You wouldn't allow you child to choose her own diet, since we know she would pick cake, ice cream and candy bars, so we cannot allow a finicky iguana to manipulate an owner in to caving in and providing what is known to be inappropriate and even dangerous diet. Iguanas require a diet higher in calcium than phosphorus, and food items and supplements offered should have a positive calcium to phosphorus ratio. Most iguanas obtain the majority of their dietary water from the moisture contained in the diet. For this reason, make sure that you feed some juicy, moist food items daily, or soak dry pelleted iguana diets. Of course, offer a large pan of water for soaking daily, or place the iguana is a separate tub for soaking.
Most iguanas relieve themselves in water, which facilitates keeping the cage clean.
Deciding whether or not to provide a vitamin and mineral supplement is something that should be discussed with your reptile veterinarian, based on the evaluation of your pet's diet, food preferences and growth rate. It is possible to oversupplement an iguana with some vitamins and minerals, which can result in clinical disease. Knowing what we do today about the nutrition of green iguanas, it is much easier to provide a good, balanced diet for all stages of their lives.