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Blekkenhorst LC, Lewis JR, Prince RL, Devine A, Bondonno NP, Bondonno CP, Wood LG, Puddey IB, Ward NC, Croft KD, Woodman RJ, Beilin LJ, Hodgson JM. Nitrate-rich vegetables do not lower blood pressure in individuals with mildly elevated blood pressure: a 4-wk randomized controlled crossover trial. Am J Clin Nutr 2018; 107:894-908. [PMID: 29868911 DOI: 10.1093/ajcn/nqy061] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 03/12/2018] [Indexed: 11/12/2022] Open
Abstract
Background Emerging evidence suggests that increasing intakes of nitrate-rich vegetables may be an effective approach to reduce blood pressure. Objective Our primary aim was to determine whether daily consumption of nitrate-rich vegetables over 4 wk would result in lower blood pressure. Design Thirty participants with prehypertension or untreated grade 1 hypertension were recruited to a randomized controlled crossover trial with 4-wk treatment periods separated by 4-wk washout periods. Participants completed 3 treatments in random order: 1) increased intake (∼200 g/d) of nitrate-rich vegetables [high-nitrate (HN); ∼150 mg nitrate/d], 2) increased intake (∼200 g/d) of nitrate-poor vegetables [low-nitrate (LN); ∼22 mg nitrate/d], and 3) no increase in vegetables (control; ∼6 mg nitrate/d). Compliance was assessed with the use of food diaries and by measuring plasma nitrate and carotenoids. Nitrate metabolism was assessed with the use of plasma, salivary, and urinary nitrate and nitrite concentrations. The primary outcome was blood pressure assessed by using 24-h ambulatory, home, and clinic measurements. Secondary outcomes included measures of arterial stiffness. Results Plasma nitrate and nitrite concentrations increased with the HN treatment in comparison to the LN and control treatments (P < 0.001). Plasma carotenoids increased with the HN and LN treatments compared with the control (P < 0.01). HN treatment did not reduce systolic blood pressure [24-h ambulatory-HN: 127.4 ± 1.1 mm Hg; LN: 128.6 ± 1.1 mm Hg; control: 126.2 ± 1.1 mm Hg (P = 0.20); home-HN: 127.4 ± 0.7 mm Hg; LN: 128.7 ± 0.7 mm Hg; control: 128.3 ± 0.7 mm Hg (P = 0.36); clinic-HN: 128.4 ± 1.3 mm Hg; LN: 130.3 ± 1.3 mm Hg; control: 129.8 ± 1.3 mm Hg (P = 0.49)] or diastolic blood pressure compared with LN and control treatments (P > 0.05) after adjustment for pretreatment values, treatment period, and treatment order. Similarly, no differences were observed between treatments for arterial stiffness measures (P > 0.05). Conclusion Increased intake of nitrate-rich vegetables did not lower blood pressure in prehypertensive or untreated grade 1 hypertensive individuals when compared with increased intake of nitrate-poor vegetables and no increase in vegetables. This trial was registered at www.anzctr.org.au as ACTRN12615000194561.
