Both arginine and citrulline are nonessential amino acids, which means your body is able manufacture them on its own and you don't need to get them from the food you eat. However, recent research seems to indicate that both amino acids may promote heart health and help improve tolerance to exercise when taken as a supplement. Knowing the food sources of these amino acids may help you up your intake.
Benefits of Arginine and Citrulline
Both arginine and citrulline play important roles in your body's production and metabolism of nitric oxide, a chemical that helps keep your blood vessels healthy by regulating blood flow and the function of platelets. Supplementation with arginine and citrulline may help improve heart health by offering protection against the buildup of plaque along artery walls, according to a study published in 2014 in Biochemical and Biophysical Research Communications. It may also help those new to working out stick with it by improving tolerance to exercise.
Animal proteins are a source of both arginine and citrulline. However, citrulline is found in very small amounts in these types of foods, according to Martin Kohlmeier, author of "Nutrient Metabolism: Structures, Functions, and Genes." Animal protein sources of the amino acids include dairy foods such as milk and yogurt, poultry, beef, pork, and seafood.
Grains, vegetables, legumes, nuts and seeds are also sources of protein and sources of both citrulline and arginine. However, like animal proteins, these foods are a better source of arginine than citrulline. But due to the role of arginine plays in the body, there seems to be more of a risk of deficiency in the amino acid than in citrulline, especially during times of stress.
If you're trying to get more citrulline in your diet, you may need to eat more watermelon. The amino acid is found in large amounts in both the rind and flesh. While your body needs to make enough arginine for good health, there are no known adverse effects from low citrulline levels, according to Kohlmeier, nor are there daily requirements for it.