a life of daily suffering to suicide, in extreme cases, the cost of anxiety and depression takes it toll, mentally, emotionally, and physically. Even financially, as employers may feel a financial impact from missed days and decreased productivity, so do individuals, who may also be less likely to pursue more rewarding streams of revenue out of fear or apathy.

Root Causes and Standard Treatments

Aside from stressful events and circumstances, genetics may make some more susceptible to these disorders, and neurotransmitter production may fall short due to issues with nutrition or gut health. Standard treatments such as medications and cognitive-behavioral therapy are effective for some, but there remains a large number of non-responders to treatment, as well as those who suffer the side effects of medications.

The Microbiome-Anxiety-Depression Connection

Scientific research has been finding intricate connections between our gut health and mental well-being. The gut-brain axis, as it is often referred to, has opened new doors to understanding and potentially treating anxiety and depression.

Emerging evidence suggests that probiotics, which are live microorganisms with potential health benefits, may play a significant role in alleviating symptoms of anxiety and depression.

In this article, we will explore scientific findings on specific probiotic strains shown to be beneficial for anxiety and depression. We will also discuss how diet can impact gut bacteria and support a healthy gut microbiome, a term referring to the collective population of bacteria living in the gut.

Depression a Symptom of Dysbiosis

Dysbiosis is an imbalance in populations of different kinds of gut bacteria, and has been associated with mood disorders. Recent research has highlighted the connection between the gut microbiota (again, a collective term for bacteria of the gut) and mental health, suggesting that the composition and balance of gut bacteria can influence conditions like anxiety and depression.

Given this link, it makes sense that anxiety and depression are often linked to gastrointestinal conditions. For example, recent studies have demonstrated connections between disruptions in the gut microbiome and the development of anxiety and depression-like behaviors in mice.

In humans, a study comparing 37 patients with depression compared to 18 patients without depression found potential correlations between microbes found in in stool samples and depression. Another stool study of 46 patients with depression and 30 healthy controls found similar correlations.

In studies with rats, giving the probiotic Bifidobacterium infantis changed their response to stress. Animal studies show that giving probiotics impacted levels of tryptophan, serotonin, and dopamine metabolites, and was linked to decreased depressive symptoms.

These findings suggest a profound impact of the health of our gut microbiome on our mental state. As part of the approach towards treating anxiety and depression, researchers are now embracing diet and probiotic treatments.

Probiotics May Be Effective Adjunct or Stand Alone Treatment for Anxiety and Depression

Numerous studies have investigated the effects of giving probiotics on symptoms of anxiety and depression. Fortunately, these have moved beyond studies in rats and mice and we have many human trials to suggest this is totally worth a shot.

Human Trials and Positive Outcomes

Here are some brief descriptions of studies on probiotics and mental health outcomes to give you an idea of the findings:

  • A double-blind, placebo-controlled trial published in the “British Journal of Nutrition” in 2011 where healthy volunteers took Lactobacillus helveticus and Bifidobacterium longum or a placebo for 30 days revealed a significant decrease in psychological stress and depressive symptoms in those receiving the probiotics.
  • Another study in “Nutrition Neuroscience” from 2016 found that consuming probiotic yogurt or a multispecies probiotic capsule for six weeks had beneficial effects on mental health biomarkers among petrochemical workers facing high-stress environments.
  • A study published in “Gastroenterology” in 2019 found that individuals who took a specific probiotic containing Bifidobacterium longum experienced reduced symptoms of depression.
  • A review published in “Nutrients” in 2020 highlighted the potential of Lactobacillus rhamnosus and Bifidobacterium longum in managing anxiety and depression.
  • A study published in “Archives of Neuroscience” in 2018 focused on symbiotic supplementation of two different strains of bacteria in patients with moderate depression and found that it significantly improved depression scores compared to the placebo group.
  • A trial published in “Gastroenterology” in 2017 involving patients with irritable bowel syndrome (IBS) and anxiety observed a reduction in anxiety scores, improved quality of life, and increased levels of beneficial bacteria in those receiving probiotics.
  • Lastly, research published in “EBioMedicine” in 2017 with pregnant and postpartum women demonstrated that probiotics reduced depression and anxiety scores compared to a placebo, highlighting the potential benefits during these crucial life stages.

