Effectiveness of nutrition and dietary interventions for people with serious mental illness: systematic review and meta-analysis.

OBJECTIVE: To review recent published trials of nutrition and dietary interventions for people with serious mental illness; to assess their effectiveness in improving metabolic syndrome risk factors. STUDY DESIGN: Systematic review and meta-analysis of randomised and non-randomised controlled trials of interventions with a nutrition/diet-related component delivered to people with serious mental illness, published 1 January 2010 - 6 September 2021. Primary outcomes were weight, body mass index (BMI), and waist circumference. Secondary outcomes were total serum cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, triglyceride, and blood glucose levels. DATA SOURCES: MEDLINE, EMBASE, PsycINFO, CINAHL, and CENTRAL databases. In addition, reference lists of relevant publications were examined for further additional studies. DATA SYNTHESIS: Twenty-five studies encompassing 26 intervention arms were included in our analysis. Eight studies were at low or some risk of bias, seventeen were deemed to be at high risk. Eight of seventeen intervention arms found statistically significant intervention effects on weight, ten of 24 on BMI, and seven of seventeen on waist circumference. The pooled effects of nutrition interventions on metabolic syndrome risk factors were statistically non-significant. However, we identified small size effects on weight for interventions delivered by dietitians (five studies; 262 intervention, 258 control participants; standardised mean difference [SMD], -0.28; 95% CI, -0.51 to -0.04) and interventions consisting of individual sessions only (three studies; 141 intervention, 134 control participants; SMD, -0.30; 95% CI, -0.54 to -0.06). CONCLUSIONS: We found only limited evidence for nutrition interventions improving metabolic syndrome risk factors in people with serious mental illness. However, they may be more effective when delivered on an individual basis or by dietitians. PROSPERO REGISTRATION: CRD42021235979 (prospective).

The effect of ultra-processed very low-energy diets on gut microbiota and metabolic outcomes in individuals with obesity: A systematic literature review.

This systematic review investigated the effects of ultra-processed very low-energy diets on gut microbiota and metabolic outcomes in individuals with obesity. MEDLINE complete, EMBASE, Scopus, Cochrane and CINAHL were searched between date of inception and October 2019. Seven trials were reviewed (a total of 130 participants, with 10 to 44 participants in each trial). Of these, five were single-arm interventions and included very low-energy diets adjunctive to comprehensive lifestyle interventions such as nutritional counselling, behavioural therapy and exercise programmes. Changes to taxa within the Firmicutes phylum were found, including reduced abundance of potentially beneficial butyrogenic microbes (Roseburia, Faecalbacterium prausnitzii, Lactobacillus, Bifidobacterium and Lachnospiraeceae). Conversely, increased abundance of potentially pathogenic or opportunistic microbes from the Bacteroidetes phylum was reported, including increases in Alistipes and Bacteroides taxa. However, outcomes were inconsistent, with some trials also showing decreases in Bacteroides taxa and increases in commensal microbiota, such as Lachnospiraceae and Bifidobacteriaceae. The changes in metabolic parameters observed from baseline to after the ultra-processed very low-energy diets were mostly beneficial or were not significantly altered. Although the selected articles were deemed to have satisfactory methodological quality, to understand the possible direct effects of these regimens on gut microbiota, further rigorously designed trials, with more standardised microbiological sequencing techniques and detailed reporting, are required. Study registration: Prospero ID: CRD42019124436.