It's possible to make, or with some research buy linseed oil without the additives, oil that you could actually eat though I suspect it wouldn't taste great. Making your own can be dangerous, though of course the techniques go waaaay back and most of the makers probably survived the process. Some of the better woodworkers on YouTube slather their pure, unadulterated BLO (boiled linseed oil) on to their projects with their bare hands. I want to get me some;)