There are two types of supplements you need for your iguana: a multivitamin supplement and a calcium supplement. Most multivitamin supplements have some calcium but not enough to counterbalance the phosphorous naturally found in the food - even when sticking to foods high in calcium. That's just one of the not insurmountable problems when feeding a vegetarian diet....actually, it is a vegan diet as many vegetarian humans eat eggs and dairy products, both of which are sources of calcium that are not available to iguanas because animal protein is unhealthful for them.

The reptile multivitamin supplements out there are about the same. You can buy a reptile multivitamin supplement (names like Herptivite, Reptivite, Reptisol, etc.) or you can buy a bird vitamin such as Avitron, or a general animal vitamin like Vionate, buy and crush the canine Pet Tabs, or get a human vitamin - Centrum contains more vitamins and trace elements than any of the reptile and pet vitamins on the market. I use Vionate because not only is it a good quality vitamin but I can buy it in 4 lb jars (I, uhm, make a lot of iguana salad...)

There are lots of calcium supplements on the market - Repcal, Reptical, Osteoform, Miner-All, and Os-Cal to name a few. Many brag about the D3 or D they have added to it, and many have A, D and E in them. While vitamins A, D, E and phosphorous are necessary to the body for use in calcium metabolism, they are already included in the multivitamin supplement (which contains many other vitamins and minerals the fortified calcium supplements do not have) and from the food. One exception: D3 (cholecalciferol) is essential to calcium metabolism, and is made in the iguana (and human, for that matter) skin by contact with sufficient UVB wavelengths. Plants contain another type of vitamin D, called D2 (ergocalciferol). D2 is not nearly as efficient, close, in fact to being worthless, at metabolizing calcium, hence the need for D3. Research suggests that iguanas may not utilize much or any of the D3 they ingest (as given in a vitamin supplement), only that made by the UVB-skin interaction.

Therefore, buying a calcium supplement that contains D3 is not necessary for the calcium metabolism. Products such as the new Solar Drops and Moon Drops is also waste for iguanas (and possibly other diurnal and nocturnal reptiles as well, especially omnivores and carnivores who get most of their D3 from the prey they eat) as it misleads people who think that they are making up for the lack of sun or other proper UVB access, and harms the iguana who ultimately suffers from metabolic bone disease because inadequate calcium is being metabolized.

I use plain old calcium carbonate, relying on the variety of fresh foods and Vionate to provide the A, E, and other vitamins and minerals, to ensure that they are getting enough calcium to balance out the phosphorous and calcium oxalates in their food. I use natural sun, augmented with UVB-producing fluorescents, as necessary for D3.

One needs to read the labels when choosing a vitamin supplement for reptiles. The ratio of vitamin A to vitamin D to vitamin E should be 100:10:1. One popular "reptile vitamin" (with the word "rep" in the name!) has an A to D ratio of over 600:1 instead of 100:10!!

Unfortunately, label reading doesn't always guarantee you are getting what the label says. Reptile vet/nutritionist Susan Donoghue found when doing analysis of reptile and mammal vitamins that Nekton Rep didn't include four of the minerals the label said it did, including calcium! She also states that no multivitamin has enough calcium for green iguanas, and that what ever multivitamin supplement is used, they will need to be additionally supplemented with a calcium supplement.

How Much is Enough?

People often write me asking how much and how often should they supplement their iguana's diet. The answer, unfortunately, is "I don't know." No one has done any studies on iguanas to determine how much of any vitamin or mineral they need on a daily basis. There are no convenient RDAs or MDVs as there are for humans.

I take the lazy way and mix the vitamins in with the food when I prepare large batches of it. If I am making food on a day to day basis, I will mix the vitamins in right before serving. You can also make large batches and mix the vitamins in right before serving.Mix the vitamins in - don't sprinkle them on top. If your iguana is eating everything or most of what is on his plate, the vitamins mixed into the food will be mostly tasteless (there are some that igs don't like, and occasionally batches of vitamins may spoil - they really have a very short shelf life - and taste off. If your ig is not eating well, getting him to eat the vitamins by sprinkling them on top is not going to keep or make your iguana healthy. You must address the underlying problem.

Based on what I have read in many different books and articles, here's what I recommend as a likely supplement schedule. Note that it is tailored to the age or condition of the iguana based on their different needs at these times.

Vitamin Supplementation, Days Per Week

Spray Vitamins

Many people ask about the spray vitamins...are they any good? First, we need to separate the two types of vitamin spray products: those that are sprayed on the body, and those that are sprayed on the food.

Body Sprays: Iguanas do not absorb oily vitamins through their skin. When I pointed this out to a Four Paws distributor, whose company makes VitaSpray, she snidely replied that "Pet owners will buy anything that has a picture of their animal on it, whether it is any good or not." So, if you have $8 to throw away, donate it to your local reptile rescue to help feed and heat their needy reptiles.

