Blood pressure-lowering effects of beetroot juice and novel beetroot-enriched bread products in normotensive male subjects

A number of vegetables have a high nitrate content which after ingestion can be reduced to nitrite by oral bacteria, and further to vasoprotective NO endogenously. In the present study, two separate randomly controlled, single-blind, cross-over, postprandial studies were performed in normotensive volunteers. Ambulatory blood pressure (BP) was measured over a 24h period following consumption of either four doses of beetroot juice (BJ), 0, 100, 250 and 500g (n 18), or three bread products, control bread (0g beetroot), red beetroot- and white beetroot-enriched breads (n 14). Total urinary nitrate/nitrite (NO x) was measured at baseline, and at 2, 4 and 24h post-ingestion. BJ consumption significantly, and in a near dose-dependent manner, lowered systolic BP (SBP, P<0·01) and diastolic BP (DBP, P<0·001) over a period of 24h, compared with water control. Furthermore, bread products enriched with 100g red or white beetroot lowered SBP and DBP over a period of 24h (red beetroot-enriched bread, P<0·05), with no statistical differences between the varieties. Total urinary NO x significantly increased following the consumption of 100g (P<0·01), 250g (P<0·001) and 500g BJ (P<0·001) and after red beetroot-enriched bread ingestion (P<0·05), but did not reach significance for white beetroot-enriched bread compared with the no-beetroot condition. These studies demonstrated significant hypotensive effects of a low dose (100g) of beetroot which was unaffected by processing or the presence of betacyanins. These data strengthen the evidence for cardioprotective BP-lowering effects of dietary nitrate-rich vegetables. Copyright © 2012 The Authors.