Vegetable nitrate intake contributes to cardiovascular health
Higher intake of vegetable nitrate may prevent thickening of the common carotid artery intima-media thickness (CCA-IMT) and reduce the risk of developing an ischaemic cerebrovascular disease event, according to a study.
Found predominantly in green leafy vegetables and beetroot, dietary nitrate dose-dependently enhances the circulating nitric oxide (NO) pool by increasing the levels of circulating nitrite, NO and related nitroso compounds. [Food Funct 2012;3:522–527; Nitric Oxide 2008;19:333–337]
To investigate the potential vascular benefits of dietary nitrate, researchers examined the medical records of 1,226 Western Australian elderly women (mean age 75 years; mean body mass index, 27 kg/m2) grouped by tertiles of vegetable nitrite intake: <53 mg/day (n=409), 53 to 76 mg/day (n=408) and >76 mg/day (n=409). Lifestyle factors and cardiovascular disease risk factors were also determined at baseline.
CCA-IMT and plaque severity were evaluated using B-mode carotid ultrasound, whereas data on ischaemic cerebrovascular disease hospitalizations or deaths (events) over 14.5 years (15,032 person-years of follow-up) were obtained from the West Australian Data Linkage System.
In the cohort, 186 (15 percent) had an ischaemic cerebrovascular disease event. Mean CCA-IMT was 0.778 mm and plaque severity was moderate to high in 120 women.
A significant association was observed between higher vegetable nitrate intake and lower maximum CCA-IMT (p=0.002) and lower mean CCA-IMT (p=0.006), with the association remaining significant following adjustment for lifestyle and cardiovascular risk factors (p≤0.01).
Every 29-mg higher vegetable nitrate intake was associated with a 0.012-mm lower mean CCA-IMT and 17-percent lower risk of 14.5-year ischaemic cerebrovascular disease events.
Vegetable nitrate intake was not associated with plaque severity.
The lowering effect of vegetable nitrate intake on CCA-IMT and risk of an ischaemic cerebrovascular event may be attributed to the augmentation of NO status. Researchers explained that nitrate has the potential to be converted into NO and to form a large and abundant storage pool for this molecule in blood and tissues via the endogenous nitrate–nitrite–NO pathway.
Findings of the present data are in line with recent studies demonstrating the beneficial effects of dietary nitrate on blood pressure, endothelial function, platelet aggregation, ischaemia reperfusion injury and exercise performance, suggesting that nitrate intake contributes to cardiovascular health. [Nat Chem Biol 2009;5:865–869; Nutr Rev 2015;73:216–235; Cardiovasc Res 2011;89:525–532]