A childhood belief about dangerous food

This is actually my dad's childhood belief.

Every day, after dinner, HIS dad would go and get some hardtack, which is an unleavened bread-thing that was believed to help digestion. No-one understood why Alan (aka, my Dad) would FREAK OUT and beg his father not to eat the stuff.

It was because, almost every night on the radio, he would hear about someone dying of a heart attack, but he heard it as "dead, at age 66. Cause of death is reported as hardtack."