Vitamin A Toxicity and Bearded Dragons

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Vitamin A Toxicity and Bearded Dragons

Postby thegreybush » Wed Jun 22, 2011 4:47 pm

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There is a common theme that gets passed around the bearded dragon community online warning careful owners not to include plants rich in Vitamin A as part of their diets, more specifically and most popular on the list is carrots and kale.

It gets asked weekly it seems: Is feeding my bearded dragon carrots/kale okay?

Yes. It is not a staple because it doesn't provide calcium.

If you don't want to get all of the information from reading what follows then please take this as the short answer. It is very very difficult to reach toxic levels of Vitamin A from plant sources. Toxicity can be reached by high levels of preformed vitamin A in multivitamins. Carrots contain moderate amounts of oxilates but unlike collard greens and dandelion greens they don't provide calcium. If that's all you get from this, then you are going to be okay. Read on if you are interested to know the difference and why the information is so muddled...

Warning. Everything below here is going to just get thrown at you and may seem incoherent because it is missing some information that relates to how each form of vitamin A actually fulfills its role as mentioned, nor how it is transported, or even why bearded dragons are sensitive to it. It only briefly mentions the real concern behind carrots (oxilates). I apologize. I don't want you to get bored 3 paragraphs in and the discussion pertains more to the misunderstanding of vitamin A toxicity. The information that pertains to the topic is covered, though, and that is why plants high in vitamin A are not going to harm your dragon.


Vitamin A comes in three forms: retinol (alcohol form), retinal (aldehyde form), and retinoic acid (acid form). These three forms are collectively known as retinoids. Foods from animal sources provide retinyl esters that convert to retinol in the intestine. Foods from plant sources provide carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein, and zeaxanthin) that have to split to form retinol in the intestine and liver. Carotenoids are only precursors to active vitamin A. More specific to this discussion, beta-carotene, depending on where it splits at the molecular level, may only yield one molecule of vitamin A but sometimes doesn't yield any at all. For similar reasons a carotenoid is not absorbed very efficiently, the other carotenoids are absorbed even worse than beta-carotene. If you want a number, beta-carotene provides 1/12th the retinol activity equivalents (RAE) as other sources (animals and supplements). You couple that with the inefficient absorption and you get an idea of why its so hard to get toxic levels of Vitamin A from plants. Your bearded dragon would get full and stop eating before it happened.

Vitamin A plays three major roles. It promotes vision, it supports reproductive health and growth, and it participates in protein synthesis and skin health. Retinol supports reproduction and is the major transport/storage form. Retinal is active in vision and helps convert retinol to retinoic acid. Retinoic acid is like a hormone and helps regulate growth and development. Animals raised on retinoic acid as their only source of vitamin A can grow normally but they become blind because retinoic acid cannot be converted to retinal. This part might seem pointless but keep this in mind: Visual activity depletes retinal so it needs constant replenishment from foods or retinol stores in the liver.

Two problems can come from vitamin A. Your beardie can either get too much of it (hypervitaminosis A) or too little of it (hypovitaminosis A). Too little of it can lead to infectious diseases, blindness, and skin problems. Too much of it can cause bone defects like osteoporosis or birth defects. Over-consumption of beta carotene from plant sources will do nothing more than turn skin yellow, BUT over-consumption of beta-carotene from supplements may be very harmful because it can act as a prooxidant, promoting cell division and destroying vitamin A, leading to hypovitaminosis A. Weird, I know, too much can lead to too little. Just understand that the source is the key: preformed and active vs. precursors.

Where did the problem with toxic levels of vitamin A come from, then? It could be argued that in captivity there has been excessive use of multivitamins in order to make up for not giving variation in their diet that has led to cases of toxicity in beardies. As mentioned on a BD.org recommended site http://www.beautifuldragons.com/Nutrition.html some multivitamins contain far too much vitamin A in proportion to D and E. Use of multivitamins is important, though. Remember that the vitamins from plants are inefficiently absorbed and we generally don't feed meaty prey that is high in vitamin A. It is also difficult to give huge variety in plants to a dragon with a picky appetite and too much fruit causes other digestive problems, so its easier to supplement and address other nutritional concerns like calcium because of its importance (a WHOLE other subject). It isn't surprising to me, though, because we generally have problems with variation in our own diets and we have come to rely on multivitamins to maintain our own health as humans (in America). Funny how those patterns seem to carry over into other areas, eh?

