Are grilled yellow sweet bell peppers less nutritious than eating them fresh? Take a look at the ORAC measurements of each form, which evaluate their total antioxidant content. The grilled version is 694 while the fresh uncooked fresh yellow pepper is 1043... that's 50% higher! Furthermore, since ORAC uses a standardized weight of 100 grams for testing the food, the destruction of antioxidants is likely an even higher amount. This is because 100 grams of grilled peppers has less water weight than 100 grams of fresh. Therefore, the grilled version is measuring a higher quantity of pepper. Not to mention, the acrylamide formation in foods (the dark brown and black grill marks) are suspected as being a possible carcinogen according to the World Health Organization.
ORAC Source
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010