I made a smoothie today with about a cup of papaya, a cup of plain yogurt, a few carrots and a half cup of orange juice. I added 2 tablespoons of the papaya seeds as well. First off, it tasted HORRIBLE, which had to be the yogurt. It was one I have never tried before, and will never try again! I only drank half of it, and shortly thereafter, I got this horrible pain in my upper intestinal tract. It has gone done and now seems to be stuck right at belly button level. The pain goes like a belt of pain from one side to the other. I'm afraid to drink any more of this stuff.
I read about papaya and it said it can cause bad abdominal pain, but I've done papaya smoothies for months with nothing like this ever happening.