The relationship between diet and diseases is a fundamental area of study in nutritional research. An unhealthy diet, characterized by high intake of processed foods, sugars, and saturated fats, has been linked to the development of non-communicable diseases (NCDs) such as obesity, type 2 diabetes, and cardiovascular diseases. On the other hand, a nutrient-rich diet, abundant in fruits, vegetables, whole grains, and lean proteins, is known to reduce the risk of these chronic conditions. Researchers study how specific dietary patterns—like the Mediterranean diet or plant-based diets—can prevent or manage diseases. Personalized nutrition, based on individual genetic and metabolic profiles, is an emerging field that explores how tailored diets can optimize health and disease prevention.