Royal jelly, also known as gelee royale and RJ, is the milky-white gelatinous substance secreted from the cephalic glands of nurse worker bees (Apis mellifera) for apparently the sole purpose of stimulating the growth and development of the queen bee. Without royal jelly, the queen bee would be no different from the worker bees and would live about as long (seven to eight weeks). With royal jelly, the queen bee can live five to seven years. This fact explains the popular belief that royal jelly has rejuvenating qualities.
Royal jelly consists of an emulsion of proteins, sugars, lipids and some other substances in a water base. Proteins make up about 13% of royal jelly. Most of the proteins comprise a family called major royal jelly proteins. One protein in royal jelly called royalsin possesses antibiotic properties against gram-positive, but not gram-negative, bacteria. About 11% of royal jelly is made up of sugars, such as fructose and glucose, similar to those found in honey. Lipids comprise about 5% of the substance and consist mainly of medium-chain hydroxy fatty acids, such as trans-10-hydroxy-2-decenoic acid, which is also thought to possess antimicrobial properties.
Royal jelly also contains vitamins, such as pantothenic acid, minerals and phytosterols. Neopterin, or 2-amino-6- (1,2,3-trihydroxypropyl)-4 (3H)-pteridinone, was initially isolated from royal jelly. Neopterin is also found in humans, and, although its precise role is not known, it appears to play an important role in the human immune system.