Watermelons are not only delicious – they also contain a lot of L-citrulline, which is said to have a performance-enhancing effect in sports. FITBOOK has all the facts about the alleged power substance – how it works, how to dose it correctly and what side effects can occur.
Sports enthusiasts have known for a long time: if you want to build or maintain muscles, you should consume protein. Because it boosts protein synthesis, the continuous build-up of proteins in the body. It also supports muscle regeneration after exercise. Protein bombs are, for example, low-fat quark, Parmesan cheese as well as chicken and lean beef. Other foods are not exactly known as sources of protein. So does watermelon. Nevertheless, they play an important role in the development of healthy and strong muscles. The reason: watermelons are rich in L-citrulline.
What is L-Citrulline?
L-citrulline is one of eleven non-essential amino acids, “NEAA” for short (“non-essential amino acids”). Other NEAAs are, for example, alanine, cysteine and proline. The term «non-essential» does not mean that these amino acids do not perform an important function in the body. On the contrary: NEAAs play an important role in digestion, the absorption of nutrients and antioxidant reactions, among other things.
Until a few years ago, the prevailing opinion was that the body can produce NEAAs itself and that additional intake from food is not necessary – in contrast to essential amino acids. Studies now indicate that this is only partially the case. Non-essential amino acids such as L-citrulline should also be ingested through food.1 In extreme cases and if you take in too little protein for a long time, a protein deficiency can occur – and this can have serious consequences.
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How does L-citrulline work?
L-citrulline affects the body in two important ways. First, it has an antioxidant effect. In other words, it protects it from free radicals that can damage cells.
Secondly, L-citrulline ensures that the body produces nitrogen monoxide (NO) as part of the so-called «NO synthesis». NO is a molecule from the group of nitrogen oxides that combines nitrogen and oxygen. During NO synthesis, L-citrulline is converted in the kidneys to arginine, a semi-essential and proteinogenic amino acid. During this process, NO is formed as a by-product.
NO…
- regulates blood flow by dilating blood vessels,2
- increases anaerobic performance of muscles during training and
- reduces muscle soreness after exercise.3
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In addition, studies indicate that L-citrulline reduces the risk of muscle damage after exercise. In general, the amino acid plays an important role in the immune system because it increases the body’s defenses against microorganism attacks – similar to L-carnitine.4
It is not for nothing that L-citrulline is now often used as a supplement in sports. Because a stimulated blood flow
- accelerates the removal of harmful substances from the body and
- it ensures that nutrients can be transported to the cells more quickly.
Both affect performance in sport. If metabolic products such as lactate, which causes sore muscles after exercise, are quickly removed due to the increased blood flow to the muscles, this reduces the risk of sore muscles because the muscles can regenerate particularly quickly. If cells are supplied with all the important nutrients, the muscles can work efficiently. You can feel that the anaerobic performance of the muscles is increased, for example, when lifting weights or strength training if you can repeat exercises more often.
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What are the side effects of L-citrulline?
L-citrulline stimulates the production of nitric oxide. This in turn widens the blood vessels, which can have a blood pressure-lowering effect. Low blood pressure can manifest itself in dizziness, tiredness and freezing. However, studies found no connection between low blood pressure and health-damaging effects – quite the contrary. Instead, they point to a possible connection between low blood pressure and a long life expectancy.5 There are no other known side effects of L-citrulline supplementation.
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L-Citrulline Dosage – How Much Before Training?
So far, there are no clear research results on the dosage of L-citrulline. However, according to current studies, there is no need to fear an “overdose” if L-citrulline is taken in its natural form, for example by eating melons or drinking melon juice, since consumption has not yet had any known side effects.
According to studies, however, the L-citrulline content of melons varies greatly and can be between 1.09 and 4.52 mg/g.6 How much of the performance-enhancing amino acid a melon contains depends on the growing area and the soil conditions. In addition to environmental factors, the type of melon also influences the L-citrulline content. It should be significantly higher in watermelons than in sugar or honeydew melons.
Most of the L-citrulline is in the fruit peel or the light part of the melon pulp. So: Don’t just nibble on the juicy red meat, but also bite into the white rind!
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If you don’t like melons, you’re in luck: the amino acid is also found in various other foods – these include:
- Chickpeas
- pumpkin
- Fish and meat, especially salmon and beef
Sources
- 1. Hou Y, Yin Y, Wu G (2015). Dietary essentiality of “nutritionally non-essential amino acids” for animals and humans. Experimental Biology and Medicine.
- 2. Moncada, S. (1994). Nitric oxides. J Hypertens Suppl.
- 3. Tarazona-Díaz MP, Alacid F, Carrasco M, Martínez I, Aguayo E (2013). Watermelon juice: potential functional drink for sore muscle relief in athletes. J Agric Food Chem.
- 4. Bruckdorfer, R. (2005). The basics about nitric oxide. Molecular Aspects of Medicine.
- 5. Wessely, S., Nickson, J., Cox, B. (1990). Symptoms of low blood pressure: a population study. BMJ
- 6. Davis, AR, Webber, CL, III, Fish, WW, Wehner, TC, King, S, Perkins-Veazie, P (2011). L-Citrulline Levels in Watermelon Cultigens Tested in Two Environments, HortScience horts.