To go along with that recent CETP trial news, here’s another one for the “We don’t know much about human lipid handing” file. A dietary study originally done back in the 1960s and 1970s has been (almost literally) resurrected, with data pulled out of yellowing stacks of paper, old cardboard boxes, and ancient-format computer tapes.
What it shows is that, under about the most controlled conditions possible in a large human trial (institutionalized patients being served standard meals), that replacing saturated/animal fat in the diet with vegetable-derived fats and oils provided. . .no cardiovascular benefit whatsoever. In fact, the lower the cholesterol levels of the patients, the higher their death rates. This was in over 9,000 subjects over five years, probably the largest study of its kind ever conducted, and it had only produced one (not very thorough) paper in 1989 that didn’t make much of an impression.
After all, Everyone Knew by that point that saturated fat was bad for you – higher cholesterol, atherosclerosis, cardiovascular mortality, and the case was closed. But the evidence for this has never been as strong as you’d imagine. Most of the studies that have backed it up are observational (with all the problems that entails), and some of them have never been fully published themselves. That Stat link in the first paragraph has more on this, and Gary Taubes has a great deal more in this book. (Whatever you think about his own dietary recommendations, it’s hard to refute his evidence that the entire official-dietary-recommendations experience has been a shambles). And there have been meta-analyses of the published data suggesting that even it doesn’t support the unsaturated-fat-good/saturated-fat-bad view. It’s interesting, in light of current evidence, to go back and read some popular cookbooks and dietary plans from the 1980s, which basically tell you to (1) cut out all saturated fat, (2) cut out the rest of the fat as much as possible while you’re at it, and (3) eat as many carbohydrates as you can hold. Well, that’s an exaggeration, but the introduction to the original edition of, say, Jane Brody’s Good Food Book starts to sound like that.
Beyond the dietary issues themselves, there’s an interesting psychological component to this story. Why was there only one paper from this huge study, and why did it take sixteen years after its completion to reach print? Its lead author was a hard-working, dedicated medical researcher:
The Frantz children always felt fortunate that their father brought his work home, his beliefs about the dangers of saturated fat shaping what the family ate. “Other kids would have ice cream; we had ice milk,” recalled Ivan Frantz. Bob said they were “reared on margarine,” foreswearing butter’s saturated fat.
It’s possible, Bob Frantz said, that his father’s team was discouraged by the failure to find a heart benefit from replacing saturated fats with vegetable oils. “My feeling is, when the overall objective of decreasing deaths by decreasing cholesterol wasn’t met, everything else became less compelling,” he said. “I suspect there was a lot of consternation about why” they couldn’t find a benefit.
The coleader of the project was Dr. Ancel Keys, author of the Seven Countries Study, Time cover subject, and the most prominent advocate of replacing saturated fat with vegetable fat. “The idea that there might be something adverse about lowering cholesterol [via vegetable oils] was really antithetical to the dogma of the day,” Bob Frantz said.
His father, he said, “was always committed to discovering the truth. He would be pleased this is finally coming out.”
It’s impossible to know for sure, but it seems likely that Franz and Keys may have ended up regarding this as a failed study, a great deal of time and effort more or less wasted. After all, the results it produced were so screwy: inverse correlation with low cholesterol and mortality? No benefit with vegetable oils? No, there must have been something wrong. The boxes full of data sat for decades, unlabled, in a far corner of a basement, and you wonder if Dr. Franz thought about them. Did he regret all the time spent on the study? Did he regret that more wasn’t done with the data it generated? We’ll never know – but what we do know is that he never threw those boxes away.