October 19/AFP - RELAXNEWS Watermelon is a sweet, low-calorie, high-fiber treat, but now research suggests that watermelon can help reduce and prevent high blood pressure.

Researchers at Florida State University discovered that watermelon is rich in the amino acid L-citrulline, a precursor of L-arginine, that reverses the effects of prehypertension by maintaining arterial function and improving proper blood flow. Published in the journal American Journal of Hypertension, the study is the first of its kind to show this benefit in humans.

"These findings suggest that this 'functional food' has a vasodilatory effect," said Arturo Figueroa, co-author of the study in a news release, "and one that may prevent hypertension from progressing to full-blown hypertension, a major risk factor for heart disease."

Why study watermelon? "Watermelon is the richest edible natural source of L-citrulline," said Figueroa, which is closely related to the amino acid L-arginine. L-arginine is required for the formation of nitric oxide, which helps the regulation of vascular tone and healthy blood pressure.

In the study, nine volunteers (four men and five women aged 51-57 years) took a daily dose of 6g of the amino acid L-citrulline/L-arginine, contained in the extract of watermelon.

Figueroa suggests that consumers can rely on synthetic pills of L-citrulline for now -- he recommends an optimal dose of 4-6g a day for people with high blood pressure, especially those who are older or with chronic diseases, such as type 2 diabetes.

Garlic is another natural food shown to have a modest effect on lowering blood pressure and may help relax blood vessels. U.S. health expert Andrew Weil, MD, suggests using garlic to help reduce blood pressure, along with other tried-and-true methods, such as eliminating salt, reducing animal protein, and eating four to five servings of nuts, seeds, and dry beans per week.

From the November 1, 2010, Prepared Foods E-dition