As a general rule there is very little you can eat as part of a normal diet that makes much difference to breastmilk. Even most medications are fine. Anything which is ever available in a paedatric dose is ok while breastfeeding. And almost every drug that is unsuitable has an alternate which is ok, apart from things like chemotherapy.

The danger of not breastfeeding is usually higher than the danger of breastfeeding while taking medication.