Parents...any LO currently drinking or feed on Nan Pro 1 and thinking abt switching to other brands? Any particular reason for switching?

The most common complaint I got about Nan Pro 1 is that the babies seem to get really gassy and have problems passing motion. I've also read online that some parents complain about their babies spitting up alot after drinking Nan Pro 1. Not too sure why but some speculate that it has something to do with the formulation of the iron.