They’re an excellent source of plant protein and contain vitamins, minerals, antioxidants, and polyphenols. But the way they’re cooked can significantly change their nutritional quality. Spanish researchers tested various cooking methods on four popular types of mushrooms—white button, shiitake, oyster, and king oyster—and found that grilling or microwaving produced the best results. Both methods increased levels of antioxidants and polyphenols (beneficial plant nutrients), and did not significantly reduce other nutrients. However, frying or boiling greatly reduced protein and antioxidant content. Study results were published in the International Journal of Food Sciences and Nutrition.