My daughter is on source cf which has some zinc but also is on another zinc med. She take 4ml extra daily. We make sure its all taken with enzymes. Her GI doc actually wanted her to be on extra zinc. She said it helps with growth. Pretty much if your body gets all the nutrients it grows at its best. Therfore, good growth, healthy lungs. Grayson has been on zinc for about a year now or a little more. She has done well with it. She is almost 17 months, 29 in tall and 21 lbs (around 40%). We are very pleased with her progress. Grayson also has short gut which she doesn't absorb well. The GI doc we have is great. I hope this might help out. You can pm me if you want more history about graycie.