Food Sprays: The makers of these sprays claim that their product delivers exactly the right amount. The only problem is that no one knows what the right amount is - not for iguanas, not for monitors, not for snakes, not for geckos, not for any reptile. No one has established their daily minimum requirements and, if they did, chances are it would vary greatly from one reptile species to another - what an herbivorous tortoise needs, for example, may differ greatly from what an omnivorous lizard needs. You are not paying for research and longitudinal studies here. What you are paying for is the pump bottle, pretty label and the nice box it comes packaged in, and a lot of water with a few additives. In my opinion, buying dry powdered vitamins is not only cheaper in the long run, it gives you better control over the amounts you add, and what you provide to your various reptiles.

Other Questionable Vitamin Products/Sources

Tums: Tums are taken by humans to neutralize stomach acid. That's fine if you have an overly acidic stomach after eating a meal, but that isn't the situation with our reptiles. We are giving them calcium because they need supplementation for body functions, bone density and, in the case of gravid females, so that their developing embryos have enough for their own development, and for oviparous species, for shelling. In order for calcium to be absorbed and utilized, it actually needs a slightly acidic environment. Tums has ingredients beside calcium that your reptiles don't need: sugar, dyes, binders, and chemicals.

Calci-Sand: The manufacturer of this made-for-reptiles product, and the pet stores and online sellers who sell it, would have you believe that your reptile can get all its calcium needs met by keeping them on this substrate. Unfortunately, this is harmful for most reptiles, such as green iguanas, because if they do ingest it, it will cause impactions, just like all other particulate substrates. Desert animals who live on sand don't ingest enough of it to make it worth the expense, not when plain, cleaned playground sand can be purchased for about $5 per 50 pound bag. Bottom line: proper calcium supplements for those who need it, healthy prey (supplemented as needed) for carnivores and insectivores, and UVB for those species dependent on UVB for calcium metabolism, is going to prevent MBD, not an overpriced, potentially harmful, substrate.

T-Rex Calci-Yum: Calcium carbonate tablets for your lizard! T-Rex says you can feed the whole tablet or pieces of it to your reptile! Of course, they won't be paying the veterinarian bills when the broken pieces lacerate your iguana's gut or the whole pill gets impacted in the gut.

T-Rex 2:1 Cal/Phos Reptile Supplement: Unfortunately, they apparently didn't bother to read a nutrition book before making this formula. Herbivores get plenty of phosphorous from the plants they eat - they certainly don't need any more! If you want to buy a T-Rex calcium product, buy their carnivore/omnivore formula, which has no phosphorous (T-Rex 2:0 Calcium/No Phosphorus). Then again, do you want to patronize a company that doesn't get it?

T-Rex Bone Aid: This is "an intensive liquid calcium supplement developed for reptiles and may be used for both critical and routine use to avoid calcium deficiency. It has been designed as the most digestible and palatable (cricket flavored) source of concentrated liquid calcium and magnesium available." Needless to say, herbivorous reptiles don't need a "cricket flavored" supplement. The only dosing information they give is for an anole and there isn't an indication as to what type of calcium this is. If you need an oral liquid calcium, you will probably be better off buying NeoCalglucon from your pharmacy.

A Final Caveat About Vitamin and Mineral Products

One last thing to keep in mind when considering buying a made-for-reptile vitamin product: they are not subject to the same truth-in-advertising nor quality control standards required to be met by producers of vitamins and supplements for humans. Human vitamin and supplement products are required to carry expiration dates. Vitamins have a rather short shelf life and should be used or discarded by the expiration date. Check the bottles of reptile vitamin products, and chances are you won't see one - pet stores generally do not turn over stock fast enough, and having to discard or return unsold stock to the manufacturer/distributor would be a hassle - and cost someone money. On the other hand, you and probably some of your family members can take the same human vitamins you use for your reptiles - a good multivitamin/mineral/trace element supplement and a calcium supplement. Just because the pet product manufacturers are making vitamins doesn't mean they really know what they are doing or that they have actually conducted rigorous tests or relied on any such tests in developing their product.

While some is good, more is not necessarily better. Over-supplementation of vitamins can be harmful. Vitamins A and D can cause serious problems, including liver, skin, and eye problems, and metabolic bone disease. Excessive amounts of calcium, previously uncommon in iguanas, may become an increasing problem as owners, scared of MBD, overcompensate and give too much calcium. Hypercalcemia may also occur in conjunction with protein/hydration induced kidney failure, can cause bone defects, cardiac changes, hyperthyroidism, shock, renal hypertension and failure and death.

It should be noted that vitamins A and D are heavily laced into dog and cat foods, another reason why they are so harmful to iguanas. Fat (both that found in commercial mammal foods and many human foods derived from animal protein or made with oils and fats, as well as the fat in soy products such as tofu) can also impede calcium metabolism, causing metabolic bone disease.

The best way to find out how you are doing supplement-wise is to have an annual blood test done on your iguana.