Green Potatoes

Potatoes come in many 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 because of 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 defense mechanisms produced in abundance when the tubers are dug up and exposed to light. The green color under potato 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. Then they are moved to a shipping truck and rolled down the freeway for 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 potatoes will have shifted from storage to growth mode. That is when trouble starts.

Is peeling enough?

Many say that peeling the green skin away makes the spud safe to eat, which is not entirely accurate. While most potato toxins are in the skin, they are also present in the rest of the potato. [Just as moldy cheese has mold growing throughout its interior, even if it is invisible.] Peeling green-skinned potatoes may not be enough, and cooking them does not affect the toxins.

Healthy individuals with good digestive systems are generally not harmed by occasional green-skinned potatoes. If you notice any of these symptoms, however, see a doctor:

• 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). You can store your potatoes in a dry, chilly 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 homegrown, add it to the compost pile or plant it.