My Favorite (poisonous) Fruit

By Carol,

Yesterday, I went for a walk around my neighborhood in the 89 degree temperatures and thought to myself– summer is officially here.  I went to the grocery store and spotted one of my favorite summer foods of all time:  cherries.   I bought a bag and as I popped one off its stem, I decided that this is the poisonous plant I will blog about this week.

Yes, cherries (more precisely, cherry pits) contain a poison.  Not an esoteric, unimpressive, unimportant type of poison either, we’re talking CYANIDE, or rather, a cyanide-like compound called amygdalin.   These types of cyanogenic glycosides or cyanogens are found in over 2500 plant species, including apple and pear seeds and in the pits of apricots, peaches, nectarines and plums. When cyanogens are ingested, the human body metabolizes them into cyanide.

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But before you snatch these healthy treats away from your kids and shove them down the garbage disposal, realize that the amygdalin is found only in the hard pits or seeds (not the tasty flesh).  In order to release the amygdalin, the pits must be chewed up before being swallowed, and the concentration of the toxin is so low that large numbers of seeds or pits are required to cause toxicity.

Cyanide toxicity resulting from unintentional ingestion of these pits and seeds is extremely rare in the United States. Realistically, the pits and seeds are more of a choking hazard than a poisoning risk.  At least a couple of times a year here at IPC, we get called about a child who has ingested 10-20 cherry pits whole.  These kids have done just fine and developed no symptoms at all.  The man, the myth, the legend, Tony Burda is known for eating his daily apple whole, seeds and all (he says the seeds “taste interesting”).  Intentional large ingestions however, have resulted in toxicity, including a few cases of ingestion of 20-40 chewed apricot pits by adults which resulted in cyanide toxicity but no fatalities.

Why would someone eat that many apricot pits, you ask? In the 70s, apricot pit/kernel extract was hailed as a ‘cancer cure’ and sold under the name Laetrile.  Its sale was restricted in the US market because it lacked efficacy and safety (not exactly a shocker since we are talking about cyanide here).  However, it is still touted as a magic cancer cure in other countries and by some alternative medicine providers, and products containing cyanogens can be purchased for consumption.  Eating the seeds from one apple or accidentally swallowing a few cherry pits whole is nontoxic, but intentionally ingesting massive amounts of these cyanogens will definitely get you sick.  Make our workload one case lighter and permanently cross apricot kernels or apricot kernel extract off your shopping list.

One cyanogenic plant that is more of a concern when it comes to unintentional poisoning is cassava (otherwise known as yuca).  Cassava is a starchy food staple in many parts of Central and South America and in Africa. In my opinion it tastes kind of like a cross between a potato and a plantain. It is used to make tapioca and Asian bubble drinks, and I’ve had it as a side dish at restaurants.  The cyanogenic glycosides in cassava are linamarin and lotaustralin instead of amygdalin. Usually, processing (drying, soaking, boiling) cassava removes 80-95% of the cyanogenic compounds, but inefficient processing can lead to much higher levels of cyanogens in these dishes.  Cassava contains a much higher level of linamarin and lotaustralin during a drought as well, and fatal cyanide poisoning has occurred after ingestion of this ‘bitter’ cassava.

Even though it is very rare to develop cyanide toxicity from ingestion of fruit pits or seeds, always call the IPC if you or your child ingests some.   These poisonous plants epitomize two important IPC mantras:

1.  Just because something is all natural, does not mean it is non-toxic.

2.  Poisoning is a matter of dose.

Check back next week—Tony and I are going to tell you about the top 5 substances we get calls about in the summer.  Stay cool, and enjoy those cherries (but spit out the pits!)

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3 Responses

  1. Daisy
    Daisy May 25, 2010 at 3:45 pm |

    This makes me wonder, however – I usually bake, on special events, with a spice called mahlab, which is made from a specific kind of cherry pits. Has this spice, since it’s already ground, ever been implicated in accidental poisonings? Google / Google scholar were unrevealing.

  2. Carol
    Carol May 26, 2010 at 8:16 am |

    Hi Daisy, good question. I could not find any documentation or case reports of mahlab causing a symptomatic poisoning. The reason is likely that it is used in such small amounts in cooking. Another example of a spice that is perfectly safe when used, well as a spice, but poisonous if ingested in large amounts is nutmeg. Tasty sprinkled on egg nog but if ingested in large amounts causes hallucinations, severe vomiting, and confusion.

  3. Camille
    Camille July 16, 2010 at 11:00 am |

    There is a possibility my almost 3 year old unintentionally swallowed 1 whole cherry pit while I was eating cherries with her. This article helped relieve my concerns. Will the pit just hopefully pass thru her system swiftly? Thanks for the help.

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