Question: what not to eat when breastfeeding a newborn?
Answer: Fish high in mercury. Fish is a great source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) — two types of omega-3 fatty acids that are important for brain development in infants, yet can be hard to find in other foods ( 5 ). ... 
Some herbal supplements. ... 
Alcohol. ... 
Caffeine. ... 
Highly processed foods.