“...can shorten your lifespan...”
The keyword is CAN not WILL! Anyone CAN posit a theory about things that can shorten your life. For example, eating too much pizza CAN shorten your life. Or drinking too much coffee CAN shorten your life, or watching MSNBC can shorten your life, etc.
It’s so easy, even the GEICO caveman can do it.
Used to watch that 'illegal', backwoods distillery show. Always saw the old, wrinkled expert barking out instructions. I want his lifestyle and Keith Richard's doctor. I'll be all set.