What fruit seeds should you not eat? A guide to toxic pips and kernels

According to the World Health Organization, some natural compounds in common plants, including fruits, can be toxic if consumed. Knowing what fruit seeds you should not eat is a vital part of food safety, as certain seeds and pits contain harmful chemicals that can affect your health.

Quick Summary

Certain fruit seeds and pits contain natural toxins like amygdalin, which converts to cyanide when crushed, or hypoglycin-A, which can cause hypoglycemia. Caution is needed with stone fruits, apples, lychee, and ackee to prevent poisoning.

Key Points

• Cyanogenic Glycosides: Many seeds and pits, particularly from apples and stone fruits, contain amygdalin, which converts to toxic cyanide when crushed.

• Toxic Kernels: The kernels inside the hard pits of cherries, peaches, plums, and apricots are highly toxic and should never be consumed.

• Hypoglycin-A in Tropical Fruits: Unripe lychee and ackee fruit seeds contain a toxin that can lead to severe hypoglycemia (low blood sugar).

• Kidney Disease Risk: Star fruit contains a neurotoxin that is dangerous for individuals with kidney disease.

• Swallowed vs. Crushed: Swallowing whole seeds is less dangerous than chewing or crushing them, as the hard outer layer often prevents toxin release.

• Safe Seed Examples: Seeds from fruits like kiwi, watermelon, and papaya are generally safe and can offer nutritional benefits.

• Proper Preparation: Always remove seeds and pits before juicing, blending, or serving these fruits, especially to children.

Understanding the Risk: How Fruit Seeds Can Be Toxic

While fruits themselves are a cornerstone of a healthy diet, their seeds or pits are not always safe for consumption. Many plants produce toxic compounds as a natural defense mechanism against pests and predators. These toxins, harmless to the plant, can pose a risk to humans, especially when the seeds are chewed or crushed, releasing the compound into the body.

The Danger of Cyanogenic Glycosides (Amygdalin)

One of the most common toxins found in fruit seeds is amygdalin, a type of cyanogenic glycoside. This compound is typically housed within the hard, protective coating of the seed or pit. When the seed is broken, chewed, or crushed, enzymes in the body can convert the amygdalin into hydrogen cyanide (HCN), a potent poison.

• Apples: Apple seeds contain amygdalin. Accidental swallowing of a few whole seeds is unlikely to cause harm, as the hard coating prevents the release of the toxin. However, consuming a large quantity of crushed or chewed seeds is dangerous.
• Stone Fruits: The kernels inside the pits of cherries, peaches, plums, and apricots are a significant source of amygdalin. The European Food Safety Authority suggests that adults should not consume more than three small apricot kernels in one sitting. For children, the risk is much higher.
• Pears: Like their apple cousins, pear seeds contain amygdalin and should be avoided.
• Elderberries: Unripe elderberries, as well as the bark and leaves, contain both lectin and cyanide, which can cause nausea, vomiting, and diarrhea.

Other Notable Fruit Seed Toxins

Not all toxic fruit seeds rely on cyanogenic glycosides. Other fruits have their own unique dangers.

• Lychee and Ackee: The seeds of these tropical fruits contain the natural toxin hypoglycin-A. Unripe ackee fruit is particularly dangerous, but the ripe, prepared flesh is safe. Unripe lychee fruit and its seeds can lead to dangerously low blood sugar levels, especially in malnourished individuals.
• Star Fruit: For individuals with kidney disease, star fruit contains a neurotoxin called caramboxin that their bodies cannot properly filter. The toxin can accumulate and cause a range of neurological issues, from confusion to seizures.
• Raw Cashews: The "raw" cashews sold commercially are actually steamed to remove a toxic compound called urushiol, the same substance found in poison ivy. True raw cashews are not safe to eat.

Can Swallowing Whole Seeds Harm You?

For seeds containing amygdalin, like those in apples and cherries, the outer shell is the key factor. If you swallow the seeds whole, they will likely pass through your digestive system without being broken down, meaning the amygdalin is not released. The risk arises when the seed is crushed, chewed, or ground up in a blender. It is always safest to discard the seeds or pits from these fruits, especially when preparing food for children.

A Comparison of Safe vs. Unsafe Seeds

Fruit Type	Toxic Compound	Risk When Ingested	Consumption Advice
Apples	Amygdalin (cyanide precursor)	High if crushed/chewed in large amounts. Low if swallowed whole.	Discard seeds completely.
Stone Fruits (Cherries, Peaches, etc.)	Amygdalin (cyanide precursor)	High if kernels are crushed or chewed.	Always remove and discard pits.
Lychee (Unripe)	Hypoglycin-A	High risk of severe hypoglycemia.	Do not eat unripe lychees or their seeds.
Ackee (Unripe)	Hypoglycin	High risk of poisoning.	Only eat properly harvested and ripe ackee flesh.
Star Fruit	Caramboxin	High risk for those with kidney disease.	Avoid if you have kidney problems.
Kiwi	N/A	Safe to eat.	Enjoy freely.
Watermelon	N/A	Generally safe to eat.	Can be eaten, roasted, or ground.
Papaya	N/A	Generally safe to eat in moderation.	Can be eaten; contains the enzyme papain.

