L-citrulline belongs the group of nonessential amino acids -- the building blocks of protein. Your body produces it through the urea cycle, a process in which carbon dioxide and ammonia are added to ornithine to create L-citrulline, which is then converted into L-arginine. Uses for L-citrulline supplements include treatment for urea cycle disorders, rare conditions that occur primarily in children. Additional uses currently being studied include the treatment of heart failure, arterial stiffness and erectile dysfunction.
Urea Cycle Disorders
Urea cycle abnormalities are genetic problems that interfere with the body’s ability to eliminate waste through urine, according to the National Institutes of Health. Individuals with an inherited urea cycle disorder typically lack a gene needed to create enzymes required to break down ammonia. L-citrulline is used in medications designed to treat these disorders, according to the U.S. Food and Drug Administration. Other management options for impairment of the urea cycle include dialysis and a protein-restricted diet.
L-citrulline may benefit heart failure patients, according to a study in the 2010 issue of the "Cardiology Journal." Participants with heart failure took 3 grams of L-citrulline each day and upon a two-month follow-up showed improved right ventricular function, according to the study. Researchers concluded citrulline improved heart function perhaps by reducing pulmonary artery pressure and increasing right ventricular ejection fraction, which refers to how much blood is being pumped out of the right side of the heart.
L-citrulline may help keep arteries healthy, according to a study published in the March 2012 issue of the "International Journal of Cardiology." Arterial stiffness occurs with age and is a characteristic of heart disease also. The small double-blind trial involved 15 healthy, middle-aged men who took 5.6 grams of L-citrulline daily for seven days. Researchers found short-term L-citrulline supplementation improved arterial stiffness without changing the overall blood pressure.
Researchers in Italy tested the effectiveness of L-citrulline for improving erectile dysfunction, according to a study in the journal "Urology." In this single-blind trial, 25 middle-aged men with mild ED took 1.5 grams of L-citrulline for a month. After supplementation their erectile dysfunction scores went from mild dysfunction to normal erectile function. Researchers deemed citrulline a safe alternative to traditional ED medication, although they concluded L-citrulline is less effective. Their study results were published in 2011.