The present disclosure relates to crystalline berberine ascorbate salts and crystalline ketone berberine adducts, which can be used in preparing pharmaceutical or dietary compositions for the treatment or prevention of bacterial infections, cardiovascular diseases or other conditions. The present disclosure also relates to methods of preparing crystalline berberine ascorbate or other berberine salts by reaction crystallization using one or more of crystalline berberine ketone adducts as a starting material.