What to Do in Case of Exposure

If you believe you have consumed a significant amount of crushed seeds from a fruit like an apple or stone fruit, or if symptoms of cyanide poisoning appear, you should seek immediate medical attention. Mild symptoms of cyanide poisoning can include headache, dizziness, nausea, and confusion. Severe symptoms can lead to seizures, coma, or even death. For accidental ingestion of one or two whole seeds, the risk is minimal, but it is always best to be cautious. For concerns related to specific fruits like lychee or ackee, pay attention to the ripeness and preparation. For additional information, the World Health Organization offers details on natural toxins in food.

Conclusion

While the risk of severe poisoning from accidentally eating a few whole fruit seeds is low, it is important to be mindful of which fruits contain potentially toxic compounds. Seeds and pits from apples, pears, and stone fruits like cherries and apricots contain amygdalin, a precursor to cyanide. Meanwhile, unripe lychee and ackee contain hypoglycin-A, and star fruit contains caramboxin, especially dangerous for those with kidney issues. Always discard the seeds and pits from these fruits, particularly when preparing food for children. For fruits like kiwi, watermelon, and papaya, the seeds are generally safe and can even offer nutritional benefits. Staying informed about these risks is the best way to ensure the safety of your diet.

Recommended Fruit Seeds to Avoid

• Apple seeds: Contain amygdalin, which becomes toxic when chewed or crushed.
• Cherry pits: The kernel inside contains a cyanogenic glycoside that can convert to cyanide.
• Peach pits: Similar to cherries, the internal kernel is poisonous if ingested.
• Apricot kernels: Contain amygdalin, and even a small number can be harmful.
• Lychee seeds: Unripe fruit seeds contain hypoglycin-A and can cause severe hypoglycemia.
• Raw Cashews: Unprocessed raw cashews contain urushiol and are not safe to eat.

Recommended Fruit Seeds for Safe Consumption

• Kiwi seeds: Tiny, digestible, and full of nutrients.
• Watermelon seeds: Edible and can be roasted or ground for consumption.
• Papaya seeds: Contain digestive enzymes and are safe to consume in moderation.

General Food Preparation Advice

• Juicing: Always remove seeds and pits before juicing or blending fruits like apples, cherries, and peaches to prevent toxins from being released.
• Serving to children: Exercise extra caution with small children by removing all seeds and pits, as they are more susceptible to toxins and are also at risk of choking.

How to Avoid Unripe Fruit

• Lychee: Choose fruit with reddish skin; green skin indicates it is unripe and potentially toxic.
• Ackee: Only consume the fruit when it has opened naturally on the tree and the black seeds are visible within the ripe golden flesh.

Frequently Asked Questions

Are apple seeds really poisonous?

Yes, apple seeds contain amygdalin, which can produce hydrogen cyanide when crushed or chewed. However, swallowing a few whole seeds is generally not harmful because the hard coating protects them from digestion.

What happens if I accidentally swallow a cherry pit?

Swallowing a whole cherry pit is unlikely to cause harm. The pit's hard shell prevents the toxic amygdalin inside the kernel from being released into your body. It will most likely pass through your digestive system intact.

Why are unripe lychees and ackees dangerous?

Unripe lychee and ackee fruits contain a toxin called hypoglycin-A, which can interfere with the body's ability to produce glucose, leading to severe hypoglycemia. It is important to only eat ripe fruit.

Can I eat the kernels from apricot pits?

No, it is not recommended to eat apricot kernels. They contain amygdalin and can lead to cyanide poisoning, even in small quantities. The European Food Safety Authority advises against it.

Are star fruit seeds toxic?

While the seeds themselves are not the primary concern, star fruit contains a neurotoxin called caramboxin. This toxin is dangerous for individuals with kidney disease, whose bodies cannot properly filter it.

What is the difference between bitter almonds and the almonds I buy at the store?

Bitter almonds contain significantly higher levels of amygdalin than the sweet almonds commonly sold in stores. Commercial 'raw' cashews are also steamed to remove a toxin called urushiol.

How do I know if I have cyanide poisoning from fruit seeds?

Symptoms of cyanide poisoning can include headache, dizziness, nausea, confusion, and rapid breathing. If you experience these symptoms after ingesting a large amount of crushed fruit seeds, seek immediate medical help.

Are the seeds in watermelon, kiwi, and papaya safe to eat?

Yes, the seeds in watermelon, kiwi, and papaya are generally safe to eat. In fact, many people consume them intentionally, as they contain various nutrients.