Inositol supplementation efficacy in improving key cardiometabolic and anthropometric indices: a GRADE-assessed...

Inositol and its derivatives may help mitigate risks associated with cardiovascular diseases; however, existing evidence remains inconsistent.

The primary aim of this systematic review and meta-analysis of RCTs was to quantify the effects of inositol and its stereoisomers on anthropometric, and cardiometabolic measures.

A systematic review and meta-analysis of RCTs was conducted to clarify this. Searches in PubMed and Scopus, along with hand-searching references, identified RCTs on inositol supplementation lasting ≥ 4-week. Using random-effects models, the analysis determined mean effect sizes as weighted mean differences (WMD) with 95% CIs. Heterogeneity was assessed via the Cochrane Chi-squared test and Galbraith plots, while the ROBI tool evaluated bias risk. The strength of the evidence was assessed using the GRADE framework.

Eighteen RCTs (n = 898) were totally included in this meta-analysis. Significant reductions in BMI (WMD (95%CIs):-0.57 kg/m²(-1.10, -0.03), I²=88.6), waist-to-hip ratio(WMD (95%CI):-0.02(-0.04, -0.001), I²=84.1), and waist circumference (WMD (95%CI):-2.36 cm(-4.39, -0.33) I²=55.0) were noted with high heterogeneity and low to very low certainty evidence. Inositol significantly decreased glucose levels (WMD (95%CI):-7.25 mg/dL(-10.98, -3.52), I²=90.7), insulin (WMD (95%CI):-4.74µU/mL(-6.16, -3.32), I²=90.6) and HOMA-IR (WMD (95%CI):-1.21(-1.58, -0.85), I²=85.0), both with moderate evidence certainty and high heterogeneity. Notable reductions in triglycerides (WMD (95%CI):-29.80 mg/dL(-48.16, -11.44), I²=96.0) and total-cholesterol (WMD (95%CI):-18.26 mg/dL(-30.75, -5.77), I² = 95.8) were observed, with high and low evidence certainty, respectively, and high heterogeneity. LDL-C and HDL-C improved with moderate certainty (WMDs (95%CIs):-5.15 mg/dL(-8.89, -1.42), I²= 0.0; and 2.76 mg/dL(1.16, 4.36), I²=52.9). Additionally, inositol significantly lowered systolic (WMD (95%CI):-5.34mmHg(-6.91, -3.78), I²=38.0) and diastolic blood pressure (WMD (95%CI):-6.12mmHg(-8.44, -3.80), I²=69.7) with low, and very low evidence certainty.

Overall, inositol may offer modest cardiometabolic benefits, with moderate-to-high certainty for improvements in insulin resistance and lipid profiles. However, existing studies show a high risk of bias and low certainty of evidence, particularly for anthropometric outcomes, creating cautious interpretation. Future research should involve large-scale, rigorous trials with standardized protocols, longer follow-up, and diverse populations.