Iguanas love to all different varieties of fresh fruit and greens. Make sure that any greens, such as lettuce, you offer the iguana is nutrious. Avoid iceburg lettuce.
They need to have lots of greens, other vegetables like Sweet potato, carrots, zucchini, squash ect. Some fruit and cooked grains are good, also mineral supplements specifically for Iguanas.
Iguanas are vegetarians in the wild. They need to be fed a large variety of fruits and vegetables. However, do not feed too many vegetables that are high in oxalates as these can cause problems in iguanas. I recommend researching iguana care in books or talking with a veterinarian who sees Exotic Pets.