Food trivia: Are green potatoes or potato eyes really poisonous?

This time of year, the potatoes you get at the store are looking pretty poor. Potatoes are typically harvested in late fall, which means that the potatoes you buy in late spring and early summer have been sitting in cold storage for months by the time you buy them. This gives many opportunities for potato eyes to start sprouting, and you may also notice a greenish tinge to your potato's flesh, particularly right up under the skin.

According to folk wisdom, any of these items may be poisonous. My grandmother used to insist that every single eye on the potato was cut out before serving, regardless of whether the eye had sprouted or not. And a lot of people have been led to believe that the green parts of potatoes are poisonous. But is it really true?

Yes and no.

Potatoes, friendly tuber though they may be, are members of the nightshade family (home to many poisonous plants such as the aptly-named deadly nightshade). Potatoes can also contain trace amounts of a nerve toxin called solanine. This toxic becomes concentrated as the potato ages. It is produced in the green parts of the potato, which usually means the leaves and stems. But it can also be produced in the flesh under the right conditions. (Incidentally, the green in a potato's flesh is due to chlorophyill.)

Thus, green skin and eyes don't necessarily mean that a potato is toxic. They are simply an indicator that the toxin may be present. But even so, the toxin is present in a potato tuber in very tiny amounts. According to Snopes, an adult would have to eat 4.5 pounds of tainted potato at once in order to feel any ill effects.

A bigger problem is that the greenish shade makes them turn bitter. Potatoes turn green when exposed to too much light, so you'll want to keep them in the dark.

Regardless, the eyes and sprouts of a potato are completely non-toxic. Solanine is not found in either the eyes or the sprouts, so there is no cause for concern.

Image courtesy Flickr/Chiot's Run