A vitamin pill — also called a vitamin supplement — is a tablet or capsule containing one or several vitamins, sometimes with minerals, taken to supplement the diet. The single-nutrient versions target known needs: vitamin D in winter, folic acid before and during early pregnancy, B12 for vegans. Multivitamins offer broad insurance in one dose. They are useful where diets fall short, but they are not a substitute for food: pills lack fibre, phytochemicals, and the food matrix that governs absorption, and megadoses of fat-soluble vitamins can cause harm. Quality varies between brands, and in most countries supplements face lighter regulation than medicines — a reason to choose reputable manufacturers.