...since no one is precisely sure of the cause, but have detected the effect.

Maybe people who take many vitamin supplements think that they don't have to keep up with other health maintenance activities, like exercise and balanced diet, and keeping after their teeth. (Bacteria that cause gingivitis have also been implicated in the development of heart disease.) If I can get health from a pill, like the Jetsons, why wear myself out doing those unpleasant day-to-day things?

Relax, Frank. This just means you don't have to spend the money on the supplements anymore. Eat more nuts. Go for walks. Use the money to buy a nice CD once a month. Live long and prosper.