What Nuts and Seeds Have Cyanide? A Guide to Cyanogenic Foods

December 25, 2025 •

4 min read

Cyanide compounds are produced naturally in thousands of plant species as a defense mechanism against predators. This raises the question: what nuts and seeds have cyanide or other cyanogenic glycosides that can be toxic if consumed in large quantities?

Quick Summary

Some nuts and seeds, particularly bitter almonds, flaxseed, and fruit pits, contain cyanogenic glycosides that can release cyanide. Proper processing, like heating or soaking, can significantly reduce the risk.

Key Points

Bitter Almonds: Raw bitter almonds contain high, toxic levels of amygdalin and are not sold in stores for consumption.
Sweet Almonds: The almonds in grocery stores are a different variety (sweet almonds) with only trace, non-toxic amounts of cyanogenic glycosides.
Flaxseeds: Ground flaxseeds contain cyanogenic glycosides, but moderate intake is safe, especially when cooked, which reduces toxin levels.
Fruit Pits/Seeds: The kernels in the pits of apricots, peaches, and cherries, and the seeds of apples, contain amygdalin, but the outer casing prevents toxicity unless a very large quantity is chewed and consumed.
Processing is Key: Heating methods like roasting and boiling destroy the cyanogenic compounds, which is why commercial nuts and seeds are safe.
Cashews Contain Urushiol: The toxin in cashews is not cyanide but urushiol, found in the shell, and it is removed by heat processing.

The Science Behind Cyanide in Plants

Cyanide does not exist as free cyanide in these plants. Instead, it is bound to sugar molecules in compounds called cyanogenic glycosides. The most common one in nuts and seeds is amygdalin, found in the Prunus family, which includes almonds, apricots, peaches, and cherries. These glycosides are stored in the plant's cells separately from the enzymes that can break them down. When the plant tissue is crushed, chewed, or damaged, the glycosides and enzymes mix, triggering a chemical reaction that releases toxic hydrogen cyanide (HCN).

Symptoms of cyanide poisoning can range from headaches, dizziness, and nausea in mild cases to convulsions, respiratory failure, and death in severe cases. However, the human body can detoxify small amounts of cyanide, and the concentration in most commercially available food products is too low to pose a threat. Processing and proper preparation are key to ensuring safety.

Specific Nuts and Seeds with Cyanogenic Glycosides

Bitter Almonds

Bitter almonds are the most well-known source of cyanogenic glycosides among nuts. They contain high levels of amygdalin—up to 50 times more than sweet almonds. They are not sold in U.S. grocery stores due to their high toxicity, and consuming just a small number can be lethal, especially for children. Sweet almonds, the variety typically sold for consumption, have a genetic mutation that drastically reduces their amygdalin content, making them safe to eat.

Flaxseeds (Linseed)

Flaxseeds contain cyanogenic glycosides, primarily linustatin, neolinustatin, and linamarin. The amount of cyanide released depends heavily on whether the seeds are whole, ground, or processed:

Whole flaxseeds: Pass through the digestive system largely intact, releasing very little cyanide.
Ground flaxseeds: When crushed and moistened, they can release cyanide. However, studies show that moderate consumption (up to 30g per meal for adolescents and adults) results in blood cyanide levels far below the toxic threshold.
Flax oil: Contains no cyanogenic glycosides.

Heating, such as in baking or boiling, effectively reduces the cyanide content.

Fruit Kernels and Pits

The kernels or seeds inside the pits of several common fruits contain amygdalin.

Apples and Pears: The seeds contain amygdalin, but you would have to chew and ingest several hundred seeds to reach a toxic dose. Swallowing them whole is harmless.
Apricots, Peaches, Cherries, and Plums: The kernels inside these stone fruits are also sources of amygdalin. Ingesting even a small number of raw apricot kernels, for example, can be dangerous.

Other Sources

Cassava: A tropical root vegetable and major food staple that contains cyanogenic glycosides. It must be properly soaked and cooked to make it safe.
Bamboo Shoots: Raw shoots contain cyanogenic glycosides and must be boiled before consumption.

