Hello, I'm from Bangkok
People here eat lots of tumeric since we love spicy food. Strange as it may seem, no one here has gallstone. Tumeric is quite safe since it is a spice and we eat a lot of curry food. The amount we eat in diet such as chicken curry food is about 1/2-2 tablespoon per day. Depending on the food. However, you can make a relatively agreeable tuna sandwich with about 1/2 teaspoon mixed with your tuna. Eat enough, you can get 2 tablespoon within a day. Experiment.
There was a study where mice was experimentally induced Gallstones were fed modest amounts of turmeric. Within 5 weeks their gallstone volume had dropped by 45 percent, and after 10 weeks, by 80 percent.
Because curcumin increases the solubility of bile, it may help prevent Gallstones from forming. So cook lots of curries--and go heavy on the turmeric.