Diet supplements are substances you eat or drink. They can be vitamins, minerals, herbs or other plants, amino acids (the individual building blocks of protein), or parts of these substances. They supplement (add to) the diet and should not be considered a substitute for food. They can be in pill, capsule, tablet, or liquid form.
Diet supplements are widely available in health food stores, grocery stores, pharmacies, on the internet, and by mail. People commonly take them for health-related reasons. Common dietary supplements include vitamins and minerals (such as vitamin c or a multivitamin), botanicals (herbs and plant products, such as st. John’s wort), and substances that come from a natural source