What foods are high in cyanide and how to prepare them safely

October 15, 2025 •

3 min read

According to the World Health Organization, cyanide is a well-known poison that occurs naturally in over 2,000 plant species. This article explores what foods are high in cyanide, the risks associated with them, and how proper preparation is essential for safe consumption.

Quick Summary

This guide details common foods that contain naturally occurring cyanogenic glycosides, which can break down into toxic hydrogen cyanide. It also outlines essential preparation techniques to reduce the risk of poisoning.

Key Points

Sources of Cyanide: Cyanogenic glycosides, not free cyanide, are the main toxic compounds found naturally in certain plants like cassava, bitter almonds, and fruit pits.
Cassava Requires Processing: Both sweet and bitter cassava contain cyanogenic glycosides, but bitter varieties have significantly higher levels and require extensive soaking, peeling, and boiling to be safe.
Bitter Almonds are Dangerous Raw: Unlike sweet almonds, bitter almonds contain high levels of amygdalin and are toxic when consumed raw. They are typically not sold for raw consumption.
Seeds and Pits are Not Edible: The seeds and pits of stone fruits like apples, cherries, and apricots contain amygdalin and should not be crushed or chewed.
Boiling Renders Bamboo Shoots Safe: Fresh bamboo shoots contain cyanogenic glycosides that can be effectively removed by boiling them thoroughly before consumption.
Safe Preparation is Key: Proper preparation methods, including soaking, peeling, and cooking, are essential for reducing cyanide levels in potentially toxic foods to safe concentrations.
Risk Factors and Health Effects: While occasional consumption of small amounts is generally harmless, chronic exposure or ingestion of large quantities can lead to thyroid and neurological problems, and acute poisoning can be fatal.

Understanding Cyanogenic Glycosides

Cyanide is a rapidly acting, potentially lethal chemical, but it is rarely found in its free form in nature. Instead, certain plants produce cyanogenic glycosides, which are chemical compounds that can release hydrogen cyanide when the plant tissue is damaged, such as by chewing or processing. The release is triggered by an enzyme that breaks down the glycoside, and the amount of cyanide produced depends heavily on the specific plant variety, its maturity, and the preparation method. Most food safety concerns surrounding cyanide are related to these naturally occurring cyanogenic compounds.

Common Foods Containing High Levels of Cyanide

Many common foods, especially those consumed in tropical regions, contain higher concentrations of cyanogenic glycosides than others. While a well-balanced diet and proper preparation methods mitigate risk for most people, some foods require particular attention.

Cassava Root: A staple food in many tropical countries, cassava is a significant source of cyanogenic glycosides. Sweet varieties contain less cyanide than bitter varieties, but both require proper preparation. Peeling, grating, prolonged soaking, and thorough cooking like boiling are crucial for safety.

Bitter Almonds: Unlike sweet almonds, bitter almonds contain high levels of amygdalin, a toxic cyanogenic glycoside. Consuming even a small amount can be dangerous. They are generally not sold raw in the United States.

Fruit Seeds and Pits: The seeds (or pips) and pits of certain fruits such as apples, apricots, cherries, peaches, and plums contain amygdalin. While the fruit flesh is safe, chewing the kernels inside the pits can release hydrogen cyanide.

Bamboo Shoots: Fresh bamboo shoots contain cyanogenic glycosides. Boiling them for at least 15 minutes destroys the toxins, making them safe to eat. Canned bamboo shoots are typically safe due to processing.

Lima Beans: Some lima bean varieties contain cyanogenic compounds. Boiling in excess water and draining can reduce cyanide levels. Commercially grown beans in the US usually have low content.

