Nitrates (NO3-) are chemicals which occur in beetroots, carrots, pomegranate, celery, lettuce and spinach. (Nitrates are also higher in foods grown in a greenhouse or hydroponically.) Recent studies of nitrates and their benefits to the human body and athletic performance show great improvements in health and disease.
Once nitrates enter the body, they are converted to bioactive nitrites (NO2-). Nitrites include preservatives found in luncheon meats, bacon, bologna, and hot dogs. Nitrites also play an important role in control of blood flow and blood pressure through conversion to nitric oxide (NO). NO causes the smooth muscles lining the walls of blood vessels to relax, thereby increasing blood flow to the area.
The conversion of nitrates to nitrites is greatly facilitated by probiotic bacteria on the back of the tongue. (Nitrates are greatly concentrated in the saliva.) The conversion uses nitrate as an electron acceptor and changes it to nitrite. NO is produced from nitrites in the stomach under low oxygen and high acid conditions.
Nitrates may be taken either as beetroot juice or as a nitrate supplement. The usual dose of beetroot juice is 2 cups; the dose of nitrates by supplementation is 10 mg/kg/day. Nitrates can be supplemented by the use of the amino acid l-arginine, which naturally produces NO in the body with the aid of enzymes.
Nitrate supplementation reduces systolic blood pressure. Some studies show that nitrates result in an improved tolerance to exercise. Others show improved muscle efficiency. To get maximum efficiency from nitrate supplementation, chlorhexadrine-based mouthwashes should be avoided. They kill the beneficial bacteria which convert nitrates to nitrites on the back of the tongue. The same may be true for alcohol-based mouth washes and chlorinated swimming pools, but further study is needed.
NO has many functions in the body besides controlling blood pressure and preventing hypertension. It is an important neurotransmitter for regulating the immune system. Nitrates prevent the clumping of platelets. An acidic and oxygen-deprived environment enhances the conversion of nitrites to NO, so dilation of the arteries occurs where it is needed most. The amount of NO that is needed for these functions can be obtained from a diet rich in vegetables.
Nitrates offer benefits to a majority of athletes, but not so much with ultra-intense athletes at the competitive level. In one study, athletes who used a nitrate-enhanced beetroot juice increased their running to exhaustion times by 15%. Even baked beetroot improved athletic performance, and studies show a reduced intake of oxygen at all levels of exercise–from walking to cycling in all age groups.
CONCLUSION: Nitrates may be the most important components of a vegetable-rich diet, supplying NO to prevent hypertension and cardiovascular diseases. Nitrate supplementation is a low-cost effective treatment of hypertension. The average dose is about 2 cups of beetroot juice around 2.5-3 hours before exercise by athletes.
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