Cyanide: Apples, Apricots, Cherries, Peaches

Welsh wisdom reworked as “An apple a day keeps the doctor away” dates back to the 1860s. One of the most popular poisons in history, cyanide, dates back far further. Surprisingly, the two are not unconnected. Almost a century earlier, in 1782 Carl Wilhelm Scheele extracted cyanogenic glycoside amygdalin from fruit pits dissolved them in water. Amygdalin exists in many plants, particularly their seeds. It is present in those of apples, pears, cherries, peaches, plums, apricots and bitter almonds. Indeed peach ‘pits’ or ‘stones’, as the seeds of fruits are often called, contain enough hydrocyanic acid to once have been used as a commercial source of cyanide.  Despite occasional deaths being reported from accidental consumption of the kernels, it is not recommended for those wishing to exit this mortal coil. Neither is the medical profession overly enthusiastic on their promotion as a cancer cure. Nor is it particularly effective. Indeed the side effects might make survivors select other options. François Bodin and C. F. Cheinisse, authors of Les Poisons (1972), recount symptoms of cyanide poisoning:

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Cyanogenetic Glucosides

“More dangerous are such things as bitter almonds, the kernels of plums, apricots and cherries, and ripe apple pits. All these contain cyanogenetic glucosides that can give rise to cyanide poisoning. Usually, this is only moderate, with distress, respiratory difficulty, and vertigo, but occasionally more serious poisoning gives rise loss of consciousness, and serious respiratory troubles. Apnoea and fatal collapse are exceptional but have occurred.”

Death is not unknown, however. Incredible though it might seem, packaged apricot kernels continue to be sold in health food stores. According to an entry in Wikipedia: 

“Apricot kernels can cause potentially fatal cyanide poisoning when consumed. Symptoms include nausea, fever, headaches, insomnia, increased thirst, lethargy, nervousness, various aches and pains in joints and muscles, and a drop in blood pressure.” 

Other sources suggest that just two to three apricot kernels for adults and a single one for children may cause cyanide poisoning. Two years ago concerns arose in Montreal after a visiting Californian was hospitalized from just such an encounter. The package he purchased from a Rachelle-Béry health food store were labelled gluten-free, pesticide-free, vegan and organic. It was only after eating a third of the bag  he read the fine print:

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Yet packaged apricot kernels continue to sold in health stores

“Caution. Do not consume more than 2-3 kernels per day. Keep out of reach of children. Pregnant and nursing women should not consume apricot kernels. Health Canada warns that eating too many apricot kernels can lead to acute cyanide poisoning.”

He spent the next eight hours at Montreal’s Hôtel-Dieu Hospital. First, he was given a large charcoal drink, then remained under observation. Finally, after all danger had passed, he was presented with a $1,125 bill and discharged. He was uninsured. Yet packaged apricot kernels continue to sold in health stores. In fact, although removed immediately by the manager at the Rachelle-Béry health food store when he was informed, when visited a few weeks later, the packages were once again being sold – and continue to be. Health Canada directs that packages must carry the warning label. Other countries are not so sanguine. The U.S. Food and Drug Administration (FDA) bans the sale for use as a health cure – cyanide, also as laetrile or vitamin B17 (there is no such thing) is often touted as a cancer cure. In the UK and Germany sale of apricot kernels are restricted and in Australia banned outright. 

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Science is the great antidote to the poison of enthusiasm and superstition

None of which can or does prevent do-it-yourself health enthusiasts. Nor does it prevent, at least in Canada, startling claims made on the packaging. ‘A Seed for Life’ proclaims one along with ‘Pesticide-Free All Natural Vegan.’ Given the risk of cyanide poisoning, this seems a trifle optimistic. Ripe apple seeds or ‘pips’ are, in contrast, often cited as hazardous to health. As always though, it is the dose that makes the poison. Swallowed whole, they pass through the system harmlessly. Even bitten or crushed, it requires more than a few to release a dangerous dose of cyanide. This occurs when  a compound known as amygdalin contained in the seeds degrades into hazardous hydrogen cyanide, lethal in high doses. How high? Eating two cups of ground apple seeds might be fatal. At the very least it could make you sick, suggests Medical News Today. Put another way, a person weighing 180-pounds (82 kg) would require 243 to  6,804 seeds (170 to 4,763 grams) to incur a risk of death. Then there are cherry pits. Cyanide toxicity is extremely rare from cherry pits, assures the Missouri Poison Center. The pits must be chewed to release the cyanogenic glycoside. Nevertheless, only about 30 crushed cherry pits would constitute a lethal dose. Foliage, twigs and bark from cherry trees also contain hydrocyanic acid. Crushed or scraped they release they giveaway the odour of bitter almonds. Since this acts as a mild sedative on the respiratory nerves, which suppress coughing, it may also be used in cough syrups, explains Rebecca Rupp (1990). She also notes that the German liqueur known as kirsch or kirschwasser (‘cherry water’) is distilled from crushed cherries, pits and all. Persons maintain an average everyday diet might be surprised to learn that many another food and flavouring may cause medical distress. Previously cited Bodin and Cheinisse helpfully draw attention to overindulgence in such items as garlic, aubergine (egg plant), sorrel, caraway seeds and nutmeg may result in poisoning. Better perhaps to heed the wisdom of Adam Smith: “Science is the great antidote to the poison of enthusiasm and superstition.”

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