Sea vegetables, legumes, whole grains (esp. cooked in bone broth), and organ meats would all be good complements to the foods your son is eating.
It's best to go for a variety of mineral-rich foods -- including some sea foods -- since the soil where your food is grown isn't necessarily going to have an adequate amount of all of them.
It's best to go for a variety of mineral-rich foods -- including some sea foods -- since the soil where your food is grown isn't necessarily going to have an adequate amount of all of them.