Green potatoes contain a natural toxin that can make you sick.

Potatoes are members of the Solanaceae family, which includes nightshades like tobacco and belladonna. When tubers are exposed to light or extreme temperatures, they undergo a process called greening. This process involves the synthesis of chlorophyll and glycoalkaloids, specifically solanine and chaconine. While chlorophyll is a harmless pigment used for photosynthesis, its presence indicates that the potato has increased its chemical defenses.Solanine acts as a natural pesticide to protect the plant from insects and fungi. For humans, consuming high levels of solanine can lead to glycoalkaloid poisoning. Symptoms typically include nausea, diarrhea, vomiting, stomach cramps, and in severe cases, neurological issues like hallucinations or paralysis. The FDA suggests that a solanine level of 20 milligrams per 100 grams of potato is the limit for safety, but most commercial potatoes contain much less.Research from the University of Nebraska-Lincoln notes that even deep-frying does not fully neutralize solanine because it has a high melting point of about 545 degrees Fahrenheit. Peeling the potato can remove a significant portion of the toxin since it is concentrated just under the skin. However, if the flesh itself has turned green, the entire potato should be discarded to avoid illness. Storing potatoes in cool, dark places is the best way to prevent this toxic buildup.