Vitamin and/or mineral supplements beyond what is needed for growth and development (known also as the dietary reference intakes which are based on age and sex) are not needed to boost the immune system in autoimmune conditions. There is little evidence that “more” of a vitamin or mineral, beyond what your teen would get from eating lots of fruits and vegetables, further supports the immune system. Vitamins and minerals are not benign, meaning over-nutrition or over-supplementation can be associated with side effects, so balance is key. Also to note that while red meat is a source of protein it is not needed in the diet. However a balance of protein sources, such as egg, poultry, fish, pulses, nuts, carbohydrate sources such as vegetables, whole grains and fruits, as well as healthy fats like olive oil, avocado are recommended.