Ingredient of the season: Citrulline

If you keep your eyes peeled in Japan this summer you're going to see several new products that contain the ingredient known as citrulline.

An amino acid first extracted from watermelon by a Japanese researcher in 1930, citrulline is said to reduce the buildup of ammonia in the bloodstream, dilate blood vessels, and promote production of nitric oxide, which amongst other things is supposed to help prevent muscle fatigue. So it's no surprise that Asahi is promoting its new Citrulline Water using sports-related advertising, and Lotte has launched Citrulline Gum to coincide with its support of the Beijing Summer Olympics.

In the U.S., citrulline supplements have apparently been marketed previously to promote circulation and prevent hardening of the arteries, but Japan's health ministry did not approve the ingredient for use in food until August of last year.

Other Japanese companies like Shiseido have also jumped on the citrulline bandwagon so it's probably only a matter of time before a dozen more citrulline products hit Japanese store shelves.