The clinical usefulness of turmeric, as a medicine, in humans has not been confirmed. It can only be sold as a spice and as a food supplement; not a medicine.
In pre–clinical, in-vitro and animal models, turmeric and derivative compounds such as curcumin and tumerone have demonstrated anti-oxidant, anti-neoplastic, neuro-protective and anti-inflammatory properties. However, drug companies develop thousands of promising new treatments that show efficacy in-vitro and in animal models but very, very few of these eventually prove to be safe and beneficial for human patients.
Most ingested curcumin is excreted through faeces (not absorbed) and more than half that is absorbed is quickly broken down (metabolised) in the intestine (studies indicate that this happens to a greater extent in humans than in animal models). Therefore, the amount of curcumin that reaches tissues outside the gut is probably pharmacologically insignificant.
Most studies have failed to demonstrate any positive results with curcumin in human studies and those that have are: small scale; mainly conducted outside of Europe and the US (China and India); poorly designed; and published in obscure journals. Additionally, many of the studies involved conflicts of interest with ‘researchers‘ owning supplement companies. To provide a real clinical benefit, curcumin must be absorbed, must be distributed in an adequate concentration in the blood and remain in the system for a sufficient period, and at an effective concentration level. This appears to be unlikely and despite promising results in animal studies. There is also little evidence that high intakes of curcumin or turmeric are associated with a decreased cancer risk in humans.
Turmeric and its derivatives are not a magic bullet or cure-all.