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Potatoes are a nutritious and versatile type of produce (from fries to mashed, they're delicious in all forms). These little spuds pack plenty of health benefits and are rich in fiber, vitamins and minerals. While most potatoes are completely safe to eat, they do contain a type of natural toxin that, if it builds up, might make you sick after consumption. That's why it's best to monitor the appearance of the potatoes you're storing (see below for more on how to store potatoes).
Lauren Harris-Pincus, M.S., RDN, author of The Everything Easy Pre-Diabetes Cookbook and The Protein-Packed Breakfast Club, explains, "Potatoes contain two kinds of glycoalkaloids, both natural toxins, called solanine and chaconine, and while the whole potato contains these glycoalkaloids, the concentration is highest in the eyes, green skin and sprouts that form."
The green hue actually comes from chlorophyll, which isn't toxic, but its green color is a good indication that there's excess glycoalkaloid concentration and that you'll want to toss the potato out. "Fresh potatoes should not look sprouted or have any green hue on the skin," says Harris-Pincus.
As they age, or with improper storage, potatoes may develop sprouting and green spots. If there isn't any sprouting, you can use the color change as an indicator of spoilage. If the skin looks greenish or if there's sprouting present, you'll need to remove the sprouts or toss the whole potato, depending on severity.
Why Is It Not Safe to Eat Sprouted Potatoes?
Sprouting means that the toxin levels are too high and the potato is no longer safe for consumption. According to Diana M. Pei, Pharm. D., a certified specialist in poison information, on Poison.org, solanine and chaconine can cause symptoms such as vomiting, abdominal pain, irregular bowel movements, diarrhea, headache, brain fog, redness or a flushed complexion, confusion or fever.
There have been a few cases of death after eating toxic potatoes, but generally you can treat symptoms at home. The onset of symptoms is typically within a few hours, but it can take up to a day, in some cases.
How to Reduce Toxicity or Remove Sprouts from Potatoes
Ultimately, the best way to protect yourself is to toss out potatoes containing green patches or sprouting. However, if you do notice sprouting or a green tint in some areas, you can try and remove them with a sharp paring knife and still cook with the rest of the potato (although this isn't recommended).
"Unfortunately, cooking does not destroy these compounds, so it's not advisable to prepare or eat potatoes with the sprouts or green parts," says Harris-Pincus. "However, it is probably OK to eat potatoes that have sprouted if you can cut away the entire sprout and any green-tinged parts of the potato, and if they are not wrinkly and shriveled," she adds.
You definitely want to be more careful if you plan on eating potatoes with the skin on in general, as that's where toxins reside. Harris-Pincus says, "I use a paring knife to dig out the eyes once I have snapped off the sprout and if there is more than a small area that looks green, I throw away the potato."
How to Store Potatoes to Reduce Sprouting
While the Costco-sized bag of potatoes might be tempting, Harris-Pincus suggests only buying potatoes as you need them to prevent spoilage. "If you do have extra, store them in a cool, dark place and make sure to keep them away from onions, which release gases and can cause potatoes to sprout faster," she adds.
Keep potatoes in a cool, dark and well-ventilated place, such as a pantry or cabinet. Avoid high temperatures, keep them away from kitchen appliances and make sure they're away from direct sunlight (read: your countertops might not be the best spot for your spuds!). Harris-Pincus says, "Excess exposure to light causes a buildup of the solanine that turns the skin green."
It's also worth noting that you shouldn't put potatoes in the refrigerator or freezer prior to cooking. "Colder temperatures lower than 50 degrees cause a potato's starch to convert to sugar, resulting in a sweet taste and discoloration when cooked," Harris-Pincus adds.
To help your potatoes last longer, keep them loose and in a dark area at room temperature (for example: a wire basket in your pantry). And lastly, wait to wash your potatoes until you're ready to cook them, as any dampness could also cause early spoilage.