A dose of watermelon a day could help keep high blood pressure at bay.
Researchers have discovered that the fruit is rich in compounds that widen blood vessels - and may cut the risk of heart attacks and strokes.
And a daily fix of its juices could be enough to lower blood pressure in patients suffering from hypertension, according to a study.
High blood pressure, which affects more than 16million men and women in the UK, doubles the risk of a fatal heart attack or stroke and is blamed for more than 60,000 deaths a year.
But watermelon is an edible source of L- citrulline - a compound vital in the production of nitric oxide, a gas that widens blood vessels.
Researchers in the U.S. gave a group of volunteers a daily dose of 6g, or slightly more than a teaspoonful, of L-citrulline extracted from watermelons.
All of those taking part had pre-hypertension, or borderline high blood pressure.
After six weeks, readings had improved in all nine participants, with none experiencing any side-effects.
But there is one catch - you'd need to eat one-and-a-half watermelons a day to achieve the same effect.
Dr Arturo Figueroa, of Florida State University, said: 'These findings suggest that this " functional food" has a vasodilatory effect, and one that may prevent pre-hypertension from progressing to full-blown hypertension, a major risk factor for heart attacks and strokes.
'Given the encouraging evidence generated by this preliminary study, we hope to continue the research and include a much larger group of participants in the next round.'
Co-researcher Professor Bahram Arjmandi said: 'By functional foods, we mean those foods scientifically shown to have health-promoting or disease-preventing properties, above and beyond the other intrinsically healthy nutrients they also supply.'
The researchers found that watermelons with orange flesh contain more L- citrulline than those with red flesh.
Both varieties are rich in vitamins A, B6 and C and high in fibre. Watermelon is also a good source of potassium, which is thought to lower blood pressure.
And lycopene, the pigment that gives the fruit its colour, is credited with a host of health benefits, from warding off cancer to boosting fertility.
Fortunately for those who aren't fond of the fruit, the L-citrulline compound can also be bought in pill form.