Apples, along with cherries, peaches, and almonds, are members of the rose family. The seeds of apples and these other fruits contain natural chemicals that are toxic to some animals. Are they poisonous to humans? Here's a look at the toxicity of apple seeds to humans.

Toxicity of Apple Seeds

Apple seeds do contain a small amount of cyanide, which is a lethal poison, but you are protected from the toxin by the hard seed coating. If you eat whole apple seeds, they pass through your digestive system relatively untouched. If you chew the seeds thoroughly, you will be exposed to the chemicals inside the seeds, but the dose of toxins in an apple is small enough that your body can easily detoxify it.﻿﻿

How Many Apple Seeds It Takes to Kill You

Cyanide is deadly at a dose of about 1 milligram per kilogram of body weight. On average, an apple seed contains 0.49 mg of cyanogenic compounds.﻿﻿ The number of seeds per apple varies, but an apple with eight seeds, therefore, contains about 3.92 milligrams of cyanide. A person weighing 70 kilograms would need to eat 143 seeds to reach the lethal dose. That's about 18 whole apples.

Other Fruits and Vegetables That Contain Cyanide

Cyanogenic compounds are produced by plants to protect them from insects, and so they can resist diseases. Of the stone fruits (apricots, prunes, plums, pears, apples, cherries, peaches), bitter apricot kernels pose the greatest risk.﻿﻿ Cassava root and bamboo shoots also contain cyanogenic glycosides, which is why these foods need to be cooked before ingestion.

The ackee or achee fruit contains hypoglycin.﻿﻿ The only portion of ackee that is edible is the ripe flesh around the black seeds, and then only after the fruit has naturally ripened and opened on the tree.

Potatoes do not contain cyanogenic glycosides, but they do contain the glycoalkaloids solanine and chaconine.﻿﻿ Cooking potatoes does not inactivate these toxic compounds. The peel of green potatoes contains the highest level of these compounds.

Eating raw or undercooked fiddleheads can cause diarrhea, nausea, cramping, vomiting, and headaches.﻿﻿ The chemical responsible for the symptoms has not been identified. Cooking fiddleheads prevents illness.

While not poisonous, carrots may taste "off" if they are stored with produce that releases ethylene (e.g., apples, melons, tomatoes).﻿﻿ The reaction between ethylene and compounds in carrots produces a bitter flavor resembling that of petroleum.