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Effect of royal jelly ingestion for six months on healthy volunteers

Hiroyuki Morita*, Takahide Ikeda, Kazuo Kajita, Kei Fujioka, Ichiro Mori, Hideyuki Okada, Yoshihiro Uno and Tatsuo Ishizuka

Author affiliations

Department of General Internal Medicine, Gifu University Graduate School of Medicine, Gifu, 501-1194, Japan

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Citation and License

Nutrition Journal 2012, 11:77  doi:10.1186/1475-2891-11-77

Published: 21 September 2012

Abstract

Background

Royal jelly is a widely ingested supplement for health, but its effects on humans are not well known. The objective was to evaluate the effects of long-term royal jelly ingestion on humans.

Methods

We conducted a randomized placebo-controlled, double-blind trial. A total of 61 healthy volunteers aged 42-83 years were enrolled and were randomly divided into a royal jelly group (n = 31) and a control group (n = 30). Three thousand mg of royal jelly (RJ) or a placebo in 100 ml liquid/day were ingested for 6 months. The primary outcomes were changes in anthropometric measurements and biochemical indexes from baseline to 6 months after intervention.

Results

Thirty subjects in the RJ group and 26 in the control group were included in the analysis of endpoints. In an adjusted mean change of the variables from the baseline, significant differences between the two groups could be found in red blood cell counts (+0.16x106 /μL for the RJ group vs. -0.01x106 /μL for the control group, P = 0.0134), hematocrit (+0.9% vs. -0.8%, P = 0.0251), log (fasting plasma glucose) (+0.01 ± 0.01 log mg/dL vs. +0.05 ± 0.01 log mg/dL, P = 0.0297), log (insulinogenic index) (+0.25 vs. -0.13, P = 0.0319), log dehydroepiandrosterone sulfate (DHEA-S) (+0.08 log μg/dL vs. +0.20 log μg/dL, P = 0.0483), log testosterone (T) (+0.12 ± 0.04 log ng/mL vs. -0.02 ± 0.05 log ng/mL, P = 0.0416), log T/DHEA-S ratio (+0.05 ± 0.05 vs. -0.23 ± 0.59, P = 0.0015), and in one of the SF-36 subscale scores, mental health (MH) (+4 vs. -7, P = 0.0276).

Conclusions

Six-month ingestion of RJ in humans improved erythropoiesis, glucose tolerance and mental health. Acceleration of conversion from DHEA-S to T by RJ may have been observed among these favorable effects.

Keywords:
Testosterone; Dehydroepiandrosterone sulfate; Erythropoiesis; Glucose tolerance; SF-36