Replacement is only on an indicated basis. Many children have occult Zinc deficiency and this may be masked in an otherwise normal hair sample. These are well recognised in autism. It is found that when the diet and digestive tract are attended to, sensitivities will in general disappear. Previously reactive foods can be reintroduced.
Some children do remain sensitive.
This is treated using Isopathy, a homeopathic technique that uses the sensitising substances in homeopathic dilution to treat it. Food allergy testing is not done as routine in view of the invasive nature and the costs involved. The diet widens in general because the child has an increasing sense of taste and smell which are both Zinc dependent. Perception improves leading to an apparent appreciation of more subtle tastes. A stable immune system increase tolerance of foods.