The Kohrle group in Germany have started looking at the host of thyroid hormone-type substances in small amounts whose biochemical importance in the body is not known. This is an interesting paper showing that one of these has an effect on insulin secretion:
3-Iodothyronamine reduces insulin secretion in vitro via a mitochondrial mechanism
July 2017Molecular and Cellular Endocrinology
ncbi.nlm.nih.gov/pubmed/287...
Ina Lehmphul at Charité Universitätsmedizin Berlin
Ina Lehmphul
20.7Charité Universitätsmedizin Berlin
Carolin Stephanie Höfig at Charité Universitätsmedizin Berlin
Carolin Stephanie Höfig
29.72Charité Universitätsmedizin Berlin
Josef Köhrle at Charité Universitätsmedizin Berlin
Josef Köhrle
46.62Charité Universitätsmedizin Berlin
There no doubt will be quite a lot more of these minor chemicals that have their own effect on body working.