Probiotic strain may increase happiness and reduce stress: Study

Writing in Nutrients​, the researchers from Fonterra Research and Development Centre in New Zealand called the results “promising” and “consistent with a previous open-label consumer study” with L. rhamnosus HN001 (also called Nutiani HN001).  

“The study found that consuming Nutiani HN001 over four weeks led to an increase in feelings of happiness and a reduction in perceived stress,” author Maher Fuad employed by the dairy co-operative told NutraIngredients.

“However, these differences were not statistically significant compared to the control group. Subgroup analyses showed that male participants had a significant improvement in happiness and a reduction in perceived stress over time.”  

Probiotics and mental health​ 

The gut microbiota communicates with the brain via a bidirectional pathway known as the gut-brain axis. This can influence mood, sleep, and cognitive functioning. Probiotic supplements can boost beneficial bacteria, supporting a healthy balance in the gut.

Previous research​ has highlighted the potential of “psychobiotics” to positively impact mental health by regulating the neuroendocrine response to stress and reducing inflammation in the nervous system. 

However, scientists point out that the clinical effects of probiotics depend on the specific strain of bacteria. Studies using the HN001 strain have previously indicated positive mental health effects in patients with prediabetes​ and post-partum depression​. 

Study details​ 

For the new study, the researchers recruited 120 healthy adults with no existing mental disorders who scored higher on a stress screening tool. 

They randomly assigned either 3 capsules of Nutiani HN001 or the same amount of maltodextrin placebo for 28 days. Using questionnaires, the scientists assessed happiness and stress scores at the start, midpoint, and end of the study.   

At the end of four weeks, 10% more participants claimed to have become happy in the probiotic group compared to placebo. However, although there was an improvement in the total happiness or stress scores, the results were not statistically significant. 

Sex-specific differences​

Additionally, the authors found a statistically significant difference in the sex subgroup analysis. They told Nutraingredients, “Further analysis of sex-specific groups revealed significant improvements in the male subgroup, with increases in happiness and reductions in perceived stress over time. The female subgroup showed similar positive trends, although these did not reach statistical significance”. 

The researchers hypothesize that the sex-specific difference may be partly due to participants’ age ranges “the majority of female participants were in the premenopausal and menopausal age range, a period which other studies suggest women are less susceptible to psychological changes after an intervention. Despite this, the observed positive trends in the female subgroup highlight the need for larger and longer intervention studies to further explore psychological outcomes between sex-specific groups.”

To further validate the positive effects of HN001, the researchers recommend a follow-up study with a larger number of participants and a longer intervention period.

Source: Nutrients​
2024, 16(17), 2936; doi: 10.3390/nu16172936​
“Effects of Lacticaseibacillus rhamnosus HN001 on happiness and mental well-being: Findings from a randomized controlled trial”
Authors: I. Al Kassaa et al.