In brief summary of this brief explanation, vitamin A sensitivity is real. You can easily reach toxic levels of vitamin A by feeding meats to a beardie or by over supplementation. Plants just cannot do it, though. In fact there is far more benefit to including vitamin A rich plants than there are drawbacks. Beardies don't eat a lot of meat products that contain high amounts of vitamin A and that may play a part as to why they're sensitive to it. I would argue that a wild beardie has less access to vitamin A sources from meat and deep green leafy veggies and was (yay free speech!) designed to make more efficient use of what it can get.

In closing, I want to explain that this subject has not been properly discussed because the bigger concern in beardie diet has always been calcium intake and preventing MBD. Learning to light properly and provide calcium is and should always be the first thing learned. However the question always comes up. Can I feed my beardie carrots/kale/etc? and we need to be knowledgeable on the advice we give about toxic levels of vitamin A. Plant source vitamin A is not dangerous. Supplements can be a problem. Feeding too many oxilate rich foods and not enough calcium can be a problem. I feed carrots daily as a salad topping. I also enrich my salads with calcium powder and ensure that they have proper UVB lighting to ensure that D3 is synthesized and it can be metabolized. Read your labels. Get some good information from the site mentioned earlier.
Last edited by thegreybush on Sat Jun 25, 2011 12:15 pm, edited 16 times in total.
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Re: Vitamin A and Bearded Dragons

Postby thegreybush » Wed Jun 22, 2011 5:16 pm

Changelog

6/22/11 Numerous edits for coherency. Added key point highlights for skimmers.
6/25/11 Title Change and Changelog. Rearranged two paragraphs for better article structure.
Last edited by thegreybush on Sat Jun 25, 2011 12:17 pm, edited 2 times in total.
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Re: Vitamin A and Bearded Dragons

Postby Jess » Wed Jun 22, 2011 8:12 pm

It makes more sense after the edits! :) Good job!
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Re: Vitamin A and Bearded Dragons

Postby BadCon » Wed Jun 22, 2011 8:25 pm

My female dragon loves carrots. I give her carrot slivers with every salad...been doing this for most of her life. She isn't yellow and and hasn't dropped dead, so I'll probably keep feeding her carrots. People should be far more concerned with proper lighting, heating, and supplementation then they should with feeding raw carrots. Once a week with Herptivite and 3x a week with calcium is all an adult dragons will ever need. Supplementation will vary of course if you battling a specific illness or mistreatment earlier in life, and depending on the specific feeders you are using. Growing dragons require more supplements too (but not MUCH more).

I wonder if that's how some of the breeders get those amazing yellow colors...they force feed carrots :lol:
My female is a "normal" colored dragon...time to get my carrot injector, I want a yellow one!!! :P
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Re: Vitamin A and Bearded Dragons

Postby thegreybush » Thu Jun 23, 2011 3:56 am

Lol, Badcon, I was thinking that exact same thing as I was writing this article.
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Re: Vitamin A and Bearded Dragons

Postby Sherri » Thu Jun 23, 2011 7:02 am

:blob5: Sticky time?!! My beardie will be very happy to get some shredded carrot every day! Thank you very much for the post! :blob5:

BadCon wrote:I wonder if that's how some of the breeders get those amazing yellow colors...they force feed carrots :lol:
My female is a "normal" colored dragon...time to get my carrot injector, I want a yellow one!!! :P


LOLOL, I was thinking the same thing :headbang:
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Re: Vitamin A and Bearded Dragons

Postby fresnowitte » Sat Jun 25, 2011 11:16 am

:headbang: Good post!
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Re: Vitamin A Toxicity and Bearded Dragons

Postby AHBD » Sat Jun 25, 2011 1:11 pm

Good post, Very informative [ and I couldn't even read it all ] This puts a myth to rest ! I wasn't even sure about that myself. I would like to mention one precaution though....for small dragons, esp. babies, the carrots should either be finely grated or not even used. Even a small chunk of a hard carrot can potentially cause an impaction because the baby can't chew it, but can swallow it and even if it's only the size of the " space between the eyes it may be too big and hard....so it's good to grate the carrots. My crix and superworms are always gut - loaded with carrots.
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Re: Vitamin A Toxicity and Bearded Dragons

Postby EmilyRussom » Thu Aug 04, 2011 6:29 am

LOVE the post. Especially because I figured out I can get Tiki to INHALE a collard green salad with carrots. She gets plenty of calcium elsewhere - not to worry. Thank you tons and bushels for this one Thegreybush.
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