Green Potatoes - Toxic Tubers?

Green potatoes

What do you know about green potatoes?

You’ve probably heard the expression that you learn something new every day, but I still can’t believe I had never heard about potatoes turning green. My father was a grocer, and I majored in home economics in high school, dietetics in college and have studied foods and nutrition my whole life, but I had never heard about these potentially toxic tubers.

Green doesn't always mean not ripe.

When I say green potatoes, I am referring to potatoes that have a greenish cast to their skin or a layer of green pigment under the skin or both. Of course, I have occasionally encountered green potatoes throughout my life, both in the grocery store, on my pantry shelf and in the occasional potato chip that has a greenish hue. I always believed that these off-color potatoes were just green—as in, not ripe. It turns out that the problem is the exact opposite.

The potato salad that almost wasn't

The subject came up for me recently when I was making potato salad and in the process of preparing some nice, organic red potatoes, I noticed the telltale green color under the skin, obscuring the white part of the potato. It was not just a bit of green but a coating on the whole potato—in fact on all of the potatoes.

Deadly sprouts

It reminded me of a news story I had just heard about a man who ate a large quantity of potato sprouts and died from it. At the time, it was reported that there is a poison that is present in the sprouts of potatoes that is not found in the potato itself. Although I have always removed the “eyes” or sprouts from potatoes, I was surprised that they were actually poisonous.


After doing some research, I found that the green coating is nothing more than chlorophyll, the stuff that makes all plants green. Excessive exposure to light and heat can produce this effect. So rather than being unripe as I had thought, green potatoes are actually, in a sense, over-ripe!

Chlorophyll in potatoes signals toxic build-up

You probably know that chlorophyll is the substance that makes plants green. In the case of green potatoes, the chlorophyll in itself is not a problem, but its presence under the skin of a potato is associated with the production of a toxin called solanine. Ingesting too much of this toxin can cause symptoms of food poisoning including nausea, diarrhea, vomiting, abdominal pain, confusion, shortness of breath, convulsions and even death.

How much is too much?

There is some controversy about how much solanine it would take to make you sick, but if you find your potatoes have a green skin or a green layer under the skin, you may want to discard them to be completely safe. On the other hand, there are some health experts that consider it sufficient to remove all green parts and sprouts from the potatoes before cooking. One caveat to this approach is that, if the potato tastes bitter after cooking, the potatoes should be discarded, since that may indicate the presence of the toxin.

As with any toxin, the risk is greater for children, the elderly, pregnant women and those with compromised health status, so extra care should be taken with food preparation for these groups, and that includes serving green potatoes.

What you can do

Here are some tips to help you avoid the potential problems that may be associated with green potatoes:

(1) Check for "greening" before you buy

(2) Store potatoes in a cool, dark place

(3) Use potatoes you buy within a few weeks

You can decide for yourself.

For more information on the U.S. government's more drastic take on greening, click on this link.

For an alternative approach to the solanine issue, click on this link.

So what happened to the potato salad?

After reading numerous articles about greening, I went back to the kitchen and decided to remove all traces of green from the potatoes, and after tasting them for bitterness, I went ahead and finished making the potato salad. I just couldn’t bear to throw away all those lovely, organic potatoes, and since I wasn’t going to be serving the salad to any of the high-risk groups listed above, I was willing to take my chances.

I told my husband about the greening controversy, but he wasn't concerned and enjoyed the potato salad without any qualms. When the salad was all gone, we had suffered no ill effects from it.

I am certainly not suggesting this approach for everyone, particularly if you are in one of the the high risk groups, but after all, we had both survived more than fifty years being blissfully ignorant of the possible danger lurking in potato salad. However, now that I know, I will check the potatoes carefully before I buy, and store them properly when I get home.

It occurred to me in the course of my green potatoes adventure that only in a land of plenty like the U.S., would we throw away food when it could be salvaged with a bit of careful preparation. But that’s a story for another time.

In the meantime, we can learn something new every day and that's a good thing.

Eat and be healthy with my warmest regards,

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