Meta-Analysis Highlights

A meta-analysis groups many studies with similar variables together to get a better idea of how significant the findings are. A meta-analysis in “JAMA Psychiatry” in 2017 concluded that probiotics could be associated with significant reductions in depressive symptoms compared to those who did not receive probiotics.

Individual studies within the meta-analysis showed varying degrees of significant effects, reflecting the complexity of this field. Differences in study findings can be related to using different strains of bacteria, different doses and durations of treatment, and other variables such as those among study participants.

Another interesting finding was that probiotics were found to be effective in reducing depression rating scales in both patients with depression and healthy volunteers. This implies that probiotics may not only alleviate symptoms of those with anxiety and depression, but may also help to prevent against depression in non-depressed individuals.

Probiotics Decrease Symptoms of Depression Across Many Studies

Below are 3 ‘Forest Plots’. These help summize study findings.

To the left you see the study author and year it was published. On the right, notice the vertical line. This vertical line is the ‘no effect line’. When the shapes fall to the left of the no effect line, it shows a decreased effect. Here it shows the studies have been finding giving probiotics to decrease symptoms of depression. If the shapes fell to the right of the vertical no effect line, that would mean they increased symptoms of depression. For more information about reading forest plots read here.

(A) estimates for probiotics associated with depression in the meta-analysis; (B) forest plots for different ages; and (C) forest plots for depression status.

Best Probiotics for Anxiety and Depression

There are just soooo many different probiotics out there, and they are all different. If your goal is to have an impact on symptoms of anxiety and depression, don’t take just any probiotic. Use strains that have demonstrated efficacy in this area.

Some specific strains that have shown promise in managing anxiety and depression are:

Bifidobacteria Species

Bifidobacterium Breve (Brain Behav Immun, 2022)

This bacteria beat placebo in its antidepressant like effects, and findings suggested changes in gut serotonin metabolism. Those receiving the probiotic had lower depression rating scores, decreased gastrointestinal abnormalities, and lower serum serotonin turnover. There were no differences in markers of inflammation between probiotic and placebo groups, suggesting inflammatory changes are not the mechanism by which they exert an effect.

Bifidobacterium longum (Gastroenterology, 2017)

In a study of adults with irritable bowel syndrome and mild to moderate anxiety and/or depression, bifidobacterium longum significantly reduced depression scores on an anxiety and depression scale more than the placebo group. However, the probiotics did not have a significant effect on anxiety, IBS symptoms, or markers of inflammation. They still had an increased quality of life compared with the placebo group. This study also observed responses to negative emotional stimuli in the brain, and found a decrease in negative response in th probiotic group.

Lactobacillus Species

Lactobacillus casei (Beneficial Microbes, 2016)

The effect of this probiotic on the physical stress responses in medical student taking a fourth-year nationwide examination was studied when giving it via a fermented milk with the probiotic once per day. The study found that beginning in weeks five and six, the treatment group reported a significantly lower rate of physical symptoms compared to the placebo group. Fecal serotonin was significantly higher in the probiotic group compared to the placebo group two weeks after the examination, suggesting increased serotonin in the gut.

Lactobacillus rhamnosus (EBioMedicine, 2017)

This strain has demonstrated anti-anxiety and antidepressant effects in animal studies. It’s believed to modulate the gut-brain axis, reducing stress hormones and promoting relaxation.

A study of its effects on depression and anxiety in women during pregnancy and in the postpartum period found women in the probiotic group had significantly lower depression scores versus the placebo group. The probiotic group also had a significantly lower anxiety score compared to the placebo group.

Lactobacillus plantarum (Nutrients, 2021)

This study measured the severity of anxiety and depressive symptoms and sleep quality in insomniacs. Compared to the control group, the probiotic group showed significant decreases in depression scores, fatigue levels, brainwave activity, and awakenings during the deep sleep stage. Their improved depressive symptoms were related to changes in brain waves and sleep maintenance.

