Which is better: citrulline or arginine?

“Faster. Above. Louder.” A simple and understandable motto of the Olympic Games.

But if you delve into the subject of sports, a beginner can easily choke on specific terms, amino acids, types of nutritional supplements, powders and bars.

If you are not afraid of difficulties and you decide to work hard or you are already swinging in the gym, you have probably heard of nitrogen donors. This essential component of sports nutrition will help your muscle growth take off.

The most popular “sponsors” of nitric oxide are citrulline and arginine.

Benefits of Using Citrulline

In 1930, citrulline was derived from the pulp and rind of watermelon, which continues to grow in popularity every day.

Citrulline is an amino acid that is not part of human DNA and is absent from building proteins, but has a variety of physiological effects. It is important that citrulline is able to prevent the breakdown of the digestive system.

Muscles produce ammonia during exercise. Ammonia buildup is known to negatively affect stamina and concentration. A person feels tired and cannot muster his strength to perform a heavy approach.

Citrulline speeds up the use of ammonia, which helps end the ornithine cycle.

The ornithine cycle is a set of reactions whose purpose is to transform toxic ammonia into urea and eliminate it through the excretory system.

About an hour after taking citrulline, the body begins the process of producing arginine, which naturally increases nitric oxide production. In turn, the muscles begin to fill with blood faster, the metabolic process accelerates, which leads to their growth.

In other words, citrulline is able to:

  • ward off fatigue during intense workouts;
  • reduce muscle pain;
  • increase muscle protein synthesis (proven by a study in 2010);
  • improve athletic performance.

Good old arginine

Later, in 1998, scientists (for which they received the Nobel Prize) discovered the beneficial biological properties of arginine. Since then, it has been actively used in the field of sports.

Arginine is an amino acid that plays a key role in nitrogen metabolism in the body. The human body can obtain arginine independently, for example, from ornithine or citrulline.

This amino acid is also found in various types of meats, seafood, seeds, and nuts.

During training, the athlete’s body experiences stress, which negatively affects the vessels. Arginine strengthens the walls of blood vessels and stabilizes blood pressure.

Supplements use a high concentration of arginine due to the fact that most of it is broken down in the stomach.

The effectiveness of arginine supplements has not been proven and remains controversial. There are a number of official studies that refute the convenience of taking arginine to increase nitric oxide in the blood and improve pumping.

  1. In the 2007 conclusion, it is said that the use of arginine did not alter the level of nitric oxide in any way and did not dilate the blood vessels, but only increased the concentration of this amino acid in the blood.
  2. In 2008, the following experiment was performed. The participants were divided into two groups. The first group took a placebo, the second – 6 grams of arginine per day, after which they all intensively participated in stationary bicycles. The tests lasted three days. Blood samples were taken before, during and after exercise.


Between the first and second group, no difference was found in blood nitric oxide concentration and ammonia content. The sports performance of the subjects was also approximately the same.

Negative results would appear to indicate low arginine utilization. But don’t rush. First, supplementation aims to increase blood arginine levels, and it does. Second, the increased production of nitric oxide is a very complex biochemical process, influenced by many factors, not just the amount of arginine in the blood. The body is organized very wisely: it does not allow you to so easily change the balance of the most important processes. Very often, the content of any useful substance becomes relevant at some point, for example, when overcoming heavy loads, after which everything quickly returns to normal. Therefore, if some indicators are measured (nitric oxide level, ammonia content, etc.), then they may simply not reflect the changes that have occurred in the body. To say with certainty that an increase in arginine content produced no beneficial effect would require large-scale studies with the most complex biochemical analyzes for dozens of indicators of dynamics. And it hasn’t been done yet. Therefore, negative results can simply be dismissed as insufficiently substantiated.Before drawing any definitive conclusions, let’s wait for a more thorough and methodical investigation. Meanwhile, the experience of many athletes speaks to the important role of arginine (and citrulline) in achieving athletic performance.

Citrulline and arginine have a complex of positive properties. In particular, arginine improves the absorption of creatine, which is why it is often used as a transport system for this supplement. The subjective experience of a significant number of athletes also indicates the positive effect of arginine and citrulline on pumping and muscle growth. However, there is still not enough research to say which of these amino acids is the best. Although athletes with recent experience increasingly prefer citrulline, due to its better bioavailability.

Leave a Comment

Your email address will not be published.