I believe that everything we eat when we are breastfeeding affects our babies.
That said, a crazy neurotic mom who is so afraid to eat anything lest their precious baby get a pimple, is not a happy and well nourished mom. If mom is not well nourished and happy, baby is not well nourished and happy.
I had two colicky and cradle cappy babies with rashes and all kinds of stuff. When I went into labor with my third, I swore off all dairy (except butter, because it has no casein or lactose). She was never colicky or cradle cappy at all. When she was about 2 months old I tried about an ounce of milk in my tea. She screamed for hours. My fourth, the same story. I am not an anti dairy person. I do dairy (organic and grass fed as much as possible), but a mom of a colicky baby is never a happy well nourished mom. Notice the theme here?