Thoughts on smoothies?

My pediatrician is SO anti-smoothie… even when my older daughter was chronically constipated. She says it doesn’t teach kids to eat their vegetables. Jokes on her though bc neither of my kids (1 and 3) will eat their vegetables but they love smoothies. Also I need a way to hide the iron fortified baby cereal in a vessel my 14 month old will eat. Am I really damaging their palates if I give them a smoothie??