There have been studies that show positive results from taking omega-3 fatty acids (I don't know the quantities, though). You could try searching bipolar plus omega-3 and hopefully something would come up.

Personally, it really helps keep my mood stable if I eat a good serving of protein at every meal (at least 15 grams), three meals a day. Reducing the intake of refined carbohydrates also helps, and eliminating wheat as much as possible.