Background: Betalains are plant bioactives serving as colour pigments in plants exclusively occurring in the Caryophyllales such as the dragon fruit (pitaya) and cactus pear (nopal). Preliminary in vitro and animal studies have demonstrated betalains’ cardioprotective potential. However, there is a lack of investigations in human randomised controlled trials (RCT), especially in nutritionally achievable amounts. Besides, the mechanism of action of betalain still remains unclear.
Objectives: 1) to investigate the effects of acute and short-term consumption of betalain-rich dragon fruit on vascular function in a healthy population and 2) to explore the mechanism of action of betalains at the cellular level.
Methods (RCT): A randomised, double-blind, controlled, cross-over trial was conducted in 19 young, healthy, non-smoking men and women assigned to consume 24 g whole dragon fruit powder (33 mg betalains) or the placebo, daily for 14 days. Flow-mediated dilation (FMD), arterial stiffness and blood pressure (BP) were measured at 0 h, 1 h, 2 h, 3 h, 4 h and finally on 14 days after daily consumption.
Methods (in vitro): The effect of betalains on vascular biomarkers was investigated in a simulated endothelial dysfunction using an in vitro model of endothelial cells. Betalain (betanin) at different doses (0.8 – 32 nM) was used to assess its effect on the relative gene expression of ICAM-1, VCAM-1 and ET-1 using quantitative PCR.
Results: Dragon fruit consumption significantly improved acute FMD at 2 h (+0.8 ± 0.3 %), 3 h (+1.0 ± 0.3 %) and at 4 h (+1.3 ± 0.4 %) post-consumption versus placebo. This effect was sustained up to 14 days (+1.3 ± 0.2 %) (P <0.05). Pulse wave velocity (PWV) was significantly reduced acutely at 3 h (-0.5 ± 0.2 m/s) whereas augmentation index (AIx) was also improved after 14 days (-7.0 ± 3.3 %) (P <0.05). No differences were found in BP across all time points. In the cell culture experiment, betanin across all concentrations significantly supressed the expression of all three vascular biomarkers with no dose-dependent effect (P <0.05).
Conclusions: Acute and short-term consumption of dragon fruit in dietary achievable amounts improved endothelial function and arterial stiffness in healthy individuals. This implies that regular dragon fruit
Betalains and Cardiovascular Health: Efficacy, Bioavailability and Mechanistic Insights
Cheok, A. (Author). 1 Jun 2022
Student thesis: Doctoral Thesis › Doctor of Philosophy