When it comes to eating fruits and vegetables for heart health, the choice of fruits and vegetables may be just as important as how many they eat, new research suggests.Health experts have long recommended the "five a day" guideline, meaning people should eat five servings total of fruits and vegetables.A group of scientists, however, contends in a new study that adhering to dietary guidelines may not provide enough flavanols — plant compounds linked to cardiovascular benefits.FORGET YOGURT AND SAUERKRAUT: 5 GUT-FRIENDLY FAVORITES MAY ALREADY BE ON YOUR SHELFFlavanols are a type of antioxidant found in plants that has been shown to help improve blood flow and reduce inflammation and has been associated with a lower risk of death from heart disease.The researchers cited previous studies that associated a daily intake of 500 milligrams of flavanols with cardiovascular benefits.Five servings a day of fruits and vegetables — long associated with improved health — may not be as effective for reducing the risk of heart disease, new research suggests.(iStock)"Evidence from the COSMOS trial, the largest randomized controlled study on polyphenols to date, demonstrated that an intake of 500 milligrams [a] day of flavanols significantly reduced cardiovascular disease mortality by 27%," they wrote."Because fruits and vegetables, including legumes, are major sources of flavanols, and fruits and vegetables are emphasized in current dietary guidelines in the U.S., [the U.K.] and by the World Health Organization, it is plausible that adherence to these dietary guidelines could already deliver sufficient flavanol intake levels."No data currently demonstrates whether the recommended fruit and vegetable intake levels and broader healthy dietary patterns provide flavanol levels associated with cardiovascular benefits, the researchers added.CLICK HERE TO SIGN UP FOR OUR LIFESTYLE NEWSLETTERThe scientists analyzed the diets and biomarker data of more than 30,000 adults in the U.S....