Sushil,
I think reserveratrol has the potential to help thal intermedia and thal minor in a different way than it would help thal majors. In thal minor & intermedia it likely helps them by increasing the number of red blood cells that will be healthy and functional.
In thal major, it will help by protecting the integrity, function and lifespan of transfused cells - also in thal majors the other protective properties and antioxidant properties that resveratrol has to offer are very very beneficial.
Sharmin