Have you heard of citrulline? It’s an amino acid that you simply produce naturally. But it’s additionally in some meals, like watermelon, in addition to offered in complement type.

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There’s quite a lot of hype about this complement, particularly within the health world, says registered dietitian Devon Peart, MHSc, BASc, RD.

“Citrulline is trendy among bodybuilders and athletes because even a small improvement in performance — even if it’s a placebo — could give them a competitive advantage.”

But what does the analysis say about citrulline? Is it a protected efficiency booster? A waste of cash? A harmful complement? Peart explains what you have to know if you happen to’re fascinated with taking a citrulline complement.

How does citrulline work?

Citrulline is concerned in your urea cycle, which eliminates waste merchandise by excreting them in urine (pee). It’s transformed into arginine, an amino acid that produces nitric oxide, a substance that relaxes blood vessels and improves blood circulate.

“The main mechanism by which citrulline could be beneficial for muscle is by increasing nitric oxide, leading to increased blood flow,” says Peart.

The forms of citrulline

There are two primary types of citrulline.


The type naturally present in your physique, in some meals and in dietary supplements is L-citrulline.

There’s some research-based evidence that L-citrulline could also be useful for athletic efficiency as a result of it improves blood circulate to working muscular tissues.

The potential profit appears to use extra to anaerobic train comparable to power coaching, quite than cardio train, like operating. Still, future analysis may supply extra readability.

One study of avid cyclers discovered that the group taking L-citrulline biked sooner and felt much less drained after biking 4 kilometers (roughly 2.5 miles). Participants took 2.4 grams of the complement daily for eight days earlier than the bike trip. 

Citrulline malate

Citrulline malate can also be receiving some consideration recently. This type is a mix of citrulline with malic acid. Malic acid is present in apples, amongst different fruits.

Citrulline malate is a direct precursor to nitric oxide. It’s thought that this type of citrulline might have greater results as a result of it probably will increase ATP — adenosine triphosphate, or the gas for working muscular tissues — manufacturing and availability.  

There’s some research that citrulline malate could also be useful for muscular endurance and power efficiency. But total proof is blended on its effectiveness, and extra analysis is required.

“In the meantime, since there is a good level of evidence for L-citrulline, I recommend using that form of the supplement until there is more evidence for the use of citrulline malate,” Peart says.

Three doable advantages of taking L-citrulline

If you’re seeking to take citrulline in complement type, Peart recommends taking L-citrulline quite than citrulline malate.

“There’s more evidence of L-citrulline’s benefits,” she notes. “And there’s less research on citrulline malate. The research that does exist is conflicting.”

People take L-citrulline dietary supplements to enhance blood circulate, which can:  

1. Give you a simpler exercise

Taking L-citrulline could profit your exercise by boosting your endurance. One research checked out how L-citrulline supplements could affect athletic performance. Researchers discovered that when contributors took 6 grams of L-citrulline for seven days, they may work tougher for longer on a severe-intensity train check. 

But a latest overview of current analysis on L-citrulline and aerobic exercise got here to a special conclusion. According to the overview, there isn’t a transparent reply as to if taking L-citrulline may also help you acquire a aggressive edge. Some research recommended a profit to taking the complement, whereas others confirmed it doesn’t make a distinction.

“The average gym-goer may notice a benefit during their workout, in terms of performance,” notes Peart. “And for avid athletes who may work out multiple times a day, L-citrulline could increase your performance and help you recover faster.”

2. Reduce hypertension

If you could have hypertension, taking a citrulline complement might assist. An analysis of research on citrulline’s effect on blood pressure discovered constructive outcomes in most research.

Study contributors took from 3 to eight grams of L-citrulline a day. Researchers analyzed outcomes anyplace from one to 16 weeks after use.

According to the evaluation, citrulline appeared prefer it might considerably decrease blood strain. But researchers really helpful bigger medical trials to not solely verify promising findings, but additionally to find out supreme dose quantities and if there have been any unwanted side effects.

3. Help with erectile dysfunction

Have you considered attempting aphrodisiacs to boost your intercourse life? Eating oysters and chocolate (sparsely) received’t damage you. But if you happen to’re utilizing an aphrodisiac due to erectile dysfunction (ED), it in all probability received’t do a lot.

But some individuals consider citrulline is beneficial for ED. They theorize that as a result of restricted blood circulate is without doubt one of the causes of ED — and since citrulline improves circulation — it might assist.

“It’s been suggested as a possibility,” states Peart. “But the jury’s still out on that.”

In one small but promising study, 50% of the contributors had constructive results. They took 1.5 grams of L-citrulline a day for a month. Twelve out of 24 individuals went from having gentle ED to typical erectile operate. Scientists really helpful additional analysis and research on this space.

Citrulline dosage

If you need to strive a L-citrulline complement, see a healthcare supplier first. Supplements themselves aren’t well-regulated within the U.S., and their unwanted side effects aren’t well-documented. Plus, some dietary supplements can work together badly with different medicines you may be taking.

If you’re cleared to take L-citrulline, a protected dosage is 3 to six grams a day. Start with the bottom quantity. You can at all times enhance the dosage to see if it impacts your outcomes if you happen to don’t expertise any unwanted side effects.

Does citrulline have any unwanted side effects?

Amino acids like citrulline may cause gastrointestinal upset. That’s why it’s vital to start out on the smallest dose to see how your physique reacts. Side results could embody:

  • Bloating.
  • Cramping.
  • Diarrhea.
  • Sweating.

Foods that include L-citrulline

L-citrulline is especially ample in watermelon. You also can increase your stage of nitric oxide — a element that will increase blood circulate — with meals excessive in nitrates, together with:

  • Beets.
  • Fennel.
  • Lettuce.
  • Parsley.
  • Radishes.
  • Spinach.

Scientists don’t but agree on the advantages of citrulline, and analysis gives blended outcomes on its scientific advantages. Want a assured dwelling run? Adopting a heart-healthy way of life — a nutritious weight-reduction plan, common train and no smoking — is a confirmed means that can assist you win at residing your finest life. 

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