Tag polyunsaturated fat

Put away the tinfoil hats–but, still, WTF?

Adele Hite, PhD MPH RD 12 Comments

I’m not a conspiracy theorist.  Really. But as I wade through the thicket of science studies and rhetoric of science readings I have on my desk, I am more and more impressed with the power of paradigmatic thinking to distort how scientific knowledge is produced and disseminated.

Daisy Zamora and company have once again climbed in their wayback machine to reanalyze data from the Minnesota Coronary Survey, which began in 1968.  The vegetable oil intervention reduced saturated fat intake by about half and cholesterol consumption by about two-thirds, while nearly tripling the intake of polyunsaturated fat. Surprise, surprise–they found that although the vegetable oil intervention reduced cholesterol levels, the intervention also led to more heart attacks and increased risk of death. [The press release on the study is here; the study itself is here.]

Let me just add that the original study outcomes–which did not support the diet-heart hypothesis even then–were not published until many years after the study ended, in fact, after its primary investigator retired.

So, we’ve seen something like this with a red-meat-causes-cancer publication, a low-carb-more-calories-more-weight-loss one, and one of Zamora’s earlier studies, which she had to move mountains to get published.

Zamora and her team’s previous trip in the wayback machine turned up some interesting findings then too, which suggested that vegetable oils, far from being the “healthy” alternative to butter, might actually be contributing to increased risk of death from heart disease.

Zamora and her co-investigators politely refer to these sort of anomalies as “incomplete publication,” as in:

“… incomplete publication of important data has
contributed to the overestimation of benefits – and the underestimation of potential risks – of replacing
saturated fat with vegetable oils rich in linoleic acid.”

All I want to say, before going back and burying my head once again in my books, is that

1) Daisy Zamora and Christopher Ramsden are rockstars, and

2) “incomplete publication” of results from diet-heart trials is part of the reason that the folks at the USDA and DHHS have published guidelines where “oils” get to have their own category.

They aren’t trying to kill us on purpose.  Really.

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Update:  You know you’ve increased the amount of sunshine in the world when your work gets Walter Willett to offer up yet another snotty comment (see here for previous peevishness) about any research that doesn’t align with his: “Walter Willett, the chairman of the nutrition department at the Harvard T.H. Chan School of Public Health, called the research ‘irrelevant to current dietary recommendations’ that emphasize replacing saturated fat with polyunsaturated fat.”

He’s right of course. Any science that doesn’t uphold the orthodoxy really is irrelevant to current dietary recommendations.

Vegetable Oil and Heart Disease: New news from the way-back machine

Adele Hite, PhD MPH RD 28 Comments

Since the 1970’s, we’ve reduced our sugar, salt, and saturated fat intake, and we’ve dramatically reduced our rates of smoking, high serum cholesterol and high blood pressure. At the same time, rates of chronic disease, including coronary heart disease, have increased—in some cases, dramatically.

The best that we can say is that since the 1970s, rates of myocardial infarction have decreased slightly—but only in white folks.

If the current health prescription is valid, then we should see dramatic differences in rates of disease and mortality between those who follow the prescription and those who don’t, and we should see clear and strong associations between “healthy” food choices and good health (because the same people eating a “healthy” diet are also taking care of their health in other ways). Yet this is not what we see.

Is it possible that our low-fat diet has removed some protective factors from our nutritional profile and exposed us to increased levels of nutrients that have negative impacts on health? I think it is, and a recent study in BMJ supports this notion.

I am a long-time admirer of one of the researchers, Daisy Zamora, and she is a good friend of mine. She’d been dropping hints about this great study she was working on for a while now—but was sworn to secrecy and now I know why. What she and her co-investigators have uncovered is data from a long-ago diet study, conducted from 1966-1973. It’s a decently large, well-run, randomized controlled trial that replaces saturated fat with safflower oil, a vegetable oil particularly high in one kind of PUFA—omega-6 (n-6) linoleic acid—and low in another kind of PUFA—omega-3 (n-3) alpha linolenic acid. The idea was that replacing “bad” saturated fat with “healthy” vegetable oil in men with premature coronary heart disease would improve survival. This did not turn out to be the case. For some reason, though, the original study only reported all-cause mortality and not deaths from cardiovascular disease and coronary heart disease.

Daisy and her co-investigators climbed into their way-back machine and this is what they found: Not only did the participants in the intervention group have an increased risk of all-cause mortality, but they had an increased risk of death from cardiovascular disease and coronary heart disease.

