The effect of a course of raw beetroot powder on the augmentation index

Objective. To evaluate the effect of a 7-day course of raw beetroot powder supplementation as a natural source of nitrate ions on the augmentation index (AIp75) measured by photoplethysmography. Materials and methods. The study included 42 men (mean age 51.3±6.6 years) with a newly diagnosed or controlled hypertension. Participants were randomized into two groups in a crossover design. Patients in Group 1 took 20 g/day of beetroot powder (equivalent to 650–700 mg of nitrates) for week 1 and no powder for week 2; patients in Group 2 followed the reverse schedule. Photoplethysmography (PPG) was performed at the beginning of the study (visit 1), one week later (visit 2), and after the second week (visit 3). The parameters of PPG were studied, the most promising of which was the augmentation index (AIp75) normalized by heart rate. The Wilcoxon’s test and Friedman’s test were used for statistical analysis. Results. In patients of Group 1, the AIp75 significantly decreased from 12.3% at baseline to 3.25% after taking beetroot for 1 week (p=0.03). In patients of Group 2, AIp75 decreased from 0.35% at baseline to –2.3% after beetroot intake, with statistically significant differences in values between visits (p=0.038). There were no considerable changes during periods of drug withdrawal. Results show that a weekly course of beetroot powder supplementation sequentially reduces AIp75, a marker of reflected wave pressure that increases with arterial stiffness and is associated with higher central arterial pressure and left ventricular afterload. Conclusion. Supplementing the diet with nitrates through beetroot powder significantly improves the augmentation index in men with hypertension. These data suggest the potential benefit of inorganic nitrate intake as a simple strategy to influence cardiovascular disease risk factors favorably. Further studies are needed to assess the long-term impact of inorganic nitrate administration on cardiovascular outcomes.