Many common foods contain naturally occurring compounds that release cyanide when the plant tissue is crushed, chewed, or processed. These include cassava, lima beans, bitter almonds, bamboo shoots, and the seeds or pits of fruits like apples, apricots, cherries, and peaches. In nearly all cases, the amounts are small enough or the processing thorough enough that these foods are safe to eat, but a few deserve real caution.
How Cyanide Ends Up in Food
Plants don’t contain pure cyanide sitting in their cells. Instead, they produce compounds called cyanogenic glycosides, which are bound to sugars and stored safely in cell compartments. When an animal bites into the plant, those compartments break open, and enzymes immediately begin splitting the sugar bond. The end product is hydrogen cyanide, a gas that interferes with your cells’ ability to use oxygen. It’s essentially a built-in pesticide: the plant poisons whatever is eating it.
This means cyanide is released only when plant tissue is damaged, whether by chewing, grinding, grating, or even cutting. Cooking, soaking, boiling, and fermenting all accelerate the release and then evaporate or wash away the cyanide before you eat the food. That’s why traditional food preparation methods exist for high-cyanide crops like cassava and bamboo: they’re specifically designed to make these plants safe.
Cassava
Cassava is the most significant dietary source of cyanide worldwide. It’s a staple for hundreds of millions of people in sub-Saharan Africa, South America, and Southeast Asia. There are two broad categories. Sweet cassava contains less than 50 mg of hydrogen cyanide per kilogram of fresh root. Bitter cassava, which is higher-yielding and more drought-resistant, contains over 100 mg/kg. Bitter varieties can be dangerous if eaten without proper preparation.
Traditional processing works remarkably well. Peeling, dicing, soaking, and then drying cassava can remove up to 95% of its cyanide content. Boiling alone drives off a large portion, and fermentation (used to make products like gari and fufu) breaks down the compounds further. Problems arise when people skip steps, often during droughts or food shortages when there isn’t time to soak or ferment properly.
Chronic exposure to poorly processed cassava is linked to two serious neurological conditions. One is konzo, a sudden-onset paralysis of the legs that is permanent and irreversible, documented mostly among children and women of childbearing age in sub-Saharan Africa. The other is tropical ataxic neuropathy, a progressive condition involving loss of coordination and vision problems. Both are associated with diets heavily dependent on insufficiently processed bitter cassava, particularly when protein intake is low.
Fruit Seeds and Stone Fruit Pits
Apple seeds, cherry pits, peach pits, apricot kernels, and plum pits all contain amygdalin, a cyanogenic glycoside that releases hydrogen cyanide when crushed or chewed. The fleshy fruit itself is safe. The concern is specifically with the seed or kernel inside the hard pit.
Apricot kernels deserve special attention because some people eat them intentionally, sometimes as a supposed cancer remedy (which has no scientific support). These kernels contain enough amygdalin to cause acute poisoning. Peach seeds are similarly concentrated: research on peach cultivars has measured amygdalin levels exceeding 2,300 mg per 100 grams in ripe seeds.
Swallowing a few apple seeds whole is not dangerous. The hard seed coat passes through your digestive system intact, so the amygdalin inside never gets released. You’d need to thoroughly chew a large number of apple seeds to approach a harmful dose. That said, the European Food Safety Authority has flagged apple juice and applesauce as containing measurable cyanide, likely from seeds crushed during processing, though at levels well below any danger threshold.
Lima Beans
Wild lima beans can contain very high levels of cyanide. In the United States, commercially grown lima beans must contain less than 200 mg of cyanide per kilogram, and most fall in the 100 to 170 mg/kg range. That’s low enough to be safe with normal cooking, but it does mean lima beans shouldn’t be eaten raw in large quantities.
Boiling is the most effective preparation method. Cooking lima beans in a large pot of water for more than 30 minutes removes about 80% of the cyanide. Alternatively, soaking the beans for 24 to 48 hours, draining the water, and then boiling briefly in fresh water also works well. Steaming is less effective because the cyanide doesn’t have water to dissolve into and escape.
Bamboo Shoots
Fresh bamboo shoots contain a cyanogenic glycoside called taxiphyllin that releases hydrogen cyanide when the tissue is cut or chewed. This is why raw bamboo shoots taste bitter and can cause nausea or worse if eaten without preparation. Boiling, fermentation, and steaming all reduce taxiphyllin levels significantly. The canned or jarred bamboo shoots sold in grocery stores have already been processed and are safe to eat directly.
Bitter Almonds vs. Sweet Almonds
The almonds you buy at the grocery store are sweet almonds, and they contain only trace amounts of cyanide, roughly 25 mg per kilogram. Bitter almonds are a different story entirely, containing about 50 times more cyanide per kilogram. Eating as few as 50 bitter almonds could be fatal for an adult, and just 5 to 10 could kill a child.
Bitter almonds aren’t commercially grown or typically sold in the United States, but they do appear in some imported products and online marketplaces. In 2014, Whole Foods recalled a batch of organic raw almonds after testing revealed high cyanide levels. The almonds, sourced from Spain and Italy, turned out to be bitter almonds mislabeled as sweet. Bitter almonds are also used to flavor traditional cookies like amaretti and macaroons, though the baking process drives off most of the cyanide.
Other Sources
Linseed (flaxseed) contains an average of about 192 mg of cyanide per kilogram, which puts it in a similar range to lima beans. The amounts typically consumed, a tablespoon or two sprinkled on food, are far too small to matter. Sorghum, a grain used in some cereals and beer, also contains cyanogenic glycosides, primarily in the leaves and sprouts rather than the grain itself. Passion fruit has measurable cyanide as well, though again at levels that pose no practical risk in normal consumption.
How Much Cyanide Is Actually Dangerous
The average fatal dose of ingested cyanide for an adult is roughly 1.5 mg per kilogram of body weight, with deaths reported at doses as low as 0.5 mg/kg. For a 70-kilogram (154-pound) adult, that translates to somewhere between 35 and 105 mg of pure hydrogen cyanide. Cyanide works by blocking your cells from using oxygen, so symptoms of acute poisoning include headache, dizziness, confusion, and difficulty breathing.
In practice, you’d have difficulty poisoning yourself with most of these foods through normal eating. The real risks are concentrated in a few scenarios: eating bitter almonds or raw apricot kernels intentionally, consuming large amounts of improperly prepared cassava, or eating raw bitter cassava root. For everything else on this list, standard cooking and the small quantities involved keep cyanide exposure far below any meaningful threshold.