Its true that one should not 100% depends on raw food. But there are several times that while cooking many of the vitamins and minerals get burned and become less nutritional. So we should avoid excess cooking of food and make it half cooked so that its easy to cook and also retain its nutritional property. Green vegetables and fruits have abundant of nutritional component and one should know importance of vitamins and minerals to our body. Their are many health sites offering us information on vitamins and minerals - Nutrition.gov Homepage and Vitamin benefits health guide