The effect of dietary nitrite/nitrate on glycaemic control: a systematic review of randomized controlled trials using beetroot-derived preparations

Abstract

Diabetes is a growing health concern, and effective glycaemic management is essential to prevent complications. Dietary nitrate- and nitrite-rich foods may influence glycaemic control, but the evidence remains inconsistent. Accordingly, this study systematically synthesised and evaluated the current evidence to determine whether beetroot-derived nitrate and nitrite interventions can improve glycaemic regulation and glucose metabolism. PubMed, Scopus, Web of Science, and Embase were searched from inception to September 2026 using pre-determined keywords to identify RCTs evaluating the chronic effects of dietary inorganic nitrate/nitrite on fasting blood glucose, fasting insulin, HbA1c, and indices of insulin resistance and sensitivity in healthy adults or those with type 2 diabetes. Screening and data extraction were conducted by at least two independent reviewers, and risk of bias was assessed using the RoB2 tool. Out of 5,374 retrieved studies, seven publications (six RCTs) met the eligibility criteria and were included. All used beetroot-based preparations (juice, extract, or powder), with intervention durations ranging from 2 weeks (crossover trials) to 6 months. No consistent or significant improvements in glycaemic indices were observed, suggesting that dietary nitrate/nitrite, particularly from beetroot, is not effective for glycaemic control. Despite observational evidence linking dietary nitrate/nitrite to glucose regulation, RCTs limited to beetroot-derived nitrate/nitrite supplementation has shown no significant effect. Given uncertainties regarding bioavailability and the potential role of other nitrate sources, beetroot-derived nitrate/nitrite interventions cannot currently be recommended specifically for glycaemic control, although nitrate-rich foods remain part of a healthy diet and further research on other sources is warranted.