A review published by Japanese scientists evaluated the effect of royal jelly on the immune system. Royal jelly contains proteins and lipids by about 10% (dry matter basis). 10 -Hydroxy-trans-2-decenoic acid (10H2DA), often referred to as “royal jelly acid,” is a significant and unique lipid component in royal jelly. The effect of 10H2DA on innate and adaptive immunity has attracted many scientists through in vitro and in vivo studies.

Royal jelly has been considered to be beneficial for the treatment of autoimmune and inflammatory diseases. It has been revealed that 10H2DA is involved in some of those activities, including inhibition of lipopolysaccharide (LPS)-and interferon (IFN)–stimulated macrophage responses, inhibition of T-cell proliferation and anti-rheumatoid activity. Other biological activities also involve estrogen-like activity, particularly easing postmenstrual syndromes, anti-tumor activity, promotion of collagen production, and neurogenic activity on brain cells.

Sugiyama, T., Takahashi, K., & Mori, H. Royal jelly acid, 10-hydroxy-trans-2-decenoic acid, as a modulator of the innate immune responses. Endocrine, Metabolic & Immune Disorders-Drug Targets (Formerly Current Drug Targets-Immune, Endocrine & Metabolic Disorders), 2012, 12(4), 368-376.