Citrulline: How It Benefits Blood Flow and Athletic Performance

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Citrulline is a natural compound, found mainly in watermelon, and plays a crucial role in the body’s nitric oxide production and amino acid synthesis. Many people turn to citrulline for its ability to support cardiovascular health, enhance athletic performance, and promote muscle recovery. This article delves into the science behind citrulline, exploring how it can contribute to overall well-being and fitness.

What Is Citrulline?

Citrulline is a non-essential amino acid, which means the body can produce it even if it’s not obtained through diet. Initially discovered in watermelon, citrulline is named after ‘citrullus,’ the Latin word for this fruit. It plays a key role in several bodily functions, primarily in the urea cycle. This cycle involves the conversion of harmful substances like ammonia into urea, which is safely excreted from the body.

Unlike some amino acids, citrulline does not directly build proteins. Instead, it increases the levels of certain key substances in the body. One of these is arginine, another amino acid that is crucial for heart health and immune system function. Citrulline also helps to boost nitric oxide production. Nitric oxide is vital for blood vessel dilation, which ensures efficient blood flow and better oxygen delivery throughout the body.

In terms of dietary supplements, citrulline is available in two main forms: L-citrulline and citrulline malate. L-citrulline is the free-form of the amino acid, while the citrulline malate combines citrulline with the amino acid malate, which plays a role in the energy cycle of cells. Both forms are popular among athletes and fitness enthusiasts for their potential to enhance endurance and recovery.

This amino acid has gained attention not just in the athletic world but also among those looking for general wellness benefits. From supporting cardiovascular health to enhancing physical performance and recovery, citrulline offers a range of advantages that we will explore in the following sections.

What Are the Benefits of Citrulline?

  • Enhances Athletic Performance: Citrulline has been shown to increase nitric oxide production in the body, leading to enhanced blood flow and oxygen delivery to muscles. This process is crucial for athletes, as it can help to improve endurance, reduce fatigue during exercise, and increase workout intensity.
  • Supports Cardiovascular Health: By aiding in the production of nitric oxide, citrulline helps dilate blood vessels, which can improve blood flow throughout the body. This effect is beneficial for heart health, as it can lead to lower blood pressure and reduced strain on the cardiovascular system.
  • Promotes Muscle Recovery: Post-exercise, citrulline can help reduce muscle soreness and accelerate the muscle recovery process. This is particularly important for athletes and fitness enthusiasts who engage in frequent and intense physical activities.
  • Boosts Immune System: Citrulline plays a role in supporting the immune system. It helps in enhancing the body’s defense mechanisms, making it more effective in fighting infections and maintaining overall health.
  • Enhances Sexual Health: The improvement in blood flow due to increased nitric oxide production also extends to sexual health. Citrulline can enhance erectile function and overall sexual performance by improving blood circulation.
  • Supports the Urea Cycle: Citrulline is crucial in the urea cycle, a process that detoxifies ammonia produced during protein metabolism. By effectively removing ammonia, citrulline helps maintain a healthy nitrogen balance in the body, which is essential for various bodily functions.
  • May Improve Digestive Health: Citrulline may contribute to better digestive health. By aiding in the removal of ammonia and enhancing blood flow to the digestive organs, it can help maintain a healthy gut environment and potentially alleviate some digestive issues.
  • Reduces Symptoms of Mild Erectile Dysfunction: Citrulline supplements may enhance nitric oxide production, improving blood flow. This effect can be particularly beneficial for individuals with mild erectile dysfunction, enhancing sexual performance and satisfaction by facilitating better blood circulation to the genital area.
  • Improves Blood Flow in Individuals with Peripheral Artery Disease: In those suffering from peripheral artery disease, citrulline can play a crucial role. It helps improve blood circulation to the limbs, potentially alleviating symptoms like pain or cramping during physical activities like walking.
  • Alleviates Symptoms of Sickle Cell Anemia: Citrulline has shown promise in improving blood flow and reducing the risk of blood vessel blockages in individuals with sickle cell anemia. This can help alleviate pain and reduce complications associated with the disease.
  • Boosts Cognitive Function: By increasing blood flow to the brain, citrulline may enhance cognitive functions. Improved circulation can lead to better oxygen and nutrient delivery to the brain, potentially enhancing memory, focus, and overall cognitive performance.
  • Supports Kidney Function: Citrulline may be beneficial for kidney health. It aids in the detoxification processes and improves blood circulation, which can contribute to the overall functioning and health of the kidneys, especially in individuals with compromised kidney function.
  • Helps in Certain Metabolic Conditions: Citrulline might improve metabolic health by enhancing insulin sensitivity and overall metabolism. This could be particularly beneficial for individuals with conditions like type 2 diabetes, as better insulin sensitivity can help manage blood sugar levels.
  • May Aid in Weight Loss Efforts: While citrulline is not a weight loss supplement, its ability to enhance exercise performance and facilitate muscle recovery can indirectly support weight loss and body composition goals by enabling more efficient and effective workouts.
  • Reduces Ammonia Levels in Blood: By efficiently converting ammonia into urea in the urea cycle, citrulline helps reduce ammonia levels in the blood. This is crucial for individuals with certain metabolic disorders where ammonia accumulation can be harmful.

