There is some evidence that taking probiotics may reduce depression symptoms in some people. However, scientists still have much to learn about the gut microbiome and how it affects the brain.

Probiotics are supplements that contain live microbes. They can include a wide range of different bacterial species, which may interact with each person’s gut flora in different ways.

Research suggests certain types of probiotic may have an effect on mood. However, they may not be as effective on their own as antidepressants.

This article looks at whether probiotics can help with depression, whether they work better than antidepressants, and how the microbiome affects mental health.

A bowl of homemade kimchi cabbage, a source of probiotics.Share on Pinterest
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There is some evidence that probiotics may reduce depression symptoms.

For example, a 2021 review of seven previous studies found that taking probiotics with antidepressants improved mood in people with major depressive disorder (MDD). Probiotics alone did not have a significant benefit.

However, a larger 2024 review including 42 studies found that taking probiotics for more than 8 weeks could be as effective as antidepressants for MDD.

A 2023 review also showed that people with anxiety or depression who received treatment with prebiotics and probiotics experienced improvements in their mood. However, this review included studies that had a mixture of methods. Some studies allowed participants to take antidepressants, while others did not.

Gaps in research

While the current evidence for taking probiotics for depression is promising, more clinical trials are necessary to identify:

  • which species of bacteria are the most helpful
  • what dosage is necessary, and whether this differs based on species
  • how long a person should take probiotics for

There is currently no evidence that probiotics alone are more effective than antidepressants. However, some studies have suggested they may be just as effective as antidepressants when a person takes them for more than 8 weeks.

Other research has found that probiotics work more effectively as a complementary treatment, in addition to antidepressants.

Whether a person takes probiotics alongside antidepressants or on their own, it may take some time for either treatment to start working.

Scientists are still learning about the complex relationship between the microbiome and mental health. Researchers refer to this relationship as the gut-brain axis, and it works in a bidirectional manner, where one influences the other.

The authors of a 2023 review note that previous studies have found people with depression have altered gut flora compared with people without depression. How these alterations may contribute to depression is unknown, but in theory, taking probiotics could potentially help address the imbalance.

The review also mentions previous research where taking probiotics or prebiotics did the following:

  • increased serotonin in the stool, suggesting an increase inside the body
  • decreased catecholamines (stress hormones)
  • decreased insulin
  • decreased inflammatory substances known as cytokines

Microbiome resources

For more research-backed information about the microbiome and how it affects your health, please visit our dedicated hub.

Probiotics are not a first-line treatment for depression. Depression treatment typically involves psychotherapy, medication, or both. These treatments have more evidence behind them.

However, people may want to try probiotics alongside treatment from a mental health professional. It is important to talk with a doctor about this to check it is safe and that a person is taking a high-quality product.

Alternatively, people can get probiotics from foods, such as:

Find out more about foods containing probiotics.

Probiotics may cause side effects for some people. Some side effects include:

People may be able to avoid this by introducing probiotics gradually. If they already take them, reducing the dose may help.

Probiotics may also have some risks. Research on this is still evolving, but some potential examples include:

Small intestinal bacterial overgrowth

There is some concern that taking probiotics under certain circumstances could pose a risk of people developing small intestinal bacterial overgrowth (SIBO), a digestive condition with links to irritable bowel syndrome (IBS).

A 2020 review notes evidence that taking probiotics may cause an increase in methane-producing microbes in the gut. If these microbes grow too much in the small intestine, people may develop SIBO.

People who already have SIBO may also find probiotics make their symptoms worse, depending on the type.

Harmful byproducts

According to the National Institutes of Health (NIH), some probiotics can produce harmful substances in the gut.

For example, some types of bacteria produce D-lactic acid. In high amounts, this can cause D-lactic acidosis, resulting in brain fog.

Severe infections

People with compromised immune systems should not take probiotics because the bacteria they contain could become opportunistic, causing an infection.

Older research discovered that adverse events occurred in children with severely compromised immune systems who took probiotics.

Research from 2019 corroborated that potential adverse effects from probiotics were greater in people with severe illnesses or compromised immune systems, such as premature infants.

Learn more about the side effects of probiotics.

Many things affect gut health and the microbiome, such as the following:

  • Eating probiotic foods: Eating fermented foods may positively affect the gut microbiome in both the short- and long-term.
  • Eating prebiotic foods: Prebiotic fiber occurs naturally in many fruits, vegetables, and whole grains. Prebiotics may help probiotics have a higher tolerance to conditions in the intestines, such as a low pH.
  • Reducing stress: A 2018 review notes evidence that stress may affect several aspects of digestive health, including intestinal permeability and inflammation.
  • Getting enough sleep: A 2023 review of past research notes that sleep deprivation can affect the microbiome and may contribute to dysbiosis (imbalanced gut flora). If possible, it can benefit overall health to stick to a regular sleep schedule.
  • Avoiding antibiotics: Antibiotics are sometimes necessary, and can be life-saving in some situations. However, taking them too frequently kills the “good” bacteria in the gut, which can lead to dysbiosis.
  • Quitting smoking, if a person smokes: A 2018 study showed that smoking affects the composition of the intestinal microbiome. The researchers suggest that this interaction may contribute to the development of some intestinal conditions, such as inflammatory bowel disease (IBD).

Learn more about caring for gut health.

If someone shows signs or symptoms of depression that do not go away, they should consult a doctor or mental health professional.

National hotlines are also available to provide 24/7 free and confidential assistance via phone or online chat from trained professionals, including:

  • Samaritans: Call 877-870-4673 (HOPE).
  • Postpartum Support International: Call 1-800-944-4773.
  • The National Suicide Prevention Lifeline: Call 1-800-273- 8255 (TALK) to speak with someone from this national network of local crisis centers or use their online chat service.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

Some research has found a correlation between taking probiotics and reduced depressive symptoms. However, it is still unclear whether probiotics are effective as a standalone treatment for depression or which types or dosages may work best.

People can get probiotics from fermented foods, such as yogurt or kimchi. A wide range of probiotic supplements are also available. However, not all these products are high in quality, and not everyone is safe to take them.

For this reason, it is important to discuss trying probiotics with a doctor first, particularly when taking them for depression.