Walmart is one, but a number of grocers carry it. We buy Qunol and I take 1000 mg twice a day with meals. I don't have any side effects from it and I'll see with my bloodwork in a few months if it has any effect on kappa levels. You can also search using "bioavailable curcumin" but there are a lot of them out there and no telling if some are overpriced spam. The below link has info on changes that make curcumin better absorbed by the GI tract.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7144558/#:~:text=To%20date%2C%20the%20curcumin%20formulation,to%20unformulated%20curcumin%20%5B15%5D.