Royal jelly is a honey bee secretion that is used in the nutrition of larvae and adult queens. It is secreted from the glands in the hypopharynx of worker bees, and fed to all larvae in the colony. When worker bees decide to make a new queen, either because the old one is weakening, or was killed, they choose several small larvae and feed them with copious amounts of royal jelly in specially constructed queen cells.

This type of feeding triggers the development of queen morphology, including the fully developed ovaries needed to lay eggs. Royal jelly is secreted from the glands in the heads of worker bees, and is fed to all bee larvae, whether they are destined to become drones (males), workers (sterile females) or queens (fertile females). After three days, the drone and worker larvae are no longer fed with royal jelly, but queen larvae continue to be fed this special substance throughout their development. It is harvested by humans by stimulating colonies with movable frame hives to produce queen bees. Royal jelly is collected from each individual queen cell (honeycomb) when the queen larvae are about four days old. It is collected from queen cells because these are the only cells in which large amounts are deposited; when royal jelly is fed to worker larvae, it is fed directly to them, and they consume it as it is produced, while the cells of queen larvae are "stocked" with royal jelly much faster than the larvae can consume it. Therefore, only in queen cells is the harvest of royal jelly practical.

A well-managed hive during a season of 5–6 months can produce approximately 500 g of royal jelly. Since the product is perishable, producers must have immediate access to proper cold storage (e.g., a household refrigerator or freezer) in which the royal jelly is stored until it is sold or conveyed to a collection centre. Sometimes honey or beeswax are added to the royal jelly, which is thought to aid its preservation.

Composition
Royal jelly is collected and sold as a dietary supplement for humans, claiming various health benefits because of components such as B-complex vitamins such as pantothenic acid(vitamin B5) and vitamin B6 (pyridoxine).

The component of royal jelly that causes a bee to develop into a queen appears to be a single protein that has been called royalactin. Jelly which had been rendered inactive by prolonged storage had a fresh addition of each of the components subject to decay and was fed to bees; only jelly laced with royalactin caused the larvae to become queens.[5] Royalactin also induces similar phenotypical change in the fruitfly (Drosophila melanogaster), marked by increased body size and ovary development.

Royal jelly has been reported as a possible immunomodulatory agent in Graves' disease. It has also been reported to stimulate the growth of glial cells and neural stem cells in thebrain. To date, there is preliminary evidence that it may have some cholesterol-lowering, anti-inflammatory, wound-healing, and antibiotic effects, though the last three of these effects are unlikely to be realized if ingested (due to the destruction of the substances involved through digestion, or neutralization via changes in pH). Research also suggests that the 10-Hydroxy-2-decenoic acid (10-HDA) found in royal jelly may inhibit the vascularization of tumors. Royal jelly has also been hypothesized to correct cholesterol level imbalances due to nicotine consumption.

There are also some preliminary experiments (on cells and lab animals) in which royal jelly may have some benefit regarding certain other diseases, though there is no solid evidence for those claims, and further experimentation and validation would be needed to prove any useful benefit. In holistic healing circles and popular alternative medicine folklore, royal jelly is believed to have anti aging properties stemming primarily from its amino acid content and broad spectrum of vitamins and minerals. Its reputation for providing fertility and libido assistance is also gaining traction within the holistic community, though little or no clinical research exists to support these assertions. Royal jelly is also widely used as a component in skin care and natural beauty products.
Royal jelly may cause allergic reactions in humans ranging from hives, asthma, to even fatal anaphylaxis. The incidence of allergic side effect in people that consume royal jelly is unknown. However, it has been suggested that the risk of having an allergy to royal jelly is higher in people who already have known allergies.