Why don't they just recommend olive oil instead of butter (in most cases)?
If the studies done with "olive oil" (which turned out in many places turned out to be a kind of canola oil, that is, the european variant), due to the high squalene content, I guess they would have found very little preventive effect, but since rape seed oil was mostly used, because of lack of squalene while very rich in phytosterols which are well documented as preventive against heart diseases as well of preventive of carcinogenesis, a good correlation was found, and honoured to olive oil.
I look forward to someone doing a big scale, double test with olive oil and rape seed oil in preventing heart diseases and carcinogenesis.
I myself only use "extra virgin olive oil", which is the real thing. That makes a difference in taste... and not just that, I gather.
Does it "freeze" when cooled down to about 2 deg C?
In case it contains lot of squalenes, the key intermediate in cholesterol synthesis which is responsible why most olive oil do not decrease cholesterol in blood, but rather increase LDL in direct contrast to rape seed/canola oil that decrease cholesterol due to its content of phytosterols, more strictly brassica sterols.