Ideally, your daughter would get all of her nutrients from food. That's because there are synergistic effects of foods and nutrients that we still don't understand completely. This synergy can't be found in a vitamin pill because the nutrients have been isolated. Therefore, even if your daughter is taking a supplement, don't get complacent about encouraging a variety of food. A twelve year old girl is going through a period of rapid growth and development.
Adequate protein is essential.
She needs about 46 grams a day. Because she eats meat, you probably don't need to be too concerned. Meeting protein requirements are easy because protein is found not only in the meat group,but also in the dairy group, and to a lesser extent in the vegetable group. Another important nutrient is iron. If she hasn't already, your daughter will soon be starting to menstruate.