Letters: January 2020

Regarding the trials of turmeric (Chemistry World, December 2019, p50), it is important to note that the concept of the microbiome is slowly coming in from the cold, even though there is not yet any agreed mechanism by which it exerts its effects. It is likely that turmeric gains its benefit by not being absorbed into the body, and therefore simply passing on down to feed our microbiota. There is ample evidence that an effective, working microbiome can produce messenger chemicals such as dopamine and serotonin that improve our health via stimulation of the gut–brain axis. Conversely, turmeric may be ineffective in those individuals whose microbiome is not working effectively. The implications of this understanding are profound. In particular, searching for bioactive compounds that explain the activity of a complex insoluble mixture such as turmeric may yet turn out to be a prolonged and expensive folly.