Citrulline is one of a few amino acids that do not help build protein, but it fills other vital roles. It's used to make another amino acid, arginine, which then synthesizes nitric oxide. Nitric oxide relaxes muscles in your blood vessels, which improves blood flow throughout your body, including your brain. Some of citrulline's benefits come from its association with nitric oxide, but it also has a direct impact on your health.
Removes Toxic Ammonia
Nitrogen is released during protein metabolism, resulting in ammonia, which must be neutralized and eliminated because it is a toxic compound in the body. The detoxifying process -- the urea cycle -- doesn’t work properly unless all of the essential components are available. Citrulline is one of those components. The urea cycle can be accelerated by increasing the amount of citrulline, reports the Bioinformatics Research Group. In addition to exerting an influence on its own, citrulline may also contribute by synthesizing arginine because it also has a critical role in the cycle.
Protect Cardiovascular Health
Your cardiovascular system benefits from citrulline through its potential to lower blood pressure and prevent atherosclerosis, or hardening of the arteries. Citrulline's role in nitric oxide production is one way it protects your health because nitric oxide lowers blood pressure and reduces the risk of atherosclerosis. But citrulline could exert a direct effect by helping your body eliminate cholesterol, which causes atherosclerosis, reported a study in the "Journal of Clinical Biochemistry and Nutrition” in July 2014. When people diagnosed with hypertension consumed citrulline-rich watermelon, their blood pressure went down, according to a report in the July 2014 issue of the “American Journal of Hypertension” in July 2014.
Improve Athletic Performance
Citrulline may boost your performance during exercise and athletic activities, but more research is still needed to verify its effectiveness. Researchers at Mississippi State University tested citrulline’s potential by studying advanced resistance-trained men. Half the men received supplemental citrulline malate, while the other half took a placebo, and both groups performed multiple repetitions of lower body resistance exercises. The men taking citrulline malate performed a significantly higher number of repetitions than the placebo group, according to the results published in the “Journal of Strength and Conditioning Research" in September 2014.
Boost Your Citrulline
Your body uses other amino acids to produce all of the citrulline it needs, so the best way to maintain healthy levels of citrulline is to consume enough total protein. Women need 46 grams of protein daily, while men should consume 56 grams, according to the Institute of Medicine. You can take citrulline supplements to boost your intake, otherwise the best food source is watermelon. While fruits aren't known for their protein content, a wedge of watermelon has nearly 2 grams of total protein and is a good source of citrulline, reports the U.S. Department of Agriculture.
- National Cancer Institute: L-Citrulline
- DermnetNZ.org: Nitric Oxide
- National Urea Cycle Disorders Foundation: What Is a Urea Cycle Disorder?
- Bioinformatics Research Group: Nitrogen Excretion and the Urea Cycle
- American Journal of Hypertension: Effects of Watermelon Supplementation on Aortic Hemodynamic Responses to the Cold Pressor Test in Obese Hypertensive Adults
- Journal of Clinical Biochemistry and Nutrition: Citrulline Increases Cholesterol Efflux From Macrophages in Vitro and ex Vitro Via ATP-Binding Cassette Transporters
- Journal of Strength and Conditioning Research: Effects of Supplemental Citrulline Malate Ingestion During Repeated Bouts of Lower-Body Exercise in Advanced Weight Lifters
- USDA Agricultural Research Service: Watermelon Serves Up Medically Important Amino Acid
- USDA National Agricultural Library: Citrulline
- Institute of Medicine: Dietary Reference Intakes: Macronutrients
- Photo Credit DragonImages/iStock/Getty Images
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