Laboratory studies of homeopathic medicines. An update

Homeopathy is one of the most common complementary and alternative therapies, used with the aim to increase the ability of the body to fight cancer, to improve physical and emotional well-being, and to relieve adverse effects of chemotherapy. Observational studies seemed to show benefits, but randomized clinical trials are very few and there is complete lack of independent replication. Research in homeopathy finds obstacles also in the widsespread belief that the efficacy of homeopathic medicines is due to placebo effects only. Therefore, preclinical and laboratory studies of homeopathic medicines and investigation of homeopathic principles (similia and dilution/dynamization), under controlled conditions, may help to clarify many still unanswered questions. We review the literature of animal models where homeopatic medicines have been tested for their effect on genotoxicity, carcinogenesis , immune modulation, and anxiety. Furthermore, the results of a series of in vitro assays of homeopathic medicines or of hightly diluted substances (e.g. histamine) will be reviewed. These studies deal with the isopathic principle (a low concentration of a toxic substance enhances self-recovery in a system damaged by a hight dose of the same substance), with induction of apoptosis in cancer cells (macrophages, lynphocytes, granulocytes basophils). Some authors showed distinct alterations in genes expression related to apoptosis by homeophatic remedies tested in different potencies, butr others did not confirm these results. This suggests that the effects observed in the in vivo experiments cannot be explained only by a direct regulation of cell growth, death or differentiation. Future research should explore subtle modulations in the expression of multiple genes, in different biological pathways, and expand the investigation on animal models of immune regulation, of stress response, and of inflammation.