Nitrate supplements
Nitrate supplements represent an exciting new category of sports supplements based on recent discoveries regarding the ability of nitrates to act as a precursor to nitric oxide. Such discoveries have helped to explain the improvements in performance that can be observed after consuming large amounts of beetroot - one of the richest natural sources of nitrate.
The nitrate-nitrite connection
Nitrate is converted to nitric oxide via nitrite. This pathway is called the nitrate--nitrite--nitric oxide (or NO3--NO2--NO) pathway to distinguish it from the more familiar L--arginine--nitric oxide synthase--nitric oxide (or L-Arg-NOS-NO) pathway. The key to this pathway is an anaerobic bacterium that occurs naturally in the oral cavity. As it turns out, the body has no mechanism other than the unique enzymes of these oral bacteria to convert nitrate to nitrite.
Nitrates in the diet
These findings are very significant in the context of modulating the body's nitric oxide levels, especially considering that leafy green vegetables such as spinach, lettuce and beet are the main sources of nitrate in the diet. Part of the nitrate (up to 25%) consumed in the form of food is actively absorbed by the salivary glands and concentrated in the saliva, where facultative anaerobic bacteria reduce nitrate to nitrite.
Nitrate supplements
This new discovery of an alternative pathway for nitric oxide production has led to the development of a whole range of new supplements that deliver different forms of nitrate to the body to increase nitric oxide levels. Some manufacturers now offer popular amino acids such as branched-chain amino acids, creatine and arginine in nitrate form, which are said to be more bioactive while providing a source of nitrate. Another approach is to develop supplements that contain concentrated plant sources of nitrate, the most popular of which is beet. However, it should be noted that spinach and leaf lettuce are also good sources of nitrate. The simplest approach to supplying nitrate is to use synthetically produced sodium nitrate or potassium nitrate.
Key to maximizing nitric oxide production from nitrate
Because of the critical role that oral bacteria play in converting nitrate to nitrite, users of nitrate supplements should avoid antibacterial mouthwashes, as these also reduce the amount of beneficial bacteria that perform the important conversion of nitrate to nitrite. Another factor that can affect the nitrate content of vegetables is the nitrate content of the soil in which the vegetables are grown. Last but not least, the time it takes for nitric oxide levels to reach their maximum after eating nitrates is another factor to consider. Most studies show that it takes about 3 hours, which is significantly longer than with ordinary pre-workout supplements.
References
- Lundberg JO & Govoni M. Inorganic nitrate is a possible source for systemic generation of nitric oxide. Free Radical Biology & Medicine. 2004;37(3):395-400.
- Bailey SJ, et al. The nitrate-nitrite-nitric oxide pathway: Its role in human exercise physiology. European Journal of Sport Science. 2012;12(4):309-320.
- Bescos R, et al. Sodium nitrate supplementation does not enhance performance of endurance athletes. Medicine and Science in Sports & Exercise. 2012;44(12):2400-2409.