Unhealthy Eating: Solanine and the Potato

Potatoes evolved in southern Peru, where 6000 years ago the Inca Indians started cultivating them, both as a nutritious food and as remedy for a variety of ills. They were planted in Chile too, as the normal migration took them to new areas. The Spanish conquistadors, arriving from Europe, looking for valuables to plunder, returned with potatoes to Europe, arriving in 1536. Their popularity at the court of King Louis XIV, and their popularity with US presidents Benjamin Franklin and Thomas Jefferson, ensured they were soon the dish of everyman, from polite society on down. In October 1995, NASA grew potatoes in space.

So dependent did many European countries become to the potato a primary food staple, that failure of a single crop could cause widespread hunger and misery. In 1845, a late fungus blight caused the widespread failure of the potato crop in western Ireland, triggering toAn Gorta Mór - the Great Irish Famine - a terrible period in Irish history during which lead to the deaths of perhaps more than 1,000,000 people of starvation and disease.

Yet oldly enough they also became a solution to famine in many countries because, if it can be kept blight-free, the crop yeilds more calories per acre than maize, rice, and soybean, and is a more reliable crop when the weather turns cold.

In the last few decade, production of potato crops has expanded rapidly in southern and eastern parts of Asia. China and India now produce a third of all the world’s potatoes.
So wouldn’t it be scary if potatoes were naturally poisonous (as the first were thought to be).

About three-quarters of a fresh potato is water, and most of the rest is carbohydrates in the form of starch and some undigestible dietry fibre. There is a little bit of protein (but not enough or course to satisfy the body’s needs if that is the only thing you have to eat, unless you also have a goodly supply of milk) a good selection of vitamins and minerals: thiamin, niacin, riboflavin vitamin C, magnesium, potassium, sodium and iron. There’s even a very, very tiny amount of fat, if you look hard enough. And there is also solanine and chaconine.

Solanine is a chemical found in the members of the Solanum plant family, which includes horsenettles, tomatoes, and belladonna or deadly nightshade. It has the molecular formula (C45H73NO15), and is classified as a glycoalkaloid poison; it causes vomiting, diarrhea, heart problems (arrhythmia), and neurological problems (dizziness, hallucinations).

In large enough doses, it can kill you.

Potatoes turn green as a defense against the light when they are exposed, and they start to churn out their glycoalkaloid poisons to dissuade amnimals from eating them (the poisons are bitter tasting). In many countries, but not all countries, potatoes are monitored for their solanine levels, to make sure the levels are kept low, but just a single potato can contain a dangerous dose. Unpeeled, green potatoes can be particularly dangerous: most of the solanine develops in the skin, and just below it. It’s a good idea to avoid green potatoes altogether. It also turns out that you best defence against solanine (apart from giving up potatoes) is to deep fry them which leeches out the toxins into the frying oil (although remeber to discard the oil!). Boiling has no effect. Oh, by the way, be careful of green tomatoes too - some varieties also have a high dose of solanine too.