Does eating purple carrots turn you purple?

Naked Scientist Jack Tavener crunched down on the science of carrots to answer Aidan's question...

Jack - Fellow Naked Scientist, Katie, is with me.

Katie - I do feel a bit like a guinea pig, because I’ve got loads of carrots sitting in front of me

Jack - Yeah...You’re still happy to eat as many of these as you can, and then see if it’s made a difference?

Katie - I mean it is a hard life, isn’t it? In the name of science I’m going to basically have a snack.

Jack - Ready? Go!

The carrots Katie is eating make a tasty snack and are packed full of nutritious goodness. One component of this is beta-carotene, an organic pigment your body can use to make Vitamin A, which boosts your immune system and, whilst they may not help you see in the dark, it can help you maintain healthy vision.

This beta-carotene is what makes orange carrots appear orange. Purple carrots on the other hand get their colour from anthocyanins, which are the same compound that makes red wine red. And just like with red wine, you might find a purple carrot might stain your tongue, but this doesn’t necessarily mean that it also discolours your skin or that your urine turns red, like when you eat lots of beetroot - that’s yet another type of pigment. What happens to the purple colour all depends on what happens to the anthocyanins from purple carrots when your body processes them.

It turns out that your body is really good at processing anthocyanins, so none builds up in your skin and only a tiny amount comes out in urine - it means you don’t turn into a human grape, but purple might not be the colour to worry about...

Surprisingly purple carrots can have levels of beta-carotene similar to orange ones! So ironically, even the purple ones could turn your skin yellow, something Kryptid also suggested on the forum.

So how many carrots, orange or purple might you need to cause this? A lot depends on the size of the carrots, how much beta-carotene is in each and the individual eating them. But from what we’ve found, what is key seems to be the consistently high levels of intake. At least 5 carrots a day, every day, over the course of a few weeks would start to cause a change, with the carotene being stored under the skin and most visible on the palms of the hand, soles of the feet or on the face's laughter lines.

You looked completely stuffed Katie, how many have you managed?

Katie - I’m on number 3, and I’m still going.

Jack - That’s pretty good. Any effects you’ve noticed yet? Your hair seems to have gone ginger.

Katie - Oh ha ha, my hair’s always been ginger, thank you very much.

I’m not sure I’ve exactly noticed any yellowing or anything like that of the skin, I do feel a bit weird having eaten so many carrots though!

Jack - Don’t worry, even if you did turn yellow, you’re totally fine. You just have to stay off foods like carrots, tomatoes, sweet potato and even spinach, which contain a lot of carotenoids, for a few weeks or months until the colour goes away.

But just before we go, some fun facts that we learned from our friends at the World Carrot Museum, who helped with some of the research we’ve mentioned - carrots aren’t only great as food, but can also be used to make lasers, antifreeze and even to reinforce concrete… so even if purple carrots are more likely to turn you yellow than purple, that’s not the only surprising thing about them.

Next time, we’re taking to the skies, with this question from Seán

Seán - Why is it that when you directly at small faint stars, they disappear, but when you look at a point near it, you can see it again?