For decades now, the government, nutritionists, and the medical profession have told us to replace dietary saturated fats with polyunsaturated fats like vegetable oils. That way, we can reduce the incidence of heart disease and live longer. This idea is so widely accepted that the bottle of Mazola corn oil is labeled “Heart Healthy” with a big red heart. The claim must be true, because otherwise the FDA would never allow Mazola to engage in misleading product labeling, amirite? No, the health benefits of vegetable oil are Settled Science. That’s why, about 25 years ago, McDonald’s had to stop cooking its french fries in beef tallow and switch to vegetable oil.
But how much real evidence do we have that vegetable oil is healthy? In general, it is hard to determine the relationship between diet and health because humans are not guinea pigs that can be subjected to a controlled diet in the laboratory. Usually, the best that researchers can do is to ask people what they eat, but people’s responses are notoriously unreliable.
Turns out, however, that over 40 years ago a rare study was done that did manage to precisely control human diets over a period of several years. The study achieved dietary control by focusing on patients confined to nursing homes or mental institutions. For some reason, however, the results of this uniquely valuable study were never published in full.
Thanks to Christopher Ramsden, who specializes in recovering lost studies, the results of the study were finally published last year, after literally being rescued from a moldy basement. And what did those results indicate?
Ramsden wondered if there was more data from the study somewhere.
In 2011, he sought out the sons of the experiment’s principal scientist, Dr. Ivan Frantz of the University of Minnesota, who died in 2009…
Dr. Robert Frantz, a physician at the Mayo Clinic, drove 90 minutes to his childhood home, to search file cabinets. On his third trip he spied moldering, unlabeled boxes in the far corner of the basement. Inside were ancient magnetic computer tapes and reams of yellowed documents. The subject line in his email to Ramsden was “Eureka.”
After getting the tapes translated into formats that modern computers can read, Ramsden and his colleagues discovered what had been hidden for nearly half a century: records on 9,423 study participants, ages 20 to 97, all living in state mental hospitals or a nursing home. It was the largest experiment of its kind.
It was also one of the most rigorous. Participants were randomly assigned either to the group eating the then-standard diet, which was high in animal fats and margarines, or to a group in which vegetable oil and corn oil margarine replaced about half of those saturated fats. Such a randomized controlled trial is considered less likely to produce misleading results than observational studies, in which volunteers eat whatever they choose. Observational studies are weaker than randomized ones because people who eat one way, rather than another, might have characteristics that benefit their heart health.
And because the Minnesota participants were in institutions that prepared all their meals and kept records, the scientists knew exactly what they ate for up to 56 months. Many nutrition studies have foundered because people misremember, or lie about, what they ate.
Analyzing the reams of old records, Ramsden and his team found, in line with the “diet-heart hypothesis,” that substituting vegetable oils lowered total blood cholesterol levels, by an average of 14 percent.
But that lowered cholesterol did not help people live longer. Instead, the lower cholesterol fell, the higher the risk of dying: 22 percent higher for every 30-point fall. Nor did the corn-oil group have less atherosclerosis or fewer heart attacks. [Emphasis added.]
Indeed, other studies also have shown that the correlation between serum cholesterol and life expectancy is positive, which means lower cholesterol is associated with shorter life. But your doc still wants you to bring down your cholesterol.
Time for McDonald’s to bring back the beef tallow fries. But of course if McDonald’s did that, all the corrupt and ignorant non-profit pressure groups would scream bloody murder.
Truly we live in a frustrating world of rent-seeking and ignorance, and rent-seeking enabled by ignorance.