While thawed frozen vegetables and greens are undoubtedly the easiest to use, the thiamine in some green vegetables and leafy greens is destroyed when they are defrosted. During the defrosting, thiaminase, the enzyme that destroys thiamine, goes about its job of destroying thiamine. Unfortunately, there is no hard information on just which green vegetables lose thiamine, how much thiamine is lost, nor how much thiamine iguanas need on a daily/weekly/monthly basis. If you are feeding your iguana mostly defrosted green vegetables and leafy greens for more than a week, supplement their diet with extra thiamine.

Thiamine, also known as vitamin B1, is important for the nervous system and helps convert carbohydrates to fat and amino acids to protein. In conjunction with the other B vitamins, thiamine helps reduce the effects of stress, promotes proper growth, and aids digestion. Thiamine interacts with other vitamins and minerals as they do their jobs within the body. Thiamine is a water-soluble vitamin. Excess amounts are flushed out of the body and so the vitamin must be a regular component in the overall diet, with enough thiamine taken in to sure the body is getting all it needs. When thiamine is lacking in the diet, the other B vitamins are unable to perform their functions properly and a variety of health problems will result. The most common signs of thiamine deficiency are tremors and partial paralysis.

Veterinarians who are not aware of the frozen greens/thiaminase connection often confuse these signs with a calcium deficiency. They begin to treat the iguana for a calcium deficiency, becoming more aggressive in treatment as the iguana fails to respond "properly." This becomes a harrowing experience for the owner, an irritating one for the vet, and an increasingly painful and debilitating one for the iguana.

By all means, keep a bag of suitable grocery store mixed vegetables on hand to use in case of extreme emergencies for a couple of meals (be sure to replace with fresh packages at regular intervals to guard against moisture loss). Better yet, consider making extra batches of the Basic Salad and freeze a couple of weeks worth a couple of times a month, using the frozen food during the month in which it was made.

If you are relying heavily on defrosted green vegetables and greens to feed your iguana, you can ensure that your iguana is getting adequate thiamine by adding some powder from a crushed thiamine (B1) supplement. You will find this product sold wherever human vitamins are sold. Use a tiny pinch per serving of salad, and half a tablet or so in a recipe batch of defrosted salad.