The Full Story
You're sipping on your delicious post-workout smoothie when you swallow something hard. You realize you unintentionally threw in some whole cherries without removing the pits and now you've swallowed some. You search the internet and are shocked to learn that you might have just swallowed one of the deadliest poisons known to man – cyanide. Oh no!
Rest assured that a small unintentional ingestion of cherry pits will not cause harm. But is it true that there is cyanide in cherry pits? What about other kinds of stone fruits? Can someone really become poisoned by eating them?
A stone fruit, also known as a drupe, generally refers to the Prunus family. Apricots, cherries, plums, peaches, mangoes, and nectarines are examples of stone fruits. In the center of the fleshy edible part of the fruit is a hard stone-like shell, which is the reason for their common name, "stone fruits". This hard shell is also often referred to as a pit or kernel. People might think that this "stone" is the fruit's seed, but this is incorrect. The seed is encapsulated within the shell.
The stone serves to protect the fruit and spread its seeds. This is the fruit's natural survival mechanism. Animals attracted to the fleshy, sweet, edible part of the fruit eat it and leave the hard indigestible pit behind. Or if the fruit is swallowed whole, the pit and the seed inside pass through the gastrointestinal tract and in the stool, intact and unharmed, returning back to the soil.
The dangerous chemical found in the seeds of stone fruits is called amygdalin. Poisoning can occur when the pit and seed are crushed or chewed before swallowing, releasing the amygdalin. Amygdalin is then converted by the body to cyanide. Many other types of plants found in the US, both edible and nonedible, also naturally contain cyanide compounds. These include cassava, lima beans, apple, Hydrangea, and bitter almonds.
The amount of amygdalin in the seeds of stone fruits varies widely, both between different types of stone fruits (e.g., cherries vs. plums) and even within the same type of fruit (e.g., cherries from one tree vs. cherries from another tree or geographic location). This makes it difficult to determine the number of seeds it takes for poisoning to occur. In general, unintentional ingestions do not lead to poisoning because it is unlikely that someone would chew or crush the kernels/seeds prior to swallowing them, and because unintentional ingestions tend to be of small amounts.
Cyanide's reputation for being deadly is well-deserved and has to do with the way it poisons the body. Cyanide poisons the most basic and fundamental units of life – the cells – by depriving them of the oxygen needed for life. While symptoms can vary depending on the amount of cyanide the body is exposed to, large exposures can quickly lead to loss of consciousness, acid buildup in body fluids, seizures, sudden loss of blood flow to vital organs, and death.
A drug called Laetrile, a chemical that comes from amygdalin found in stone fruit seeds, gained popularity in the 1970s as a treatment for cancer despite no evidence to support this claim. It was even marketed as a new vitamin "vitamin B17". Subsequently, health-food stores began to sell apricot kernels for their natural amygdalin content and its claimed anticancer benefits. As a result, several cyanide poisonings from ingestion of large amounts of apricot kernels occurred in the US. Scientific studies have shown that Laetrile has no anticancer activity in humans, and it has since lost much of its popularity. However, there are still some apricot kernel products being sold, especially on the internet, with the same claims about the benefits of "vitamin B17".
Although unintentional ingestion of a few stone fruit pits is typically not a concern, prevention is key; ingestion should always be avoided and the pits should never be crushed or chewed. Children should be taught to spit out the seeds/pits when snacking on stone fruits.
If you have any questions about stone fruits or if someone has ingested the pits, kernels, or seeds, check the webPOISONCONTROL® online tool or call Poison Control at 1-800-222-1222 for guidance.
Serkalem Mekonnen, RN, BSN, MPH
Certified Specialist in Poison Information
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