Iguana Food Pyramid
The pyramid is a guide to feed your iguana. You do not have to follow the schedule exactly (see special considerations). It is based off of research on the macronutrient and calcium requirements of various types of reptiles outlined in the Merck Veterinary Manual as well as individual scientific studies about wild iguana's diets. This pyramid is also based off of what experienced iguana breeders have found to work for their animals.
The iguana food pyramid is designed to be a user-friendly guide. The foods on the bottom are the most important, however all the food groups are necessary for a healthy iguana. The key on the right side describes how many times to feed this food group per a week. When the pyramid level is broken in half, you can choose either food group. The larger the section, the more important it is.
This guide is made to combat the incomplete knowledge of iguana nutrition. Many new owners are confused about what to feed their pets while experienced owners are looking for the best diet possible.
There is no such thing as a complete guide to iguana nutrition because there is no realistic way for the in-home keeper to formulate a total diet. It is conventional wisdom that variety is the key to combat an incomplete diet, but that isn’t always the case. For example, almost all the foods an iguana is fed will be deficient in calcium and iodine. This is simply a product of commercial agriculture raising plants and insects so that they grow as cost effectively as possible.
This guide will get you as close as possible to a complete diet without expensive scientific testing. The most important thing in any animal’s diet is feeding appropriate foods in appropriate ratios in order to get the correct balance of protein fat and carbohydrates. It will also help you understand other nutrients how to get them too.
Key Food Groups:
Iguanas are true herbivores. Numerous stomach content studies have shown only plant matter in the wild iguana's stomach (Hirth, 1963). This is even true for juveniles, as plant matter has been found in iguanas' stomachs even shortly after hatching (Iverson 1982). Greens are by far the most important part of an iguana’s diet, especially in a mature animal. 85% of iguanas in one stomach content study had primarily leaves in their stomachs (Van Devender 1982).
Iguanas primarily ferment their food to get maximum energy from it. For this process fiber is required and greens offer the highest fiber content of any food group. Not enough fiber can cause gastrointestinal problems for the iguana (Allen and Oftedal 2003).
Greens should be feed every day. Greens generally can be divided into four categories, staple, occasional rare and never foods. To make a green an every day green, it must be rich in nutrients like calcium, low in phosphorus and low in anti-nutrients like oxalates and goitrogens. Occasional greens are rich in nutrients, but contain too high a level of oxalates or goitrogens to be fed every day. Rare greens have very high oxalates and goitrogens. They should be avoided. Never greens have high phosphorus, low calcium and sometimes have high oxalates.
Staple greens are escarole, endive, alfalfa and dandelion greens.
Occasional greens are bok choy, collard greens, mustard greens, turnip greens, watercress
Rare greens are kale, dark lettuces, parsley, swiss chard, spinach
Never greens are iceburg lettuce, cabbage
This is the part of an iguana's diet that will bring in a diversity of nutrients and a ton of beta-carotene. 33% of juvenile iguanas in the Van Devender (1982) study were observed with a flowers in their stomachs, but no adults. This indicates that as an iguana ages they depend more heavily on leaves for nutrition. However, a captive animal should still readily be fed vegetables in order to promote a diverse, nutrient-rich diet. Good vegetables are often bright in color and not too high in oxalates and phosphorus. Sometimes the healthiest foods are also the strangest, such as prickly pear leafs and hibiscus flowers.
Some of the best vegetables include acorn squash, butternut squash, bell peppers, prickly pear leafs, hibiscus, common button mushroom, okra, and pumpkin.
Other good vegetables include asparagus, broccoli, brussel sprouts, carrot, green beans, snap peas, tomato, yellow squash and cucumber.
Check out the nutritional analysis of vegetables.
Liberally sprinkle a vitamin supplement on the iguana's food. A vitamin and mineral supplement is essential when feeding a home made diet to ensure no nutrients are missing, however there is quite a variety of supplements on the market. When looking for a supplement to a healthy iguana diet, as outlined here, there are a few key nutrients one should consider. Most greens, fruits and vegetables are low in magnesium, iron and iodine. Make sure your supplement provides these nutrients as well as ample amounts of B vitamins. Often iodide is provided using kelp as an ingredient. Additionally, vitamin A should be provided in a beta-carotene form. The average healthy iguana diet will provide more than enough vitamin A, and supplementing it in a retinol form can cause overdose. When offered as beta-carotene, an iguana's body can process out the excess vitamin it does not need.
Liberally dust foods with a calcium powder. A calcium supplement should be purchased separately from a vitamin and mineral supplement. This is because calcium needs to be supplemented in a much higher level than any other mineral. Many foods for iguanas are deficient in calcium and calcium is required more than any other mineral in reptiles. Also be sure that you have proper UVB lighting. Without UVB, iguanas cannot have enough vitamin D in their system to process the calcium they are eating. Studies of iguanas that had only dietary vitamin D and no UVB light show that these animals still develop metabolic bone disease (Allen and Oftedal 2003).