The blue line is the safflower oil group; the red line is the control group. To put it rather simplistically, the widening gap between the two groups means the intervention group died a lot faster than the controls.

Although the switch to safflower oil did lower total cholesterol, these reductions didn’t help those participants live any longer than those who kept eating saturated fat. In fact, as the authors note, “the increased risk of death in the intervention group presented fairly rapidly and persisted throughout the trial.”  (Hmm. Maybe this whole “cholesterol lowering” thing isn’t as important as we thought.)

Furthermore, the authors go on to point out that the relationship between linoleic acid consumption and increased mortality was particularly robust in smokers and drinkers, “suggesting that diets high in n-6 [linoleic acid] may be particularly detrimental in the context of oxidative stress induced by smoking and alcohol.”

Everyone knows that if you are a smoker you should quit and that alcohol should be used in moderation. But, with this evidence in mind, if you decided to keep on smoking and/or you want to drink immoderately, you may want to consider a breakfast of eggs and bacon rather than whole wheat toast and “heart healthy” margarine before you do.

The entire article is available online. Read it for yourself and see what you think.  Anybody besides me wondering how the American Heart Association will respond to this study?

Kinky Stuff about Fatty Acids

Adele Hite, PhD MPH RD Leave a comment

That’s fatty ACIDS. It’s not that kind of site.

I was a young adult in the 1980s, just after the first Dietary Guidelines rocked our world. Yes, I remember the bacon-and-eggs frowny face on the cover of Times. It was in the checkout lane as I was buying my low-fat, fruit-and-sugar filled yogurt. Of course, I would soon come to my senses and switch to fat-FREE yogurt. Why? Because animal fat, including whatever remaining milkfat was in my yogurt, has Very Scary saturated fat in it. Did I know what that meant? Of course not. But I do now.

At my house, we like to joke that fats suffer from a serious PR problem (that’s what passes for humor around here). It’s so easy to think FAT=FAT. And “saturated” fat sounds even more ominous and creepy, saturating our blood with icky gooey . . . um . . . somethingy. Surely those loverly ladies Mona Unsaturated Fatty Acid (MUFA) and Polly Unsaturated Fatty Acid (PUFA)—Moofa and Poofa to friends—are better company to keep.  That seems to be what the folks at Harvard think, anyway.

Enter actual biochemistry.

In biochem class, I found out that “saturated” simply meant that the carbon chain of a fatty acid was fully “saturated” with hydrogen and therefore, there are no double bonds.  That’s not very scary.

Yeah, but my BFF, Polly Unsaturated, as it turns out, was more of a frenemy than I thought.


Kinda cute. Check out those double bonds. That’s what makes Poofa unsaturated.

Turns out, miss Poofa is into some radically kinky stuff.

Just about everyone has heard of antioxidants. They are why we are supposed to eat fruitsandvegetables. The point of antioxidants is to deal with “free radicals,” which sound like some kind of hippie flashback, but is simply a term to describe a molecule with one or more unpaired electrons that reacts easily with other molecules. In cell membranes, they can really cause problems because the long, straight profile of a fatty acid chain can get oxidized by reacting with a free radical, causing it to bend, which weakens the integrity and functionality of the membrane.

Prime targets of free radicals are unsaturated bonds, specifically: Poofas.

Even a middle-schooler can see (I know, I asked one) that this just doesn’t look good for the cell membrane.   It gets worse. The reaction that occurs not only damages that particular fatty acid, but is a self-propagating reaction. It starts and then it doesn’t stop—until an antioxidant comes along. The results: lotsa crooked Poofas.

The academic-industrial complex has recited to us the story that we should increase the consumption of corn and soybean oils—which contain about 60% of these fatty acids—because they are so good for us. They have the population studies to prove it. But this tale is as twisted as an oxidized Poofa. Ever since 1980, when we told people to start eating more Poofas, folks who are concerned about their health have eaten more Poofas. While we don’t really know if consuming corn and soybean oil will make you a healthier person, we do know that caring about your health will.  And even though people who care about their health are generally more healthy than people who aren’t, as a population we are all less healthy.  Could it be the Poofas that have saturated our food supply?

By sheer coinkydink, corn and soybean oils happen to be big moneymakers for food processors. That’s why I really get bent out of shape when we’re told that we grow soy and corn so we can feed it to cows. That’s like saying we drill for oil so we can make lipstick.

We may find out in the long run that it isn’t just our increase in carbohydrates, but our increase in Poofa–and the corresponding decrease in not-so-scary saturated fat–that is truly at the root of our current health crises. In which case, miss Poofa can kiss my butter.