The German Federal Institute for risk assessment (BfR) has cautioned that green and potatoes and those in an advanced stage of germination should not be consumed, after a case of poisoning was discovered in Germany.

BfR has revised the safe limit of the natural ingredient glycoalkaloids in potatoes, which can cause a health risk if consumed at high levels.

Naturally derived from glycoalkaloids, the poisonous chemical compound solanine also occurs naturally in tomatoes and aubergines.

Cases of solanine-related illnesses, linked to the consumption of potato-based dishes, were observed in November 2015. Investigations showed that potatoes had a content of glycoalkaloids at 236mg per kilogram. Specifically, the potatoes were found to contain glycoalkaloids α-solanine at 141mg/kg and glycoalkaloids α-chaconine at 95mg/kg. Potato salad contained a lower glycoalkaloid content of 124mg/kg.

The current safe limit for glycoalkaloid content in potatoes is no more than 200mg/kg. On the basis of this, the BfR has set a provisional No Observed Adverse Effect Level (NOAEL) of 0.5mg of glycoalkaloids per kilogram of body weight per day.

The BfR added that the glycoalkaloid content in potatoes for consumption should not exceed 100mg per kilogram at fresh weight.

Glycoalkaloid poisoning can cause a range of symptoms, from nausea, stomach-aches, vomiting, diarrhoea and fever. In worse cases, poisoning can cause loss of consciousness, and brain function loss, as well as damaging the cardiovascular system.

When cultivated, harvested and stored properly, potatoes usually contain between 20mg/kg to 100mg/kg of glycoalkaloids, but studies have occasionally recorded levels of over 200mg/kg.

According to BfR, only a few cases of potato-based solanine poisoning have been recorded, but many more related illnesses may have been overlooked due to the non-specific nature of the symptoms.

The latest data for Germany, published in 2005 by the Bundesamt für Verbraucherschutz und Lebensmittelsicherheit (BVL), found only one case of high glycoalkaloid content in 222 potato samples tested, at 271mg/kg.

The most notable case was recorded in Canada in 1984, where consumption of baked potatoes containing 500mg/kg caused 61 cases of poisoning among school children and staff.