Well, I am shocked: researchers recently discovered some lost data from a 40-year-old study on heart disease, analyzed the lost data, and discovered … wait for it … the animal fats we’ve been consuming for hundreds of thousands of years appear to be better for our health than the chemically extracted vegetable oils we’ve only been consuming for the past 100 years.
I know, I know … you can’t believe it either, can you? The new analysis has (fortunately) been making a bit of a splash in the media. Here are some quotes from an article published in the online edition of Forbes:
In an exceedingly strange turn of events, data from a clinical trial dating from the 1960s, long thought to be lost, has now been resurrected and may contribute important new information to the very contemporary controversy over recommendations about dietary fat composition.
The American Heart Association has long urged people to increase their consumption of polyunsaturated fatty acids (PUFAs), including omega 6 PUFAs, and reduce their consumption of saturated fatty acids. The recommendations are based on the simple observation that PUFAs lower total and LDL cholesterol while SFAs have the opposite effect. However, the cardiovascular effects of substituting PUFAs for SFAs have never been tested in randomized, well-controlled clinical trials, and a growing proportion of experts now suspect that simple changes in total cholesterol and LDL cholesterol may not tell the whole story.
Let’s just stop and re-read part of that paragraph.
However, the cardiovascular effects of substituting PUFAs for SFAs have never been tested in randomized, well-controlled clinical trials …
We’ve never had anything remotely resembling actual proof that substituting vegetable oils for animal fats prevents heart disease. But the lack of proof didn’t stop an entire industry from building up around the belief that vegetable oils are better for our health – just visit your grocery store and look at all the tubs of Smart Balance and other butter substitutes touting the fact that they contain less saturated fat.
The lack of proof didn’t stop The Guy From CSPI from harassing the restaurant industry into substituting vegetable oils for the lard and tallow they once used to fry foods. (And a chicken-fried steak hasn’t tasted the same since.) The lack of proof didn’t stop schools, hospitals, company cafeterias, and just about every other institution that serves meals from dumping butter in favor of margarine. The lack of proof doesn’t stop the average doctor, dietitian or nutritionist from believing that hundreds or even thousand of studies have shown that animal fats cause heart disease.
Let’s read on:
One trial that actually tested the hypothesis was the Sydney Diet Heart Study, which ran from 1966 through 1973. In the trial, 458 men with coronary disease were randomized to a diet rich in linoleic acid (the predominant omega 6 PUFA in most diets) or their usual diet. Although total cholesterol was reduced by 13% in the treatment group during the study, all-cause mortality was higher in the linoleic acid group than in the control group. However, in the original publications, and consistent with the practice at the time, deaths from cardiovascular (CVD) and coronary heart disease (CHD) deaths were not published.
Now, in a new paper published in BMJ, Christopher Ramsden and colleagues report that they were able to recover and analyze data from the original magnetic tape of the Sydney Diet Heart Study. The new mortality findings are consistent:
- All cause: 17.6% in the linoleic group versus 11.8% in the control group, HR 1.62, CI 1.00-2.64)
- CV disease: 17.2% versus 11%, HR 1.70, CI 1.03-2.80
- CHD: 16.3% versus 10.1%, HR 1.74, CI 1.04-2.92
Once again, let’s re-read part of the text above and let it sink in for a moment:
Although total cholesterol was reduced by 13% in the treatment group during the study, all-cause mortality was higher in the linoleic acid group than in the control group.
One of the goals of the original study was to lower cholesterol levels by swapping vegetable oils for animal fats. That goal was achieved – yahoo! Open the champagne.
And then the study subjects had to go and ruin the party by dying prematurely at a higher rate — from both heart disease and all causes combined — despite their lower cholesterol levels. The operation was a success, but unfortunately the patient died.
I’ve read the full text of the study, which includes this paragraph in the discussion section:
The traditional diet-heart hypothesis predicts that these favorable, diet-induced changes in blood lipids will diminish deposition of cholesterol in the arterial wall, slow progression of atherosclerosis, reduce clinical cardiovascular risk, and eventually improve survival. As expected, increasing n-6 from safflower oil significantly reduced total cholesterol. However, these reductions were not associated with mortality outcomes. Moreover, the increased risk of death in the intervention group presented fairly rapidly and persisted throughout the trial. These observations, combined with recent progress in the field of fatty acid metabolism, point to a mechanism of cardiovascular disease pathogenesis independent of our traditional understanding of cholesterol lowering.
That’s the polite, academic way of putting it. Allow me to interpret for the non-academic masses:
The Lipid Hypothesis is a crock of @#$%. Cholesterol doesn’t cause heart disease. Saturated fat doesn’t cause heart disease. TIME magazine, your doctor, your government health officials, and everyone else who warned you to cut back on saturated fats, switch to vegetable oils, and lower you cholesterol to save yourself from heart disease had no @#$%ing clue what they were talking about.
This wasn’t some namby-pampy observational study based on food-recall surveys, by the way. It was a controlled clinical trial. The subjects in the intervention group were given the safflower-oil products to consume, they received ongoing dietary counseling, and they kept daily food diaries … until they died, anyway.
The explanation we’re given for the “lost” data just now being discovered and analyzed is that a computer data tape was misplaced back in the day. (For those of you who were born after 1970, that’s how digital data used to be stored – on magnetic tape.) The explanation is probably true … but given that the original study was completed around the time the arterycloggingsaturatedfat! theory was sweeping the medical world, I can imagine another scenario:
“Did you finish crunching the numbers, Jenkins?”
“Yes, sir. The men who switched to safflower oil lowered both their total cholesterol and their LDL by a significant amount. Thirteen percent, in fact.”
“Yes, but … uh …”
“Well? What are you waiting for?”
“How soon do I get tenure, sir?”
“Out with it, Jenkins!”
“The men who switched to the safflower oil also had significantly higher rates of cardiovascular disease, heart disease, and overall mortality.”
“Hmmm. That’s not at all what we expected.”
“I know, sir.”
“Good thing you misplaced the data.”
“No, sir, I have it right—”
“I said, good thing you misplaced the data.”
“Oh. Right. And, uh, for how many years did I misplace it, sir?”
“I’d say … let’s see … about forty years.”
“Why forty years, sir?”
“Because we’ll all be retired by then.”
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