WASHINGTON - Watermelon reduces high blood pressure in overweight people and could slash the risk of a heart attack, new research shows. Scientists found that the fruit significantly reduces blood pressure in overweight people, even when they are exposed to cold weather.

More people die of heart attacks in cold conditions because the stress put on the body by trying to keep warm causes blood pressure to increase. This forces the heart to work harder, meaning people face a higher risk of heart attacks and strokes. The study, published in the American Journal of Hypertension, revealed that eating watermelon is good for heart health and can reduce the risk of heart problems in cold conditions.

Professor Arturo Figueroa, from Florida State University, said: ‘The pressure on the aorta and on the heart decreased after consuming watermelon extract.’ Scientists looked at 13 middle-aged obese men and women who suffered from high blood pressure over a 12 week period. Test participants’ hands were dipped into cold water to simulate cold weather conditions, while scientists took their blood pressure . Then, every day half of the participants took watermelon extracts - four grams of amino acid L-citrulline and two grams of L-arginine per day.

The other half were given a placebo, and after six weeks the participants switched roles. It was revealed that watermelon lowered blood pressure and reduced cardiac stress, even in cold conditions. ‘That means less overload to the heart, so the heart is going to work easily during a stressful situation such as cold exposure,’ said Professor Figueroa. L-citrulline and L-arginine supplements are available from some health food shops but would have to be taken in high doses to reduce blood pressure .

The news comes just after it was revealed that working out in warm water can reduce blood pressure . Researchers at the University of Sao Paulo, Brazil, found aquarobics in warm water can lower blood pressure even in people for whom medication has not worked. It’s not clear why warm water has this effect. One theory is that heat dilates blood vessels, improving the flow of blood through the body.