Peanut butter is sold as a health food

Peanut butter is sold as a health food, and the most potent natural liver carcinogen known to science was discovered because it killed over 100,000 English turkeys in 1960.

That year, young turkeys on farms within about a hundred miles of London began to die. They went quiet, stopped eating, sat with their heads drawn back and were dead within days. Vets had never seen anything like it. They called it Turkey X disease.

By the time it burned out, well over 100,000 birds were dead, along with ducklings and young pheasants on other farms. The common thread was the feed, and a new ingredient in it: peanut meal, shipped in from Brazil. Outbreak after outbreak traced back to mills that had used the same Brazilian groundnut meal.

The meal had been colonised by a mould, Aspergillus flavus, which makes a poison the scientists named after it: aflatoxin. Fed to rats in the lab, it wrecked their livers and then gave them liver cancer. For years afterwards the standard test for a suspect batch was to feed it to day-old ducklings and look at their livers.

It is now classed as a definite cause of cancer in humans, and it lives where the mould lives: in peanuts, maize, tree nuts, cottonseed and dried figs, crops stored warm and damp in bulk. It is behind tens of thousands of human liver cancers every year, mostly in countries where peanuts and maize are the daily staple.

Europe sets a legal limit for aflatoxin in peanuts and turns shipments away at the border every year for breaking it.

Nobody has ever needed a border inspection for aflatoxin in a sirloin.

The turkeys were fed peanuts because peanuts were cheap. We are told to eat them because they are full of healthy fats. Both were sold the same nut.