First, don't give up on his diet! It can take lots of tries before some kids realize that broccoli, mango, or flounder actually tastes good. Keep putting different foods on his plate -- you never know what might happen. That said, most children, including picky eaters, don't need multivitamins if they are getting at least some of all the food groups on a somewhat daily basis, especially meat, vegetables (all colors), dairy, and fruit. If your child isn't, visit your doctor to go over his diet to see if a multivitamin makes sense -- and if so, whether to get one with iron.

If your pediatrician thinks a vitamin is a good idea but doesn't have a specific brand in mind, you'll have to read labels carefully because nutrient amounts vary between brands. And because most vitamins for kids are designed for ages 4 and up, you'll likely need to split each pill in half for a 3-year-old -- not always easy.

The good news is that there are all sorts of colors, shapes, and flavors available, designed to tempt the most picky children (though many kids don't like the liquid formulas). In fact, chewable vitamins can be yummy, so you could have another problem -- stopping your son from eating more than one. Overdosing can be dangerous; make sure he knows they're not candy, and store them out of reach.