B12 Vitamin
A vitamin is a chemical substance that’s required for a particular chemical reaction to occur in the body, but isn’t synthesized by the body, and so should be included in the diet. The diet requirements for normal function are generally comparatively little. Most vitamins that are known today were discovered because their deficiency causes distinguishable diseases. Examples are scurvy, due to a deficiency of vitamin C, which ultimately motivated English sailors to carry limes onboard ship, and beriberi, due to a deficiency of thiamin, or vitamin B1.