A Narrative Review of 30 Years of Basic Research in Homeopathy

Background: The research field of basic homeopathic research is diverse, covering multiple areas, from physical investigations to animal research. Even though there are still a lot of open research questions, it is also possible to extract trends and testable hypotheses from the variety of approaches and results hitherto obtained. Taking the working group coordinated by Stephan Baumgartner as an example, the development and the results from the different experimental assays used over the last three decades were assessed. Methods: A narrative literature review was conducted on all original research (including replication trials and collaborations) published over the past 30 years by members and collaboration partners of the Baumgartner working group. After the literature search, all publications were categorized into different experimental assays. Results were extracted and discussed. Results: Twenty experimental assays were identified, covering the fields of physical investigations, bioassays with plants and microorganisms, and cell-based assays. A total of 32 original research articles were published, including seven publications on replication trials. The assays introduced the concept of systematic control experiments for investigating the stability of experimental setups. Treatment groups involved potency levels above the inverse of Avogadro’s constant in 28 publications. Twenty-four publications reported significant differences between control and treatment groups, and an additional three publications reported day-dependent effects. Conclusion: Overall, 20 experimental assays were used within 30 years. They showed the relevance of replication trials to detect possible influencing factors and outlined the value of systematic control experiments. Synthesizing and comparing all results obtained, some tentative overarching trends and patterns were identified, such as influences of the physiological status of the organism on the effects of homeopathic preparations. These patterns and trends can be developed into testable hypotheses to approach the mode of action of potentised preparations.