Development of a simple bioassay to enable citizen science projects in basic homeopathic research

Homeopathy is a form of complementary medicine that - despite the controversial debate in the media - is frequently used in several countries worldwide. Criticisms of homeopathy primarily concern the process of potentisation, arguing that high dilutions are unlikely to contain any active ingredient. To overcome the current impasse, citizen science may offer a promising means of encouraging dialogue and collaboration. Accordingly, our objective was to develop a very simple bioassay that would facilitate replication and multi-centre trials without the need for sophisticated equipment. Cress seeds ( Lepidium sativum L.) were grown in vitro within calcium nitrate salt tolerance levels, resulting in a moderate reduction of the seedling length compared to cress grown in water. Screening experiments were conducted with seven homeopathic preparations ( Aurum muriaticum natronatum , Nitricum acidum , Carbo vegetabilis , Natrium muriaticum, Nux vomica, Phosphorus and Silicea ) in the potency levels 10x, 20x, 30x (applied as commercially available globules) with 160 cress seeds per condition. Corresponding systematic negative control (SNC) experiments were performed to assess the stability of the experimental set-up. The primary outcome parameter was total seedling length, whereas shoot length and root length were considered secondary parameters. The experiments with the homeopathic samples demonstrated unequivocal, statistically significant growth-modulating effects compared to control (unimpregnated globules) for multiple preparations in different potency levels for both sets of parameters (p < 0.001 for root length for the combined 10x and 20x treatments; whereas for the 30x treatments p < 0.001 for root and total length and p < 0.01 for shoot length). The SNC experiments did not result in statistically significant effects, thus documenting the stability of the experimental set-up. The results of this very simple bioassay provide a foundation for future citizen science initiatives in homeopathic basic research. Further replication experiments are necessary to identify potential influencing factors, including seasonal effects.