Comparison of Cyanide-Containing Foods and Preparation


Food Type	Raw Cyanide Content	Primary Cyanogenic Compound	Safe Preparation Methods
Cassava Root	Varies by variety; Bitter varieties (up to 400 mg/kg) are much higher than sweet varieties (15-50 mg/kg).	Linamarin and lotaustralin.	Peeling, grating, prolonged soaking, fermentation, and thorough boiling.
Bitter Almonds	Approximately 50 times higher than sweet almonds.	Amygdalin.	Roasting, but best to avoid raw bitter varieties.
Fruit Pits/Seeds	Content varies significantly by fruit and species (e.g., apple seeds ~0.6mg/g).	Amygdalin.	Do not chew or crush seeds/pits; avoid consumption.
Bamboo Shoots	Up to 1000 mg/kg in fresh shoots.	Taxiphyllin.	Thorough boiling for at least 15-20 minutes, discarding the water.
Lima Beans	Content varies; wild types are highest.	Linamarin.	Boiling in fresh water and draining.

Safe Handling and Processing of Cyanogenic Foods

Proper processing is key to preventing cyanide poisoning from these foods. Peeling cassava, grating and soaking it, and thorough cooking like boiling are effective methods. For bamboo shoots, boiling is the most common method, as heat breaks down the toxins. Commercially canned bamboo shoots are processed to be safe.

Potential Health Effects of Ingesting Cyanide from Food

While proper preparation minimizes risk, consuming large amounts or insufficient processing can be harmful. Acute poisoning symptoms include headache, dizziness, nausea, and in severe cases, loss of consciousness or cardiac arrest. Chronic exposure from poorly processed foods can lead to thyroid issues and neurological disorders.

Conclusion

Foods high in cyanide are safe to eat when properly prepared. Traditional and modern processing methods effectively reduce the cyanogenic glycoside content. Awareness of which foods contain these compounds and following recommended preparation techniques are essential for safety. A balanced diet also supports the body's natural detoxification processes.

Citations

Food and Agriculture Organization. "Detoxification of cassava products and effects of residual toxins on consuming animals." FAO.org, 2025.
Centers for Disease Control and Prevention. "Cyanide." CDC.gov, 2024.
Everyday Health. "Can You Get Cyanide Poisoning From Eating Almonds?" EverydayHealth.com, 2025.
Medscape. "Cyanide Toxicity Clinical Presentation." Medscape.com, 2025.
Canadian Food Inspection Agency. "Natural toxins in fresh fruit and vegetables." Canada.ca, 2019.
Food Standards Australia New Zealand. "Cyanogenic glycosides in cassava and bamboo shoots." FoodStandards.gov.au.

Frequently Asked Questions

Sweet cassava contains much lower levels of cyanogenic glycosides (under 50 mg/kg) than bitter cassava (up to 400 mg/kg). While sweet cassava requires standard cooking, bitter cassava needs more extensive processing like grating, soaking, and prolonged boiling to be safe for consumption.

Apple seeds contain a small amount of amygdalin, which releases cyanide when chewed or crushed. However, a person would need to crush and ingest a large quantity of seeds, approximately 100 grams, to risk poisoning. Accidentally swallowing a few whole seeds is not harmful.

To make fresh bamboo shoots safe, you must boil them thoroughly. Boiling them for at least 15-20 minutes in water is effective, as the heat breaks down the cyanogenic glycosides. Discard the water after boiling.

Only bitter almonds contain significant levels of amygdalin, which produces cyanide. Sweet almonds, commonly sold in stores, come from a different plant variety and contain only trace amounts due to a genetic mutation. Bitter almonds are not typically sold for raw consumption.

No, it is not safe to eat the kernels inside the pits of stone fruits. Chewing these kernels releases amygdalin, which can break down into toxic hydrogen cyanide. The flesh of the fruit is safe, but the pits should be discarded.

Properly processed foods like tapioca flour and canned products typically have very low to non-existent cyanide levels. The industrial processing methods effectively remove the cyanogenic compounds.

Symptoms of acute cyanide poisoning include headache, dizziness, nausea, vomiting, stomach pain, rapid breathing, and potential confusion or loss of consciousness. Severe cases can lead to cardiac arrest.