Choline is the most recent compound to be added to the list of essential nutrients. Though not a B vitamin, it is a water-soluble compound and its function in the body is intertwined with that of folate and vitamin B12. In addition, it forms the critically important neurotransmitter, acetylcholine, and it is part of two of the most abundant phospholipids in cell membranes. The primary sign of a choline deficiency is liver damage. Though we are capable of synthesizing choline, it is considered an essential nutrient because many people, particularly men, require dietary sources to meet their needs. Excessive intake of choline, typically only through supplementation, causes a fishy body odor and a slight drop in blood pressure.