Nutritional diseases are health conditions that arise from an imbalance in nutrient intake. This can occur due to deficiencies, excesses, or imbalances of essential nutrients like vitamins, minerals, proteins, carbohydrates, and fats. Common examples include scurvy, caused by a lack of vitamin C, and obesity, which can result from excessive calorie consumption. These diseases can affect anyone, but certain populations, such as the elderly or those with limited access to healthy foods, are at higher risk. Prevention often involves a balanced diet rich in a variety of foods, ensuring that all necessary nutrients are consumed in appropriate amounts.