I am a heavy Pepsi drinker and sometimes I drink way too much in one day. A few months ago, I started experiencing breast tenderness, pain and swelling with one breast feeling really lumpy. I became concerned but before I scheduled an appt to see my doctor, I wanted to make sure it wasn't related to the caffeine intake. I was suspicious that it was because I had noticed whenever I drink alot in one day or for a couple days straight with not much water, my breast would become tender swollen and very sensitive.. .. Anyway, I decided to stop all caffeine and within 3 days the breast tenderness had decreased drastically as well as the swelling.. I noticed the one breast which had felt lumpy no longer felt that way and appeared almost normal.. I know for sure that caffeine is the culprit but I'm still going for a mammogram just to be sure.