For those searching for an optimum dose this
article notes that:
Snehasikta Swarnakar, senior scientist at Indian Institute of Chemical Biology (IICB)`s Drug Development Diagnostic and Biotechnology Division said...
It (curcumin) has been shown to be a good cure for gastric ailments like inflammation and ulceration. While its low doses are not effective, at high doses it might aggravate the situation. But we have come up with the optimum dose at which curcumin is therapeutic. ... For rats, the proper dose is around 50 mg per kg of their body weight, which is equivalent to 100 mg per kg of body weight in humans.