14 November 2013

Solanine poisoning

[T]he potato is the most common cause of solanine poisoning in humans. But how do you know when solanine is present in a potato? The tuber is turning green.

Though the green color that forms on the skin of a potato is actually chlorophyll, which isn’t toxic at all (it’s the plant’s response to light exposure), the presence of chlorophyll indicates concentrations of solanine. The nerve toxin is produced in the green part of the potato (the leaves, the stem, and any green spots on the skin).

The reason it exists? It’s a part of the plant’s defense against insects, disease and other predators. If you eat enough of the green stuff, it can cause vomiting, diarrhea, headaches, paralysis of the central nervous system... but in some rare cases the poisoning can cause coma—even death...

Fatal cases of solanine poisoning are very rare these days. Most commercial varieties of potatoes are screened for solanine, but any potato will build up the toxin to dangerous levels if exposed to light or stored improperly. Often, the highest concentrations of solanine are in the peel, just below the surface and in the sprouted “eyes”—things that are typically removed in cooking preparation...
More at the Smithsonian's Food & Think blog.  Photo credit unknown.


  1. A different neurotoxin, but wild potatoes were brought to light recently as having ODAP naturally occurring in the seeds. Krakauer came to his final conclusion about its role in the death of McCandless only just recently. http://www.newyorker.com/online/blogs/books/2013/09/how-chris-mccandless-died.html

  2. The PBS kids' show _Arthur_ had an episode called "Don't Eat the Green Ones," wherein DW (Arthur's younger sister) thinks she's going to die after eating a green potato chip and two kids tell her this myth. Much more entertaining than this synopsis sounds.


  3. A woman I went to school with ended up in the hospital from eating green potatoes. Her son did not get sick because he refused to eat the potatoes complaining they tasted nasty. She got better and now knows not to eat green potatoes.

  4. This post made me look something up that I've always wondered about. My family has planted sweet potatoes in the past and my parents and I have all eaten both tuber and leaves. (Of course, we all know potato leaves are poisonous and would never eat a green potato.) They use the terms "yam" and "sweet potato" interchangeably (ESL) so I wondered maybe what they planted were actually yams (I didn't think so because yams are monocots while potatoes are dicots; Wikipedia confirms).

    So, a quick google search yielded this: Sweet potatoes and Potatoes are related at the order level: both are from Solanales; but sweet potato leaves are edible (commonly eaten in Polynesia, Asia, and Africa, but not in the US). Looking at Solanaceae, the deadly nightshade family (does not include sweet potatoes), Wikipedia seems to suggest that only some members are toxic.


  5. I have read somewhere that you would have to eat around 2kg of it to be affected, hence eating 100g of potatoes of which a few percent is green would be no hazard?

    1. I think you are remembering dosages causing death. Sx are said to occur at about 25 mgm.

  6. The solanine(I assume) in nightshades aggravates my arthritis. I don't eat potatoes, peppers, eggplant, tomatoes... Bad, generally inflammatory food for me.


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