So, your child has announced he is becoming a vegetarian! He could be trying to define himself by choosing a special eating plan (temporary growth stage) or it could be the beginning of a lifelong choice. In both cases, you need to help your child build a balanced daily menu which supplies all his nutritional needs. For healthy growth, your child needs to have a good amount of protein.
As a vegetarian, your child has many food options to incorporate protein into his daily diet. Foods rich in protein include eggs, milk, cheese, cottage cheese, yogurt, tuna, salmon, beans, soy, tofu, hummus, lentils and more. Sit with your child and help him build several high-protein food options for his weekly menu. It is important that he feels involved and that his decision to be a vegetarian is his own (an age-appropriate understanding of his decision).