Quick answer

Arginine comes from protein foods: meat, poultry, fish, eggs, dairy products and legumes, with seafood, nuts, seeds and soy protein among the richer sources. US adults average about 4.4 g a day from food. Watermelon adds citrulline, which the body turns into arginine: about 365 mg in a cup.^1,2,3

Key facts

A nutritious diet supplies about 4 to 5 g of arginine a day.³
The milk of most mammals, including cows, is relatively low in arginine.²
The kidneys turn about 80% of the body's citrulline into arginine.³
In a US national survey, a tenth of adults took in more than 7.5 g of arginine a day from food.²

Foods that contain arginine

Arginine is found in many protein foods, especially animal foods and nuts. NIH names meat, poultry, fish, eggs, dairy products and legumes.^1,3

A review of arginine nutrition lists seafood, nuts, seeds, meats, algae, watermelon juice, and rice and soy protein concentrates among foods relatively high in arginine, and notes that the milk of most mammals, including cows, is relatively low.²

Seafood, meat and poultry^1,2
Nuts and seeds^2,3
Legumes, and soy and rice protein concentrates^1,2
Eggs and dairy products, though milk itself is relatively low^1,2

None of these sources gives grams per serving, so read the list as a guide to food groups rather than a league table. The common thread is protein, since arginine is one of the amino acids that protein is made of.³

How much a typical diet supplies

A nutritious diet supplies about 4 to 5 g of arginine a day.^1,3

In a US national survey, adults averaged 4.4 g of arginine a day from food. A quarter took in less than 2.6 g, and a tenth more than 7.5 g.²

So three quarters of US adults take in at least 2.6 g a day without trying. Supplement amounts are best judged against that: 1 g on top of an average 4.4 g diet adds less than a quarter.²

Your body makes its own

Adults make arginine mainly in the kidneys, from citrulline produced in the small intestine.^2,3

Because the body makes arginine, it has traditionally not been counted as an essential amino acid for healthy adults, unlike the amino acids that can only come from food. The gut makes citrulline from other amino acids, and the kidneys finish the job.²

Watermelon and citrulline

Watermelon is the best-known food source of citrulline, which the body turns into arginine: 1 cup of diced seedless watermelon has about 365 mg of citrulline.³

The kidneys turn about 80% of the body's citrulline into arginine, and citrulline may raise blood arginine more efficiently than arginine itself, because more of it is absorbed from the gut.³

Watermelon shows up twice in the sources: the review above lists watermelon juice among foods relatively high in arginine, and NIH names watermelon as the best-known food source of citrulline.^2,3

Food or a supplement?

In adults, about 40% of the arginine eaten is broken down in the small intestine before it reaches the bloodstream.²

That loss in the gut applies to arginine from food and supplements alike, and it is one reason extra arginine does not turn gram for gram into higher blood levels.²

Food spreads a few grams across the day, while supplement studies gave 2 to 20 g a day, at once or in a few doses. The side effects NIH describes were reported at supplement amounts of 9 g a day and more.³

What’s in ours

Ashwagandha Complex: L-Arginine, 300 mg per serving, from the label

If you are thinking of a supplement

The cautions in the sources we use concern supplements, not food. Ask your doctor first if you have had a heart attack, take medicine for blood pressure or your heart, or have kidney disease.^4,5,6

Questions people ask

Which foods have the most arginine?

The review we use names seafood, nuts, seeds, meats, algae, watermelon juice and soy and rice protein concentrates as relatively rich, without amounts per serving, so we do not rank them.²

Is there arginine in plant foods?

Yes: nuts, seeds, legumes and soy protein all contain it, and the body makes its own from citrulline. The survey figures above cover all US adults, so they say nothing specific about people who eat no animal foods.^1,2

Is watermelon a good source of L-arginine?

Watermelon is best known for citrulline, about 365 mg in a cup of diced seedless fruit, and the kidneys turn most citrulline into arginine. Watermelon juice also appears among foods relatively high in arginine itself.^2,3

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Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.