I noted decades ago that researchers had divided France into two zones for bowel cancer: the high rate zone corresponded with the area that cooked largely with butter and the low rate zone was the one cooking with olive oil. More recently, I noted another epidemiological report that observed high rates of bowel cancer in a large region where cooking was done with ghee (clarified butter, or what I choose to call "overheated butter").
Putting 2 and 2 together to make 6, I argued that there may be carcinogens in overheated butter, but none in hot olive oil, if it evaporates at a lower temperature than needed to form carcinogens. Could it be possible, I asked, that other fats than those in butter also form carcinogens when overheated? If so, would the scorching of meats and fats increase cancer risks?
I wrote to the Association for International Cancer Research (AICR) with these thoughts, and they replied that they would fund research on this. It was not long before there were reports that warned of the dangers of scorching meats, and also of keeping old cooking oils too long.
There was a Ministry of Food warning of the dangers of eating too much "red meat", which I queried, pointing out that the scorched bits of red meat tended to be consumed far more in barbecued form than (say) chicken, where the scorched skin tends to be discarded. So my own hunch about the statistical evidence still suspects scorched fats, rather than red meat as such.
Surely for definitive answers, some researchers must examine the molecular structure of overheated fats and meats.
Cliff Bore, Kingston upon Thames