Potatoes are a vegetable – a white vegetable.  They are not a green vegetable.  In other words, if you see any green under the skin, you don’t want to eat it.

It’s rare, but some potatoes develop a green tint. That color is caused by high levels of chlorophyll, which by itself is harmless.  But it is also a sign of solanine, which can cause nausea, headaches, confusion, convulsions, and neurological problems.

Solanine is a toxin that is developed in the potato at the same time as chlorophyll. Potatoes naturally produce tiny but safe amounts of solanine, which functions as the potato’s defense against insects. Levels increase when potatoes are exposed to light and warm temperatures over a prolonged period, preparing the potato to sprout.

Most green potatoes never reach the market, but if they are stored improperly, solanine may develop. A green potato can be safe if all of the green area and sprouts are cut off and thrown away. When cutting a potato in half, if the potato’s border has any green tone, it’s best just to discard it.  Once the potato is cooked, if it tastes bitter, it should be thrown away.

To Prevent Solanine

To prevent the development of solanine, store potatoes in cool, dimly lit areas such as a brown paper bag in the bottom of a refrigerator. Storing potatoes in a dark place in a cool garage or basement would be another safe place, ideally 40 degrees or cooler but not actually freezing.

Oh No, I Ate Potatoes that are Green

If a person does consume green potatoes or sprouts, even a relatively small amount can be unsafe.  It’s best to call the National Poison Control Center at 800-222-1222 or 911. The technical term is solanum tuberosum poisoning.