I'm afraid for my life. All these years I've been eating the seeds of fruit, such as apples, oranges, apricots, peaches, plums, etc. I started when I began living with my grandfather, a dentist, about 10 years ago. He said they were good for the teeth because of the minerals they contained. Over the years I've cultivated a taste for them, and was extremely delighted when I found I could buy them in quantities of a pound or more at health food stores. Recently, however, a friend told me that all fruit seeds contained cyanide, and that he had read an item in a newspaper once about someone who had died from eating apple seeds! I am especially concerned about apricot kernels, my favorite. What's a lethal dose? Can any be eaten safely? If so, about how many? I really like them and would be loath to give them up, but on the other hand I really don't want to be slowly poisoning myself and my guests and roommates.
John T., Phoenix
You’ve got good reason to be afraid, pal. Fruits of the rose family–including cherries, apples, plums, almonds, peaches, apricots, and crabapples–contain in their seeds substances known as cyanogenetic glycosides, which on ingestion release hydrogen cyanide gas through an enzymatic reaction. They can most certainly do you in. Since 1957, Turkey–a big apricot country–has reported nine cases of lethal poisoning from apricot seeds. Unfortunately, victims of such poisonings have a habit of kicking the bucket before doctors have a chance to ask them how many seeds they’ve eaten; in addition, the amount of amygdalin–the most important cyanogenetic glycoside–varies from species to species, and since the poisoning does not involve a direct transfer of cyanide from one place to another, “lethal dosages” of these various seeds are hard to pin down. Use the following as guidelines: (1) bitter almonds contain by far the greatest amount of amygdalin, and it takes 50-70 of them to kill an adult, 7-10 to kill a child. (2) Ingestion of about a cupful of any of the above seeds is pushing things a bit.
If you’ve been munching on seeds for years and have never felt any ill effects, you can safely continue to eat them in similar quantities without worrying. Keep in mind, however, that one gluttonous binge will put you away forever. Sub-lethal doses of cyanide gas are detoxified and passed out of the body rapidly, so it’s impossible to slowly poison yourself over a period of time. Symptoms of cyanide poisoning are excitement, convulsions, respiratory distress, and spasms. Another warning sign is death, which can occur without any of the other symptoms.
All of this, by the way, applies only to fresh seeds. Roasting the seeds will destroy the enzymes needed to produce the lethal reaction without appreciably affecting the mineral content of your munchies. Note to shocked almond freaks: regular old almonds contain far less amygdalin than the bitter variety.
Send questions to Cecil via firstname.lastname@example.org.