The Right Chemistry: Tomatoes were once considered deadly

Called the “poison apple” in the 19th century, its toxicity was later debunked and is now known to have numerous health benefits.

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Salem, N.J., a Saturday in August. Dressed in period costume, a man strides up the stairs in front of the courthouse, faces the crowd that has gathered, reaches into a basket, picks up a tomato and proceeds to take a bite. The onlookers cheer and burst into applause. They are watching a re-enactment of a historic event that took place in 1820 when Robert Gibbon Johnson ate a tomato in full view of an audience that expected him to foam at the mouth, twitch and then expire. That didn’t happen. Johnson had proved the “poison apple,” as the tomato was known at the time, was not poisonous after all. And so, as the story goes, the tomato growing industry in the United States was born.

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A great story, repeated in numerous articles and books, but it presents a problem — there is no evidence it happened. Johnson was, indeed, a real person, a horticulturist and founder of the Salem Historical Society, but there is no record of him having any special connection to tomatoes. It seems Salem postmaster and amateur historian Joseph Sickler cooked up the captivating account 100 years after the supposed event in order to bring attention to Salem. And it did — the story appeared in Stewart Holbrook’s 1946 book, Lost Men of American History, and really took wings in 1949 when the CBS radio show You Are There, broadcast the re-enactment live. 

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The cloud of being poisonous really did did hang over the tomato in the early 19th century. There are two accounts of the origin of the toxic tomato tale, an apocryphal one involving European aristocrats, and a more realistic one of mistaken identity.  

Tomatoes were introduced into Europe by the Spanish conquistadors, but because of their scarcity could only be afforded by the wealthy who commonly ate from dishes made of pewter, an alloy of tin and lead. As the story goes, the acids in the tomato leached lead from the pewter and resulted in the demise of the diner. While tomatoes are, indeed, acidic, the probability of the trace amounts of lead leached from pewter causing death is on par with the probability of giant tomatoes attacking humans as in the 1978 cult film, Attack of the Killer Tomatoes.  

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Today, Italians are huge consumers of tomatoes, so it is ironic the poison legend traces back to 16th century Italian herbalist Pietro Andrae Matthioli, who classified the tomato as part of the deadly nightshade family. The tomato plant does resemble the belladonna bush, the berries of which were known to be poisonous. While the leaves and stem of the tomato plant do contain some of the alkaloids that make belladonna berries toxic, its fruit does not. And, indeed, the tomato is a fruit, according to the definition of a fruit being the sweet and fleshy product of a tree or plant that contains the seeds needed for reproduction.  

Amazingly, it was a ruling by the U.S. Supreme Court in 1893 that declared the tomato to be a vegetable, not a fruit. A prevailing law at the time required a tax to be paid on imported vegetables, but not fruit. The John Nix & Company was a large importer of tomatoes and argued since the tomato was botanically a fruit, it should be exempt from the tax. However, the Court decided in this case applying the dictionary definition of a fruit is not appropriate and the tomato should be classified according to how it is perceived by the public, which is as a vegetable. Today, it is New Jersey’s official state vegetable. 

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Real credit for popularizing the tomato goes not to Robert Gibbon Johnson, but to Dr. John Cook Bennett, a quixotic physician with an unsavoury history of having launched a medical diploma mill, selling medical degrees to anyone who could come up with $10. He also ensnared women in sexual relations, declaring he had been sanctioned by God to practise “spiritual wifery.” Bennet claimed to have travelled through Europe and seen that tomatoes cured diarrhea and indigestion, and prevented cholera. He recommended tomatoes replace calomel because they were less harmful, predicting “a chemical extract will probably soon be obtained from it which will altogether supersede the use of calomel in the cure of diseases.” Although his claims of the medicinal value of tomatoes were illusionary, replacing calomel, a concoction made with toxic mercury chloride, was a good idea. 

Bennett’s prediction of a tomato extract came to fruition in 1837, when Dr. A.J. Holcombe of Alabama introduced his tomato pills “possessing hepatic, cathartic, and diuretic qualities.” Holcombe’s pills were soon joined by those produced by “Dr.” Archibald Miles and Dr. Guy Phelps, triggering a lusty advertising battle between the two men. Miles, who actually had no medical education, called Phelps a “quack’ and a “charlatan,” prompting Phelps, a Yale-trained physician, to retort Miles had “about as much claim to the title of doctor as my horse.” The battle, with the combatants hurling insults of “fraud” and “copycat” at each other petered out after a couple of years when allegations emerged neither pill actually contained tomatoes. Still, for a period, the pills did supply people with a dose of placebo that was certainly preferable to calomel. 

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The “tomato pill” reemerged in a different guise in the 20th century when epidemiological studies indicated a reduced risk of prostate cancer in men with higher consumption of tomatoes and tomato products. The theory was lycopene, the compound responsible for the fruit’s red colour, had anti-cancer properties, and lycopene supplements appeared on shelves. While there appears to be substance to the tomato’s role in reducing the risk of prostate cancer, studies using lycopene supplements have disappointed. It seems it’s the collage of the numerous compounds found in tomatoes that produce the benefits. Those benefits may even extend to the cardiovascular system, as demonstrated by a recent study of the dietary habits of more than 7,000 seniors. Consumption of one large tomato a day was associated with a significant decrease in the risk of hypertension. Although there is the usual caveat tomato consumption may just be a marker for a healthy diet that includes lots of fruits and vegetables, there is enough noise in the scientific literature about the benefits of tomato consumption to pay attention.

Maybe we should all be re-enacting Robert Gibbon Johnson’s act of bravery … every day.  

Joe Schwarcz ([email protected]) is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.

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