The Great Cholesterol Myth (13 page)
Read The Great Cholesterol Myth Online
Authors: Jonny Bowden
And as much as we enjoy talking about this stuff and would be happy to chat about it if you met us at a cocktail party, the truth is it causes many people’s eyes to glaze over pretty quickly. So if you’re interested in reading about double bonds, saturation, chain length,
and other cool biochemical stuff, please, by all means, be our guest! That information is widely available. It’s not controversial, it’s not debated, and it’s not really germane to our story. So, mercifully, we’ve decided to forgo it here and instead give you the big picture—what you really need to know about saturated, polyunsaturated, and monounsaturated fats.
Saturated fats are primarily found in animal foods (meat, cheese, butter, eggs) and, less often, in certain plant foods, such as coconut, coconut oil, and palm oil. They tend to be solid at room temperature (think butter) and soften when warm.
WHAT YOU NEED TO KNOW
• Saturated fat has been wrongfully demonized.
• Saturated fat raises “good” (HDL) cholesterol.
• Saturated fat tends to change the pattern of your “bad” (LDL) cholesterol to the more favorable pattern A (big, fluffy particles).
• Several recent studies have shown that saturated fat is not associated with a greater risk of heart disease. One study from Harvard concluded that “greater saturated fat intake is associated with less progression of coronary atherosclerosis, whereas carbohydrate intake is associated with a greater progression.”
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• In the Nurses’ Health Study, refined carbohydrates were independently shown to be associated with an increased risk for coronary heart disease.
• Omega-6 fats—e.g., vegetable oils—are pro-inflammatory.
• The balance between omega-6 and omega-3 is far more important than saturated fat intake is.
• Low-fat diets work because they reduce omega-6 fats, not because they reduce saturated fat.
Chart by Michelle Mosher.
They also have a few other characteristics worth mentioning. Saturated fats are very stable. They’re tough—when exposed to high heat they don’t “mutate” or “damage” as easily as their more delicate cousins, the unsaturated fats do. That’s one reason why lard (with its high concentration of saturated fatty acids) is actually a better choice for frying than the cheap, processed vegetable oils that gradually replaced it as restaurants tried to be more health conscious.
The problem with vegetable oils is that they’re nowhere near as resistant to damage as saturated fats are. When you heat and reheat them for frying, as virtually every restaurant in America does, it causes the formation of all sorts of noxious compounds, including carcinogens. Compared to saturated fat, the unsaturated fatty acids in vegetable oils are much more easily damaged by high heat and more susceptible to oxidation and the production of free radicals. Those vegetable oils transform into all sorts of mutant molecules under the stress of high heat and reheating, but when high heat is applied to saturated fat, it behaves like the strong, silent uncle at the family gathering; everyone else is going nuts, but he’s calm and serene! (We’ll talk about some of the other problems with the overuse of vegetable oils in our diet later on.)
Now let us ask you a question, and please answer honestly: Did you just shudder in horror when we implied a few sentences ago that using lard for cooking might actually be a good idea? You probably thought to yourself, “Now they’ve gone too far. Did they really say lard is better to fry with than canola oil? That’s nuts!”
We’d be surprised if you didn’t recoil in horror. Most people would do just that—and it’s because most people have totally bought into the idea that saturated fat is the worst thing on the planet.
The idea that lard—with its high content of saturated fat—could ever be a better choice than those high-omega-6 vegetable oils that are continually pushed on us is in direct opposition to fat theology, the deeply held belief that saturated fat and cholesterol are the root of all heart disease evil. That notion has been the prevailing dogma about saturated fat, cholesterol, and heart disease for decades. By now you’re more than familiar with this notion, known as the diet–heart hypothesis—it’s the mantra that has guided public policy on diet and heart disease for virtually every major governmental and mainstream health organization, such as the American Heart Association.
There’s only one problem.
It isn’t true.
Despite its horrible reputation, saturated fat is far from a dietary demon. More and more health professionals, researchers, scientists, doctors, and nutritionists are beginning to reexamine the case against saturated fat, and they’re finding that it’s based on very little solid evidence (and a lot of guilt by association).
Look, there is no shortage of studies pointing to an association between increased saturated fat intake and cardiovascular risk, but there are a few things to know about those studies.
Dr. Jonny:
When I was in fifth grade back in Queens, New York, there was a kid named A.J. who was always, and I mean
always
, getting in trouble. But it was for the most minor stuff: coming in a couple of minutes late from recess, whispering in class, or, worst case scenario, throwing a spitball. There could be five other kids doing the same thing, but A.J. would always be the one to get caught. Singled out, reprimanded, parents called in to school, the whole humiliating deal.
