Does bipolar disorder affect the gut microbiome?

The human gut contains trillions of bacteria, called the gut microbiota. Other microorganisms can also live in the gut but in fewer quantities, including over 140,000 viruses. These microbiota and microorganisms can live in the following parts of the digestive tract:

• stomach
• small intestine
• large intestine

Besides digestion, the gut microbiome plays an important role in supporting a person’s immune system and brain health.

The gut links to the brain via millions of nerves, which researchers call the gut-brain axis. This link facilitates the exchange of information between the two organs.

Specific gut bacteria species produce chemical substances that the brain needs, called neurotransmitters. For example, the gut is one organ that produces the neurotransmitter serotonin, which is crucial to brain health, mood, and behavior.

However, according to a 2020 review, individuals with certain psychological disorders, including bipolar disorder, have different gut bacteria species than those without psychological conditions.

People with inadequate gut microbiomes are prone to inflammatory digestive diseases such as irritable bowel syndrome (IBS).

A 2022 study suggests people with bipolar disorder have a higher risk of inflammatory bowel disease (IBD). However, more research is necessary to understand how IBD can affect bipolar disorder.

Similarly, a 2016 systematic review and meta-analysis found that those with IBS were prone to mental health conditions, and those with IBS were twice as likely to have bipolar disorder as those without IBS.

A 2019 review article suggests gut bacteria diversity differs in those with bipolar than those without the condition. Specifically, there was an imbalance in the ratio of certain bacteria that usually live in the gut.

People with bipolar disorder have lower levels of Faecalibacterium. These healthy bacteria helps reduce inflammation in the gut lining, making it more hospitable for other microorganisms, thus maintaining a balanced gut microbiome.

Medications that help treat bipolar disorder may also modify the bacteria ratio in the gut.

It is important to note that every person’s gut microbiome is different, and it is difficult to attribute bipolar disorder to any one factor since other health conditions can coexist.

Despite the lack of wide-scale research to prove any causal relationship, some speculate that improving the gut microbiome, in general, may benefit mental health conditions.

A common approach to promote gut health is consuming probiotics, often called “good bacteria.”

A doctor may recommend probiotics when there is a loss of healthy gut bacteria, such as after a person has taken a course of antibiotics.

Probiotics come in different strains, and each has specific benefits for the gut, such as helping to replenish the microbiome and stimulating nerves to move food through the digestive system.

Probiotics can come from food and supplements. Another method showing promising results for resolving infections is fecal microbiota transplantation, in which a doctor transfers bacteria from one healthy individual to another.

Benefits

Research from 2020 is mainly inconclusive as to whether probiotics benefit those with bipolar disorder. A 2018 study produced promising results, but further research is necessary to conclude probiotics efficacy for people with bipolar disorder.

Nevertheless, there are advantages to taking probiotics. First, probiotics can help reduce gut inflammation, one of the most vital links to bipolar disorder. Additionally, they help balance gut bacteria, which may help to:

• decrease digestive issues
• improve gut function
• protect the digestive tract from harmful bacteria
• prevent or improve certain health conditions, such as:
  • IBD
  • IBS
  • high levels of blood cholesterol

Risks

Probiotics can take some time to work. Possible side effects may include:

• bloating and gas
• nausea
• an unpleasant taste in the mouth
• changes in stool
• abdominal discomfort
• fatigue
• headaches

However, side effects are usually not severe.

If a person wishes to add probiotics to their routine, they should discuss this with a doctor. While supplements are an option, some could make false claims, stating that they benefit consumers more or contain different bacteria than they actually do.

Introducing probiotics

People should consider bacteria types and counts when taking probiotics. Strain diversity is essential.

Common strains in commercial use include Lactobacillus, Bifidobacterium, and Bacillus. The following foods are also rich in probiotics:

• yogurt
• kefir
• sauerkraut
• tempeh
• kimchi

For a person to achieve gut microbiome robustness, it may be beneficial to diversify dietary intake to include nutritional sources with compounds other than probiotics.

Bipolar disorder is not the only condition tied to the gut microbiome. Other investigations concerning digestive tract health include the following conditions:

• schizophrenia
• autism
• depression

Research suggests people with these conditions, along with bipolar disorder, have significant alterations in gut microbiome composition compared with those without mental health disorders.

These alterations can cause digestive health conditions in addition to affecting mental wellness. For example, IBD often occurs along with depression, with more than 20% of people with IBD having depression symptoms and sleep disturbances.

A 2022 study found those with schizophrenia tend to develop IBD at a younger age.

As with bipolar disorder, though researchers speculate there is a link between gut health and these mental health disorders, more research is necessary to identify the relationship and use it to determine possible treatments.

Probiotics help reduce inflammation and support the body’s immune system by promoting gut microbiome health.

Both inflammation and overstimulation of the immune system can contribute to mental health disorders, making probiotics a potential factor in lessening the severity of conditions such as bipolar disorder.

However, research is still inconclusive. Researchers have not established a direct correlation between specific gut health conditions and bipolar disorder.

However, if a person appropriately consumes probiotics under the guidance of a medical professional, it may produce various health benefits ranging from immune support to fewer bouts of indigestion.