I got the oatmeal cereal and it says it has a bunch of vitamins and such in it, but I'll definitely be checking it over. he gets vitamins (vi-tri-sol) or however it's spelled almost daily too. I haven't given him cereal every day either and am still breastfeeding him for the most part.
Definitely introduce it slowly. I had to give it to my boy to get his reflux under control and he didn't poop for days and he was crying because he was all impacted and he needed a harsh laxative. Then after I took him off it I ended up reading that babies don't have enough of the enzyme that aids in the digestion of grains and that rice cereal not only has no nutritional value but that it contains arsenic 😳 so I threw mine away because I was already traumatized by the constipation and idk if that other stuff is true but it was the icing on the cake.