The reason we have to be aware of Vitamin A overdose (aka. hypervitaminosis A) is because Vitamin A is a fat-soluble vitamin. This means that it gets stored in your body (mostly in your liver) so taking too much Vitamin A is something to be careful of.
Vitamin A overdose and toxicity “danger levels” start to develop when taking in around 25,000IU or more of Vitamin A per day for a long time. And a long time can mean months, or even years.
Some of the symptoms include blurred vision, bone pain, headaches, diarrhea, loss of appetite, skin scaling & peeling and muscular weakness.
So how exactly does Vitamin A overdose occur? Toxicity occurs by either consuming too much preformed Vitamin A (the kind that comes from animal sources such as turkey, liver, eggs) or by taking too many supplements with preformed Vitamin A (usually in the form of retinyl palmitate or retinyl acetate).
Preformed Vitamin A is absorbed quickly and eliminated slowly.
This is because in order to pass through the body, Vitamin A gets paired up with special binding proteins. Problems arise when these binding proteins become full and free retinol starts to do its damage.
Vitamin A toxicity can also be from long-term low intakes or short-term high intakes. And children are more vulnerable to Vitamin A overdose and toxicity than adults because children can reach toxic Vitamin A levels at smaller doses.
Also, be careful if you’re pregnant. Too much Vitamin A, especially Vitamin A supplements, can cause birth defects. Talk to you doctor first and a safer bet is to take beta carotene instead.
Which leads us into the next topic of Vitamin A toxicity... beta carotene.
Is Beta Carotene Toxic?
In short, no.
But they do have some minor (and funny looking) side effects. The only side effect known by taking too much Vitamin A beta carotene is your skin starts to turn colors. It becomes like a yellow-orange tint. Think of someone whose spray-on tan went really bad. That’s what you’ll look like from taking in too much beta carotene.
The extra beta carotene (aka. hypercarotenodermia) gets stored in the fat under your skin and will show through. You’ll probably look more yellow than orange-y but at least you can brag to your friends “Hey look at me, I got some color!”
If you want to play magician and have your “tan” disappear then give it a few weeks, lay off the carrots and the beta carotene and you should be good to go.
Your best bet is to get most (if not all) your Vitamin A from beta carotene sources. The Vitamin A RDA, which is the minimum amount of Vitamin A you should get per day, is between 2300IU to 3000IU, depending on if you’re man or woman.
And in order to get all of the Vitamin A benefits, it’s better to get between 10,000IU and 15,000IU of Vitamin A per day (most of it being from beta carotene sources!).