Cruciferous vegetables improve glycaemic control compared to root/squash vegetables in a randomized, controlled, crossover trial: The VEgetableS for vaScular hEaLth (VESSEL) study

Aims: Higher cruciferous vegetable (e.g., broccoli) intake is associated with lower risk of type 2 diabetes and cardiovascular disease, but limited causal evidence exists. We investigated if cruciferous vegetable intake improved glycaemic control compared to root/squash vegetables in non-diabetic adults with elevated blood pressure. 

Materials and Methods: This randomized, controlled, crossover trial consisted of two 2-week dietary interventions (300 g/day cruciferous [active] and root/squash [control] soups with standardized lunch/dinner meals) separated by a 2-week washout. Participants were blinded to the intervention allocation. Glycaemic measures were a pre-specified secondary outcome. Flash glucose monitoring measured interstitial glucose every 15-min throughout both interventions. Mealtimes and consumption were recorded in food diaries. Differences in continuous glucose, glycaemic variability (coefficient of variation [CV]), and overall, lunch, and dinner postprandial glucose response (PPGR; 2-h mean glucose [PPGR 2-h] and area under the curve [AUC]) were assessed using linear mixed-effects regression. 

Results: Eighteen participants (female = 89%) completed the study (median [IQR] age: 68 [66–70 years]). Glycaemic variability was lower in the active versus control (mean difference: −2.0%, 95% CI −2.8, −1.1, p < 0.001). Overall PPGR 2-h and AUC were lower in the active versus control (mean difference: −0.14 mmol/L, 95% CI −0.24, −0.04, p = 0.005 and −20.1 mmol/L × min, 95% CI −34.1, −6.1, p = 0.005, respectively), driven by the dinner PPGR (p = 0.004 and p = 0.003, respectively). There was no difference in mean continuous glucose for active versus control (p = 0.411). 

Conclusions: Cruciferous vegetable consumption improved postprandial glycaemic control compared with root/squash vegetables. The clinical impact remains uncertain and warrants further investigation, particularly in individuals with impaired glycaemic control. 

Clinical Trial Registry: This trial was registered at www.anzctr.org.au (ACTRN12619001294145).