If you’ve ever heard someone complain that “food allergies are everywhere nowadays” and that these allergies make it harder to serve food to large groups of people, you can safely correct them: Food allergies have been around for millenia.
In fact, the Roman poet Titus Lecretius Cato wrote, “What is food to one, to another is rank poison,” and that was way back in the 1st century BCE. From his word choice of “poison,” we can infer he meant the foods created awful symptoms upon consumption—like an allergic reaction.
The term “food allergies” only came about in the last century or two, but awareness of food allergies can be traced back to 2500 BCE.
Ancient Understandings of Food Allergies
Ancient doctors understood that certain foods could trigger weird symptoms for some people, even if it took millenia for doctors to understand why allergic reactions happened. Because certain foods caused problems for some and not others, they understood that the individuals were sensitive to the food, and not that the food was universally harmful to humans. Indeed, the word allergy comes from Greek meaning “to react differently.”
In 2500 BCE, Chinese emperors advised some people to avoid certain foods if it gave them strange skin symptoms (which historians believe might have been what we now call eczema).
Later in Greece, Hippocrates noticed that some of his patients had adverse reactions after eating cheese, whereas the rest of the population could eat as much of it as they wanted without a problem. Hippocrates made a conclusion: These individuals had “hostile humors” in their body that made them prone to such bad reactions from food.
“Humors” refers to the ancient theory of disease in which a healthy body required a balance of the four humors, or bodily fluids: blood, black bile, yellow bile, and phlegm. According to this old theory, too much of any one humor could put the body out of balance, and cause behavioral changes or disease. (The four humors theory is also behind the ancient practice of bloodletting.)
Historical Accounts of Food Allergies
Thanks to doctors’ letters and notes, historians have found numerous accounts of food allergies throughout time. In the 12th century, the Jewish physician Moses Maimonides wrote letters to Prince Al-Afdal, who had been suffering asthma attacks after meals. Maimonides wrote a letter advising Al-Afdal to avoid milk, nuts, and legumes.
In the 15th century, the British King Richard III had a strawberry allergy. He infamously was known to use this against his adversaries: He once fed himself strawberries in the company of a political enemy, and then accused the opponent of poisoning him and ordered for his execution.
In 1662, the chemist Jean Baptiste van Hemont reported asthma attacks after eating fish (another common food allergen today).
Around 1800, the physician Robert Willan reported hives from eating almonds and anaphylaxis from seafood. His research into these symptoms eventually inspired him to start a new medical specialty: dermatology.
The Science Behind Food Allergies
As scientific methods and technology became more advanced, so did researchers’ understanding of food allergies. It took time to discover exactly what was behind food allergies—immunoglobulin gamma E, or IgE.
Let's back up. In 1906, the Austrian pediatrician Clemens von Pirquet described allergies as “supersensitivity without immunity.” To test supersensitivity, researchers began using blood serum tests.
It became clear that whatever caused allergies was linked to the blood. In 1919, researcher Maximilian Ramirez noticed that a patient developed an allergy to horse dander after receiving a blood transfusion from someone with the same allergy. Transferring allergies became known as the P-K test (named after two researchers—Otto Prausnitz and Heinz Küstner—who ran these tests frequently).
For decades, the P-K test was used to diagnose a patient with allergies. If the blood transfusion caused an allergic reaction in another person who previously had no sensitivities, the original “blood donor” was confirmed to have sensitivities.
But what was going on in the blood? It wasn’t until the 1960s that Japanese immunologist Kimishige Ishizaka discovered the antibody IgE and its role in allergies. Immunoglobulins are proteins of the immune system that help fight pathogens. They’re in the blood, which explains why doctors could transfer sensitivities through blood transfusions.
Other immunoglobulins had already been discovered, and Ishizaka had to prove that the allergic reactions weren’t being caused by any of the other antibodies, and that the allergic activity was being caused by a new isotype. Ishizaka named it gamma E.
Food Allergies Today
Once doctors knew about IgE, it was easier to test for allergies—and to find treatments for people with allergies and asthma. While doctors have many treatments for seasonal allergies, effective treatments for food allergies remain scarce: The only solution is just avoiding the food altogether. That said, many people mysteriously "outgrow" their food allergies over time, while others may suddenly start having a food allergy in adulthood.
Food allergies in children increased by 18 percent from 1997 and 2007, especially peanut and tree nut allergies, according to the Centers for Disease Control and Prevention. In total, 32 million Americans have food allergies today, with the most common being dairy, egg, peanuts, tree nuts, wheat, soy, fish, and shellfish.
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