Board Thread:Naruto Discussions/@comment-30168130-20170423205927/@comment-4366149-20170424002703

The manga was never explicit on this, but it did make it clear that dojutsu changes the quality of chakra (qaulifies like "more sinister", "more powerful", "darker", "stronger", etc., have been used in the manga to describe the changes that dojutsu impacts on chakra). Kurama, Karin, and Sasuke, are some of the characters that have testified to this.