“Namely, these gut species, Eggerthella and Eubacterium ventriosum, have been shown to produce butyrate — an important precursor molecule to GABA, a brain chemical that functions in regulatory control of glutamate,” he explained.
The intestinal bacterial strains Eggerthella, Subdoligranulum, Coprococcus and Ruminococcaceae have been reported to be associated with major depression in earlier studies.
And a small study in the journal Nutrition found that 3 probiotic strains — Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium bifidum — helped reduce symptoms of depression. Other research has linked several strains, including lactobacillus and bifidobacterium, to improvements in mental health.
Species of Bifidobacterium, Lactobacillus (lactic acid bacteria), and Lactococcus are found in the colon where they exert a positive influence on whole body health, including anxiety and stress.
A multi-strain Lactobacillus/Bifidobacterium probiotic blend has been the most researched for its ability to decrease symptoms of anxiety.
A troubled intestine can send signals to the brain, just as a troubled brain can send signals to the gut. Therefore, a person's stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression. That's because the brain and the gastrointestinal (GI) system are intimately connected.
Some research shows that certain Lactobacillus species improve stress resilience and anxiety. Some studies even show that taking probiotics can help alleviate symptoms of depression. Probiotics help to support human health by keeping the gut ecosystem balanced and preventing dysbiosis.
Scientists studying over 700 people who were prone to anxiety found that eating fermented foods containing probiotics was linked to reduced symptoms of social anxiety. Whether or not you're consuming probiotics, it's important to feed your good gut bacteria if you want a diverse and healthy microbiome.
High-level scientific evidence shows how healing your gut can improve anxiety symptoms. More and more research is revealing the strong link between brain and gut health.
Various bacteria such as Streptococcus spp., Enterococcus spp., Escherichia spp., Lactobacillus plantarum, Klebsiella pneumonia, and Morganella morganii have the ability to produce serotonin20,21,22,23.
But not every probiotic is best for treating depression. A 2018 study found that the probiotic Lactobacillus plantarum P8 may be helpful for depression. It was shown to relieve stress and anxiety and improve memory and learning. Bifidobacterium is another probiotic shown to improve mental health.
Accumulating studies have shown an association between dysbiosis and depression (Fig. 1) by reporting changes in the gut microbial composition of MDD patients compared to healthy individuals, particularly in terms of microbial diversity and the relative abundance of specific bacterial taxa.
Chronic inflammation caused by a leaky gut may result in psychiatric symptoms like anxiety and depression. During periods of stress or inflammation, tryptophan, a building block for serotonin production, can be converted into kynurenic acid via the kynurenine pathway.
When you are anxious, some of the hormones and chemicals released by your body enter your digestive tract, where they interfere with digestion. They have a negative effect on your gut flora (microorganisms that live in the digestive tract and aid digestion) and decrease antibody production.
The enteric nervous system — an out-branching of the central nervous system — serves the GI tract, making a direct connection between our brain and gastrointestinal system. That connection can cause normal physiologic processes to be interpreted as painful under stressful or anxiety-provoking situations.
"Stress impacts our ability to control inflammation and that can increase stress on the gastrointestinal tract." Interestingly, gastrointestinal distress can also lead to anxiety.
Research has long suggested a link between our diet and our mental health. The gut microbiome — the collective genome of trillions of bacteria that live in the intestinal tract that are created largely by what we eat and drink — appears to influence our mood and mind-set.
More evidence from 2020 also suggests that probiotics and prebiotics can have a positive effect on mental health conditions. Finally, a study from 2021 also notes positive effects of probiotics on anxiety and stress. To sum it all up, researchers seem to believe that probiotics may help with: anxiety.
Gut serotonin is crucial for balancing your mood and supporting healthy digestion. Taking a probiotic with 30 billion or 100 billion CFUs, getting regular sunshine and exercise, and eating plenty of tryptophan-rich foods are all powerful ways to boost your serotonin levels and support your gut health.
When your body doesn't have enough good bacteria, bad bacteria can thrive. The following can be signs of a gut bacteria imbalance: Autoimmune problems, such as thyroid issues, rheumatoid arthritis and type 1 diabetes. Digestive issues, such as irritable bowel syndrome, constipation, diarrhea, heartburn or bloating.