Answer: Tomatoes

In the 18th century Europeans really disliked tomatoes. It wasn’t the taste or texture people found off putting, it was the widespread belief that tomatoes were poisonous and over-consumption would lead to madness or death.

While it would be easy to write off the confusion as related to the fact that the tomato is in the nightshade family (and therefore Europeans might have been confused as to whether or not the fruit of the plant was safe to eat), that only played a minor role in the belief that tomatoes were poisonous because, in all actuality, they were actually killing people. How exactly were tomatoes killing off enough Europeans to create a general fear of them?

Tomatoes are highly acidic and that acid can cause metals to leach out of the containers they are cooked and served in. This is a benefit when cooked in cast iron (as it boosts the amount of available dietary iron in the prepared food), but wealthy Europeans ate off pewter plates which introduced a much more dangerous kind of leaching. Pewter is made with lead and the acidity of the tomatoes readily liberated some of that lead from the plates with each serving. It doesn’t take many servings of lead-laced tomatoes to cause serious health problems (and even death).

Because the mechanism of death was unknown (and the lead in the plates wasn’t even a suspect), the people astutely (but incorrectly) linked tomato consumption with the illness which in turn led to a general public distrust of them.