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Affiliation(s)
- Lauren C Blekkenhorst
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Joshua R Lewis
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
- Center for Kidney Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia
- School of Public Health, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Richard L Prince
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
- Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
| | - Amanda Devine
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Nicola P Bondonno
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
| | - Catherine P Bondonno
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Lisa G Wood
- School of Biomedical Science and Pharmacy, University of Newcastle, New Lambton Heights, New South Wales, Australia
| | - Ian B Puddey
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
| | - Natalie C Ward
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
- School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Bentley, Western Australia, Australia
| | - Kevin D Croft
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
| | - Richard J Woodman
- Flinders Center for Epidemiology and Biostatistics, Flinders University, Adelaide, South Australia, Australia
| | - Lawrence J Beilin
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
| | - Jonathan M Hodgson
- Medical School, Royal Perth Hospital Unit, University Western Australia, Perth, Western Australia, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
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Blekkenhorst LC, Bondonno NP, Liu AH, Ward NC, Prince RL, Lewis JR, Devine A, Croft KD, Hodgson JM, Bondonno CP. Nitrate, the oral microbiome, and cardiovascular health: a systematic literature review of human and animal studies. Am J Clin Nutr 2018; 107:504-522. [PMID: 29635489 DOI: 10.1093/ajcn/nqx046] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/21/2017] [Indexed: 12/25/2022] Open
Abstract
Background Dietary nitrate is an important source of nitric oxide (NO), a molecule critical for cardiovascular health. Nitrate is sequentially reduced to NO through an enterosalivary nitrate-nitrite-NO pathway that involves the oral microbiome. This pathway is considered an important adjunct pathway to the classical l-arginine-NO synthase pathway. Objective The objective of this study was to systematically assess the evidence for dietary nitrate intake and improved cardiovascular health from both human and animal studies. Design A systematic literature search was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines by using key search terms in Medline and EMBASE databases and defined inclusion and exclusion criteria. Results Thirty-seven articles on humans and 14 articles on animals were included from 12,541 screened references. Data on the effects of dietary nitrate on blood pressure, endothelial function, ischemic reperfusion injury, arterial stiffness, platelet function, and cerebral blood flow in both human and animal models were identified. Beneficial effects of nitrate on vascular health have predominantly been observed in healthy human populations, whereas effects in populations at risk of cardiovascular disease are less clear. Few studies have investigated the long-term effects of dietary nitrate on cardiovascular disease clinical endpoints. In animal studies, there is evidence that nitrate improves blood pressure and endothelial function, particularly in animal models with reduced NO bioavailability. Nitrate dose seems to be a critical factor because there is evidence of cross-talk between the 2 pathways of NO production. Conclusions Evidence for a beneficial effect in humans at risk of cardiovascular disease is limited. Furthermore, there is a need to investigate the long-term effects of dietary nitrate on cardiovascular disease clinical endpoints. Further animal studies are required to elucidate the mechanisms behind the observed effects.
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Affiliation(s)
- Lauren C Blekkenhorst
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Nicola P Bondonno
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Alex H Liu
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Natalie C Ward
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Biomedical Sciences and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Richard L Prince
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
| | - Joshua R Lewis
- Medical School, Queen Elizabeth Medical Center Unit, University of Western Australia, Nedlands, Western Australia, Australia
| | - Amanda Devine
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Kevin D Croft
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia
| | - Jonathan M Hodgson
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Catherine P Bondonno
- Medical School, Royal Perth Hospital Unit, University of Western Australia, Perth, Western Australia, Australia.,School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
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Melnikov VN, Divert VE, Komlyagina TG, Consedine NS, Krivoschekov SG. Baseline values of cardiovascular and respiratory parameters predict response to acute hypoxia in young healthy men. Physiol Res 2017; 66:467-479. [PMID: 28248531 DOI: 10.33549/physiolres.933328] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The majority of the available works have studied distinct hypoxic responses of respiratory and cardiovascular systems. This study examines how these systems interact while responding to hypoxia and whether baseline metrics moderate reactions to a hypoxic challenge. Central hemodynamic, aortic wave reflection, and gas exchange parameters were measured in 27 trained young men before and after 10-min normobaric isocapnic hypoxia (10 % O2). Associations were assessed by correlation and multiple regression analyses. Hypoxic changes in the parameters of pulse wave analysis such as augmentation index (-114 %, p=0.007), pulse pressure amplification (+6 %, p=0.020), time to aortic reflection wave (+21 %, p<0.001) report on the increase in arterial distensibility. Specifically, initially compliant arteries blunt the positive cardiac chronotropic response to hypoxia and facilitate the myocardial workload. The degree of blood oxygen desaturation is directly correlated with both baseline values and hypoxic responses of aortic and peripheral blood pressures. The hypoxia-induced gain in ventilation (VE), while controlling for basal VE and heart rate (HR), is inversely associated with deltaHR and deltasystolic blood pressure. The study suggests that cardiovascular and respiratory systems mutually supplement each other when responding to hypoxic challenge.
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Affiliation(s)
- V N Melnikov
- Institute of Physiology and Basic Medicine, Novosibirsk, Russia.
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