The only way to test your hypothesis scientifically is by re-introducing the deleted items one by one and checking if the depressive symptoms resolve. However, I think it is more likely that it is the psychological effect of being prevented from eating specific foods that may cause more disturbance of mood than the absence of an unknown nutrient from one of those foods.
Hence, I think it is more useful if you sit with your son and explain to him why omitting those foods is necessary for his own better health and get him used to the idea rather than experimenting with those foods.
On the other hand, you need to make sure that there is significant improvement in his primary problems for which you have changed his diet and omitted those foods. If there is no improvement there within, say, a reasonable period of two weeks, then the diet modification may not be justifiable at all. I say this because most medical experts are agreed on the fact that allergy tests
have limited application in clinical use.
- Dr. Taher