Why can very-low-calorie diets require vitamin and mineral supplements?

Very-low-calorie diets (VLCDs) require vitamin and mineral supplementation because the extreme restriction of food intake—sometimes as low as 300 calories per day—makes it difficult for the body to obtain the essential nutrients required for proper physiological function.1

When caloric intake is severely limited, the diet may become nutritionally unsound, failing to provide the necessary vitamins, minerals, and macronutrients needed to maintain health. Because these restrictive plans can be dangerous, they should only be undertaken under strict medical supervision to ensure that the dieter receives adequate nourishment despite the significant reduction in food volume. In cases of fasting or highly restrictive dieting, supplements are often necessary to prevent deficiencies that occur when the body is deprived of its standard intake of food.1