05 Mar Immunogreulatory Activity
Various in vitro experiments have examined the actions of royal jelly and its constituents on the immune system.
Experiments in animals have demonstrated immunoregulatory activities, with the administration of royal jelly (500 to 1,500 mg/kg body weight/day) increasing survival in tumor-bearing mice and demonstrating positive effects on bone marrow stem cells and tumor-induced splenic hematopoiesis.
Additionally, auto-immunity was inhibited in systemic lupus erythematous-prone mice, with a delay in disease progression, decreased proteinuria, and increased survival.
Increased healing rates were observed in guinea pig tympanic membrane perforation.
In an in vitro study using lymphocytes from healthy volunteers and patients with Graves disease, royal jelly caused lymphocytes to proliferate and certain cytokines to be secreted, suggesting a potential immunomodulatory role in the management of this disease.
In rats and in vitro experiments, insulin-like activity has been shown with royal jelly, and components may be structurally and functionally related to insulin. In an insulin-resistance model in rats, royal jelly reduced plasma insulin and triglycerides without affecting plasma glucose levels.
Traditional use of royal jelly in preventing aging has led to experiments regarding neuronal activities. Stimulation of production of glial cell line-derived neurotrophic factor has been demonstrated in the adult mouse brain, with a prediction of a neuroprotective role for royal jelly.
In addition, 10-hydroxy-trans-2-decanoic acid increased the generation of neurons from neural stem (progenitor) cells in vitro, while adenosine monophosphate stimulated neuronal differentiation of pheochromocytoma PC12 cells.
Activity on the pituitary gland in middle-aged rats has also been demonstrated, and orally administered royal jelly increased granule cell content in the hippocampus, with an observed improvement in induced cognitive impairment in mice.
A meta-analysis of royal jelly’s reported effects on serum lipids in experimental animals and in humans found significant, positive results.
The substance significantly decreased serum and liver total lipids and cholesterol in rats and mice, and retarded the formation of atheromas in the aortas of rabbits fed hyperlipidemic diets.
Meta-analysis of controlled human studies also showed significant reduction in total serum lipids and cholesterol, and, in those with hyperlipidemia, it normalized HDL- and LDL-cholesterol determined from decreases in beta/alpha lipoproteins.
The author of this meta-analysis concluded: “The best available evidence suggests that royal jelly, at approximately 50 to 100 milligrams per day, decreased total serum cholesterol levels by about 14% and total serum lipids by about 10% in the group of patients studied.”
One group of researchers has reported that a royal jelly extract has potent antibiotic effects against gram-positive bacteria, but not against gram-negative bacteria. Royal jelly has exhibited immunomodulating effects in an animal model, stimulating antibody production and immunocompetent cell proliferation.
It has been claimed, anecdotally, for some time that royal jelly has anti-inflammatory effects and wound-healing properties. These claims were given preliminary support in a study of streptozotocin-diabetic rats. The researchers were looking for a hypoglycemic effect from royal jelly; none was found, but the researchers noted that royal jelly showed some anti-inflammatory activity and that it shortened healing time in desquamated skin lesions.
There have been scattered repots that royal jelly and its constituent 10-hydroxy-2-decenoic acid might have anti-cancer effects. There was one report that both provided complete protection against transplantable mouse leukemia. Tumor growth inhibition of other cancers has been associated with royal jelly supplementation in other animal models. More research is needed.
Small clinical trials have demonstrated mixed effects on the lipid profile in humans. Royal jelly administered at 10 g/day for 14 days increased serum high-density lipid (HDL) levels in elderly participants, while a trend toward improved low-density lipid (LDL) levels was seen with no effect on serum triglycerides.
In another trial, 6 g/day for 4 weeks resulted in decreased serum total cholesterol and LDL, but had no effect on HDL or triglycerides.