In a study recently published in the journal Nutritional values, Researchers investigate the combined effects of calorie restriction (CR) and clinical psychological intervention (CPI) on gut microbiome composition and stress-related mental health outcomes in women.

Study: The effects of calorie restriction and clinical psychological intervention on the interplay between gut microbiota composition and stress in women. Photo credit: Natalia Deriabina / Shutterstock.com

The effects of lifestyle interventions

Common mental and metabolic disorders such as obesity, depression and diabetes have biological and lifestyle causes, leading to their co-occurrence and increased morbidity and mortality rates. Although drug treatments exist for many of these disorders, adherence to therapy is challenging and side effects such as weight gain can reduce patient compliance, ultimately increasing the risk of adverse outcomes.

Lifestyle interventions, including diet and stress reduction, are gaining popularity due to their potential benefits. The gut microbiome, which is influenced by diet and stress, plays a critical role in mental and physical health. Therefore, further research is needed to better understand the synergistic effects of nutritional and psychological interventions on the gut microbiota and mental health and to optimize these approaches for improved health outcomes.

About the study

The study cohort consisted of 41 women who completed a 2-week inpatient lifestyle intervention at La Pura Women’s Health Resort. The intervention included a combination of dietary CR and CPI.

Study participants were excluded if they were currently pregnant or suffering from a serious chronic illness. Regardless of randomization, all participants were able to use La Pura’s leisure and wellness facilities.

Study participants were randomly assigned to either a very low calorie diet (VLCD) or the FX Mayr diet (FXM). VLCD consisted of 630-700 kcal/day divided into three meals. FXM consisted of 700-800 kcal/day divided into two meals, with additional measures such as long chewing, no meals after 7 pm, and oral magnesium sulfate supplementation.

Within each dietary group, study participants were randomly assigned to receive either CPI or a single stress prevention lecture. CPI included sessions on muscle relaxation, psychoeducation, mindfulness training, and biofeedback.

Clinical variables included age, body mass index (BMI), morning cortisol level, C-reactive protein (CRP), and interleukin 6 (IL-6). Psychometric outcomes were assessed using the Brief Symptom Index (BSI), Perceived Stress Scale (PSS), and Burnout Dimension Inventor (BODI). Fasting blood and stool samples were collected at baseline and follow-up for microbial analysis using 16S ribosomal ribonucleic acid (rRNA) sequencing.

The gut microbiome was analyzed by measuring α-diversity, microbial composition, and β-diversity indices. Taxonomic changes and the relationship between gut microbiota and psychometric outcomes were also further investigated.

Statistical analyses included repeated measures analysis of variance (ANOVA), permutational multivariate analysis of variance (PERMANOVA), and multilevel dimensionality reduction analyses to understand how dietary and psychological interventions affect the gut microbiome and mental health.

Study results

Bacteroides and Alistipes remained the dominant genera, while Faecalibacterium, Escherichia shigella, UCG-002, And Clostridia UCG-014 decreased in relative frequency. In contrast, Rhodospirillales order, Phascolarctobacterium, Parabacteroides, Prevotella, Odoribacter, And Akkermansia In addition, α-diversity indices, including species richness, Shannon index, and Firmicutes/Bacteroidetes ratio, decreased significantly over time.

Multilevel principal component analysis (PCA) revealed a separation between the baseline and follow-up samples, with the FXM samples further clustering along the negative scale of the first principal component (PC1). Oscillospira was negatively associated with PC1, while Agathobacter, Subdoligranulum, E. xylanophilum, Fusicatenibacter, E. ventriosum, Roseburia, UCG-002, And Faecalibacterium were positively associated.

Regarding β-diversity, the best performing PERMANOVA model showed significant effects of time point interaction with diet, CPI and age. FXM showed more pronounced changes in β-diversity than VLCD.

After the intervention, samples were separated by diet in a principal coordinate analysis (PCoA). Six bacterial families, including Bifidobacteria And Ruminococcaceae, significantly reduced relative frequency after CR.

At the genus level Dialister, Bifidobacterium, Faecalibacterium, And Subdoligranulum significantly reduced. Lachnospiraceae Genres such as E. ventriosum Group, E. xylanophilum group, Coprococcus, Agathobacter, Fusicatenibacter, And Roseburia, also decreased. Under Flavonifactor, Oscillospiraceae, Oscillibacter, And Oscillospira increased, while UCG-002 reduced.

Overview of basic taxonomic characteristics and changes during the intervention period. (A) Relative frequency in the intervention groups; (B) relative changes in frequency rank in the entire cohort; (C–E) Changes in bacterial diversity, Shannon index and Firmicutes/Bacteroidetes ratio; (F) multilevel PCA biplot, colored by baseline (beige), FXM (light pink = with CPI, dark pink = without CPI) and VLCD (light blue = with CPI, dark blue = without CPI) and taxonomy (gray arrows) as well as BMI category (shapes). FXM – FX-Mayr diet, VLCD – very low calorie diet, CPI – clinical psychological intervention, BMI – body mass index.

Stratification by intervention group revealed nutritional patterns, with significant reductions in Agathobacter And E. ventriosum group across both diets and significant increases in Oscillibacter only in FXM. Stratification by CPI subgroups showed no significant results after p-value adjustment.

Sparse partial least squares (sPLS2) analysis selected 40 taxa and 12 clinical variables, highlighting key differences by sampling time. FXM was more positively associated with the first component than VLCD. Key determinants of the first component included taxa and clinical parameters, with microbial genera grouped according to their positive or negative association with psychometric values ​​and BMI.

The sparse partial least squares discriminant analysis (sPLS-DA) model for diet classification effectively discriminated between FXM and VLCD. The stress reduction model showed a moderate separation driven by specific taxa, such as Bifidobacteria And Oscillospiral.

Conclusions

After two weeks of CR, the composition of the gut microbiome was altered in overweight women with psychological stress based on dietary protocols and psychological interventions. The FXM diet resulted in significantly higher levels of Oscillibacterwhich is associated with improved mental health and less stress.

The metabolic and mental health benefits of CR may be mediated by its anti-inflammatory properties and regulation of the hypothalamic-pituitary-adrenal axis. Significant microbial changes included reduced abundance of Firmicutes and Lachnospiraceae/Ruminococcaceae families. Both FXM and CR lead to significant increases in Oscillibacter, Akkermansia, And Odoribacterwhich are associated with positive health effects.