Effect of brown seaweed on plasma glucose in healthy, at-risk, and type 2 diabetic individuals: systematic review and meta-analysis

CONTEXT: Sustained hyperglycemia triggers chronic disease, including type 2 diabetes. A considerable volume of research has explored the effects of brown seaweed on plasma glucose control, but equivocal findings have been reported. OBJECTIVE: A systematic review and meta-analysis was conducted to assess the evidence from human randomized controlled trials (RCTs) on the effects of brown seaweed on plasma glucose in healthy, at-risk, and individuals with type 2 diabetes. DATA SOURCES: MEDLINE/PubMed, EMBASE, and the Cochrane Library were searched for reports published between 2000 and 2020. DATA EXTRACTION: Population, intervention, comparator, outcome, and study design data were extracted. DATA ANALYSIS: Eighteen RCTs met our inclusion criteria. The reported results varied across and between populations. Meta-analyses showed a significant effect, favoring the intervention group for both fasting (mean difference –4.6 [95% CI –7.88, –1.33]) and postprandial (mean difference –7.1 [95% CI –7.4, –6.9]) plasma glucose. CONCLUSION: Brown seaweed and its extracts show potential for preventing and managing hyperglycemia. Our meta-analysis confirms that brown seaweed positively affects plasma glucose homeostasis, with particularly promising postprandial plasma glucose effects. However, further research is needed because no high-quality RCT was identified. Species-specific and dose–response research is also required. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42020187849.