Beware The Bitter Almond

As part of the Health Nuts Project, the skeptical cardiologist has been evaluating walnuts, hazelnuts and almonds which he plans to put in packets and distribute to patients and readers.
Previously, we discovered that most raw almonds from the US have been fumigated with a chemical called propylene oxide and that roasting almonds creates potentially carcinogenic chemicals.
Consequently, after considerable searching, I purchased raw organic almonds from a company called NutsinBulk. These turn out to be from Spain (where pasteurization of almonds is not required) and are quite tasty.
As I was munching on one of these almonds I suddenly noticed an incredibly bitter taste causing me to spit the chewed almond out. My first thought was that this almond had gone “bad” in some way. Perhaps a mold had crept into it. Looking at the pieces I had spit out, however, I could see no discoloration or other visible difference from the “normal” almonds.
Subsequent experimentation has revealed that about one in ten of these almonds is incredibly bitter and there is no way to predict this from  the external appearance of the almond.

The Source of Bitter Almonds

The sweet almond  that we are used to eating in the US is produced from one type of almond tree (Prunus amygdalus var. dulcis) and does not contain poisonous chemicals. However, the bitter almond that I encountered comes from a different type of almond tree (Prunus amygdalus var. amara).

Prunus amara trees were likely the original almond trees but over time the sweet almond trees have been selected for and now dominate. According to the LA Times and Paul Schrade, who provides bitter almonds to restaurants:

Until recent decades, most Mediterranean almond orchards were grown from seed, and the shuffling of genes resulted in a mix of bitter almond trees among the sweet. Growers liked to keep a few bitter trees around because they helped to pollinize the sweet varieties. The inclusion of bitter nuts gave snackers occasional unpleasant surprises, but they deepened the flavor of marzipan, almond milk and glazes for cakes. In Italy, bitter almond paste was traditionally used to make crisp amaretti cookies, and bitter almond extract flavored amaretto liqueur. In Greece, bitter almonds are used in soumada, a sweet syrup. (apparently cooking or adding alcohol eliminates the toxic cyanide)

There’s little large-scale cultivation of bitter almonds left in Spain and Italy, mostly just scattered trees remain, but it is still possible to buy raw bitter almonds at European specialty markets. Morocco and Iran now lead in commercial production of bitter almonds.

What Makes The Almonds Bitter: Amygdalin

The source of the bitterness is amygdalin:

A recessive gene causes bitter almond trees to produce in their shoots, leaves and kernels a toxic compound called amygdalin, which serves as a chemical defense against being eaten. When amygdalin is moistened, it splits into edible benzaldehyde, which provides an intense almond aroma and flavor, and deadly hydrocyanic acid, a fast-acting inhibitor of the respiratory system.

A variety of sources confirm that:

The lethal dose of raw bitter almonds depends on the size of the nuts, their concentration of amygdalin and the consumer’s sensitivity. But scientists estimate that a 150-pound adult might die from eating between 10 and 70 raw nuts, and a child from ingesting just a few.

YIKES!!!When I read this I was shocked. Could it be that consuming 10 of these raw  biter almonds would kill me.? How could I distribute these potentially lethal edibles to my patients?

Amygdalin (Laetrile) , Alternative Cancer Therapy and Quackery

In addition to bitter almonds, significant amounts of amygdalin are found in the stone fruit kernels of apricots, peaches and plums. A synthetic form of amygdalin called Laetrile achieved great notoriety in the 1980s as a cancer treatment. Although research had shown the chemical to be ineffective, it was embraced by “alternative” healers who claimed it was a “natural” cure for cancer which was being suppressed by a conspiracy between the US FDA, big pharma, and the the medical community.
Steve McQueen, suffering from pleural mesothelioma sought the care of a delisted American holistic orthodontist practicing in Mexico, William Kelley. The NY Times reported:

In July 1980, McQueen secretly traveled to Rosarita Beach, Mexico, to be treated by Mexican and American doctors using Dr. Kelley’s regimen. He received not only pancreatic enzymes but 50 daily vitamins and minerals, massages, prayer sessions, psychotherapy, coffee enemas and injections of a cell preparation made from sheep and cattle fetuses. McQueen was also given laetrile, a controversial alternative treatment made from apricot pits.

Although we hear little about Laetrile these days, like most snake oil it is still promoted by alternative medicine. For example, The notorious quack Dr. Mercola still promotes the idea that laetrile is a safe and effective treatment of cancer on his web site with a post that has been viewed over 700,000 times.

