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Postprandial effects of beetroot enriched bread on peripheral microvascular function and blood pressure in normotensive men

Published online by Cambridge University Press:  27 January 2012

D. A. Hobbs ,
T. W. George ,
L. Methven  and
J. A. Lovegrove
D. A. Hobbs
Affiliation:
Department of Food and Nutritional Sciences, University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK
T. W. George
Affiliation:
Department of Food and Nutritional Sciences, University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK
L. Methven
Affiliation:
Department of Food and Nutritional Sciences, University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK
J. A. Lovegrove
Affiliation:
Department of Food and Nutritional Sciences, University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK Institute for Cardiovascular and Metabolic Research (ICMR), University of Reading, Whiteknights, PO Box 226, Reading, Berks, RG6 6AP, UK
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Abstract

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Proceedings of the Nutrition Society , Volume 70 , Issue OCE6: Winter Meeting, 6–7 December 2011, 70th Anniversary: Body weight regulation – food, gut and brain signalling , 2011 , E376
Copyright
Copyright © The Authors 2012

The cardio-protective effects of beetroot, such as blood pressure reduction(Reference Webb, Patel and Loukogeorgakis1) have been attributed to its high nitrate content(Reference Lundberg, Weitzberg and Cole2). Following ingestion, dietary nitrate is reduced to nitrite by oral bacteria, and further to the vasodilator nitric oxide (NO) endogenously(Reference Lundberg, Weitzberg and Gladwin3). This study investigated the effects of enriching bread with nitrate-rich beetroot on postprandial peripheral microvascular function and blood pressure (BP).

Twenty four healthy men were recruited to a randomly controlled, single blind, cross-over, postprandial test meal study. Peripheral microvascular function was measured using laser Doppler imaging (LDI) with iontophoresis at baseline, 2, 4 and 6 hours after consumption of 200 g control bread (no beetroot,<0.8 mM nitrate) or 200 g bread enriched with 100 g red beetroot 6.4 mM nitrate). Ambulatory BP (ABP) was measured at baseline, every 30 min from 8 am until 10 pm, and every 60 min from 10 pm until 8 am, and blood samples were taken at baseline and 30, 60, 90, 120, 150, 180, 210, 240, 300, 360 and 420 min after consumption of intervention breads. The participants followed a low nitrate and nitrite diet for 48 hours prior to and during the study day. A low nitrate and nitrite standard meal was provided for the evening before the study day.

Preliminary results show a significant reduction in diastolic BP (DBP) from 0 to 120 minutes post ingestion of beetroot enriched bread compared to the control bread (no beetroot) (Fig. 1A, P=0.025). Endothelium-dependent (LDI-ACh, Fig. 1B) and endothelium-independent (LDI-SNP) vasodilation increased following ingestion of beetroot enriched bread, compared to the control bread (no beetroot), but did not reach statistical significance (LDI-ACh, P=0.08). Plasma nitrite concentration significantly increased from 0 to 7 hours after ingestion of beetroot enriched bread compared to control (no beetroot) (Fig. 1C, P=0.01).

Fig. 1. The effect of beetroot enriched bread on the change from baseline in (A) diastolic BP (B) LDI-ACh response and (C) plasma nitrite concentrations. Data expressed as means±SEM.

In conclusion, this study demonstrated significant blood pressure lowering and a tendency for increasing peripheral microvascular function after ingestion of beetroot enriched bread, occurring in conjunction with a significant increase in plasma nitrite concentration. Beetroot enriched bread may serve as a good vehicle to increase consumption of cardio-protective beetroot in the diet.

References

1.Webb, AJ, Patel, N, Loukogeorgakis, S et al. (2008) Hypertension 51(3), 784–90.CrossRefGoogle Scholar
2.Lundberg, JO, Weitzberg, E, Cole, JA et al. (2004) Nat Rev Micro 2, 593–602.CrossRefGoogle Scholar
3.Lundberg, JO, Weitzberg, E & Gladwin, MT (2008) Nat Rev Drug Discov 7(2), 156–67.CrossRefGoogle Scholar
Figure 0

Fig. 1. The effect of beetroot enriched bread on the change from baseline in (A) diastolic BP (B) LDI-ACh response and (C) plasma nitrite concentrations. Data expressed as means±SEM.