Ban the potato?

Posted on Wednesday, October 26th, 2011

I recently attended a talk at our local horticultural society about growing vegetables and was intrigued by a suggestion by the speaker that, if potatoes were discovered today, they would be banned due to their poisonous nature.

Now, I’ve always been aware that you should avoid eating green potatoes, but I haven’t really considered them an extreme danger to health. It’s not like eating hemlock or foxgloves, is it? Surely the speaker’s suggestion that eating just two shoots from chitting potatoes could kill you was a gross exaggeration? As a regular potato grower I decided I should find out more.

It turns out that all parts of potato plants contain glycoalkaloid toxins called ’solanine’ (the botanical genus for potato plants is Solanum) and chaconine (though I’ll just refer to them as ’solanine’ in this blog). But these are particularly concentrated in parts of potatoes which are green below the skin (where they have been exposed to light) and in the sprouts. The leaves, flowers and fruits are also highly poisonous.

Solanine is the same poison which gives deadly nightshade (Atropa belladonna) it’s epithet; both plants coming from the same family ‘Solanaceae‘.

The normal concentration of solanine is a maximum of 7.5mg per 100g of potato, with a higher concentration in the skin than in the flesh. Green potatoes can have up to 80mg per 100g, which can be a fatal amount. Many years ago there was an outbreak of solanine poisoning in Scotland which resulted in the death of a 5 year old child. The child had eaten potatoes which had 41mg of solanine per 100g of potato.

Deaths are rare from this poisoning, but not unknown. Symptoms of mild poisoning include diarrhoea, vomiting and severe abdominal pain. More acute cases may suffer from a general weakness, drowsiness and confusion. The symptoms can occur within minutes or up to two days after ingestion.

PotatoesSo, having scared myself (and maybe you!) about eating potatoes, what should we do about it?

Well, I for one would abhor a ban. No more chips? Not on your Nelly!

However, I would recommend caution when growing and storing potatoes. Obviously, never eat a green potato or potato sprouts. But also consider how you grow potatoes if you have children or animals in the house. Chitting potatoes left on a windowsill may be a great curiosity for little hands. And berries on potato plants left to go to seed would be at the right level for peckish children and pets.

So be cautious about this potentially dangerous foodstuff, but don’t let it stop you enjoying your spuds!