What Foods Should I Avoid While Breastfeeding?

I really want to eat prawns, crabs and oysters this xmas, is that okay? what foods are a big NO NO when breastfeeding?

What Foods To Avoid While Breastfeeding?

I am wondering what foods you are supposed to avoid while beastfeeding. I have heard several different things, so I am really wanting to hear personal experiences with it, not just something you’ve read somewhere.
For example, I’ve heard to avoid chocolate. Other people said chocolate won’t hurt. I ate chocolate cake last night, and my baby was fussy all day. Has anyone else figured out things that they couldn’t eat while breastfeeding?