Unfortunately, there is not just one vitamin or supplement that will cover everything your teenager needs. Even if she is eating a healthy diet on most days, she still may need additional nutrients in a pill form, including iron, calcium, and vitamin D. As a start, you can try this Smarty Pants Gummy developed for teenage girls, but please note that it does not contain iron or calcium, and one serving is 4 gummies. Your teenager may need to take several pills or gummies per day to meet her needs. Smarty Pants also has a version for teenage boys as teen boys likely need a daily multivitamin as well!