How Processing Affects Cyanide Content

The toxicity of cyanogenic foods is not a simple yes-or-no issue. The method of processing can dramatically alter the cyanogen levels. The key is understanding how to break down or remove the toxic compounds.

Roasting and Boiling: High heat is highly effective at reducing or eliminating cyanogenic glycosides. Roasting is standard for commercial almonds and cashews, and boiling is essential for roots like cassava and vegetables like bamboo shoots.
Soaking: Prolonged soaking can help leach cyanide compounds out of some foods, like cassava.
Milling: Crushing or grinding a seed makes the cyanogenic glycosides more bioavailable and thus more dangerous if eaten raw.

Safety in a Nutshell

Commercial processing ensures that the nuts and seeds you find in a typical grocery store are safe. For instance, the cashews sold as "raw" in stores have already been heat-treated to remove the toxic urushiol from their shells. However, special care should be taken with wild or unprocessed products, especially bitter almonds, which are not intended for consumption.

Comparing Cyanogen Levels in Nuts and Seeds


Item	Cyanogen Presence	Typical Form Consumed	Safety Level	Key Processing Step	Notes
Bitter Almonds	High	Unprocessed	Extremely Toxic	Boiling/Heating	Avoid raw consumption entirely.
Sweet Almonds	Trace	Raw, Roasted	Very Safe	Roasting/Heat Treatment	Genetically mutated to be safe.
Flaxseeds (Ground)	Medium	Ground	Moderately Safe	Cooking	Consume in moderation; heat reduces risk.
Apple Seeds	Low	Whole (intact)	Very Safe	N/A	Tough casing prevents release; requires mass consumption.
Apricot Kernels	High	Unprocessed	Toxic	Boiling	Can be used as a food flavoring after processing, but risky.
Cashews	None (Urushiol)	Roasted	Very Safe	Roasting/Steaming	Toxin is in the shell, removed during processing.

Conclusion

In conclusion, while it is true that many nuts and seeds contain cyanogenic glycosides that can release cyanide, the risk of poisoning from typical store-bought products is extremely low. The food industry's safety measures, including specific processing techniques like heating, effectively neutralize these naturally occurring toxins. The key takeaway is to avoid raw, unprocessed bitter almonds and uncooked fruit kernels, particularly those from the Prunus family. For common items like sweet almonds, flaxseeds, and cashews, enjoying them in moderation as part of a balanced diet is perfectly safe. For more information on food toxins, you can consult reliable sources like the World Health Organization (WHO).

Frequently Asked Questions

No, it is highly unlikely to get cyanide poisoning from commercially available sweet almonds. These almonds have been selectively bred to contain only trace amounts of cyanogenic glycosides, which are not dangerous in typical servings.

Apple seeds contain a compound called amygdalin, which can release cyanide when chewed. However, the dose is extremely small. You would need to thoroughly chew and swallow a very large quantity of seeds, hundreds at once, to cause acute poisoning.

Yes, cashews labeled 'raw' in stores are safe. They have been shelled and heat-treated (steamed or roasted) to destroy the toxic urushiol, a compound related to poison ivy that is present in the cashew shell.

Yes, cooking methods involving heat, particularly boiling, are very effective at reducing or eliminating cyanogenic glycosides in foods. This is the standard practice for preparing foods like cassava and bamboo shoots, which contain these compounds.

Plants produce cyanogenic compounds as a natural defense mechanism against herbivores and insects. The bitter taste and toxic effects deter predators from eating them.

Yes, it is safe to eat ground flaxseeds in moderation. While grinding releases the cyanogenic glycosides, the human body can safely detoxify the small amounts of cyanide produced from typical serving sizes. Cooking flaxseeds also reduces the cyanide content.

Symptoms of cyanide poisoning can include headaches, dizziness, nausea, vomiting, stomach cramps, and mental confusion. In severe cases, it can lead to more serious issues like seizures or even death.