That could apply to a lot of things: sugary foods, alcohol, soda. I'm not sure how it has worked in the US but in the UK there have been warnings not he cigarette boxes since the 70's.
Edit:
Just checked how it worked in the US. These messages appeared on packaging:
1966-1970: Caution: Cigarette Smoking May be Hazardous to Your Health
1970-1985: Warning: The Surgeon General Has Determined that Cigarette Smoking is Dangerous to Your Health
After that there are several more informative ones including specific illnesses that smoking can cause.
So the entire time this man smoked there were warnings on the box that smoking was bad for his health - he ignored them.