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The 12-year study, which involved more than 800 participants, is the first to use a specific biomarker (in this case, urine analysis) to measure polyphenol levels, instead of relying on questionnaires. "The results corroborate scientific evidence suggesting that people consuming diets rich in fruit and vegetables are at lower risk of several chronic diseases and overall mortality," lead author Raúl Zamora Ros, PhD, of the University of Barcelona, said in a statement. "This methodology makes a more reliable and accurate evaluation of the association between food intake and mortality or disease risk," added colleague Cristina Andrés Lacueva, PhD.
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A polyphenol-rich diet includes at least 650 milligrams a day. Below is a list of 20 commonly available foods that are among the 100 richest dietary sources of polyphenols (polyphenol content listed as mg/100 g serving):
Don't stick to just the top-listed foods, though. "Any plant-based foods are good in their whole form," Angela Lemond, RDN and spokesperson for the Academy of Nutrition and Dietetics, tells Yahoo Shine. In general, polyphenol-rich foods are bright-or dark-colored and have a strong or astringent flavor. She recommends adding fruits and vegetables to breakfast and lunch, since most people focus on their dinner menus. Another trick is to slip vegetables into sandwiches and pack a colorful salad for lunch. She also says, "Branch out from your favorites and experiment with seasonal produce." The orange and red foods that are now hitting markets and farm stands are great sources of polyphenols. For kids, Lemond suggests cutting fruits and vegetables into snack sizes and storing them at eye level in the refrigerator.
Polyphenols are found in thousands of combinations in hundreds of different foods, and for maximum benefit, its helpful to eat a variety over the course of the day to keep blood levels high. Consume produce when it's fresh, because the beneficial compounds deteriorate with age. "There is also some destruction with heat," says Lemond. Cooking, especially deep-frying and boiling, can destroy them, but steaming retains the highest degree. Because some nutrients are released by cooking, she generally recommends eating a mixture of raw and cooked food. Processing foods can destroy the healthy compounds, so choose whole grains that are minimally processed. Also, leave skins on fruits and vegetables for maximum benefit.
Spices and herbs such as cloves, rosemary, oregano, and many others are superrich in polyphenols, so season your meals liberally. Beverages contain polyphenols too, especially coffee, green and black tea, red wine, and beer. Dark juices and citrus juices are good choices, but to keep calories in check, avoid high levels of added sugar.
To learn more, Phenol-Explorer is an open-access database that lists values for over 500 different polyphenols found in more than 400 foods. It also includes information on the effects of processing and cooking on nutrient retention.