Is it safe to eat potatoes that have sprouted?
I'm talking about potatoes that have gone somewhat soft and put out shoots about 10cm long.
Other online discussions suggest it's reasonably safe and the majority of us have been peeling and eating soft sprouty spuds for years. Is this correct?
store potatoes with apples to avoid this: http://lifehacker.com/5954159/store-potatoes-with-an-apple-to-keep-them-from-sprouting?utm_campaign=socialflow_lifehacker_twitter&;utm_source=lifehacker_twitter&utm_medium=socialflow
Not safe enough for me to try it. Potatoes actually contain a very dangerous toxin called solanine. This toxin is concentrated enough in the green parts in the plant to cause solanine poisoning. This includes the sprouts/eyes, and the potato itself if it's green.
This article from the New York Times health guide indicates that it is something to be taken seriously. Per this article, if the sprouts have been removed, and the potato is not green then it is safe to eat as far as solanine poisoning is concerned.
However, a potato as far gone as you have described sounds disgusting. A soft potato is on its way to going bad. Where I am from, potatoes are cheap enough that it's just not worth the gross factor for me to eat a potato that has 10 cm sprouts and is squishy. I do eat potatoes that have little nub sprouts on them and that are slightly less than firm, after removing the sprouts of course.
Just to add to this amazing answer, if your potato has a small green layer, it's safe to eat, **as long as you make sure you remove *all* the green parts.** Otherwise, just throw it out.
To add to what @Edwin said: leaving a potato in sunlight will make it turn green; that's chlorophyl, and it's okay to eat. That's different from the green from solanine, which isn't okay to eat.
@PeteBecker, my understanding is that the green is caused exclusively by chlorophyll, and chlorophyll content of the potato correlates with solanine content, though they are produced by separate processes. Note however, that solanine is concentrated near the skin of the potato and can be significantly reduced by peeling. More info