The immunostimulatory effects and chemical characteristics of heated honey

Ethnopharmacological relevance: In traditional Chinese medicine (TCM), honey has been used as an additive in the heat-processing of herbal medicines to enhance their immunostimulatory activities. Aim of the study: We investigated the immunostimulatory activity of heated honey in vitro and in vivo. Materials and methods: For the in vitro study, we compared the differences among the inducible effects of honey subjected to various heating conditions on granulocyte colony-stimulating factor (G-CSF) secretion from the cultured enterocytes and investigated the active ingredient. For the in vivo study, we conducted a survival test of mice infected by Streptococcus pyogenes with and without oral administration of heated honey. Results: We found that heating the honey induced the appearance of G-CSF secretions from the cultured enterocytes, and that this appearance depended on the heating temperature and time. No G-CSF secretions appeared when honey was not heated. Mice infected with Streptococcus pyogenes that were fed heated honey revealed prolonged survival. The active ingredient in heated honey was a high-molecular compound with about 730 kDa. When this compound was hydrolyzed, galactose, glucose, rhamnose, α-ribofuranose β-ribofuranose 1,5′:1′,5-dianhydride, and 5-hydroxymethylfurfural were generated. Conclusions: Heated honey reveals immunostimulatory activity both in vitro and in vivo. These results support the scientific evidences of the TCM theory.