Apples are a popular and healthy fruit, and a big part of American culture and history. Apples are easy to cultivate and tailor to certain tastes because of their resilient genetic diversity. They also have antioxidant properties that help protect against cancer-inducing oxidative damage, which can lead to various health problems. The saying “an apple a day keeps the doctor away” has withstood the test of time because of the impressive health profile of apples.

But as you bite deep into an apple, you are confronted with something not so sweet in its core: tiny black seeds. Unlike the sweet tang of the fruit, the tiny black seeds are another story. They contain amygdalin, a substance that releases cyanide when it comes into contact with human digestive enzymes. But acute toxicity is rare if you accidentally eat some of the seeds.

Cyanide is a chemical known as one of the deadliest poisons. It has been used in chemical warfare and mass suicide. Many compounds that contain cyanide—called cyanoglycosides—are found in nature, often in fruit seeds. Amygdalin is one of these.

Apple seeds, and many other fruit seeds or pits, have a strong outer layer resistant to digestive juices. But if you chew the seeds, amygdalin could be released in the body and produce cyanide. Small amounts can be detoxified by enzymes in your body. However, large amounts can be dangerous.

According to the Centers for Disease Control and Prevention (CDC), 1–2 mg/kg is a fatal oral dose of cyanide for a 154 lbs. (70 kg) man. Most apple cores contain around 5 apple seeds. However, this amount will vary based on the health of the plant. You would need to finely chew and eat about 200 apple seeds, or about 40 apple cores, to receive a fatal dose.

The Agency for Toxic Substances & Disease Registry (ATSDR) says that exposure to even small amounts of cyanide can be dangerous. Cyanide can harm the heart and brain, and even lead to coma and death. ATSDR adds that people should avoid eating the seeds of apples, and the pits of fruits that include:

  • peaches
  • apricots
  • cherries

Symptoms of cyanide poisoning can occur quickly. They include shortness of breath and seizures. Both can lead to loss of consciousness.

Apple seed oil is a byproduct of juice processing. It’s made from the raw apple pomace. The amount of amygdalin found in apple seed oil is generally very small.

People use it for its fragrance, to condition hair, and calm skin inflammation. Some studies suggest that it’s also a good source of antioxidants and shows some potential as an anticancer agent. Another study found apple seed oil to be active against bacteria and yeast.

Apple seeds contain amygdalin, a substance that releases cyanide into the blood stream when chewed and digested. However, apple seeds in small amounts do not contain enough cyanide to cause harm. However, it is better to spit out seeds to avoid any potential issues.