Health Benefits of Citrulline

Citrulline, also commonly referred to as L-citrulline, is a non-essential amino acid. It’s considered non-essential because your body makes it on its own, specifically in the liver and intestines. It also exists in some foods, including watermelon, where it was first discovered. The name “citrulline” comes from the Latin “Citrullus,” which translates to watermelon.

Unlike other amino acids, citrulline doesn’t build proteins. Instead, it plays an important role in the urea cycle, helping your body to get rid of harmful substances, particularly ammonia. It also plays an important role in widening your blood vessels (vasodilation) and may play a part in muscle building.

While the human body makes citrulline, some people increase their numbers by eating foods with the nutrient in them. Some people may also take citrulline supplements to improve athletic performance. Supplements go by a couple of different names: L-citrulline and citrulline malate. Citrulline malate is a mix of citrulline and DL-malate, a compound that may help turn food into energy.

Health Benefits

While citrulline is necessary for the urea cycle, it also has a few other benefits as well. One of the biggest benefits associated with the amino acid is that it promotes vasodilation, the widening of your blood vessels. Current studies show that single doses of the nutrient don’t appear to have any impact. Long-term use, however, has shown to provide results for those with, or at risk for, heart disease.

Other health benefits of citrulline include:

May Improve Athletic Performance

Several studies show that citrulline may help to improve your athletic performance. It may do this by increasing the amount of oxygen in your muscle tissue. While supplements may not help your body use more oxygen, they could help improve the oxygen usage in your muscles, which can then help to improve your endurance.

Some studies also show that citrulline may help improve your weight training performance. One study found that men who took a citrulline malate supplement were able to do 53% more repetitions than those who took a placebo. The supplement also appears to have led to reduced muscle soreness two days later.

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Boosts Heart Health

Some research has shown that the blood vessel-widening properties of citrulline may be beneficial for your heart health. The amino acid may help to lower blood pressure in individuals with hypertension, a risk factor for heart disease. Other research suggests that citrulline doesn’t offer any benefit to those with high blood pressure, so more studies are needed. 

Improves Erectile Dysfunction

L-citrulline may help to boost L-arginine, which helps to boost nitric oxide production. Nitric oxide aids in blood vessel relaxation, which allows more blood to flow through your body. Some research shows that this may help individuals with erectile dysfunction. One small study showed that half of the men who took an L-citrulline supplement had an 8.3% improvement in erectile dysfunction scores over men who took a placebo. 

May Provide Antidepressant Effects

Some studies have discovered a link between low levels of arginine and citrulline and a greater risk of depression. One study found a link between bipolar disorder and reduced levels of nitric oxide. The research seems to suggest that increasing citrulline and arginine may help to reduce depressive symptoms. 

May Help Those with Sickle Cell Disease

Research indicates that citrulline may help to improve pain in people with sickle cell disease. Supplementation may help to improve blood health as well as overall well-being. There aren’t many studies available, however, so more research is needed to confirm the effectiveness of such a treatment. 

Health Risks

In general, citrulline supplements are considered safe, even at higher doses. Even so, there are some instances in which taking it can pose a potential risk:

Pregnancy Concerns

There is not enough research showing the effects of citrulline during pregnancy or while breastfeeding. As such, women who are pregnant or nursing should consult with their doctor before taking a supplement or avoid taking it. 

Medication Interactions

Citrulline may interact with certain medications. If you take phosphodiesterase-5 inhibitors for erectile dysfunction, taking citrulline may cause your blood pressure to drop too low, leading to hypotension. Similar effects may occur if you take medications for high blood pressure or nitrate medications for heart conditions. Talk to your doctor first before adding any supplement, including citrulline, to your regimen. 

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Amounts and Dosage

Your body makes citrulline itself. You can increase your levels by consuming certain foods, such as:

You can also find powdered citrulline supplements, which you mix with water or blend into a smoothie. In general, the recommended dose ranges between 3 and 6 grams per day of L-citrulline or 8 grams of citrulline malate. 

WebMD Medical Reference Reviewed by Dan Brennan, MD on November 06, 2020

Sources

Sources:

ESHA Research, Inc., Salem, Oregon.

The International Journal of Nutritional Sciences: “Citrulline: Modulation on Protein Synthesis, Intestinal Homeostasis, and Antioxidant Status.”

Amino Acids: “Almost All About Citrulline in Mammals.”

Current Opinion in Clinical Nutrition and Metabolic Care: “Influence of L-Citrulline and Watermelon Supplementation on Vascular Function and Exercise Performance.”

American Journal of Physiology: Endocrinology and Metabolism: “Acute Ingestion of Citrulline Stimulates Nitric Oxide Synthesis but Does Not Increase Blood Flow in Healthy Young and Older Adults with Heart Failure.”

Immunology, Endocrine & Metabolic Agents in Medicinal Chemistry: “Effects of Oral L-Citrulline Supplementation on Lipoprotein Oxidation and Endothelial Dysfunction in Humans with Vasospastic Angina.”

Nitric Oxide: Biology and Chemistry: “Two Weeks of Watermelon Juice Supplementation Improves Nitric Oxide Bioavailability but Not Endurance Exercise Performance in Humans.”

Journal of Strength and Conditioning Research: “Citrulline Malate Enhances Athletic Anaerobic Performance and Relieves Muscle Soreness.”

Cardiology Journal: “Effect of L-Arginine or L-Citrulline Oral Supplementation on Blood Pressure and Right Ventricular Function in Heart Failure Patients with Preserved Ejection Fraction.”

Urology: “Oral L-Citrulline Supplementation Improves Erection Hardness in Men with Mild Erectile Dysfunction.”

Journal of Affective Disorders: “Global Arginine Bioavailability Ratio is Decreased in Patients with Major Depressive Disorder.”

Neuropsychobiology: “Nitric Oxide and Neopterin in Bipolar Affective Disorder.”

Journal of the National Medical Association: “Oral Citrulline as Arginine Precursor May Be Beneficial in Sickle Cell Disease: Early Phase Two Results.”

The British Journal of Nutrition: “Dose-Ranging Effects of Citrulline Administration on Plasma Amino Acids and Hormonal Patterns in Healthy Subjects: The Citrudose Pharmacokinetic Study.”

© 2020 WebMD, LLC. All rights reserved.

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