True diarrhea is actually not common in newborns, but is commonly described by many new parents who aren’t accustomed to what is often normal breastfed baby poop. That’s because just like trying to distinguish between spitting up and vomiting, it can actually be fairly difficult to distinguish and describe the difference between true diarrhea and normal—albeit watery—baby poop. In the case of a newborn who is just getting into the swing of eating, I can tell you that poop can change texture, consistency, frequency, and color fairly frequently as the intestinal tract gets used to the whole process—even when solid food has yet to be introduced into the mix. I might also add that it’s not uncommon for a breastfed newborn’s poop to be fairly consistently watery and have little, if any, substance. For lack of a better, more polite way to put it, it can literally “squirt” out.
As for common foods that can affect a breastfed baby’s pooping pattern, it is certainly possible for a breastfed baby to react to something his mother has had to eat or drink. It is therefore worthwhile to be on the lookout for any changes that seem convincingly related to particular foods and see if stopping them makes a difference. If so, be sure to discuss your observations with your baby’s pediatrician.
For the most part, however, foods that mom’s most commonly avoid eating or drinking while breastfeeding include things like caffeine (blamed for babies’ irritability) and potentially gas-inducing veggies such as broccoli and cabbage.
The bottom line is that I think it’s well worth paying attention to both your diet and your baby’s resulting poop. That said, you should rest assured that determining cause and effect when it comes to any changes is not something you have to do on your own. Believe me when I tell you that all pediatricians I know welcome the opportunity to take a look for themselves to help determine if any poop in question is normal, whether it should be tested, and what dietary factors may or may not be causing problematic pooping.