Green Potatoes

Potatoes come many of colors: blue, purple, red, yellow, and white. But why does potato skin turn green sometimes, and can it hurt you?

Green-skinned potatoes (Rasbak) CC BY-SA 3.0

The simple answer is yes. Green-skinned potatoes can make you sick. According to WebMD, you can peel green-skinned potatoes, but those potatoes are still not entirely safe to eat. It’s all about toxins.


Potato toxins

Like other members of the nightshade family, potatoes produce toxins. The toxins produced by potatoes are called solanine and chaconine. These toxins are part of a potato plant’s defense mechanisms. They are produced in abundance when tubers are exposed to light. The green color under a potato’s skin is chlorophyll. You can use it as a signal that lets you know a spud’s chemistry has changed.


Why do potato skins turn green?

Tubers belong underground. Uninjured potatoes are relatively stable in cool, dark locations. Expose them to light once and nothing happens. Expose them to light several times and things start happening. Imagine, if you will: First, they get dug up at the farm and see daylight for the first time. They get moved to a shipping truck and roll down the freeway with more sunlight. Drop them off at the processing plant and they get more light. You get the idea. By the time they leave the grocery store (where they got even more light) and arrive at your kitchen, some of those potatoes will have shifted from storage mode to growth mode. That’s when trouble starts.


Is peeling enough?

Many people say that peeling the green skin away makes the spud safe to eat. That’s not entirely accurate. While most of those toxins are stored in the skin, they are still present in the rest of the potato. Just as a moldy cheese will also have mold growing throughout its interior, even if you can't see it. Peeling a green-skinned potato may not be enough. And cooking them does not affect the toxins.


All that being said, if you are generally healthy with a good digestive system, you may be fine with an occasional green-skinned potato. If you notice any of these symptoms, however, see a doctor:
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• Abdominal pain
• Diarrhea
• Feeling out of sorts or confused
• Fever
• Flushed skin
• Headache
• Vomiting

Preventing green-skinned potatoes

You can’t control what happens to your potatoes before they arrive at your home (assuming you haven’t started growing your own yet). What you can do is store your potatoes in a dry, cool location with as much darkness as possible. Your refrigerator or pantry are ideal.


If an occasional green-skinned potato appears, throw it in the trash if it was from the store. If it was homegrown, you can.add it to the compost pile or plant it instead of putting your tummy at risk.