Apples causing health damage

With 2 Turkey legs missing I ate an apple inside my house, 3 blocks high, at the end of the apple my hunger was restored but suddenly it was as if something was beating me up or gravel was being poured on me, I started losing hearts as if the apple was poisoned or something - when the being hit effects stopped my hearts regenerated back to full. The only other food I have eaten was cooked pork/chicken/steak which functioned as normal without any bad effects.