Greens

In nature, iguanas primarily eat the leaves of trees, vines, and shrubs. The closest things humans can offer to their scaly &iends are leafy green vegetables. Leafy green vegetables should make up the majority of the diet, roughly half to two-thirds of the total amount of food offered. A list of leafy greens would include spinach, chard, collards, mustard greens, beet greens, bok choy, cabbage, broccoli, turnip greens, carrot tops, parsley, cilantro, lettuce, arugula, endive, escarole, dandelion greens, leeks, scallions, kale, watercress, and many others. Most grocery stores will carry at least a few of these plants. Some of the plants on this list are great for iguanas, and others are problematic for one reason or another. The problematic varieties can still be included in the diet, just in small quantities. These will be discussed later on in this section.

Out of the aforementioned plants, the best ones to offer seem to be collard greens, mustard greens, dandelion greens (the flowers are excellent to feed, as well), and turnip tops. At least one of these should be included in every meal and should be a substantial portion of the meal. AlI of these have excellent calcium to phosphorus ratios, as well as being high in many other vitamins and minerals. Almost as good as these best varieties are carrot tops, escarole, leeks, scallions, and celery leaves. These vegetables can also make up a significant portion of the diet.

Questionable Greens

Some greens lack nutrients, have a poor ration of calcium to phosphorus, or contain chemicals, which may be detrimental to the health of your iguana. Most of these can be fed to your iguanas in small quantities for variety but must not become a significant portion of the diet.

One category of greens and other vegetables that may cause problems is vegetables in the cabbage fami1y. These include cabbage, kale, bok choy, Chinese cabbage, broccoli, Brussels sprouts, broccoli rabe, and cauliflower. AlI of these pJants contain chemicals called goitrogens. Goitrogens interfere with the absorption of iodine by the digestive tract. Eventually, the lack of iodine will cause goiter (abnormal swelling of the thyroid gland), which is how these substances got their name. There is some debate about whether or not kale is as problematic as the other crucifers. A number of iguana owners have claimed that they have fed their iguanas large quantities of kale without any known deleterious effects.

For now, however, research would suggest considering kale and the related vegetables as items to feed to your iguana only occasionally.

Another category of greens that are best fed sparingly are those that contain high levels of chemicals known as oxalates or oxalic acids. Oxalates bind with calcium and prevent it &om being absorbed by the gut. Spinach, chard, beet greens, beets, sorrel, and rhubarb have high levels of oxalic acids. Therefore, although these vegetables are rich in many nutrients, they should not be fed &equently. When feeding any of these items, it would be beneficial to include some very calcium-rich greens or a little bit of calcium supplement.

The last category of problem greens is lettuce. Lettuces are low in most nutrients, including calcium. Iceberg lettuce is primarily water with little nutritional value. Other lettuces, such as romaine and Boston, are better but not among the best things to feed to your lizards. The various lettuces can be fed to your iguanas in tiny amounts or as emergency food but mostly they should be avoided. Iceberg lettuce is especially bad, as it has so little nutritional value but is loved by many iguanas. Oftentimes, iguanas will ignore all other foods and pig out on iceberg lettuce. Most people familiar with iguanas will have heard of these little "lettuce addicts" and "lettuce junkies:' When an iguana becomes a "lettuce addict," he will stop eating all other vegetables except lettuce and may go days without eating if lettuce is withheld. These iguanas invariably are malnourished and suffer ttom a variety of ailments. Converting a "lettuce addict" over to a healthy diet is a long process, and so me iguanas die of their dietary deficiencies before they make the switch. No matter how much your iguana may love lettuce, feed it spanngly or not at all.