In a recent study published in the journal Nutrients, researchers investigated the effects of combining caloric restriction (CR) with a clinical psychological intervention (CPI) on women's gut microbiome composition and stress-related mental health outcomes.
Study: The impact of calorie restriction and clinical psychological intervention on the interplay between gut microbial composition and stress in women. Image credit: Natalia Deriabina / Shutterstock.com
Impact of lifestyle interventions
Common psychiatric and metabolic diseases, such as obesity, depression and diabetes, share biological and lifestyle pathways that lead to their co-occurrence and increased morbidity and mortality. Pharmacological therapies exist to manage many of these diseases, but adherence is challenging and side effects such as weight gain reduce patient adherence and ultimately increase the risk of adverse outcomes.
Lifestyle interventions such as diet and stress reduction are becoming increasingly popular due to their potential benefits. The gut microbiota, which is influenced by diet and stress, plays an important role in mental and physical health. Therefore, further research is needed to better understand the synergistic effects of diet and psychological interventions on the gut microbiota and mental health, and to optimize these approaches to improve health outcomes.
About the Research
The study cohort consisted of 41 women who completed a 2-week inpatient lifestyle intervention at La Pla Women's Health Resort. The intervention included a combination of dietary CR and CPI.
Study participants who were currently pregnant or had a severe chronic illness were excluded. Regardless of randomization, all participants had access to La Pla's leisure and wellness facilities.
Study participants were randomly assigned to either a very low calorie diet (VLCD) or the FX Meyer diet (FXM). The VLCD included 630-700 kcal per day divided into three meals. The FXM included 700-800 kcal per day divided into two meals. Additionally, it included habits such as extended chewing, fasting after 7 pm, and oral magnesium sulfate supplementation.
Within each diet group, study participants were additionally randomized to receive either the CPI or a single stress prevention lecture. The CPI included sessions of muscle relaxation, psychoeducation, mindfulness training, and biofeedback.
Clinical variables included age, body mass index (BMI), morning cortisol, 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 Outcome Scale (BODI). Fasting blood and stool samples were collected at baseline and follow-up for microbial analysis by 16S ribosomal ribonucleic acid (rRNA) sequencing.
The gut microbiota was analyzed by measuring alpha diversity, microbial composition, and beta diversity indices. Taxonomic variation and the relationship between gut microbiota and psychometric outcomes were also further investigated.
Statistical analyses included repeated measures analysis of variance (ANOVA), permutation multivariate analysis of variance (PERMANOVA), and multilevel dimensionality reduction analyses to understand how dietary and psychological interventions affect gut microbiota and mental health.
Research findings
While Bacteroides and Alistipes remained the predominant genera, the relative abundances of Faecalibacterium, Escherichia coli-Shigella, UCG-002, and Clostridia UCG-014 decreased. In contrast, the genera Rhodospiralles, Phascolarctobacterium, Parabacteroides, Prevotella, Odoribacter, and Akkermansia increased. Furthermore, alpha-diversity indices including richness, Shannon index, and Firmicutes/Bacteroides ratio significantly decreased over time.
Multilevel principal component analysis (PCA) revealed separation between baseline and follow-up samples, with FXM samples clustering more along the negative scale of the first principal component (PC1). Oscillospira was negatively correlated with PC1, while Agathobacter, Subdoligranulum, E. xylanophilum, Fusicatenibacter, E. ventriosum, Roseburia, UCG-002, and Faecalibacterium were positively correlated.
Regarding β-diversity, the best performing PERMANOVA model showed significant effects of time point interactions with diet, CPI, and age, with FXM showing more pronounced changes in β-diversity than VLCD.
After the end of the intervention, samples were separated by diet with principal component analysis (PCoA).Six bacterial families, including Bifidobacteriaceae and Ruminococcaceae, showed a significant decrease in relative abundance after CR.
At the genus level, Dialister, Bifidobacterium, Faecalibacterium, and Subdoligranulum were significantly decreased. E. ventriosum group, E. xylanophilum group, and Lachnospiraceae genera including Coprococcus, Agathobacter, Fusicatenibacter, and Roseburia were also decreased. In Flavonifractor, Oscillospiraceae, Oscillibacter, and Oscillospira were increased, and UCG-002 was decreased.
Summary of taxonomic baseline characteristics and changes during the intervention period. (A) Relative abundance across intervention groups; (B) relative change in abundance rank across cohorts; (C–E) changes in bacterial richness, Shannon index, and Firmicutes/Bacteroidetes ratio; (F) multilevel PCA biplots colored according to baseline (beige), FXM (light pink=with CPI, dark pink=without CPI), VLCD (light blue=with CPI, dark blue=without CPI), classification (grey arrows), and 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 diet-related patterns, with a significant decrease in Agathobacter and E. ventriosum groups in both diets and a significant increase 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 the main differences according to sampling time point. FXM was more positively correlated with the first component than VLCD. Major determinants along the first component included taxa and clinical parameters, and microbial genera were clustered by positive or negative correlations with psychometric scores and BMI.
A sparse partial least squares discriminant analysis (sPLS-DA) model for diet classification effectively differentiated between FXM and VLCD, while the stress-reduced model showed moderate separation by certain taxa such as Bifidobacteria and Oscillospirales.
Conclusion
After 2 weeks of CR, the composition of the gut microbiota in overweight women with psychological stress was altered based on dietary and psychological intervention: the FXM diet significantly increased Oscillibacter levels, leading to improved mental health and reduced stress.
The metabolic and mental health benefits of CR are likely due to its anti-inflammatory properties and regulation of the hypothalamic-pituitary-adrenal axis. Major microbial changes include a decrease in the families Firmicutes and Lachnospiraceae/Ruminococcaceae. Both FXM and CR lead to a significant increase in Oscillibacter, Akkermansia, and Odoribacter, which are associated with positive health outcomes.
Journal References:
Bellach, L., Kautzky-Willer, A., Heneis, K., et al. (2024). Effects of caloric restriction and clinical psychological intervention on the interplay between gut microbial composition and stress in women. Nutrients. doi:10.3390/nu16162584
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