Combinations of Lactobacillus and Bifidobacteria Species (Symbiotics)

Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum (Nutrition, 2016)

A study conducted to study effect of probiotics on symptoms of depression, metabolic profiles, and serum CRP (a marker of inflammation) in patients with major depressive disorder gave these probiotic, but patients were told not to change their diet or physical activity. After eight weeks, patients who received probiotics experienced significantly decreased depression scores compared to the placebo. Additionally, serum insulin levels and CRP decreased significantly compared to placebo.

Bifidobacterium longum and Lactobacillus acidophilus (Nutrition Research, 2008)

A study with volunteers with symptoms of stress induced gastrointestinal symptoms were randomized to receive either a probiotic containing Lactobacillus acidophilus  and Bifidobacterium longum or a placebo without probiotics during a 3-week period. The consumption of probiotics significantly reduced 2 stress-induced gastrointestinal symptoms (abdominal pain and nausea/vomiting). In contrast, the probiotics did not significantly modify the other physical and psychological symptoms and sleep problems induced by stressful life events.

Lactobacillus helveticus and Bifidobacterium longum (Clinical Nutrition, 2019 and British Journal of Nutrition, 2011)

A clinical trial was completed to determine the impact of probiotic and prebiotic supplements on depression. All patients had mild to moderate major depression and took antidepressant drugs (sertraline, fluoxetine, citalopram, or amitriptyline) for a minimum of three months before starting the trial. The people taking the probiotics had a significant decrease in depression, though there was no significant effect in the prebiotic supplement or placebo groups. This suggests that the probiotic significantly improves symptoms of depression. They also found the probiotics may have impacted serotonin metabolism by affecting enzyme activities in the gut.

In another study, healthy volunteers who took Lactobacillus helveticus and Bifidobacterium longum or a placebo for 30 days showed decreased psychological stress, including depression, in subjects who took the probiotics regularly.

Diet Linked to Anxiety and Depression

Another key point is that your diet plays the biggest role in the composition of your microbiome. Probiotics are unlikely to be of benefit as long as processed foods are consumed on a regular basis. This is because what you eat is also the what the bacteria of your gut will be eating.

You can support healthier populations and diversity of bacteria by eating a diet full of different fruits, vegetables, grains, beans, and nuts and seeds. Studies show that diets higher in sugar, meat, and low in fiber do not support the types of bacteria that we are talking about being beneficial for reducing symptoms of anxiety and depression.

Diet plays a pivotal role in shaping the gut microbiome, and a diet low in fiber, nutrition, and with processed foods is a risk factor for depression. Consuming probiotics and prebiotics (fiber that bacteria eat) through food, not just supplements, has been shown to have beneficial effects on mental health biomarkers.

Conclusions

In conclusion, the emerging evidence linking probiotics to improved mental health is promising. Though research in this area continues to evolve, there is low risk and good general safety in trying probiotics. Incorporating probiotics into your diet may be a small yet significant step towards better mental well-being.

Using probiotics is unlikely to be of benefit if not also eating a healthy diet, or continuing to consume ultra processed foods on regular basis.

It’s important to know that while many studies have shown the benefit of reducing measures of anxiety and depression with probiotics, not all studies have found a significant effect. There are many factors that can be at play with these conditions, and probiotics and gut health are just one piece of the puzzle.

Finally, always consult with a healthcare professional to help you develop a treatment plan and before making any significant dietary changes or starting a new supplement regimen. If you would like more help from a registered dietitian, consider our nutrition services as a complementary treatment.


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Anne Marie Berggren RDN, MS, CDN, CNSC is a Registered Dietitian with a Master's Degree in Nutrition, training in integrative and functional nutrition, nutrition for mental health, obesity and weight management, is a board certified nutrition support clinician, and an adjunct professor for the Stony Brook Graduate Nutrition Program teaching advanced clinical nutrition.

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