What Are Those Sprouts That Grow on Potatoes? (And Are They Safe to Eat?)

NatalieMaynor, Flickr // CC BY 2.0
NatalieMaynor, Flickr // CC BY 2.0 / NatalieMaynor, Flickr // CC BY 2.0

No matter how hard you try to conserve food, finding the occasional piece of produce rotting in your fridge is unavoidable. But a vegetable's expiration date isn't always obvious. Before it rots, a potato may grow knobby, greenish bumps on the outside that weren't there when you bought it. They may not look appetizing, but are potato sprouts unsafe to eat?

Sprouts are simply a sign that a potato is trying to grow. When they're harvested, potatoes enter a natural dormant state, but they only stay that way for so long. After enough time has passed, tiny tubers will erupt from the potato's "eyes" or buds. If the potato were still in the ground, these sprouts would eventually form new plants.

The question of whether or not a sprouted potato is still OK to eat is complicated. The sprouts themselves shouldn't be eaten, as they contain high concentrations of the toxins solanine and chaconine. These toxins, called glycoalkaloids, can cause headaches, vomiting, and digestive issues when consumed in high quantities.

But cutting the sprouts off the outside of a tuber doesn't automatically make it 100 percent nontoxic. Poison Control recommends tossing out any potatoes that have grown sprouts, though that may be a very cautious approach. Toxic glycoalkaloids are present throughout potatoes, but they're most concentrated in the eyes, skin, and sprouts. The Poison Control also advises against eating potato peels under any circumstances.

Dr. Rich Novy, a geneticist from the USDA Agricultural Research Service, told Best Food Facts that potatoes that have sprouted are fine to eat in most cases. The biggest chemical change that takes place when a potato sprouts is the conversion of starches to sugars to feed the growing buds. If a potato still feels firm after the sprouts have been removed, it has most of its nutrients and can be salvaged. But if it feels soft and wrinkly, it's gone bad and should be tossed out.

The best way to avoid making tough decisions about old produce is to store it properly. Here's where you should be keeping fruits and vegetables to make them last longer.