Recently, a renewed interest in vegetarian diets is expressively considered. Vegetarian diets are comprising a wide range of dietary sources for numerous and individual dietary requirements. Basically, the vegetarian diets were classified into lacto-ovo-vegetarians, lacto-vegetarians, ovo-vegetarians and vegan which have further restrictions imposed and exclude animal origin foods. Additionally, vegetarians tend to have lower overall cancer rates, lower body mass index,adjustable blood pressure, have higher levels of dietary fiber, minerals, vitamins and phytochemicals. Increasing public awareness about vegetarian diets has propelled the consumption of these foods to unprecedented levels, particularly in countries where the population is aging and health care costs are rising. Many topics should be focused to valorize this concept such as vegetarian functional foods, nutraceuticals and phytochemicals, health-promoting components, development of vegetarian diets, vegetarian diets and disease prevention, challenges and deficiency, regulations and health claim as well as effect of food processing on their bioactive compounds.