Nitric oxide (NO) is an important cell signaling molecule generated by virtually every cell in the body. One of its most important functions is vasodilation, or the relaxation and widening of the inner muscles of your blood vessels. This dilation allows for increased blood flow, decreased blood pressure, and better nutrient and oxygen delivery to your muscles during training. This, in turn, promotes greater performance and enhances another highly sought-after aspect of training: the pump!
Alongside caffeine, ingredients that promote an increase in nitric oxide are typically the most desired components in a pre-workout supplement. There’s no shortage of available options on the market, including the old-school arginine, several arginine forms, and the very common citrulline or citrulline malate, which is a combination of citrulline and malic acid.
The majority of these nitric oxide-boosting ingredients tend to address only one of the body’s nitric oxide pathways: the arginine-nitric oxide pathway.  While there's no doubt that this pathway is an effective route for boosting nitric oxide production in the body, most supplements neglect the other pathway for boosting nitric oxide levels, the nitrate-nitrite pathway, and may be even more powerful than the citrulline-arginine path!
As the name implies, citrulline nitrate is a compound containing a molecule of citrulline bonded to a molecule of nitrate. Those of you familiar with pre-workouts know pure l-citrulline, or have at least seen it on many an ingredient label. It’s a nonessential amino found in watermelons that has been shown to be superior to arginine for increasing nitric oxide production in the body. It’s also backed by several studies noting improvements in athletic performance.
However, you might not be familiar with the nitrate component of citrulline nitrate. Nitrates (NO3−) are naturally occurring polyatomic ions present in several foods common to the human diet, including:
When ingested, either from food or supplements (e.g., citrulline nitrate or creatine nitrate), the nitrate molecule is converted to nitric oxide via the nitrate → nitrite → nitric oxide pathway.  Similar to citrulline, nitrates have been noted to help reduce blood pressure, support cardiovascular function, and serve as a potential ergogenic aid for athletes as they can decrease oxygen consumption for a given workload. [3,4]
This reduction in the oxygen “cost” of exercise may lead to greater energy efficiency during training, which increases the total time spent training before the onset of fatigue.  From an athletic performance standpoint, the end result is better performance with greater muscle efficiency and less fatigue. 
Additionally, nitrates may also help to relax blood vessels, making them more flexible and subsequently reducing the burden on the heart to pump blood to the body’s appendages. In other words, citrulline nitrate offers a double dose of benefits in your pre-workout.
C4® Extreme contains a full gram of NitraMax (NO3-C)™ Citrulline Nitrate in its fully disclosed formula. NitraMax (NO3-C)™ and Citrulline Nitrate (NO3-T®) are the only patented, legally licensed forms of citrulline nitrate on the market. C4® Extreme is also flavored and colored with ingredients from natural sources; contains zero calories, carbs, or sugar; and is also available in two naturally sweetened "Natural Zero" flavors.
For pre-workout users who want a more explosive kick and the added benefits of testosterone support, C4® Ultimate Power contains one gram of Citrulline Nitrate (NO3-T®). For added nitric oxide support, C4® Ultimate Power also includes 6 grams of citrulline malate along with a comprehensive matrix of proven ergogenics, energy boosters, focus enhancers, and the well-known P6® Testosterone Technology Blend.
- Moncada, S., Higgs, E. A., Hodson, H. F., Knowles, R. G., Lopez-Jaramillo, P., McCall, T., Schulz, R. (1991). The l-Arginine: Nitric Oxide Pathway. Journal of Cardiovascular Pharmacology, 17.
- Lundberg JO , et al. "The Nitrate-nitrite-nitric Oxide Pathway in Physiology and Therapeutics. - PubMed - NCBI." National Center for Biotechnology Information, www.ncbi.nlm.nih.gov/pubmed/18167491.
- Alsop P, Hauton D. Oral nitrate and citrulline decrease blood pressure and increase vascular conductance in young adults: a potential therapy for heart failure. Eur J Appl Physiol. 2016;116(9):1651–1661. doi:10.1007/s00421-016-3418-7
- Bailey SJ, Winyard P, Vanhatalo A, Blackwell JR, Dimenna FJ, Wilkerson DP, Tarr J, Benjamin N, Jones AM. Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol. 2009;107:1144–1155. doi: 10.1152/japplphysiol.00722.2009
- Lansley KE , et al. "Dietary Nitrate Supplementation Reduces the O2 Cost of Walking and Running: a Placebo-controlled Study. - PubMed - NCBI." National Center for Biotechnology Information, www.ncbi.nlm.nih.gov/pubmed/21071588#.
- Fulford J, Winyard PG, Vanhatalo A, Bailey SJ, Blackwell JR, Jones AM. Influence of dietary nitrate supplementation on human skeletal muscle metabolism and force production during maximum voluntary contractions. Pflugers Archiv. 2013;465:517–528. doi: 10.1007/s00424-013-1220-5.
For more on citrulline nitrate, check out this extensively detailed write-up of the innovative double-action nitric oxide amplifier from our friends at PricePlow.