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!!!

  • A Tenter

    Thank you for your very important and informative website on the danger of eating green potatoes..publishers should include a food safety page including this type of information…
    I first learned of this danger as I was gleaning interesting information from 92 Civil War letters of my great great Grandfather. He writes in many of his letters of the severe illness that eating very green potatoes caused, including hospitalization and extreme weakness; Recovery was slow..No doubt the storage conditions were filthy in their encampments..Things are much better now; but I see some pretty green potatoes in the bags and I just purchased a large bag of Montana potatoes from the farm; the potatoes in the center of the bag were realy green!
    Again, thank you for information that should be up front for all to see.. Encluding info on the dangers of raw red kidney beans. Keep up the good work. ATV

  • Ginger

    I grew up on a potato farm in NW MI and have known about green potatoes and sprouts my whole life. I recently was having a potato emergency and bought a bag of MI russets that were in a plastic bag (that was all that was available at the moment). In the store, under florescent lighting, they looked fine, at home in my kitchen, the entire bag was green, all over. So disappointing! One tip I have is only buy your potatoes in a paper bag and make sure the screen has been facing downward. Store lights will turn the potatoes green fast. My dad would get so upset when he noticed the potato bags upside down in the stores (we delivered our potatoes to all the local stores) and would take the time to educate every produce manager about the damage light can do to a potato. Potatoes need to breath, so putting them in a plastic bag will shorten their life, as will storing them next to onions. I always try to buy potatoes that have been grown in the state that I reside as I don’t really need a potato that has traveled 2000 miles from Idaho. The short exposure time at farm markets is nothing to worry about, most stands won’t have their produce out in direct sunlight, precisely to avoid the green potato from happening.

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