I have always thought that the blend of ingredients included prune juice.
i remember some years back, asking my parents if that was the taste I couldn't place--My dad loved it, but he told me "it couldn't possibly have prune juice in it--he could drink plum juice, but prune juice always made him sick to his stomach" My mom told me to let that one go.
I agree that it does.... First of all no self respecting company is going to give out ingredients in their recipe next they are not going to say that prune juice (which most people don't like) is in their product and lastly I KNOW for a fact that you drink enough dr pepper it will cause you the runs! Also side point an actual doctor told me to drink dr pepper when I was constipated because it would help because of that SECRET ingredient! Lol
It is funny that people are wondering about it. But I CLEARLY remember reading it on the label years ago. It actually read "contains real prune juice" I told friends and family that and by the time I got around to purchasing one again (since I don't really care for it) That part of the label was gone. And so was my proof. I find it funny that the Dr. Pepper website wont fess up to it.
When I was visiting England in 1999 I bought a bottle of Dr. Pepper in the airport and on the side of the label, adjacent to the bottling information was written "a prune flavored beverage". I remember this very distinctly because I'm from Texas (where we drink a lot of DP) and I had never seen that before.