Rapeseed oil may be better than the more conventional canola oil if it’s cold-pressed, but “better” is not the same as “good.”
Paleo and PUFAs
Rapeseed oil is still extremely high in omega-6 fats, which are inflammatory. One of the main health problems in America today is the extremely high levels of omega-6 fats that are present in the Standard American Diet (SAD) relative to omega-3 fats. They’re both polyunsaturated fats (PUFA), but omega-6 fats are inflammatory, whereas omega-3 fats have anti-inflammatory properties. In order to keep our internal inflammation down (which we absolutely want to do) we need to be sure to consume at least as many omega-3 as omega-6 fats, if not more. By consuming vegetable oils that are almost entirely omega-6 PUFAs, we throw this ratio way off.
PUFAs are also extremely unstable. They are much more likely than saturated or monounsaturated fats to oxidize when exposed to heat and light, which means they go rancid as soon as you add them to the oven or stovetop, assuming they haven’t already gone rancid before you bought them (which they probably have).
Cold-Pressed Doesn’t Help
Mark Sisson addressed the question of whether or not cold-pressed rapeseed could be a healthy source of fat.