Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Thiamine (B1) Supplementation for Green Iguanas and Other Reptilian Herbivores

©1997 Melissa Kaplan


Freezing green vegetables, especially the leafy greens, causes the thiamine (vitamin B1) to leach out. When frozen greens are fed over a long period of time and no provision is made for adding back in thiamine to the diet, a deficiency, hypothiaminosis, will occur. This causes tremors and twitches.

Unfortunately, calcium deficiency, which is all too common in captive green iguanas, also causes twitching and tremoring of the toes and muscles of the legs. Many vets are not aware of the thiamine loss linked to green vegetables and will assume that the iguana is suffering from calcium deficiency and so make their recommendations accordingly. The only problem is that no amount of additional calcium is going to make twitches and tremors related to hypothiaminosis go away...only adding thiamine to the diet will.

(By the same token, I've been getting a lot of mail lately from some ill-informed people whose iguanas are suffering from metabolic bone disease [calcium deficiency] who are insisting that all they need to do is give their iguana B1 to "fix" it. Just as adding calcium will not correct a thiamine deficiency, so too will adding thiamine not fix a calcium deficiency!)

The best way to replace the lost B1 is by buying a vitamin B1 supplement, now widely available in health food stores, supermarkets, drug stores, vitamin stores , and online vitamin sellers (such as

The older versions of my iguana care information out there on the web refer to the use of brewer's yeast to replace thiamine. This is because when I first found out about the thiamine loss and started recommending replacement of it in defrosted salads, there were few stand-alone thiamine products available and they weren't easily found.

For the past several years, however, vitamin sellers have been stocking thiamine (B1) products, making them widely and easily available. A thiamine supplement is healthier than the formerly recommended brewer's yeast for your iguana and other herbivores as the yeast is very high in phosphorous and other things the reptiles don't need or don't need more of. (This also nicely illustrates why I do not give permission for my articles to be replicated on other people's websites: people who access those sites do not realize they are often getting outdated information.)

If you buy B1 in tablet form, you can use a pill crusher to crush it and store the left-over extra powder as you only need a small pinch of the vitamin for a serving of salad. If you buy the B1 in a powder-filled capsule, you can dump some capsules out into a small container and take your pinches from there.

Follow the directions on the bottle of B1 to make sure you store it properly to maximize its shelf-life.

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