A dietary supplement is a manufactured product intended to supplement the diet when taken by mouth as a pill, capsule, tablet, or liquid.A supplement can provide
nutrients either extracted from food sources or synthetic, individually or in combination, in order to increase the quantity of their consumption. The class of nutrient compounds includes
vitamins,
minerals,
fiber,
fatty acids and
amino acids. Dietary supplements can also contain substances that have not been confirmed as being essential to life, but are marketed as having a beneficial biological effect, such as plant
pigments or
polyphenols. Animals can also be a source of supplement ingredients, as for example
collagen from chickens or fish. These are also sold individually and in combination, and may be combined with nutrient ingredients. In the United States and Canada, dietary supplements are considered a subset of foods, and are regulated accordingly. The
European Commission has also established harmonized rules to help insure that food supplements are safe and properly labeled.