I agree with you, its a tricky balence of avoiding food triggers, and yet thinking long term to get the nutrition to heal. We found that both my wife and I were badly Iodine deficient, calcium deficient, vit D and vit C, a range of vit B. Its more than diet, its the body's ability to absorb and digest that can lead to the deficiency. we are now working on the digestion with carefully targed enzymes, supplements, and diet. its alot of work, but shows results. Our son turned out to have a very hard time digesting protiens and fat. enzymes help short term, but the key is getting the liver to heal. Calcium deficiency and eczema go hand in hand, but, you need enough stomach acid and bile to absorb the calcium.
if you want to read up on calcium, look for Dr. Carey Reams and RBTI, he was very good at matching the correct type of calcium to body conditions. most calcium supps are no good, and could make problems worse.