L-citrulline is a naturally occurring amino acid. It is found in some foods like watermelons and is also produced naturally by the body.L-citrulline is used by mouth for heart failure and improving athletic performance. It is also used for sickle cell disease, erectile dysfunction, high blood pressure in the lungs, and many other conditions. But there is limited scientific research to support these other uses.

How does it work?

L-citrulline is a naturally occurring amino acid found in food, such as watermelon. It is also made naturally in the body. The body changes L-citrulline into another amino acid called L-arginine and also to a chemical called nitric oxide. L-citrulline might help increase the supply of ingredients the body needs to make certain proteins. It might also help open up veins and arteries to improve blood flow and reduce blood pressure.

Possibly Effective for L-citrulline

Exercise performance.

Taking L-citrulline by mouth might be effective for improving some types of exercise performance. L-citrulline may help some athletes work harder, lift weights longer, and go faster on an exercise bike. But L-citrulline does not seem to help people run longer on an aerobic treadmill test.

Heart failure.

L-citrulline can help people with heart failure who are already treated with standard medications. Taking L-citrulline by mouth seems to reduce blood pressure in the lungs in these patients. This helps the heart work better, allowing people with heart failure to walk farther.