About Green Potatoes

Seeing green on your potatoes? Those areas contain a harmful toxin. Cut out those spots and throw them away.

Photography Credit: Elise Bauer

Green = vegetables = good, right?

Not when it comes to potatoes.

Here’s an important piece of information that my mother taught me years ago, but fewer and fewer people these days seem to know about. Green in potatoes indicates the presence of a rather harmful toxin. When you see patches of green in your potatoes as you peel them, cut out the green parts entirely and discard them.

What is the green? Actually it’s chlorophyll. Not bad for you at all. But the chlorophyll indicates that the potato has been exposed to sunlight. And where the potato has been exposed to light is where a natural toxin in the potato (solanine) becomes concentrated at harmful levels. So, never store your potatoes on the counter. Always keep them in a cool, completely dark place.

Solanine is a natural defense mechanism of the potato to ward off fungus and pests. It will also be triggered when a potato is bruised, so if your potato is at all damaged or bruised, discard it.

According to the Wikipedia, deep-frying potatoes at a high temperature (306°F) effectively lowers the level of toxins. But boiling them (212°F) has no effect. Best to stay on the safe side and just cut away the green parts. The NIH website mentions that the potato sprouts can also have concentrated solanine, so those too should never be eaten.

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One of the things we’ve been noticing recently is that more often than not the bag of potatoes we buy from our local grocer contains several potatoes with green splotches. Once in a while is one thing, but every time? We’ve complained to our store’s manager and if you are finding green in the potatoes from your produce supplier, we urge you to do the same.

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Showing 4 of 60 Comments

  • Rod cupp

    Would to much water turn potato green?i planted mine and hilled when plant was six inches high. We had a lot of rain. Garden flooded. After drying out we dug a hill. Two of the eight had green on sides. These spuds were approximately eight inches deep,no chance of sunshine getting on them. Could being in wet conditions cause green and is it toxic

  • Joe

    Yes, solanine is toxic and it should be avoided. Should it be feared? No. According to Dr. Holt from the University of Missouri – Columbia, there have not been any reported cases of potato poisoning deaths in the US in 50 years.

    According to the International Program on Chemical Safety, the toxicity of solanine varies from species to species but the LD50 ranges from 20mg/kg to 590 mg/kg. (LD50 is the concentration at which 50% of the sample population died, in the units of mg of toxin per kg of body weight.) Being conservative, we could take about 25mg/kg to be a safe number to use for humans.

    Also according to the Wikipedia article and other sources, the normal concentration of solanine in healthy white potatoes is 200mg/kg of potato. After exposure to sunlight the concentration can go as high as 1000mg/kg.

    So using my weight – about 150 lbs – an LD50 of 25mg/kg and a green potato solanine concentration of 1000mg/kg I would need to eat 3.75 POUNDS of purely GREEN potato to reach a dosage that would be likely to kill me.

    I’m not going to sweat the tiny bit of green potato.

    Here’s a thought that should be even more upsetting. Do you think that the potatoes that are used to make french fries, hash browns, tater tots, etc. in a huge factory are even examined for green spots? Or do they simply get peeled, sliced, packaged, and sent out to you and me? The Wikipedia article referenced above notes that the average person probably gets about 12.5mg/day, which for me is only 0.18mg/kg per day. Luckily it’s nowhere near the LD50, so I’m still safe.

  • Selah

    I’d never heard anything like this before thank you for drawing attention to it!!!

  • Nick

    From what I’ve heard, potatoes always contain this toxin but to a much lesser extent. I wonder if the chemical builds up in your system like mercury can from eating too much tuna….I sure as heck don’t wanna turn green.

    All members of the nightshade family (tomatoes, eggplants, bell peppers, potatoes) have this toxin, but in low enough concentrations that it isn’t a problem. The toxins help repel pests. In the case of the potato tuber however, the solanine can become concentrated to harmful levels when exposed to light. Don’t know about build-up. Haven’t seen it mentioned as an issue. ~Elise

  • Anonymouse

    True story: I was talking to my grandmother about her childhood once, and she mentioned that she’d had a very young sister who died from eating a bad potato. I thought she was joking because she mentioned that it was green and that’s what made her sick, so it’s crazy to read this now.

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