Fruit is a less essential part of the iguana diet. 9-15% of iguanas had fruit in their stomach contents (Van Devender 1982). However, almost all fruit you can buy in the store is heavily domesticated and has little relation to the nutritional content of its wild relatives. The low fiber content of domestic fruit is especially concerning for captive iguanas. Fruit should be used as a flavor and moisture enhancer more than a nutritional component of the food, but is great to feed in moderation.
Some healthy fruits include berries, cantelope, dates, figs, guava, kiwi, mango, oranges, papaya and pineapple.
Allen, Mary E., and Olav T. Oftedal. Nutrition in Captivity. Biology, Husbandry and Medicine of the Green Iguana. 4: 47-74 (2003).
Hirth, H. F., Some Aspects of the Natural History of Iguana iguana on a tropical strand. Ecology 44:613-615, (1963).
Iverson, J. B., Adaptations to Herbivory in Iguanine Lizards. Iguanas of the World: Their Behavior, Ecology and Conservation. 60-76 (1982).
Troyer, K. Transfer of Fermentation Microbes Between Generations in a Herbivorous Lizard. Science 216:540-542 (1982).
Van Devender, R. W., Growth and Ecology of the Spiny-Tailed and Green Iguanas in Costa Rica, with Comments on the Evolution of Herbivory and Large Body Size. Iguanas of the World: Their Behavior, Ecology and Conservation. 162-183 (1982).
These dietary guidelines are designed for an average, healthy, iguana. As with anything, if your reptiles are ill you need to consult a veterinarian for advice. That being said, there are some normal dietary considerations that apply to many iguanas. If your iguana is sick, please check out our diagnostics page.
Herbivorous reptiles need healthy gut bacteria in order to digest their food. It is highly recommended that newly hatched iguanas be provided with fresh fecal material from a healthy adult in order to seed their gut bacteria as well as access to clean soil to consume. It is the natural behavior of newly hatched iguanas in the wild to consume adult fecal material and soil shortly after hatching (Troyer 1982).
Many captive animals of all kinds suffer from obesity. The best thing you can do for an obese iguana is cut fruit out of the diet. Obesity is deadly. It can cause liver failure and many other issues. Supplementing with a very small amount of omega 3 fish oil is also wise to prevent liver disease in obese animals.
Juveniles and Breeding Females:
Young iguanas are growing fast and need more protein and calcium than older iguanas. It is wise to offer alfalfa to them for a healthy source of plant protein and calcium. Occasional fruit is also a good source of energy for young animals. This also applies to females developing eggs, known as gravid females.
Not eating is a common occurrence with many pet reptiles. Usually the issue is with the temperature of the enclosure, or another husbandry problem. Ensure that your tank is up to standards and visit a veterinarian. In the mean time, water is the most important nutrient for an iguana. Make sure your animal does not become dehydrated. Also remember that eating any food is better than eating no food. Even if all your iguana will eat is iceberg lettuce, this is better than not eating anything at all. Work on getting them to eat healthy foods, but again, unhealthy food is better than no food. For tips and tricks to get your animal to eat see our "appetite stimulation" page.
There are many key nutrients in an iguana's diet. Calcium is a particularly important nutrient that many beginner keepers do not offer enough of. It is imperative to supplement your iguana with calcium and provide proper UVB lighting.
The key nutrients are listed in alphabetical order.
Definition-natural plant flavonoid pigments that appear blue or purple
Function-a weak antioxidant that enhances color
Foods-acai, eggplant, blood orange, blackberry, raspberry, blueberry,
Definition-a red-orange pigment in plants that can be converted by some animals to vitamin A
Function-A vitamin A supplement for omnivores and herbivores that cannot be overdosed as well as an antioxidant that enhances color
Foods-carrot, pumpkin, sweet potato, spinach
Definition-an abundant chemical element that essential for life
Function-building blocks for bones and teeth and an essential element for cell physiology
Foods-calcium carbonate supplement, prickly pear leafs, alfalfa, collard greens, oranges, mustard greens, bell peppers
Definition-a biological molecule made of chemically linked sugars. Carbohydrates include, sugars, starch and fiber.
Function-simple energy source for animals
Foods-almost all foods, especially plants
Definition-a chemical element that is an essential mineral
Function-Copper has many functions, including collagen formation, enzyme cofactors, incorporating iron into red blood cells and generation of energy from carbohydrates. It is usually abundant in foods for iguanas and inhibits zinc uptake, so copper intake needs to be limited.
Foods-spinach, turnip greens. asparagus, beans, nuts, kale, mushroom, pumpkin
Definition-a biological molecule that is found in plants and animals
Function- a dense energy source and an energy storage method
Fiber - Click Here for More Information
Definition-a type of complex carbohydrate in plants that cannot be digested
Function-Fibers add bulk to the stool and are digested by gut bacteria in uromastyx into essential fatty acids.
