Probiotic may help students manage stress levels, says new RCT

By Stephen Daniells

- Last updated on GMT

The new study tested how a probiotic dairy product may protect against stress for university students defending their thesis.   Image © skynesher / Getty Images
The new study tested how a probiotic dairy product may protect against stress for university students defending their thesis. Image © skynesher / Getty Images

Related tags microbiota-gut-brain axis gut-brain axis Probiotics Danone Nutricia Lactobacillus rhamnosus

Supplementation with a specific probiotic strain may reduce perceived stress levels by university students, says a new study from Belgium.

Four weeks of supplementation with Lactobacillus rhamnosus​ CNCM I-3690 also protect the gut from stress-induced damage, according to findings published in Gut Microbes.

“We present the first clinical evidence of reduced subjective but not objective markers of stress with L. rhamnosus CNCM I-3690, which was safe and well tolerated,” ​wrote scientists from University Hospitals Leuven, Katholieke Universiteit Leuven, Danone Nutricia Research, and the Vib Center for Microbiology (Leuven).

“These anxiolytic effects were independent of barrier-protective effects and thus attractive for the reduction of subjective stress in both GI disorders and health.”

Microbiota-gut-brain axis

The study adds to the ever-growing area of research around the microbiota-gut-brain axis, that bi-directional interaction between the gastrointestinal tract and the nervous system. The area is gaining increasing attention from scientists and consumers.

A 2015 review in Neuropsychiatric Disease and Treatment​ by Linghong Zhou and Jane Foster from McMaster University in Canada noted that the bacteria present in the gut affects the communication between belly and brain, and the lack of healthy gut microbiota leads to dysfunction in the gut–brain axis, which in turn may lead to neuropsychological, metabolic, and gastrointestinal disorders.

The new study indicates that probiotic supplementation may help with subjective stress in college students, although objective stress, as measured by cortisol levels, were unaffected.

Study details

Healthy female or male students aged between 20 and 30 were recruited to participate in the randomized, controlled and parallel-group study. Ninety-two participants were randomly assigned to receive an acidified milk (placebo) or a non-commercialized fermented dairy product containing L. rhamnosus​ CNCM I-3690 containing 100 billion CFUs per 100 g. Two 100 ml bottles were consumer twice a day for four weeks. An additional 23 students were recruited to a no-intervention group and served to confirm previous findings on the impact of psychological stress on intestinal permeability. The no-intervention group also allowed the scientists to exclude any potential effect of the dairy product being consumed in both the probiotic and placebo groups.

After four weeks, all of the students defended their thesis in a public forum, which acted as the stress event.

The data showed that measures of permeability (leakiness) of the small intestine increased in the placebo group, but not in the probiotic group.

While salivary cortisol levels increased across the groups, the stress-induced increases in scores on the State-Trait Anxiety Inventory (STAI) were significantly lower in the probiotic group, compared to placebo.

In addition, “a stress-preventative effect of the probiotic was found for PSS [Perceived Stress scores] and more pronounced in subjects with high stress-induced cortisol,”​ said the researchers.

“Probiotics may affect gut-brain signaling independent of changes in permeability,” ​they added. “Indeed, although the test product prevented a stress-induced increase in FEM [fractional excretion of mannitol, a measure of permeability], no mediating effect of FEM was found for STAI and PSS with placebo treatment, suggesting that barrier stabilization by ​L. rhamnosus CNCM I-3690 is not critical for its stress-mitigating effect.”

“Subjective but not objective stress-markers were reduced with L. rhamnosus vs. placebo, suggesting anxiolytic effects, which were independent of barrier stabilization and attractive for the reduction of stress in both health and disease,” ​they concluded.

Source: Gut Microbes
Jan-Dec 2022; 14​(1):2031695. doi: 10.1080/19490976.2022.2031695
“Lactobacillus rhamnosus CNCM I-3690 decreases subjective academic stress in healthy adults: a randomized placebo-controlled trial”
Authors: L. Wauters et al.

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