I've found apples are the one fresh fruit that really help to prevent constipation for me. I've found them to be amazing. I was suffering quite badly from constipation - and had even resorted to drinking prune juice (looks like liquid vegemite!) and my Ob told me to eat 1-2 apples a day. I followed his advice and within 2 days everything was back to normal. Soo much nicer to eat an apple or 2 a day than drink prune juice and eats prunes!