The Mediterranean secret to longevity and a healthy heart is down to a simple tomato sauce, researchers believe.Sofrito - made out of tomato as the main ingredient along with onion, olive oil, corn flour and occasionally garlic - is eaten widely around the Med but scientists could help prevent a heart attack or stroke.Spanish researchers have found that tomato-based sauce contains as many as 40 antioxidants, called polyphenols, which are believed to protect the heart from 'oxidative stress.'Polyphenols are natural antioxidant molecules derived from vegetables.But to get the health benefits the ingredients have to be combined in the sauce, rather than eaten separately.Scientists from the Universty of Barcelona tested various sauces available from supermarkets made using ingredients that had been produced on regular farms.Rosa Lamuela said: 'Those sofrito which contain extra-virgin olive oil have better antioxidant properties as they are richer in phenolic compounds.'Those with better antioxidant properties are the ones which contain protocatechuic acid, for instance quercetin.'The differences found among sofrito samples may be due to their different ingredients - tomato, garlic, onion, olive oil - and different proportions used to cook them.'Experiments on supermarket sofrito revealed the eating the combination of ingredients as a sauce brought greater health benefits than eating each on its own.Anna Vallverdz Queralt added: 'First, there is a synergistic effect among ingredients which is translated into a higher number of total polyphenols.'Second, the sofrito contains more polyphenols than tomato or tomato juice because garlic, oil and onion provide polyphenols too.'The researchers used a technique called high-resolution mass spectroscopy also found a number of other health-protecting compounds including carotenoids, another kind of antioxidant in the sofrito.The study was published in the journal Food Chemistry.(dailymail.co.uk)ANN.Az