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Cyanide and Almonds

July 26, 2010

I will start this post by saying I love almonds. I eat them all the time. The almond is known botanically as Prunus amygdalus Batsch. It is from the Rosaceae family and the Prunus genus (that wasn’t intended to rhyme). They were originally indigenous to the Middle East, but flourish throughout the world now. My love of almonds lead me to cyanide and perhaps an adjustment in my dietary choices.

Not that I was feeling particularly morbid or anything, but I became intrigued by cyanide as I had heard recently that it was a naturally occurring substance. Distorted through my haze of Hollywood envisioned spy rings and shadow governments, cyanide was something someone of some importance had in their pocket should that crisis moment arise (“or for the unthinkable” in the parlance of movies). Insert cyanide, induce froth at the mouth.

Tamil Tiger

A young member of the Tamil Tiger's women's wing, the Freedom Birds, displaying her cyanide capsule which she was instructed to take if captured by the military. Farrell, T. (2002). Can Tigers Enter the Mainstream? Fortnight, 403: 16-17. Click on the image to go to the article itself.

Well, there is a bit more to it than that. According to the Agency for Toxic Substances & Disease Registry at the Center for Disease Control (CDC), cyanide is:

“Cyanide is usually found joined with other chemicals to form compounds. Examples of simple cyanide compounds are hydrogen cyanide, sodium cyanide and potassium cyanide. Certain bacteria, fungi, and algae can produce cyanide, and cyanide is found in a number of foods and plants. In certain plant foods, including almonds, millet sprouts, lima beans, soy, spinach, bamboo shoots, and cassava roots (which are a major source of food in tropical countries), cyanides occur naturally as part of sugars or other naturally-occurring compounds. However, the edible parts of plants that are eaten in the United States, including tapioca which is made from cassava roots, contain relatively low amounts of cyanide.”

“Hydrogen cyanide is a colorless gas with a faint, bitter, almondlike odor. Sodium cyanide and potassium cyanide are both white solids with a bitter, almond-like odor in damp air.”

Amygdalus salicifolia Boiss. & Balansa from Turkey circa 1857 graciously contributed by Friedrich-Schiller-Universität Jena. It contains natural amounts of hydrogen cyanide.

Wait a minute now. Cyanide exists in my spinach, almonds, and lima beans? It smells like almonds?  Say it ain’t so! But if it is occurs naturally and so many people consume it, how bad could it be? Well, according to Science (circa 1966), cyanide’s predominant toxic effect “appears to be the inhibition of the respiratory enzyme, cytochrome oxidase”, which subsequently diminishes the utilization of oxygen in the body (Way, Gibbon, Sheehy (1966).

Scientific to the point of making it seem innocuous! And at small doses, it is. In fact, over 2000 species of plants are found to be cyanogenic. However, unlike humans, plants have mechanisms to metabolize cyanide (consume it), including the presence of the cyanoalanine synthase (Miller, Conn, 1980). In other words, it digests the cyanide. That is a nifty trick.

But it must have some utility, right? That all depends on the context in which you use it. Returning again to the Agency for Toxic Substances and Diseases Registry:

” Cyanide and hydrogen cyanide are used in electroplating, metallurgy, organic chemicals production, photographic developing, manufacture of plastics, fumigation of ships, and some mining processes.”

That sounds perfectly acceptable, perfectly industrious, but what about for medical care? Surely someone has tried this, right? Well, never fear, because if it exists in nature, someone has tried to consume it. During World War I, a certain form of cyanide derived from copper, cyanocuprol, was used in Japan as a treatment for both tuberculosis and leprosy (Otani, 1916). Even Otani cautions that any interval between injections of cyanide less than two weeks apart will be dangerous. Not sure what dangerous equates to in this caution, but when dealing with cyanide I suspect it is easy to imagine it being fairly severe.

So, thanks for that, cyanide. My love of almonds has certainly hit a snag. Unless there is some superhero power latently lurking behind almond cyanide exposure.

9 Comments leave one →
  1. July 26, 2010 8:20 am

    Thanks for the informative post. You may be interested in this discussion of a paper about the cyanide content of cassava, and how to get rid of it:

    • July 26, 2010 8:52 am

      Many thanks for this Luigi! I was not aware of your Agricultural Biodiversity Weblog, but will certainly subscribe. Quite intrigued to start reading through your posts. Will certainly follow up with more as well!

      • July 26, 2010 9:52 am

        We do indeed:

        In fact, I picked up your post from your own Twitter feed, to which I subscribe. I now subscribe to the RSS feed of your blog too.

      • July 26, 2010 10:01 am

        Not to quibble, especially after your kind words about our site, but you have a typo early on. It should be amygdalus, rather than amygadlus. Fix that and your Google fu will shoot up, I’m sure.

        And if it is P. amygdalus, how can it also be P. dulcis?

      • July 27, 2010 6:14 am

        Thanks for that, Jeremy! No quibbling at all; that is indeed very helpful! Let me look into the mystery of the P. amygdalus and dulcis as well and get back to you. Sincere thanks for letting me know! By the way, big fans on this side of your and Luigi’s blog. Great material so please let me know if you ever want to work a bit together!

  2. July 27, 2010 7:12 am

    It’ll be interesting to have that mystery solved.

    We’re always on the lookout for opportunities (like how, as individuals, we can get access to JStor :))

  3. March 12, 2011 12:21 am

    Domesticated sweet almonds do not contain glycoside amygdalin which is what creates the cyanide. Therefore cyanide is not an issue.

    • siah nyde permalink
      September 11, 2012 1:28 am

      How can one tell the difference between domesticated and wild almonds? Do domesticated almonds wear collars for example?


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