Aren most important nutrients, like protein and fiber, fairly stable in food and unaffected by cooking?
No, cooking affects most nutrients, including macronutrients like protein and fiber. While cooking seldom destroys protein or fiber, overcooking (either for too long, or at too high a temperature) can alter the structure of nutrients and decrease their health benefits. In some cases – like heating polyunsaturated oils – helpful macronutrients are actually converted into harmful ones. Nutrition has traditionally focused on macronutrients like protein and fiber, and micronutrients like vitamins and minerals. But there are also a vast array of other nutrients in food. Plant foods contain thousands of compounds that are collectively known as phytonutrients (phyto=plant).
