Hypervitaminosis A

Some have been conducting research on the effects of specific vitamins on certain species of insect-eating lizards. Preliminary results of their ongoing research suggest a possible relationship between vitamin A, vitamin D3, and calcium metabolismo Excess vitamin A in cornmercial reptile supplements may have a negative effect with several species of insect-eating lizards, notably certain species of true chameleons (Le., C. johnstoni and C. pardalis), day geckos and fat-tail geckos. Because of an interrelationship between vitamin A, vitamin D3 and calcium, it appears that too much vitamin A may deplete calcium reserves, resulting in symptoms of metabolic bone disease. Other effects of hypervitaminosis A inc1ude excessive shedding and eye problems. Some of these effects can be offset by increasing the amount of vitamin D3, but there ~ a risk of administering too much vitamin D3. Unfortunately, many of the reptile vitamin/ mineral supplements presentIy available contain many times the amount of vitamin A required by most lizards. For species with low vitamin A tolerance, these vitamin/mineral supplements may prove detrimental over time. With vitamin Asensitive species, some herpetoculturists choose not to use any cornmercial vitamin/mineral supplements, and instead simply use a vitamin D3 and calcium supplement. Other vitamins are provided through careful gut loading of the insects being offered. Cut loading of insects with beta-carotene is the method most often used by herpetoculturists for supplying vitamin A to their insect-eating lizards. Care is given not to feed insects a diet which is high in formed vitamin A, but instead to feed a diet low in vitamin A, inc1uding fresh vegetable matter, ground rodent chow and flaked baby cereal. Another method is to mix one part of a cornmercial supplement with 2-to-5 parts calcium carbonate. Hopefully, cornmercial vitamin/ mineral supplements with lower vitamin A levels will become available in the very near future.