Why Colonial Americans Feared Salad (And They Were Right)

Raw vegetables were literally considered poison for 300 years. New research suggests our ancestors understood something we forgot.

For most of Western history, eating raw vegetables was considered medically dangerous. This wasn't ignorance. It was the dominant medical framework for over a thousand years.

The system was called humoral medicine, rooted in the writings of Hippocrates and Galen. Every food had a "temperature" and "moisture" profile. Raw lettuce was classified as cold and wet, believed to extinguish the body's vital heat, dull the senses, and (according to medieval physicians) "extinguish lust." Raw apples were thought to damage the nerves and corrupt the blood.

This wasn't fringe thinking. European medical texts from the 1200s through the 1700s consistently warned against uncooked fruits and vegetables. Cooking was considered essential: it "pre-digested" food by adding heat, making it safe for the stomach. Salad, by definition, was suspect.

Here's the thing: they weren't entirely wrong, just for the wrong reasons.

In colonial America, fresh fruit season reliably coincided with outbreaks of dysentery, cholera, and typhoid. Historical records from the 1700s and 1800s show that summer and early fall (peak harvest for raw produce) were consistently the deadliest months for gastrointestinal illness. Colonists called it "the summer complaint," and physicians directly blamed fresh fruit and raw greens.

As food historian Nina Teicholz documented, "even in the warmer months, fruit and salad were avoided, for fear of cholera." A pioneering 1888 US government nutrition report concluded that Americans would be best to "avoid leafy vegetables" entirely, because they provided so little nutritional content relative to the risk. The result: Americans ate four to five times more butter and six times more lard than we do today, and virtually no raw greens.

The real culprit, of course, was contaminated water used to irrigate and wash crops, combined with poor sanitation. But the correlation between raw produce and illness was real, observable, and deadly.

Fast forward to today, and leafy greens remain one of the most common sources of foodborne illness in the United States.

Between 2014 and 2023, the CDC linked leafy greens (romaine lettuce, spinach, spring mix) to dozens of multistate E. coli and Salmonella outbreaks. In 2018 alone, a romaine lettuce E. coli outbreak sickened 210 people across 36 states, killing 5. The FDA launched an entire Leafy Greens STEC Action Plan in response.

The numbers are striking. The CDC estimates that produce (fruits and vegetables combined) causes 46% of all food-borne illnesses in the US each year. Leafy greens alone account for the largest share of any single food category. Contamination comes from irrigation water tainted with animal runoff, processing facilities, and the simple fact that greens are eaten raw, with no "kill step" like cooking.

A 2022 FDA sampling study found detectable levels of pathogenic bacteria on roughly 1 in 100 samples of leafy greens at retail. That might sound small, but across billions of servings per year, it translates to tens of thousands of illnesses annually.

The salad-as-health-food era is surprisingly recent. It really took off in the 1970s and 1980s, riding the same wave of low-fat dietary advice that told Americans to replace butter with margarine and lard with vegetable oil. The "eat more plants" message was never really about leafy greens being uniquely nutritious. It was about displacing animal fats from the plate.

Meanwhile, the core problem colonial Americans observed hasn't gone away. Raw produce still carries inherent contamination risk. The difference is we've built an industrial supply chain around it, with pre-washed bags and triple-rinsed labels that create a false sense of safety. Washing reduces but does not eliminate pathogens. Once E. coli or Salmonella is internalized in leaf tissue (drawn in through roots or stomata), no amount of rinsing removes it.

This isn't an argument against ever eating a vegetable. It's an argument for understanding the tradeoffs.

Cooking greens eliminates virtually all pathogenic risk. Sauteed spinach, braised kale, roasted broccoli: these deliver the same (or better) micronutrient profiles as their raw counterparts, with the bonus of improved bioavailability for fat-soluble vitamins when cooked in healthy fats like butter or tallow.

If you do eat raw greens, buy whole heads over pre-cut bags. Pre-cut, bagged salad mixes have higher contamination rates because the cut surfaces release plant juices that feed bacterial growth during transport and storage.

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