Hi, have not used it for my own toddler, but I know my mother used to give it to us in our bottles as babies. I actually take the pills myself, they are fantastic for skin, hair, nails and give an energy boost if you are feeling low. Don't be chicken, it really is harmless, totally natural and can only do good. It probably is in Marmite, but I doubt you'd get it in the quantities that the powder would provide. It's also totally safe in pregnancy - so would also be totally safe to give to a toddler.
Hope that helps,
Cate