Roasting coffee beans cuts the health benefits - and could even affect your risk of heart attack and stroke

Caffeine compounds found in coffee are known to ward off high blood pressure 

But study found coffee beans that have been highly roasted are less beneficial

Coffee beans are roasted to bring out their aroma and flavour 

The type of roasted coffee you drink could affect your risk of heart attack and stroke, British scientists say.Caffeine compounds found in coffee are known to ward off high blood pressure.But a study has found that if the coffee beans have been highly roasted then the drink is less beneficial for your health.

A coffee that is highly roasted could lose some of the benefits for blood pressure, heart attack and stroke, because of the chlorogenic acid lost during the roasting process.It means more than three times as much highly roasted would have to be drunk to get the benefits of a normal mug. This is a polyphenol – a plant-based micronutrient that protects the heart.

Reading University’s Dr Jeremy Spencer, co-author of the research, said: ‘We found the more gently you carry out the heating process, the more you keep low levels of these compounds, which improve the function of your circulatory system and reduce the risk of developing high blood pressure.’

Coffee beans are roasted to bring out their aroma and flavour, and become richer and more bittersweet the longer they are heated. Restaurants often serve highly roasted coffee after a meal, because the depth of flavour works following rich food.

Researchers compared differently roasted instant and pre-ground coffee, ranging from Nescafe Green Blend, which includes unroasted beans, to Sainsbury’s ‘after-dinner’ and ‘continental-style’ varieties – the highest roasted of those analysed. Green coffee beans are fashionable among the health-conscious, and Nescafe states that its brand contains antioxidants on the jar.

The study found it contained 121.25mg of chlorogenic acid per cup when brewed, compared with just 27.33mg for Sainsbury’s French coffee.Morrisons full roast coffee had 37mg, compared to 54mg for its gold decaf brand.Sainsbury’s breakfast coffee had 94.47mg of chlorogenic acid, with its French coffee offering the lowest level. Nescafe gold decaf contained only 43.26mg.The study said 400mg of chlorogenic acid may cut blood pressure in healthy people.As a consequence of the drop in chlorogenic acid, the study said, choice of coffee ‘may have a large influence on the potential health potential of coffee intake’.Chris Stemman, of the British Coffee Association, said: ‘It’s also important to remember that other components of coffee, such as caffeine, are also associated with positive effects on health.’