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Many of us dread the passage of time. While no one has yet to escape aging, the new challenges of growing older can cause distress in even the most rational individuals. This is why it isn't surprising that the supplementation industry is researching every possible remedy for the problems arising from this natural phenomenon.
Citrulline is a rare amino acid in our diet. When consumed in sufficient quantities, however, it may support normal cardiovascular health thanks to its antioxidant properties. This effect can potentially extend to the whole body and could improve sexual performance in both men and women. Are you ready to learn more about it?
Contents
- 1 Weekly newsletter with the best personal finance tips
- 2 Key Facts
- 3 The best Citrulline: Our Picks
- 4 Shopping Guide: Everything You Should Know About Citrulline
- 4.1 What is citrulline exactly?
- 4.2 What is the purpose of citrulline?
- 4.3 What foods are rich in citrulline?
- 4.4 What types of citrulline supplements are there?
- 4.5 What are the benefits of citrulline supplementation?
- 4.6 Are citrulline or arginine supplements better?
- 4.7 Is citrulline supplementation safe?
- 5 Buyer's Guide
- 6 Summary
Key Facts
- Citrulline is an amino acid rarely found in our diet, except for watermelon.
- Its consumption promotes blood flow and could improve sexual performance, increase muscle growth, and serve as a nutritional supplement in individuals with low levels of amino acids.
- There are various factors to evaluate before purchasing a citrulline supplement. These include the presence of potential allergens, the product type, or the compatibility with a vegan diet, among others.
The best Citrulline: Our Picks
We know just how difficult it can be to find the right supplement for your needs, which is why we have selected some of the best citrulline products currently available out there. Each of them stands out for its overall quality and value for money. We have included a description for all of them, so you can make an informed decision and reap all the benefits of citrulline.
Shopping Guide: Everything You Should Know About Citrulline
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What is citrulline exactly?
However, our organism can synthesize it from other amino acids – such as glutamine – without needing to ingest it directly. This characteristic makes citrulline a non-essential amino acid (1).
The intestine absorbs it efficiently, which means that it can cross the body's natural barriers easily to reach the bloodstream. The kidneys then metabolize it, transforming it into arginine. In the liver, citrulline will become part of the urea cycle, a chemical process that allows your body to eliminate toxins and potentially harmful substances.
Discovered in the 1930s, this amino acid is particularly attractive for its role as a pharmaconutrient, being able to be transformed into other compounds that are vital to the body. As a dietary supplement, it may be very beneficial for ill or convalescent people (2).
What is the purpose of citrulline?
Citrulline may be a powerful protector of the endothelium, the tissue that forms the blood vessels. In that regard, it increases the levels of vasodilatory substances, such as nitric oxide, and prevents the immune system from acting indiscriminately on the vessel tissue. This, in turn, contributes to combating premature aging of your arteries and veins.
In addition, studies have shown that citrulline had an anabolic potential by stimulating muscle blood flow and activating a chain of signaling molecules that regulate the growth of muscle fibers. In the table below, you can learn more about the different actions of this amino acid (2, 3):
| System | Function of citrulline | Consequence |
|---|---|---|
| Musculoskeletal | Activation of muscle synthesis.
Increase of the muscular blood flow. |
Muscular growth.
Prevention of catabolism (muscle breakdown). |
| Hepatic | Urea metabolism | Elimination of excess ammonia in the blood |
| Cardiovascular | Arginine synthesis.
Synthesis of nitric oxide (through arginine). |
Vasodilation.
Decrease in arterial stiffness. Reduction of blood pressure. Prevention of myocardial damage. Prevention of endothelial dysfunction. |
| Immune | Decrease in the number of circulating white blood cells | Protection against endothelial damage mediated by white blood cells |
| Metabolism | Muscle vasodilation in response to increased glucose.
Increased cellular activity. Increased lipolysis (destruction of fat cells). |
Decreased insulin resistance.
Increased energy synthesis. Reduction of body weight. |
Please keep in mind that this amino acid is still undergoing many investigations. Most of the findings presented above are the result of testing on animals (mice) or small groups of humans. While its beneficial role in cardiometabolic health has been proven (3), more studies are required to validate the incredible potential of this substance.
What foods are rich in citrulline?
The content in the watermelon will depend on characteristics such as skin color, thickness of the rind, and the presence or absence of seeds, among others. It is estimated that the yellow watermelon is the richest in citrulline (around 36 milligrams per 100 grams) and that the common red watermelon has the lowest content (16 mg per 100 g) (4).
You should know that most of the effects of citrulline observed were obtained after supplementation with doses ranging from 3 to 5 grams (3,000-5,000 mg) (2). While the consumption of watermelon can add small amounts to your diet, reproducing the effects witnessed in clinical trials is challenging.
However, it is possible to extract the citrulline directly from the watermelon's skin. The dehydrated powder is then used to create natural supplements that provide this amino acid in a concentrated and convenient form. That way, you won't need to eat large quantities of watermelon, which could also be costly in the long run.
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What types of citrulline supplements are there?
- Citrulline or L-citrulline: This is the name under which the active form of the amino acid is marketed, without any additional molecules.
- Citrulline malate: The amino acid is combined with malic acid (malate), a compound found in nature and that was first isolated in apple cider. It is very present in the chemical reactions necessary to produce energy (ATP).
In that regard, citrulline malate supplements may provide the benefits of citrulline with an additional energy boost that can come in very handy for athletes and anyone looking to gather their strength during the day (5, 6). If you don't need to raise your energy levels, L-citrulline supplements are more affordable.
