L-citrulline, often referred to as simply citrulline, is an amino acid first isolated in 1930 in watermelon. Your body produces citrulline, so it isn't considered an essential amino acid that you must get from your diet. However, body builders and athletes may take it as a supplement to enhance aerobic performance. Before adding citrulline to your diet, consult with your physician because it can be detrimental if you have specific health conditions. If you choose to take the supplement to boost your workout performance, the best time to take the supplement is around the time of exercise.
Citrulline plays a role in your body’s metabolic processes and in the urea cycle, the process by which the liver and kidneys rid the body of ammonia and lactic acid buildup. Citrulline isn't essential to many proteins in the body, but is found in the hair, skin and neural cells. You naturally synthesize the amino acid in the intestines and get some in trace amounts in foods such as watermelon. Citrulline is often marketed as a supplement in a salt form of the amino acid called citrulline malate.
Bodybuilders and athletes take citrulline or citrulline malate to enhance blood flow to the tissues and muscles, which may speed up recovery. By assisting the body in more efficiently reducing lactic acid buildup, citrulline can help you last longer during exercise.
A study published in a 2002 issue of the “British Journal of Sports Medicine" found that 18 men who took 6 grams of citrulline malate daily for 15 days experienced changes in metabolism that promoted aerobic energy production during exercise, resulting in less fatigue and greater energy. An older study in a 1998 issue of “Medicine and Science in Sports Medicine” found that citrulline malate can influence lactic acid metabolism. Researchers compared two groups of basketball players’ ability to perform on a cycle ergometer after taking different dosages of citrulline malate for 13 days. Those who took a higher dosage of the amino acid showed significant improvements in their maximal workout on the ergometer in one of two tests, indicating that the amino acid supplement may improve aerobic performance.
Dosages and Timing
Because it's a supplement, no official dosages are recommended. Most products recommend that you take between 1/4 and 1 teaspoon -- or the equivalent of 2,000 to 6,000 milligrams of citrulline -- two times daily. Taking the supplement around the times of your workout -- a dose before and a dose after -- could be effective in maximizing your results. Citrulline is fast-acting. You may see results in just three to five days of use.
Check with your health care provider before taking any supplement. Citrulline can be detrimental to people with kidney disease or abnormalities. You should also consult with your doctor to ensure that citrulline doesn't interact negatively with other medications or supplements you might be taking.