Green Potatoes

Q. Why do potatoes go green?

Potatoes will often go green when they’re not stored properly and they're exposed to light. This is due to formation of chlorophyll (which is found in all green plants), however the green colour is a useful indicator that levels of certain toxins that are harmful to humans, known as glycoalkaloids, may be increased.

Q. Is there a risk from eating green potatoes?

Glycoalkaloids are a group of toxins that are naturally present in potatoes, with concentrations highest in the sprouts and peel of potatoes. The levels can also increase when potatoes are damaged or when potatoes are exposed to light for prolonged periods. If a potato has gone green it’s likely to contain higher levels of the toxins.

Whilst not acutely toxic in humans, there are a number of reports suggesting that ingestion of potatoes containing high levels of glycoalkaloids have led to poisoning incidents where the main symptoms displayed are irritation of the gut and also drowsiness. These symptoms have also been shown at high doses of glycoalkaloids in controlled experiments using human volunteers.

Available evidence suggests that there is not a link between exposure to elevated levels of glycoalkaloids from green potatoes and incidents of spina bifida or other malformations of the fetus.

Q. Can I eat green potatoes if I peel them?

Peeling of green potatoes will greatly reduce the levels of glycoalkaloids as they are localised just below the surface of the peel. However, if these potatoes taste bitter after peeling, then it’s best not to eat them.

Last reviewed: 13/4/2015