In addition, you can purchase supplements that blend citrulline with other L-citrulline function-enhancing molecules. These include the amino acids arginine and ornithine, which are part of the cycles of protein synthesis and waste disposal along with citrulline.
- Citrulline + arginine: The combination of arginine and its precursor, citrulline, will produce a remarkable rise in the levels of the former. As you now know, higher arginine levels enhance the creation of the vasodilator nitric oxide, which may lower blood pressure, increase muscle blood flow, and regulate the immune function (7, 8).
- Citrulline + ornithine: Ornithine is an amino acid linked to the metabolism of both citrulline and arginine. It may improve the response to stress, thus reducing the feeling of fatigue (9). While no reliable studies have been conducted on the actual effectiveness of this blend, it is marketed to the public as a supplement that speeds up muscle recovery.
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What are the benefits of citrulline supplementation?
-
- Cardiovascular health: Citrulline may attenuate the increase in blood pressure that occurs during stressful or physically demanding situations. This would be particularly beneficial for individuals diagnosed with prehypertension (above-normal blood pressure, but too low to need medication).
- Muscle growth: Citrulline generates an increase in muscle blood flow and stimulates muscle protein synthesis, favoring an increase in lean mass.
- Sports performance: Enhanced blood flow leads to a discreet-yet-significant increase in sports performance in older adults. In addition, it promotes post-training recovery. Note that young and healthy people cannot benefit from this phenomenon.
- Nutrition: Studies have demonstrated that our organism is very tolerant to this amino acid and can absorb it well. This can be useful for convalescent individuals who require additional nutrition to improve their blood protein levels.
Many people wonder whether or not citrulline supplements may contribute to weight loss. In reality, this amino acid increases lean mass and could even promote greater bone density, which would lead to paradoxical weight gain. That being said, this would not alter your physical appearance.
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Are citrulline or arginine supplements better?
Both supplements are able to increase the concentrations of the vasodilator nitric oxide in your body, potentially leading to a lowering of the blood pressure. However, these products have significant differences, as you can see in the following table (18, 19, 20):
| Arginine | Citrulline | |
|---|---|---|
| Effects | Tissue renewal.
Increase of muscle mass. Reduction of blood pressure. Increase of muscular perfusion. Improvement of sexual health. Activation of the immunity. |
Increase of the levels of arginine and its benefits.
Improvement of the nutritional status. Increase of muscle mass. Reduction of blood pressure. Improvement of sexual health. Regulation of immunity. |
| Absorption | Good | Better |
| Side effects | Gastrointestinal intolerance.
Arterial hypotension. Recurrent cold sores. |
None |
| Interactions | Antidiabetics.
Antihypertensive drugs. |
Antidiabetics.
Antihypertensive drugs. Nitrates. |
| Long-term safety | Up to 3 years | Up to 6 months |
Studies in rats seem to confirm the activity of citrulline in increasing muscle mass and sports performance. In addition, these supplements may be better absorbed by the organism, and their intake would not cause gastrointestinal discomfort (the main side effect of arginine supplements).
The big remaining question regarding citrulline is its long-term safety. While arginine appears to be safe for long periods (up to 3 years in humans), the amino acid citrulline needs further study before it can be recommended for supplementation for more than six months at a time.
Is citrulline supplementation safe?
While there have been no reports of relevant drug interactions, the effect of this supplement on blood pressure and metabolism could impact the effect of antidiabetics, antihypertensives, and nitrates (such as drugs for angina pectoris or erectile dysfunction). If you are treated with any of these, you are strongly advised to seek medical guidance before supplementing.
In a similar vein, the use of citrulline without medical supervision is not recommended for pregnant or breastfeeding women. These supplements should not be used freely by minors under the age of 18, by individuals with chronic diseases, or by people undergoing surgery.
Buyer's Guide
As you noticed in our selection of products earlier, there is a wide range of citrulline supplements available on the market. If you're wondering how to pick the right one for your needs, the section below is what you need. We have detailed the main shopping criteria to take into account before you make your purchase.
Allergies & Intolerances
Watermelon allergy is a rare food intolerance. However, most citrulline supplements consist of the extract of this fruit, which is why you should avoid them if you suffer from this type of allergy. If you are intolerant to gluten, lactose, or nuts, on the other hand, carefully check the list of excipients before use.
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Vegan or Vegetarian Diet
Citrulline is of plant origin, so you will find many vegan-friendly supplements out there. However, make sure that the capsule and excipients are free of animal products before you buy any product. You will want to avoid supplements that contain lactose and gelatin as part of their composition.
Dosage Form
Citrulline products come in capsule and powder form. The former provides a comfortable and fast supplementation, being particularly handy for individuals needing low doses of the amino acid. Powder preparations allow you to personalize the amount of citrulline you consume each day, adapting to your own needs.
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Summary
Citrulline is an amino acid with incredible potential. Its effects on cardiovascular health and muscle performance could improve the quality of life of older adults, allowing them to enjoy a fuller life both at the athletic and intimate levels. Indeed, it stands as an alternative to manage erectile dysfunction.
If you need to boost your cardiovascular and muscle health, citrulline may be able to support you during the more intense periods. This natural substance could enhance your recovery process or your libido. Who knew that watermelon could be so miraculous?
We hope you enjoyed our guide on citrulline. Don't forget to share it on your social media and leave us a comment in the section below!
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