Solanine in Green Potatoes

Have you heard of solanine?

You’ve probably heard the maxim that you learn something new every day, but I still can’t believe I had never heard about green potatoes. 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 never knew about these potentially toxic tubers.

Green doesn't always mean unripe

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 not ripe. It turns out that the problem is the exact opposite.

The potato salad that almost didn't happen

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 trace of green but a coating on the whole potato—in fact on all of the potatoes.

Deadly solanine 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, called solanine, 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.

Overexposed

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 buildup of solanine

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 does it take?

There is some controversy about how much solanine it would take to make you ill, 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 safe 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 danger is higher for children, the elderly, pregnant women and those with a compromised health status, and extra care should be taken with food fed to these groups.

Steps you can take

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

*Check for greening before you buy
*Store potatoes in a cool, dark place
*Use potatoes you buy within a few weeks

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 could not bear to throw away all those organic potatoes, and since I wouldn't be serving the salad to any of the vulnerable 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 definitely not suggesting this approach for everyone, especially if you are in one of the the high-risk groups, but after all, we had survived more than fifty years being blissfully unaware of the possible danger lurking in potato salad. Having said that, now that I know about green potatoes, I will check carefully before I buy, and store potatoes properly when I get home.

Read and decide for yourself

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

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

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