L-Citrulline

Story

Connected to · 2

cofactor · 1

Hypertension
Whether a blood vessel can relax depends on whether its lining makes enough nitric oxide (NO). Citrulline is converted in the body to arginine, which is then used to make NO: in a small crossover trial of 10 men, 6 g of citrulline a day for 7 days raised blood arginine as much as taking arginine itself, and mean arterial pressure fell somewhat.

contrast · 1

Beta-Alanine
Citrulline is converted in the body into arginine, which raises nitric oxide and improves blood flow: in Bailey 2015, a small crossover trial of 10 healthy men, it extended tolerance of high-intensity exercise. Beta-alanine, by contrast, buffers acid in muscle through carnosine. The two are often put in the same pre-workout product, but their combined effect has not been tested directly in a trial.

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Stop 1/5

Why not just take arginine

EVIDENCERCT 2

READ THE ORIGINAL

L-citrulline is the ingredient in pre-workout supplements sold for the pump and more blood flow. In the body it first becomes arginine, which the lining of your blood vessels uses to make nitric oxide (), a gas signal that relaxes and widens vessels. The name comes from *citrullus*, Latin for watermelon, and watermelon (especially the pale rind next to the skin) is still its best-known food source.

It is an amino acid that is not built into proteins: it does not become part of muscle, and unlike leucine it does not switch on muscle building directly. Its real role is upstream on the nitric oxide route: citrulline becomes arginine, and arginine becomes nitric oxide.

The counterintuitive part: to raise the arginine in your blood, taking citrulline works better than taking arginine. A large share of swallowed arginine is broken down by the enzyme arginase in the gut and liver. Citrulline slips past that step, enters the blood and is turned back into arginine, mainly by the kidneys.

One safety point up front: if you use a nitrate heart medicine such as nitroglycerin, do not take it. If you have used it together with an erectile-dysfunction drug and feel dizzy, see your vision go dark, feel close to fainting or have chest pain, get medical care immediately.

Educational content, not medical advice — consult a clinician.

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L-Citrulline

Story

Connected to · 2

cofactor · 1

Hypertension
Whether a blood vessel can relax depends on whether its lining makes enough nitric oxide (NO). Citrulline is converted in the body to arginine, which is then used to make NO: in a small crossover trial of 10 men, 6 g of citrulline a day for 7 days raised blood arginine as much as taking arginine itself, and mean arterial pressure fell somewhat.

contrast · 1

Beta-Alanine
Citrulline is converted in the body into arginine, which raises nitric oxide and improves blood flow: in Bailey 2015, a small crossover trial of 10 healthy men, it extended tolerance of high-intensity exercise. Beta-alanine, by contrast, buffers acid in muscle through carnosine. The two are often put in the same pre-workout product, but their combined effect has not been tested directly in a trial.

Read full story

Stop 1/5

Why not just take arginine

EVIDENCERCT 2

READ THE ORIGINAL

L-citrulline is the ingredient in pre-workout supplements sold for the pump and more blood flow. In the body it first becomes arginine, which the lining of your blood vessels uses to make nitric oxide (), a gas signal that relaxes and widens vessels. The name comes from *citrullus*, Latin for watermelon, and watermelon (especially the pale rind next to the skin) is still its best-known food source.

It is an amino acid that is not built into proteins: it does not become part of muscle, and unlike leucine it does not switch on muscle building directly. Its real role is upstream on the nitric oxide route: citrulline becomes arginine, and arginine becomes nitric oxide.

The counterintuitive part: to raise the arginine in your blood, taking citrulline works better than taking arginine. A large share of swallowed arginine is broken down by the enzyme arginase in the gut and liver. Citrulline slips past that step, enters the blood and is turned back into arginine, mainly by the kidneys.

One safety point up front: if you use a nitrate heart medicine such as nitroglycerin, do not take it. If you have used it together with an erectile-dysfunction drug and feel dizzy, see your vision go dark, feel close to fainting or have chest pain, get medical care immediately.

Educational content, not medical advice — consult a clinician.