Can Probiotics Lower Cortisol?

In this probiotics for cortisol guide, I am going share some research on the use of probiotic bacteria to modulate cortisol through the gut & brain axis.

According to the NHS, having too much cortisol may be because of Cushing's Syndrome and treatments may need to be prescribed by your doctor.

What Is Cortisol?

Cortisol better known as the "stress hormone" is produced by the adrenal gland and is released in response to stress and low blood-glucose concentration. 

It has many functions in the body, including regulating blood pressure and heart rate, controlling the body's use of carbohydrates, fats, and proteins, and reducing inflammation.

If you have higher than usual levels of cortisol may have negative effects on health, such as weight gain, suppressed immune function, and high blood pressure.

Several studies have hinted that certain probiotic bacteria may help to lower cortisol levels and potentially assist with mental well-being.

Probiotics May Help Lower Cortisol

An excerpt from this Chinese research paper published in 2019 claimed that probiotics could help reduce cortisol levels in the body based on previous animal & human studies. 

It was thought that this could have a positive effect on mood, cognition and that probiotics could be a potential therapy for lowering cortisol through the gut & brain axis. 

The researchers were very clear on the fact that not enough research had presently been carried out to make any claims on the efficacy of probiotics for reducing or impacting cortisol.

L. Helveticus and B. Longum Reduced Urinary Cortisol Scores

This 2019 double-blind, placebo-controlled trial from Tehran University investigated the effects of prebiotic and probiotic consumption on serum inflammatory cytokines, Beck Depression Inventory (BDI) score, and urinary cortisol in patients with major depressive disorder (MDD).

The BDI score decreased significantly in the probiotic-treated group compared to the control group whilst inflammatory cytokine levels were similar between groups.

Cortisol levels decreased by 20% and 19% of baseline in the probiotic and prebiotic groups, respectively, and remained unchanged in the placebo group.

Probiotics improved depression symptoms, but serum inflammatory marker levels were not affected. Prebiotics did not affect depression symptoms or inflammatory marker levels.

The strains that showed promise were L. helveticus R0052 and B. longum R0175 at 1 billion CFU suggesting that probiotics could in fact alter cortisol through the gut & brain axis.

Bifidobacterium longum 1714 Lowered Salivary Cortisol Scores

In this study, a repeated measures, placebo-controlled design was used to evaluate the effects of a probiotic strain on salivary cortisol, stress response, cognition, and brain activity patterns.

22 healthy male participants completed neurocognitive and acute stress visits, and then received a placebo for four weeks followed by the 1714 probiotic strain for four weeks.

Daily online questionnaires were also completed throughout the study. The results showed that the probiotic strain was associated with reduced stress and improved memory.

It found that the stressor significantly increased salivary cortisol levels at all visits. However, total cortisol output, measured by AUCg, was significantly affected by the probiotic condition, with cortisol output being lower post-1714 compared to both the post-placebo and the first visit.

Additionally, the study found that state anxiety was significantly elevated post-stressor at both the first visit and post-placebo, but not post-1714.

These findings suggest that 1 Billion CFU of Bifidobacterium longum 1714 consumption may be associated with reduced cortisol levels and improved memory.

Prebiotics Lowered Waking Cortisol Response

This 2015 study from the Department of Psychiatry, University of Oxford, found that taking Bimuno-galactooligosaccharides (B-GOS) prebiotics daily for 3 weeks significantly lowered the salivary cortisol awakening response compared to a placebo. 

Participants in the study also showed decreased attentional vigilance to negative information after B-GOS intake. These findings suggest that B-GOS prebiotic fiber may be useful in the treatment of stress-related disorders by lowering cortisol.

The study did not test probiotics along with the prebiotic fiber but they are both often used together as prebiotic fiber can act as a source of fuel for probiotics and encourage the growth of new probiotic strains.

Closing Thoughts

Probiotics may be able to help lower cortisol levels in the body, according to several studies shared in this guide.

The 2019 study from Tehran University found that probiotics improved depression symptoms and decreased cortisol levels in patients with major depressive disorder.

Further research is needed to confirm the efficacy of probiotics for lowering cortisol. The content in this blog post is not medical advice and I am not a Doctor.