Definition: Citrulline, also commonly referred to as L-citrulline, is an amino acid that exists in some foods, including watermelon, where it was first discovered. The name “citrulline” comes from the Latin “Citrullus,” which translates to watermelon.

Health Benefits:

Citrulline, plays an important role in the urea cycle, helping the body to get rid of harmful substances, particularly ammonia. It also plays an important role in vasodilation and may play a part in muscle building.

May Improve Athletic Performance

Several studies show that citrulline may help to improve athletic performance. It may do this by increasing the oxygen in the muscle tissue.

Some studies also show that citrulline may help improve 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.

Boosts Heart Health

Some research has shown that the blood vessel-widening properties of citrulline may be beneficial for 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 boost L-arginine, which boosts nitric oxide production. Nitric oxide aids in blood vessel relaxation, which allows more blood to flow through the 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.

Cautions:

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.

Dosage:

In general, citrulline supplements are considered safe.

The recommended dose ranges between 3 and 6 grams per day of L-citrulline or 8 grams of citrulline malate.