Ancel Keys is one of the prominent researchers involved in the Lipid Hypothesis which says that cardiovascular disease is caused by cholesterol. It’s one of the main reasons for advocating vegetable oil, because vegetable oils lower cholesterol. (Or at least they lower certain measures of cholesterol. I have seen a claim that those measures are problematic, but I haven’t investigated that.)
Keys wrote:
… it is easy to rule out of primary consideration many factors that show no consistency with regard to the relative frequency of the disease [coronary heart disease]. Climate, race, the use of alcohol and tobacco, degree of urbanization and in dustrialization, the stress forces of exposure to telephones, radios, street traffic hazards, personal cleanliness, indulgence in competitive business and sports, avail ability of doctors and hospitals seem to fall in this category; any or all of these may exert some influence but, if so, it would seem to be minor and secondary to other and more basic factors.
He goes on to say that serum cholestoral concentration correlates well with coronary heart disease (CHD) so it should considered as a primary factor.
Wikipedia says:
After fifteen years follow-up, the study [a later study by Keys] confirmed the results of larger studies that reported earlier on the predictive value for heart attack of several risk factors: blood pressure, blood cholesterol level, and cigarette smoking.
So later it turned out Keys was wrong to rule out tobacco as an important risk factor for CHD. And he didn’t just rule it out. He said it was easy to rule out.
There are other problems. Basically if you read the research on the lipid hypothesis, the quality seems to bad poor. But it’s been super influential anyway, with Americans getting 20% of their calories for vegetable oil being a downstream consequence (which may be the biggest cause of the obesity problem and some other health problems). A previous, related consequence of the lipid hypothesis was the health “authorities” pushing transfats into our diets for 10+ years. People have been so happy with the lipid hypothesis, or biased towards it, or something, that they have ignored decades of research indicating that it may be wrong or indicating that the omega 6 fat in vegetable oil is bad for us. Keys himself was biased and cherrypicked what countries he did his big research in in order to get the results he wanted (he already knew, in advance, what results to expect from some countries). And it was just correlation research the whole time, not explanations or figuring out causes.
This says basically that cholesterol is good for us and that Ancel Keys and the Lipid Hypothesis are bad. I don’t know where/how to get useful, rational responses about this from people who disagree.