Probiotics mitigate stress and inflammation in malnourished adults via gut microbiota modulation: a randomized controlled trial.

2025-07-16
Frontiers in nutrition 12
- Maryam Ahmadi-Khorram
- Alireza Hatami
- Parastoo Asghari
- Ali Jafarzadeh Esfehani
- Asma Afshari
- Fateme Javdan
- Mohsen Nematy

PubMed: 40740643
DOI: 10.3389/fnut.2025.1615607

Objective

Malnutrition negatively affects mental health by altering neurotransmitter function and increasing stress responses. The gut-brain axis is pivotal in this process, and probiotics may mitigate stress. The current study examined the effects of multi-strain probiotic supplementation on stress levels in underweight individuals using the Perceived Stress Scale (PSS).

Methods

A double-blind, randomized, placebo-controlled trial involved 100 underweight participants were randomized to receive either a probiotic supplement (Lactobacillus acidophilus, L. casei, L. rhamnosus; 3 × 10⁹ CFU) or placebo for 8 weeks. Stress levels, anthropometric measures, and inflammatory markers (ESR, CRP) evaluated at baseline and post-intervention.

Results

Ninety participants (mean age: 26.22 ± 7.42 years) completed the study (probiotic: n = 47; placebo: n = 43). Baseline age (p = 0.051) and gender (p = 0.101) showed no significant differences. Post-intervention, the probiotic group exhibited significant weight increases (p = 0.005), waist circumference (p = 0.038), and hip circumference (p = 0.008), and a significant reduction in Perceived Stress Scale (PSS) scores (p < 0.001) in comparison to the placebo. Inflammatory markers (ESR, CRP) also decreased significantly in the probiotic group (p < 0.001). Within-group analysis revealed improvements in anthropometric measures and inflammatory markers in both groups (p < 0.05), but stress reduction was more pronounced in the probiotic group (34% vs. 9.3%, p = 0.017). A significant time-group interaction was observed for stress scores (p < 0.001).

Discussion

The findings suggest that probiotic supplementation reduces stress levels in underweight individuals, possibly through gut microbiota modulation and inflammation reduction. Further research with larger samples and microbiome analysis is warranted.

Conclusion

In conclusion, administering probiotics to underweight patients positively impacts their mental health and exhibits anti-inflammatory effects.

Clinical trial registration

https://irct.behdasht.gov.ir/trial/69130, identifier IRCT20230310057667N1.

Research Insights

Supplement	Health Outcome	Effect Type	Effect Size
Lactobacillus acidophilus L-92	Improved Anthropometric Measures	Beneficial	Small
Lactobacillus acidophilus L-92	Reduced Inflammation	Beneficial	Moderate
Lactobacillus acidophilus L-92	Reduced Perceived Stress	Beneficial	Moderate
Lactobacillus acidophilus L-92	Reduced Stress	Beneficial	Large