J.R.
Not to poo-poo all the advice all the other moms have given, but perhaps 13 months old is a bit young for a vitamin. All of the over the counter vitamins are for children over 2. I have an 18 month and wanted to start her on vitamins. I spoke to my pediatrician, and he recommended that I didn't. He said there is no proof that they are beneficial. Plus, under 2, their bodies still tell them what food to eat to get the nutrients they need. It wasn't the advice I wanted to hear because I want my daughter to get all of her nutrients, but I will be waiting until she is 2 to start. Then, I will be using Arbonne's children's chewables. I believe these are the only vitamins that actually properly deliver the right amount of nutrients to the child.
Good luck.