Cyanogenic Glycosides in Common Fruit Pits and Seeds
Many popular fruits from the Rosaceae family—including apples, cherries, apricots, and peaches—contain a naturally occurring toxin called amygdalin in their seeds and pits. When these seeds are crushed, chewed, or ground, the amygdalin breaks down into hydrogen cyanide, a highly poisonous chemical.
Apples and Pears
- Apple seeds are known to contain amygdalin.
- While swallowing a few whole seeds is unlikely to cause harm, chewing or crushing a large quantity can release cyanide.
- Pears also contain this compound in their seeds.
Stone Fruits (Cherries, Apricots, Peaches, Plums)
- The pits (stones) of stone fruits are also a source of amygdalin.
- The hard outer shell protects the compound, but if the pit is cracked open and the kernel inside is ingested, it can be hazardous.
- The concentration of amygdalin varies by fruit variety. Raw apricot kernels, in particular, are so risky that their retail sale is banned in some regions.
The Danger of Raw Legume Seeds
While cooked legumes are a healthy part of many diets, several types are toxic if consumed raw or improperly cooked. This is often due to lectins, a group of proteins that can cause digestive issues and other health problems.
- Raw Kidney Beans: These beans contain high concentrations of a lectin called phytohaemagglutinin. Ingesting just a few uncooked beans can cause severe nausea, vomiting, and diarrhea. The toxin is destroyed by boiling the beans thoroughly.
- Other Beans: Other common beans, like Lima beans, also contain cyanogenic glycosides and require proper cooking to be safe.
Extremely Potent Toxic Seeds
Some seeds contain highly potent toxins and should be avoided at all costs, even in small quantities. These are typically from ornamental or wild plants and are not meant for human consumption.
- Castor Bean (Ricinus communis): These seeds contain ricin, one of the most potent naturally occurring toxins. Ingesting even one or two chewed seeds can be lethal. While castor oil is safe due to processing, the seeds themselves are deadly.
- Rosary Pea (Abrus precatorius): Containing abrin, which is even more toxic than ricin, these seeds are often used in jewelry. If scratched or broken, they are extremely dangerous and can be fatal.
- Ornamental Plant Seeds: Many garden plants, such as Foxglove and Lily-of-the-Valley, produce toxic seeds that can cause serious health issues. Always keep these away from children and pets.
Other Seeds to Approach with Caution
- Nutmeg: While a common spice in small amounts, consuming large quantities of nutmeg seeds (just a few teaspoons) can be toxic due to the compound myristicin. This can cause symptoms like nausea, dizziness, and hallucinations.
- Lychee Seeds: These contain natural toxins that can significantly affect blood glucose levels and cause inflammation in the brain, especially in malnourished children. They are also a choking hazard.
- Raw Cashews: Raw cashews are sold in stores after being steamed to remove a toxin called urushiol, the same irritant found in poison ivy. Consuming truly raw, unsteamed cashews from the shell can cause a severe allergic reaction.
Comparison of Harmful Seeds
| Seed Type | Primary Toxin | Risk Level | Symptoms | Prevention |
|---|---|---|---|---|
| Apple/Cherry Pits | Amygdalin (becomes cyanide) | Low (if intact) to Moderate (if crushed) | Headache, nausea, dizziness, seizures | Don't chew or crush pits/seeds; remove before blending |
| Raw Kidney Beans | Phytohaemagglutinin | Moderate to High | Severe nausea, vomiting, diarrhea | Boil thoroughly before consumption |
| Castor Bean | Ricin | Extremely High | Severe vomiting, diarrhea, seizures, organ failure, death | Avoid consumption entirely |
| Rosary Pea | Abrin | Extremely High | Vomiting, liver failure, convulsions, death | Avoid consumption and handling |
| Raw Cashews | Urushiol | Moderate | Allergic reaction (rash, swelling) | Only eat steamed/processed cashews |
| Nutmeg (Large Doses) | Myristicin | Moderate | Nausea, dizziness, hallucinations | Use only in small, culinary amounts |
| Lychee Seeds | Various toxins | Moderate to High | Nausea, low blood sugar, brain inflammation | Avoid consumption |
The Importance of Proper Preparation
For many seeds that contain toxic compounds, the risk is mitigated through proper preparation. This includes boiling certain beans to deactivate toxins or cooking apricot kernels to reduce cyanide content. Heat processing, such as pasteurization used for some fruit juices, can also neutralize toxins like cyanide. It is also important to note that the flesh of most fruits with toxic pits is perfectly safe and nutritious to eat.
Conclusion: Navigating Seed Safety
While an array of seeds offers significant health benefits, knowing which seeds are harmful to eat is essential for your well-being. By exercising caution with fruit pits, ensuring proper cooking of legumes, and being aware of dangerously toxic ornamental seeds, you can protect yourself and your family from accidental poisoning. Always remove fruit pits before blending smoothies, and for ornamental plants, remember the rule: admire their beauty, but never consume their seeds. If you suspect that you or someone has ingested a poisonous seed, especially a crushed one or one from a highly toxic plant, seek immediate medical attention or contact a poison control center. For information regarding common poisonous seeds found in garden plants, you can visit the Children's Hospital of Philadelphia's Poison Control Center website.