But there were a couple of other kids in the class who were real pieces of work. One kid, Gilbert, compulsively lit firecrackers, scaring everyone to death, and then disappeared before he could be caught at the scene of the crime. Another kid named Howie took delight in breaking people’s windows with rocks. A third one, Corky, was a bully. And yet none of them ever managed to get caught. Rarely did any of these kids even get a stern talking–to. The role of the “bad kid” in the class was played by A.J., who would have to serve detention, sit in the corner, and be yelled at in front of the class, all for fairly meaningless infractions, while the kids who were doing all the really bad stuff got off scot-free.
Now it’s not that old A.J. didn’t do anything wrong. But unlike the other kids, he never beat anyone up, he never did anything mean, he never destroyed anyone’s property—and yet whenever there was trouble, he was always the scapegoat.
I think saturated fat is like that kid A.J. It’s not that it’s perfect. It’s just that it’s far less important than the stuff we ignore—such as high intakes of omega-6 fatty acids, low intakes of omega-3s, and obscene intakes of sugar and processed carbs.
Is saturated fat so wonderful that we should all resolve to melt a ton of butter and add it to our smoothies right this minute? No, of course not. Saturated fat has some negatives. It is mildly inflammatory. It may contribute to insulin resistance.
If the dietary dictocrats are going to warn us against inflammatory food components, why choose saturated fat, a relatively minor factor in inflammation compared to the omega-6 to omega-3 ratio? If they’re going to warn us about saturated fat because of its purported connection to insulin resistance, why do they continue to promote ridiculously high carbohydrate intakes, which are demonstrably worse?
Saturated fat is a lot like A.J. Not perfect, but it doesn’t deserve to get beat up. And the irony is that while everyone’s pushing him around and blaming him for everything bad that happens, the real culprits are getting away.
A little backstory about meta-analyses and why people do them. Say you want to learn about the sex habits of college students. There are probably a couple dozen relevant studies you could look at, but as with any other area of research, there’s no guarantee that all the studies will reach the same conclusions. In fact, it’s almost certain that they won’t. One study might find, for example, that college kids are having more sex, while another study might find that they’re actually having less. (A critical look at these two studies might uncover the fact that researchers in the two studies used slightly different definitions of the term “sex” when they surveyed the students, something that might account for the difference in results.)
Sometimes researchers overlook an obvious variable that could skew the results. Although researchers always try to control for these variables (such as age, sex, and smoking) and generally “match” subjects by the most important criteria, they don’t—they can’t—always control for every variable that might make a difference (and this is particularly true in diet research). The point is, if you look at anything worth studying you’re going to find a whole bunch of research on it, and among those research studies you’re almost guaranteed to encounter conflicting findings and areas of disagreement about how to interpret those findings.
Even something that now seems as clearly connected as the link between smoking and cancer started out as a hypothesis and had to be tested in all sorts of populations under all sorts of conditions. Studies can and do reach different conclusions depending on the statistical measures used, the populations studied, and even the definition of terms. (Is a “smoker” defined as anyone who has even one cigarette a week? Or is a “smoker” defined as someone who smokes at least half a pack a day?)
Which brings us, finally, back to meta-analysis.
Sometimes researchers gather up a whole bunch of these individual studies whose results are clustered all over the place like pins on CNN’s election maps. Then they’ll ask, “What do these studies, taken together as a whole, really tell us about what’s going on?” They’ll gather up all the studies on, say, smoking and cancer, college students and sex, or saturated fat and heart disease. They’ll examine them scrupulously, tossing out any studies whose methods,
designs, or data don’t meet the highest standards of research excellence. (Meta-analyses typically exclude small pilot studies, unblinded studies, studies with too few participants, or studies that do not collect data on something the researchers consider important.)
Once the “best-of-the-best” studies are selected for inclusion (and lesser studies are eliminated), the researchers go to work and apply every statistical manipulation you can imagine to tease out the real relationships from the mass of accumulated data. They look at the findings of the individual studies and compare them. They pool the subjects from all the studies. They look for trends, directions, statistical significance, and hidden relationships. And though meta-analyses themselves are not infallible, they’re a great way to look at the big picture to gauge what’s really going on.
Number one, the associations are far weaker than one might suspect, given how entrenched the belief is that saturated fat clogs your arteries. In many of these studies, the major “risk” examined was cholesterol, so we wind up with a circular argument in which higher saturated fat intake increases the risk for heart disease, but
only
if you accept the use of cholesterol levels as a stand-in for heart disease. Studies that measure the effect of saturated fat on heart disease and mortality
directly
—rather than indirectly by measuring its effect on cholesterol—are few and far between. But there are some important ones, which we’ll discuss in a moment.