Foods- all vegetables and fruit
Definition-substances that disrupt the production of thyroid hormones
Function-These anti-nutrients should be avoided in excess in order to maintain thyroid health of iguanas. They are less harmful when proper iodine supplementation is provided.
Foods-cassava, soy, peanuts, strawberries, spinach, bok choy, broccoli, cabbage, kale, turnip
Definition-a chemical element abundant in the ocean that is an essential mineral
Function-key component of hormones made by the thyroid
Foods-kelp, ocean fish, shrimp, spirulina, scallops, standard table salt
Definition- A category of nutrients that makes up the bulk of foods. It includes protein, fat(lipids), carbohydrates and water.
Function-each macronutrient has a different function, but protein, fat(lipids) and carbohydrates can all provide energy. The ratios of these nutrients in a diet is extremely important.
Definition-a chemical element that is required by living organisms other than carbon, hydrogen, nitrogen and oxygen
Function-builds bones, tissue, catalyzes biological reactions, transports oxygen and many more
Foods-all foods have some mineral content
Definition-a specific organic acid found in plants and animals
Function-binds with calcium to form kidney stones and prevents calcium from being used in the body
Foods-soy, nuts, beans, spinach, swiss chard, beets, collard greens, okra, blueberries, grapes, raspberries
Definition-chemicals naturally produced by plants that are not of conventional nutritional value
Function-functions vary but they are usually antioxidants, anti-inflammatory and promote liver health
Foods-plants, especially ones rich in color
Protein - Click Here for More Information
Definition-a biological molecule made of chemically linked amino acids
Function-maintains the structure of the body and excess can be used as an energy source
Foods-all foods have some protein, with insects being especially high as well as a decent amount of protein in nuts, seeds and greens
Definition- an abundant chemical element that essential for life
Function-enables cell function and builds bones, but is easily consumed in excess in an iguana diet. Excess consumption impairs calcium absorption and can cause muscle disorders.
Foods-asparagus, beans, soy, seeds, cricket, mealworms, mushroom
Definition-A vital organic compound that an organism cannot synthesize on its own. They can be divided into fat soluble and water soluble.
Function-each vitamin has its own function in the body
Definition-a group of related fat-soluble nutrients (carotenoids and retinoids) that are essential for the body.
Function-In iguanas carotenoids can be converted to retinoids. Carotenoids come from plants and cannot be overdosed, so they are the safest form of vitamin A for uromastyx. Vitamin A is needed for immune responses, night vision and many other functions in the body.
Foods-sweet potato, carrots, spinach, kale, dandelion greens, collard greens, mustard greens, pumpkin, butternut squash, cantaloupe, bell peppers, kelp, spirulina, tomatoes, papaya
Definition-a fat soluble vitamin derived from UVB light or dietary sources
Function- needed to absorb calcium and other minerals from food
Foods-UVB lighting should be provided for iguanas so that they can synthesize vitamin D, numerous studies have indicated that dietary supplementation is not an effective source of vitamin D in diurnal reptiles.
Definition-a fat soluble vitamin that acts as a powerful antioxidant
Function-protects against free radical damage, ageing and heart disease. It is especially crucial in a high fat diet. Most foods high in vitamin E are also high in fat, so a balance is difficult to achieve.
Foods-sunflower seeds, greens. almonds, broccoli
Science Behind the Pyramid:
The proportions of the pyramid are based on macronutrient balancing. According to the Merck Veterinary Manual, herbivorous reptiles need a diet of 18-22% protein, 3-6% fat and 20-35% fiber on a dry matter basis. However, it is likely that these protein and fat requirements are slightly high for the uromastyx do to the extremely harsh environment it is adapted to. To achieve close to these macronutrient ratios the pyramid recommends how often to feed a portion of seeds, greens, fruits or vegetables. There is a total of 9.5 portions of these food groups fed each week.
7 greens portions/9.5 total portions=73.7% greens
2 vegetable portions/9.5 total portions=21.1% vegetables
0.5 fruit portion/9.5 total portions=5.3% fruit
The most important macronutrient is protein. The diet aims to achieve a 18% dry matter protein content. Greens, vegetables, and fruit are typically 20%, 10%, and 5% protein, respectively. Multiplying the % of protein by the proportion of portions gives us:
.737x20% + .211x10% + .053x5% = 17.1% protein
Therefor this food pyramid provides an adequate amount of protein considering the Iguana's unique nutritional requirements. Using this same method fat and fiber can also be calculated. Greens, vegetables, and fruit are typically 2%, 2%, and 2% fat, respectively. They are typically 25%, 25%,and 15% fiber, respectively.
.737x2% + .211x2% + .053x2% = 2.0 % fat (goal 3%-6%)
.737x25% + .211x25% + .053x15%= 24.5% fiber (goal 20%-35%)