Passover foods: If a potato looks like this, it may cause poisoning

As potatoes star throughout the Passover holiday, get to know a curious 40-old case, and the varieties that can cause poisoning.

 A farmer handles a large stock of potatoes that he can?t sell to restaurants or catering services, as they are closed due the coronavirus disease (COVID-19) outbreak, at his property in Purmer, Netherlands, April 3, 2020.  (photo credit: REUTERS/EVA PLEVIER)
A farmer handles a large stock of potatoes that he can?t sell to restaurants or catering services, as they are closed due the coronavirus disease (COVID-19) outbreak, at his property in Purmer, Netherlands, April 3, 2020.
(photo credit: REUTERS/EVA PLEVIER)

Passover is considered the Feast of Unleavened Bread, but in practice it should be called the Potato Feast, as potatoes an ingredient that stars throughout the holiday. This interesting story that took place over 40 years ago is a warning sign for all potato lovers, and it’s a worthwhile read.

78 kids with diarrhea

In 1979, a mistake made by a catering company led to 78 school children being poisoned by potatoes.

Returning to school in south London after a holiday, a large number of boys suddenly became ill and began to suffer from symptoms ranging from vomiting and diarrhea, to fever, some even falling to coma and nervous system problems in the most severe cases, according to the iflscience website.

The cause of the disease was quickly identified: Everyone had eaten potatoes cooked about 14 hours earlier.

"These boys showed signs of peripheral circulatory collapse, even when dehydration was only mild," the doctors wrote in a British Medical Journal case report published that year. Symptoms lasted for six days.

 Passover Seder (credit: MIRIAM ALSTER/FLASH90) Passover Seder (credit: MIRIAM ALSTER/FLASH90)

"Potatoes are such a common ingredient in the Western diet that most people are surprised to find that they’re the product of a poisonous plant," the team wrote.

"In fact, potato stems and leaves contain a number of alkaloid glycosides, called solanines, which are highly toxic,” they added. The authors cited other cases, including a man who was poisoned after eating the leaves and seeds of potatoes.

What is the real danger of potatoes?

The main danger stems from eating green potatoes, the ones that have just come out of the ground.

The Israeli Health Ministry, on its website, states under the heading "Avoid eating green potatoes" that green potatoes or with green spots may contain high levels of glycoalkaloids (solanine and chaconine) — natural toxins.

Potatoes naturally contain these toxins in very low concentrations. "Potatoes exposed to light, moisture and heat can contain high-level toxins," wrote the researchers. 

"Eating these potatoes causes disease of the digestive system, nervous system and symptoms such as very strong pain, nausea, vomiting, diarrhea, dizziness, intestinal cramps, loss of sensitivity and hallucinations. In extreme cases, a very high level of 3-6 mg per kg of body weight can cause death," they wrote. 

"Fortunately, few people cook green or sprouted potatoes because of their appearance and bitter and unpleasant taste, so in practice solanine poisoning is very rare, except during periods of food shortage," they added.