Nitrate Nitrite health benefit and side effects, review
Feb 15 2016

Ingestion of vegetables rich in inorganic nitrate has emerged as an effective method, via the formation of a nitrite intermediate, for acutely elevating vascular nitric oxide levels. As such a number of beneficial effects of dietary nitrate ingestion have been demonstrated including the suggestion that platelet reactivity is reduced. Dietary nitrate (250ml beetroot juice) elevates circulating nitrate and nitrite levels in both sexes and attenuates ex vivo platelet aggregation responses to ADP and, albeit to a lesser extent, collagen but not epinephrine in male but not female volunteers. These inhibitory effects are associated with a reduced platelet P-selectin expression and elevated platelet cGMP levels. In addition, we show that nitrite reduction to NO occurs at the level of the erythrocyte and not the platelet.

The presence of nitrates and nitrites in food is associated with an increased risk of gastrointestinal cancer. Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced in the body through the oxidation of nitric oxide and through a reduction of nitrate by bacteria in the mouth and gastrointestinal tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure–lowering effects of the Dietary Approaches to Stop Hypertension (DASH) diet. See also nitrosamine information.

Cochrane Database Syst Rev. 2013 Aug 6. Nitrates for acute heart failure syndromes. Current drug therapy for acute heart failure syndromes (AHFS) consists mainly of diuretics supplemented by vasodilators or inotropes. Nitrates have been used as vasodilators in AHFS for many years and have been shown to improve some aspects of AHFS in some small studies. The aim of this review was to determine the clinical efficacy and safety of nitrate vasodilators in AHFS. To quantify the effect of different nitrate preparations (isosorbide dinitrate and nitroglycerin) and the effect of route of administration of nitrates on clinical outcome, and to evaluate the safety and tolerability of nitrates in the management of AHFS.SEARCH  There appears to be no significant difference between nitrate vasodilator therapy and alternative interventions in the treatment of AHFS, with regard to symptom relief and haemodynamic variables. Nitrates may be associated with a lower incidence of adverse effects after three hours compared with placebo. However, there is a lack of data to draw any firm conclusions concerning the use of nitrates in AHFS because current evidence is based on few low-quality studies.

Circ Heart Fail. 2015. Acute Dietary Nitrate Intake Improves Muscle Contractile Function in Patients With Heart Failure: A Double-Blind, Placebo-Controlled, Randomized Trial. Skeletal muscle strength, velocity, and power are markedly reduced in patients with heart failure, which contributes to their impaired exercise capacity and lower quality of life. This muscle dysfunction may be partially because of decreased nitric oxide (NO) bioavailability. We therefore sought to determine whether ingestion of inorganic nitrate (NO3 (-)) would increase NO production and improve muscle function in patients with heart failure because of systolic dysfunction. Using a double-blind, placebo-controlled, randomized crossover design, we determined the effects of dietary NO3 (-) in 9 patients with heart failure. After fasting overnight, subjects drank beetroot juice containing or devoid of 11.2 mmol of NO3 (-). Two hours later, muscle function was assessed using isokinetic dynamometry. Dietary NO3 (-) increased breath NO by 35% to 50%. This was accompanied by 9% and 11% increases in peak knee extensor power at the 2 highest movement velocities tested (ie, 4.71 and 6.28 rad/s). Maximal power (calculated by fitting peak power data with a parabola) was therefore greater after dietary NO3 (-) intake. Calculated maximal velocity of knee extension was also higher after NO3 (-) ingestion. Blood pressure was unchanged, and no adverse clinical events occurred. In this pilot study, acute dietary NO3 (-) intake was well tolerated and enhanced NO bioavailability and muscle power in patients with systolic heart failure. Larger-scale studies should be conducted to determine whether the latter translates into an improved quality of life in this population.

Risk for infants
High intake of these substances in infants may cause methemoglobinemia.