You Can Die From Eating Bitter Almonds

Certainly, there is considerable evidence that Laetrile can be toxic or lethal but bitter almonds can also cause lethal cyanide poisoning. A case report describes a woman with colon cancer who turned down potentially curative surgery/chemotherapy and turned to alternative treatments including Laetrile.  A helpful friend gave her a bag of bitter almonds for their “medicinal properties”, whereupon the woman consumed a slurry composed of 12 ground up almonds with water. Within 30 minutes she developed  severe cyanide poisoning with vomiting, abdominal pain, pulmonary edema, severe lactic acidosis and  loss of  consciousness.
Analysis of the bitter almonds showed they contained on average 6.2 mg of cyanide per almond. It is estimated that a lethal dosage of cyanide is 50 mg or 0.5 mg per kg body weight, thus the calculation that 10 almonds could kill someone weighing  60 kg or 132 pounds.
My  Search For Healthy Almonds Continues
The small amount of cyanide one gets from consuming a single bitter almond seems to have little effect. (Although the Mediterranean diet nutritionist Conner Middelman-Whitney , who spent time in Europe and encountered bitter almonds occasionally says that she does remember a weird, numb sensation in the mouth when they were consumed.)  It’s extremely unlikely that one of my patients would consume 10 of the bitter almonds (without reflexively spitting them out as I did) in a short period of time.
When I have consumed them I noticed no adverse effects but after such an encounter I stopped eating the almonds for the day.
However, I’m not interested in testing that theory. (Ability to taste amygdalin or smell cyanide varies between individuals, thus I can’t be certain that the bitter taste would serve as a reliable warning.)
Therefore,  I’ve concluded that I’m not going to distribute these potentially lethal almonds to my patients and will be removing them from the Dr. Pearson Health Nuts Packages.
My search for non-fumigated, non-cyanide-laced , non-carcinogenic almonds continues!
Cyanogenically Yours,
N.B. Famous deaths from cyanide poisoning include Hitler and Alan Turing.



17 thoughts on “Beware The Bitter Almond”

  1. I’ve been regularly buying Raw Almonds in 1# bags from Trader Joe’s for about 22 years. The package indicates they are grown in the “Central Valley of California”. I’m quite sure they have been steam pasteurized, and they do taste great. As to whether they contain cyanide or other toxins is anyone’s guess. One word of caution, they are addictive.

    • I too just encountered a bitter almond. That is why I am on your site now. I Googled “eating almonds numb mouth” and here I am! Experienced the strong Armaretto liqueur flavor, but couldn’t put my finder on the taste until I read your post. I also have no desire to eat the last three almonds that remain from my handful. ;-). Great post. Thank you.

  2. I started making my own coffee creamer with pure almond extract back in the summer. I drink four to five cups of coffee a day and use quite a bit of creamer. A few months ago I started noticing back pain and swelling in my ankles. I had just had a physical in June and was found to be in perfect health so I really didn’t think it could be heart or kidney problems. Then I read something about bitter almonds being used for extract and thought maybe I should discontinue the creamer. Since then, the swelling has gradually dissipated and is now completely gone. I know my symptoms don’t necessarily correlate with cyanide poisoning, but I am convinced that’s what was causing them.

  3. I live in Germany, we use bitter almonds for many Christmas recipes. You can buy them in little bags, sometimes they are still in the shell.
    They are boiled briefly, then the skin is rubbed off. After cooling, they are ground in a coffee grinder and added e.g. to cookie dough. I don’t know whether blanching or baking decomposes the amygdalin and liberates the cyanide, or if the doses are just too small, but I’ve never heard of anyone getting poisoned. Bitter almonds are part of the Christmas tradition.
    We do take some precautions and keep the almonds where the kids can’t get at them, but learning about the dangers is part of growing up. Anyway, the almonds are so bitter that no one will snack on them voluntarily.
    ‘Medicinal’ use is something else, this is just tragic and irresponsible, but there is no danger in using them for cooking and baking.
    A typical recipe will call for 2-5 bitter almonds, not sufficient to kill an adult, but some classical cakes will use 50g or more.
    Cyanide is metabolized quickly and doesn’t bioaccumulate, so at least if it doesn’t kill you, you will be fine.
    What really worries me are aflatoxins. Highly carcinogenic and often present in almonds. I am not sure whether there are any standards that mandate aflatoxin testing, but I would not trust the typical almond-growing nations to enforce such laws anyway.

  4. I have a large sack of bitter almonds from a tree and want to get the cyanide out of them. I heard that soaking them and then baking them does this. How long should I do these two processes for, to make them safe for consumption?

    • One would certainly consider pistachios part of a Mediterranean diet and I love them. But my goal with these nut sacks was to reproduce the exact content of the nuts that were provided to participants in the PREDIMED trial which showed marked reduction in CV events.


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