Food Sources of Citrulline

Food SourceCitrulline Content per Serving
Watermelon (1 cup)250 mg
Cucumbers (1 cup)150 mg
Pumpkins (1 cup)200 mg
Bitter Melon (1 cup)130 mg
Squash (1 cup)210 mg
Muskmelon (1 cup)240 mg
Gourds (1 cup)180 mg
Walnuts (1 oz)3 mg
Almonds (1 oz)2 mg
Chickpeas (1 cup)5 mg
Amounts listed are approximate

Are Citrulline Supplements Safe?

Citrulline is generally considered safe for most people when consumed in moderate amounts, either through dietary sources or as a supplement. This amino acid is naturally occurring in the body and in many foods, making it a familiar substance to our biological systems. The side effects are rare and usually mild, typically seen only at very high doses. Studies have shown that even in supplement form, citrulline is well-tolerated by the body and does not pose significant risks when used appropriately. However, it’s always advisable for individuals, especially those with pre-existing health conditions or those taking medication, to consult with a healthcare provider before starting any new supplement, including citrulline, to ensure it aligns safely with their health needs and conditions.

Medication Interactions with Citrulline

  • Nitrates (for heart disease): Citrulline has the potential to enhance the blood-pressure-lowering effects of nitrates, which are commonly used in treating heart conditions. This combination can lead to an excessive drop in blood pressure, causing symptoms like dizziness or fainting, especially when standing up.
  • Blood Pressure Lowering Medications: Since Citrulline can naturally lower blood pressure by increasing nitric oxide production and dilating blood vessels, taking it alongside other blood pressure medications might cause blood pressure to drop too low. This hypotensive effect could result in symptoms like lightheadedness, weakness, or even the risk of falls.
  • Erectile Dysfunction Drugs (such as Viagra, Cialis): Erectile dysfunction medications, like Viagra and Cialis, work by increasing blood flow. When combined with Citrulline, there’s a risk of further enhancing this effect. This can lead to a significant decrease in blood pressure, which may manifest as lightheadedness, blurred vision, or in severe cases, a risk of heart attack or stroke.
  • Medications that Increase Blood Flow (vasodilators): Vasodilators are medications designed to widen blood vessels. When used with Citrulline, the combined effect on blood vessel dilation can be amplified, potentially leading to low blood pressure. This might result in dizziness, fainting, or even a risk of heart complications if the blood pressure drops too sharply.
  • Any Medications Metabolized by the Liver: Citrulline might interfere with the liver’s ability to metabolize certain medications, potentially altering their effectiveness or increasing the likelihood of side effects. This interaction can affect a wide range of drugs, as many are processed in the liver.

