RESUMEN
Background: Several randomized controlled trials (RCTs) have explored the impact of melatonin on body composition and blood pressure (BP). However, the findings from these studies remain a topic of debate. This systematic review and meta-analysis of RCTs sought to evaluate the effects of melatonin consumption on body composition (body weight (BW), body mass index (BMI), waist circumference (WC), hip circumference (HC)) and asleep/daytime BP (systolic blood pressure (SBP) and diastolic blood pressure (DBP)) in adults. Methods: In order to identify eligible RCTs, a systematic literature search was carried out up to June 2024 in PubMed, Embase, Scopus, and Web of Science without any language restrictions. The I2 statistic was used to perform heterogeneity tests on the selected studies. After evaluating random effects models based on heterogeneity tests, the weighted mean differences (WMD) with a 95 % confidence interval (CI) were calculated using pooled data. Results: Overall, 28 studies (n = 1,543 participants) met our inclusion criteria. A pooled analysis of studies demonstrated that melatonin consumption led to a significant reduction in HC (WMD: 1.21 cm; 95 % CI: 1.94 to -0.49; P = 0.001), and daytime DBP (WMD: 1.40 mmHg; 95 % CI: 2.46 to -0.34; P = 0.009) in comparison with the control group. However, no substantial effects were observed on BW, BMI, WC, and SBP compared to the control group. Conclusion: The current meta-analysis of RCTs shows that treatment with melatonin reduces HC and daytime DBP levels in adults. However, further well-designed RCTs with large sample sizes and long durations are necessary to determine the effect of this supplement on body composition and BP.
RESUMEN
INTRODUCTION: Several randomized controlled trials (RCTs) have demonstrated the beneficial effects of chromium supplementation in managing type 2 diabetes mellitus (T2DM). The current systematic review and meta-analysis aimed to investigate the associations between chromium supplementation and body composition in patients with T2DM. METHODS: To achieve this, PubMed, Scopus, Embase, Cochrane Library, and Web of Science were searched for randomized clinical trials (RCTs) that reported the effects of chromium supplementation on body composition such as body weight (BW), body mass index (BMI), fat mass (FM), and waist circumference (WC) in patients with T2DM from inception until July 2023. Weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated using a fixed-effects model. RESULTS: The meta-analysis included a total of 14 RCTs. The results showed that chromium supplementation did not have any significant effect on FM (WMD = -0.43%; 95% CI -0.94, 0.09), BMI (WMD: 0.09 kg/M2, 95% CI: -0.03, 0.20), WC (WMD: -0.47 cm, 95% CI: -1.10, 0.16), and BW (WMD: -0.26 kg, 95% CI: -0.69, 0.16). However, subgroup analysis revealed that chromium intake decreased FM in subjects aged ≥ 55 years and when chromium picolinate was used as an intervention. Additionally, there was a non-linear association between the dose of chromium supplementation and BW. CONCLUSIONS: The meta-analysis suggests that chromium supplementation does not significantly reduce BW, BMI, WC, and FM in patients with T2DM. Further RCTs with large-scale are required to determine the possible anti-obesity effects of chromium in patients with T2DM.