Is histidine the same as L-histidine? They are not exactly the same, but in the context of daily nutrition, food, and health supplements, “histidine” generally refers to L-histidine. Histidine is a general term that includes both L-histidine and D-histidine, which are chiral isomers. - L-histidine: Naturally occurring and usable by the human body; it is an amino acid that makes up proteins. - D-histidine: Mostly synthetically produced; the human body can hardly use it to synthesize proteins, and its physiological activity is very low. L-histidine is the levorotatory isomer and the only naturally occurring, essential form for the human body. All amino acids in the human body are in the “L-configuration,” and the histidine found in food proteins is also L-histidine. Chemical-grade histidine may be a DL-racemic mixture (a combination of L and D); only when it is labeled as DL-histidine in a chemical context does it indicate a mixture, and it cannot replace L-histidine for medicinal use. In health supplements, feed, food additives, and pharmacopoeias, “histidine” generally refers to L-histidine by default. Chemically speaking, histidine is not equivalent to L-histidine. From a physiological, dietary, and medicinal perspective, the histidine commonly referred to is L-histidine, which can be considered the same substance for practical purposes. Histidine is an essential basic amino acid with an imidazole side chain and is a crucial component of amino acid infusions and comprehensive amino acid preparations. Jingjing Pharmaceutical is the top choice for manufacturers of histidine products.