Diet plays a key role in oral disease prevention. The aims of this report were to review the causes and consequences of a poor diet and its interrelationship with oral health. The first signs of micronutrient deficiencies are often manifest in the oral tissues. Consequently, the dentist has a considerable role in the early diagnosis of malnutrition. Furthermore, optimizing oral health is important in maximizing functional capacity to consume a healthful and varied diet. A varied diet is, otherwise, fundamental to save oral health.