Nitrate is most often used for
Nitrate (NO3-) is a small molecule produced in the body to limited amounts (as a byproduct of nitric oxide) and is obtainable via consumption of vegetables, particularly beetroot and other low-calorie tuber vegetables such as turnips and leafy green vegetables such as spinach or rocket (arugula). It appears to be a potent regulator of blood flow and vasodilatation via its metabolite nitric oxide, and has greater relative affinity for areas of the body with poor oxygenation as the conversion of nitrite (NO2-, a metabolite of nitrate) to nitric oxide is undergone by deoxygenated blood.
In regards to cardiovascular health, it appears to reduce blood pressure in instances where blood pressure is raised. This appears to occur in people with hypertension and can occur in otherwise healthy persons undergoing exercise with little effect on resting blood pressure in healthy persons. It may exert endothelial protective effects, and is thought to be a link between vegetable intake and cardiovascular health.
It appears to enhance exercise performance secondary to reducing the oxygen cost of exercise (and thus prolonging time to exhaustion, thought to be due to increased mitochondrial efficiency). There is little to no effect on acute power output, but seems to reduce the rate of fatigue seen with continued muscle contractions and as such seems to have most benefit in exercises ranging from 1 minutes up to 10 minutes and as such exerts most benefit during anaerobic cardiovascular exercise or muscular endurance events (sports requiring anaerobic intervals such as hockey or rugby, some benefit to rowing and crossfit-type exercises) but although it does have benefit to prolonged cardiovascular exercise (5km jogs or 10km cycling events) the magnitude of effect appears to be lesser.
Due to interactions with nitric oxide, it appears to also be kidney protective and may help to regulate blood flow during the aging process (which is associated with reduced nitrate levels in circulation); the anti-aging effects, however, are preliminary at this moment in time. Due to endogenous production of nitrate and some disease states with lower circulating nitrate (cardiovascular diseases and aging) nitrate may have pseudovitamin-like properties but more evidence is required to support this claim.
Nitrate has the potential to form carcinogenic nitrosamines, although the practical significance of this in living systems is not known (epidemiological survey research has failed to show a significant link after controlling for other confounds, but some nitrosamines themselves are proven carcinogenic; practical relevance of nitrates and subsequently forming nitrosamines following supplemental or vegetable intake in a mixed diet is not really known). Although the carcinogenic potential cannot be ruled out at this time, it cannot be supported reliably either.
The optimal dosage of nitrate supplementation tends to be 0.1-0.2mmol/kg (or 6.4-12.8mg/kg), which is the range of:
- 440-870mg for a 150lb person
- 580-1,160mg for a 200lb person
- 730-1,450mg for a 250lb person
Supplementation of nitrates via beetroot is equally feasible, and beetroot itself is dosed according to its nitrate content.
A randomized controlled trial noted that a single 2g dose of commercially available amaranth (red spinach) extract can increase nitrate levels for up to 8 hours.
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Although the food products that contain nitrates differ widely, the nitrates present in processed meats and vegetables are chemically identical.
From an epidemiological perspective, nitrates are commonly thought to be adverse to health due to a long-standing restriction on how much nitrate can be in drinking water (50mg/L) or ground water (due to accumulating in vegetables) due to the risk of infantile methemoglobinemia (baby blue syndrome)[reference|url=http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1525621/|title=Survey of Literature Relating to Infant Methemoglobinemia Due to Nitrate-Contaminated Water][reference|url=http://jama.jamanetwork.com/article.aspx?articleid=366259|title=Cyanosis in Infants Caused by Nitrates in Well Water] which does appear to apply to vegetables.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/10615207|title=Dietary nitrate in man: friend or foe|published=1999 May|authors=McKnight GM, Duncan CW, Leifert C, Golden MH|journal=Br J Nutr][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/21075182|title=Vegetable-borne nitrate and nitrite and the risk of methaemoglobinaemia|published=2011 Jan 15|authors=Chan TY|journal=Toxicol Lett] More commonly, the association between processed meat products that are pink in color (which very commonly use sodium nitrate as a preservative) and cancer occurrence also paints nitrates in the same negative light.[reference|url=http://www.biomedcentral.com/1741-7015/11/63|title=Meat consumption and mortality - results from the European Prospective Investigation into Cancer and Nutrition] Conversely, vegetables are commonly stated to not be associated with cancer risk (which then raises concern about whether or not they are the same molecules).
Both consumption of vegetables (most commonly researched is beetroot[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/23640589|title=Beetroot juice and exercise: pharmacodynamic and dose-response relationships|published=2013 May 2|authors=Wylie LJ, Kelly J, Bailey SJ, Blackwell JR, Skiba PF, Winyard PG, Jeukendrup AE, Vanhatalo A, Jones AM|journal=J Appl Physiol]) and consumption of the sodium nitrate preservative cause increases in serum nitrate and nitrite, and are considered bioequivalent. In some studies that assess nitrate's bioactivity, liquid solutions of sodium nitrate are even used.[reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19913611|title=Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise|published=2010 Jan 15|authors=Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B|journal=Free Radic Biol Med][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/21276184|title=Nitrite supplementation reverses vascular endothelial dysfunction and large elastic artery stiffness with aging|published=2011 Jun|authors=Sindler AL, Fleenor BS, Calvert JW, Marshall KD, Zigler ML, Lefer DJ, Seals DR|journal=Aging Cell][reference|url=http://www.ncbi.nlm.nih.gov/pubmed/19913611|title=Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise|published=2010 Jan 15|authors=Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B|journal=Free Radic Biol Med]
There are still differences between eating processed meat and vegetables in this regard (intake of sodium through the preservative sodium nitrate and higher intake of potassium via vegetables; less conversion of nitrate into nitrosamines with coingested antioxidants) but the molecule itself is the same.