The Scientific Reason Why Some Potato Chips Are Green

Even though they're pretty unhealthy, there's nothing as tempting as a potato chip as an occasional treat for that crispy and salty deliciousness. As anyone who's ever popped open a bag of potato chips has likely noticed, though, potato chips are more often than not ... well, potato chip-colored, while occasionally, one or a few turn up green. There are even some playground superstitions about whether or not green-hued potato chips are safe to eat. As it turns out, there's a perfectly natural reason some chips end up greenish in color, and even some truth about whether or not you should eat them. There's much more to the story than that.

To fully understand why this natural green-tinted potato phenomenon can sometimes occur, the first step is to understand how potatoes are grown. Potatoes begin life underground. Occasionally, though, a little bit of the potato will get exposed to some sunlight. And even just a little sunlight can start a process within the plant to produce a natural compound that's crucial to several of the potato's most important biological functions (via WebMD).

If even just a few sun rays touch the exposed skin of a potato while it's still growing, the process of producing chlorophyll will begin. What's more, potatoes can start to produce chlorophyll after they're dug up, in the truck, or in the factory before they get processed. What's important to note here is that chlorophyll itself is what makes plants green. The same is true about a plain old potato that's been allowed to sunbathe for too long. Alone, chlorophyll is perfectly safe to eat, according to Medical News Today.

Per the U.S. Department of Agriculture (USDA) United States Standards for Grades of Potatoes, however, potatoes deemed to be more than 5% green are considered unusable and not allowed into public consumption. Occasionally, though, some greenish potatoes do make it through, and even if they aren't green when they're evaluated, certain lighting and temperatures in warehouses or even the supermarket can still make them produce chlorophyll, and therefore show green. That's why, on rare occasions, you may find a green-hued potato chip in your snack bag (via Mental Floss).

Eating some chlorophyll, such as in a green-tinted potato, is nothing in and of itself to be worried about. But there is some truth to the notion that green potatoes, and also green potato chips, should be avoided, at least in large quantities. That's because a potato that began to produce chlorophyll is a sign that another process has also started inside the plant that produces a glycoalkaloid called solanine, according to Science Direct.

When some people tell you that you shouldn't eat too many green potato chips, it's not the green stuff itself that they're talking about, it's the solanine, which is a neurotoxin that can also be found in the highly poisonous nightshade. Any potato with more than 0.1% solanine is considered unsafe to eat, as it could induce terrible nausea and headaches, among other side effects, according to Medical News Today. The good news, though, is that even if a green-tinted potato shows signs that it might also have some solanine in it, green potato chips are pretty rare, and even so, you'd have to eat a lot of them to feel any ill effects — we're talking pounds. If that's the situation you're faced with, it's best to put the potato chips aside, anyway, and maybe pick up some carrots instead.