Please make the following in red clear for me.
Exercise has been shown to both prevent and treat osteoporosis, help manage diabetes, reduce the risk of addiction relapse... contribute to optimism and a positive mindset. What all this information points to is that exercise is not a silver bullet---it's platinum.
Is this saying "exercise acts as a catalyst like platinum"?
No. It's comparing silver with platinum. Platinum is a more precious and valuable metal than silver, so a platinum bullet is better than a silver bullet.
:up: (...as long as there are no werewolves around!) :-)