Choline chloride and choline bitartrate are used in dietary supplements. Choline hydroxide is known as choline base. Choline can also be released from more complex choline containing molecules. The enzyme acetylcholinesterase converts acetylcholine into the inactive metabolites choline and acetate. Because it contains phosphatidylcholines, lecithin is a source of choline, an essential nutrient. Sarcosine is found naturally as an intermediate in the metabolism of choline to glycine. AChE is a hydrolase that hydrolyzes choline esters. Elevated ALT may also be caused by dietary choline deficiency. Nonetheless, there is little acetylcholine in the human body relative to other forms of choline. Cholinesterases are enzymes that facilitate hydrolysis of the esters of choline. Trimethylglycine is a functional metabolite of choline. Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. N-cyclohexylcholine inhibits choline uptake primarily in brains. The phosphate serves as a link to another alcohol-usually ethanolamine, choline, serine, or a carbohydrate. Symptomatic choline deficiency is rare in humans.