Breastmilk is not usually messed with when a mother has food poisoning. As long as the mother isn’t seriously sick, she can still breastfeed her child if she wishes to. Symptoms such as diarrhea and vomiting might be uncomfortable, but they are confined to the digestive system. This is the system that most food poisoning symptoms are going to affect, so as long as the poisoning stays relatively mild, it’s safe for her to breastfeed her child.
In fact, breastfeeding should rarely be stopped. Only in extreme cases of food poisoning where mother has been hospitalized should the mother consider stopping for a day or two. Typically, you never want to go longer than a day if possible without breastfeeding your child.