Food can be a battle ground with children, getting it right from the start is definitely the best way to go. The following website has some good advice:

https://www.helpguide.org/articles/healthy-eating/healthy-food-for-kids.html

For a list of the most common childhood eating disorders look at:

https://www.eatingdisorderhope.com/treatment-for-eating-disorders/family-role/eating-disorders-in-children-12-and-under

If you have concerns see your GP. He or she can refer you to a paediatric dietician.