Supplement Interactions with Citrulline

  • Nitric Oxide Boosters (e.g., L-Arginine, Beetroot): These supplements are used to increase nitric oxide levels in the body, similar to Citrulline. When combined, the effect of both supplements on nitric oxide production might be amplified, leading to excessive blood vessel dilation. This could result in very low blood pressure, and symptoms such as lightheadedness or fainting, particularly in sensitive individuals or when taken in high doses.
  • Blood Pressure Lowering Supplements (e.g., Hawthorn, Coenzyme Q10): Supplements like Hawthorn and Coenzyme Q10 are known for their ability to lower blood pressure. If used in conjunction with Citrulline, which also has blood pressure-lowering effects, there might be a cumulative effect leading to hypotension. This significant drop in blood pressure could lead to symptoms like dizziness, blurred vision, or even more severe cardiovascular issues.
  • Herbal Supplements with Diuretic Properties (e.g., Dandelion, Green Tea): Diuretic supplements increase urine output and can lower blood pressure. Combining these with Citrulline may result in an additive hypotensive effect, potentially causing an excessive drop in blood pressure. This is especially risky for individuals already prone to low blood pressure or those on blood pressure medications.
  • Stimulants (e.g., Caffeine, Guarana): Stimulants like caffeine and guarana typically increase heart rate and blood pressure. Using them with Citrulline might counteract the vasodilating effects of Citrulline, leading to unpredictable cardiovascular responses. This could manifest as irregular heart rhythms, increased blood pressure variability, or reduced effectiveness of either supplement.
  • Anticoagulants or Antiplatelet Supplements (e.g., Fish Oil, Garlic, Ginkgo Biloba): These supplements possess blood-thinning properties and can increase the risk of bleeding. When used with Citrulline, which may also influence blood flow, there could be an increased risk of bleeding, particularly during surgery or for individuals with bleeding disorders.

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L-Citrulline Powder by NOW Foods

  • Healthy Immune System Function*

Citrulline is a non-essential amino acid that is an important intermediate in the urea cycle, functioning along with other amino acids to rid the body of ammonia, a byproduct of protein metabolism.* Citrulline also plays an important role in the healing process and in the maintenance of a healthy immune system.*

This product is sold by weight not volume.

Natural color variation may occur in this product.
Take 1/2 level teaspoons 1 to 2 times daily between meals.

Amount per 1/2 Level Teaspoon Serving
L-Citrulline … 1.5g (1,500mg)

Food First!

Although this article discusses supplements in detail, don’t forget that we are absolutely committed to the “Food First” approach to nutrition. When it comes to your health, the totality of your eating habits far surpasses the impact of individual nutrients or any single supplement you consume. Even though this article doesn’t delve into the broader picture of your overall diet, it’s crucial to keep this element at the forefront of our minds. Your food needs to provide all the vitamins, minerals, fiber, and phytochemicals to nourish your body systems down to the cellular level.

Food choices, rather than supplements, are the most critical factors for a healthy gut microbiome. These trillions of tiny inhabitants in your gut affect your brain waves; they orchestrate your immune system. They possess the power to create molecules that can switch genes on or off and are even capable of synthesizing neurotransmitters. Opting for organic foods and steering clear of plastic packaging (including those labeled BPA-free) is a smart move to limit toxin exposure. The sum of all these parts leads to a powerful conclusion: the ultimate key to your health lies in the quality and balance of the food you consume. Supplements are secondary.

To Sum It Up

Citrulline supplements offer a range of health benefits that can be a valuable addition to a healthy lifestyle. From enhancing athletic performance and cardiovascular health to promoting muscle recovery and boosting immune system function, Citrulline has proven its versatility. It also shows potential in improving sexual health, supporting kidney function, and aiding in certain metabolic conditions. The ability of Citrulline to reduce symptoms of mild erectile dysfunction and improve blood flow for those with conditions like peripheral artery disease further underscores its varied benefits. Moreover, its role in reducing ammonia levels in the blood and possibly aiding in cognitive functions makes it an interesting supplement for overall well-being. While Citrulline is generally considered safe and well-tolerated, it’s important to use it responsibly as part of a balanced approach to health.

This Article is Not a Substitute for Medical Advice

Dietary supplements are not designed to diagnose, treat, cure, or prevent any disease. The Supplement Sciences website seeks to provide comprehensive access to the most relevant supplement information along with convenient online ordering. We do not provide medical advice and cannot guarantee that every product suggested is completely without risk. Since each person is unique in their health history and medication use, it is important to discuss supplements with your personal physician. Specifically, pregnant women and individuals being treated for cancer or liver or kidney problems must consult their physician about every nutritional supplement they plan to take. People taking medications for the treatment of HIV or with a history of organ transplant must not take supplements without consulting with their physician.

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