According to this message going viral on Whatsapp, apple seeds contain cyanide and can be fatal if chewed. Hence, you should remove the seeds before eating apples so as to avoid the chances of accidentally swallowing them. Here is the full text of the message:

In a recent murder case in Australia, a woman killed her husband by giving him crushed apple seeds. I didn’t know till now that apple seeds contain Cyanide. I researched the info online and was surprised to find that apple seeds do contain Cyanide. This is also one reason why insects hardly hit an apple crop. Maybe, they know instinctively. Please make sure the seeds are removed before eating apples. Especially children should not be given a whole apple. Instead cut and remove the seeds before giving it to them. You can google for the veracity of my observation, if in doubt. Google says: “When the seeds are damaged, chewed or digested, the plant compound known as amygdalin in the seed degrades into Hydrogen Cyanide. This is very poisonous and lethal in 4, 5 doses.” Please spread the message around to as many people as you can.