Antioxidants are substances that are capable of slowing down the autoxidation process of other compounds or neutralize free radicals. They have been used in food processing industries as a means to hinder oxidation, enhance flavor, aroma and color. Antioxidants have also been used and valued for treatment of various diseases such as cancer and coronary heart disease. Even though, synthetic antioxidants including butylated hydroxytoluene (BHT) may cause side effects to human health and presumed unsafe to be used, they are the ones in a great use in the area of food processing industries as most food and pharmaceutical products contain them. The objective of this review work is therefore to provide an overview of the findings related to the presence of antioxidants in plant sources particularly those that have not been extensively studied and evaluated such as fruits and vegetables by-products. To minimize their effects, researches have been conducted aiming to substitute them with antioxidants from natural sources. Recent studies show that synthesis of natural antioxidants from fruit and vegetable waste has gained great attention. Further research has to be performed on plant phenols and processing of agricultural and industrial by-products as a potential source for extraction of antioxidants. In order to increase the affirmative effect and usefulness of antioxidants to human health, it is recommended to follow a balanced and varieties of diets instead of taking antioxidant supplements on a regular basis. Therefore, we should consume a diet high in antioxidant rich fruits and vegetables day by day. Furthermore, nutritional importance, promotion of health and prevention against damages caused by free radicals can lead to the potential applications of antioxidants in food industries in more intensified approaches. In a nutshell, antioxidant foods and ingredients are an important component of the food industry and thus reconsidering the health implications of adding antioxidants to foods require unfathomable investigations.