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Citrulline, a non-essential amino acid found in watermelon rinds (and in other fruits & veggies, though in lower amounts), is being added to Japanese energy drinks and even chewing gum - just in time to take advantage of the 2008 Beijing Olympics hype machine. It's also being trumpeted as a natural sex enhancer due to its beneficial effect on blood flow.

Sounds good, right? Probably tastes good too, at least in the forms Japanese food companies are packaging Citrulline.

One of these is Citrulline Gum, made by Lotte. I'm assuming it tastes like watermelon. The other is Citrulline Water, a sports drink made by Asahi Drinks (a divison of one of Japan's biggest beer brewers).

If you're an athlete - and I use the term loosely - citrulline can do a number of things to help improve your performance. For one, it acts to dilate (widen) blood vessels, thereby improving circulation. It also acts to increase levels of nitric oxide, or NO - a chemical used by muscles. When hard-working muscles become fatigued, lactic acid begins to build up resulting in that familiar "burn". Citrulline helps break down lactic acid while at the same time assisting the body in eliminating harmful ammonia through the urea cycle.

These same properties have attracted notice from sexual function researchers both professional and, er, amateur. A clip featured on CNN likens citrulline's effects on blood flow to that of a well-known prescription medicine... the little blue pill whose name need not be named! 

Citrulline may seem new, but it really isn't. Isolated from extract of watermelons in 1930 by a Japanese research scientist, this non-essential amino acid (a-amino-d-ureido-n-valeric acid) has long been available in the U.S. in supplement form. Of course, supplements are typically expensive - not so the new products from Japan that tout this interesting ingredient for its very useful effects on the human body. If they prove to have staying power beyond this summer's Beijing Olympics, expect to see citrulline snacks make their move to the U.S. and give a little extra "muscle" to the booming energy drinks & snacks market. (via Japan Marketing News)