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

TL;DR

Eating cruciferous vegetables like broccoli improves blood sugar control after meals compared to root or squash vegetables in adults with high blood pressure.

Contribution

This study provides causal evidence that cruciferous vegetables improve postprandial glycaemic control compared to root/squash vegetables.

Findings

Glycaemic variability was 2.0% lower with cruciferous vegetables compared to root/squash vegetables.

Dinner postprandial glucose response was significantly reduced with cruciferous vegetables.

No difference in mean continuous glucose levels was observed between the two vegetable types.

Abstract

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.

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.

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).

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.

This trial was registered at www.anzctr.org.au (ACTRN12619001294145).

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