The Great Cholesterol Myth (14 page)

Number two, as scientists have looked more carefully at the association between saturated fat in the diet and levels of cholesterol in the blood, they are beginning to see that even here the relationship is murky. Saturated fat, as we’ve pointed out, does in fact raise overall cholesterol levels, but its effect is still more positive than negative, because it causes HDL levels to go up more than LDL levels. Even more important, saturated fat has a positive effect on the particle sizes of both LDL and HDL, making
more
of the big, fluffy, benevolent particles and much
less
of the small, dense, inflammatory particles (such as LDL pattern B and HDL-3). (It’s called
shifting the distribution
of LDL particles.) And, as we’ve been saying, the particle size of cholesterol molecules is far more important than their sheer numbers. Later, when we examine the twin principles of fat theology, you’ll learn exactly why this is so and exactly why
particle size
is what we should be looking at.

One of the basic tenants of fat theology is that saturated fat increases the risk of heart disease. In the scientific literature, this issue is as far from being settled as you might think from listening to CNN. Recently, Patty Siri-Tarino, Ph.D., and Ronald Krauss, M.D., of the Children’s Hospital Oakland Research Institute together with Frank B. Hu, M.D., Ph.D., of Harvard, decided to do a meta-analysis—a study of studies. In this case, they looked at all previously published studies whose purpose was to investigate the relationship of saturated fat to coronary heart disease (CHD), stroke, or cardiovascular disease (CVD). Note that this is one of those hard-to-find studies we mentioned earlier: a study of the
direct effect
of saturated fat on health. The researchers weren’t just interested in the effect saturated fat had on
cholesterol
—they wanted to know the effect saturated fat had on
heart disease
. (Remember, they are
not
the same thing!)

Twenty-one studies qualified for inclusion in their meta-analysis, meaning these studies met the criteria for being well designed and reliable. All in all, the twenty-one studies included 347,747 subjects who were followed for between five and twenty-three years. Over this period of time, 11,006 of the subjects developed coronary heart disease (CHD) or stroke.

Ready for the findings?

How much saturated fat people ate predicted absolutely nothing about their risk for cardiovascular disease. In the researchers’ own words, “Intake of saturated fat was not associated with an increased risk of coronary heart disease (CHD) or stroke, nor was it associated with an increased risk of cardiovascular disease (CVD).” Those folks consuming the highest amount of saturated fat were statistically identical to those consuming the least amount when it came to the probability of CHD, stroke, or CVD. Even when the researchers factored in age, sex, and study quality, it didn’t change the results. Saturated fat did bupkis—it didn’t increase or decrease risk in any meaningful way. Period.

“There is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD,” the researchers concluded.
¹

Now—and this is a very important point—it’s not that there’s no evidence that saturated fat doesn’t raise cholesterol. There is, and we’ll examine that more in a moment. But the above meta-analysis didn’t just look at cholesterol levels; it looked at what we really care about—heart disease and dying. So never mind whether saturated fat raises my cholesterol level. What I really want to know is, what does eating saturated fat do to my chances of getting a heart attack? The meta-analysis looked at exactly that real-life endpoint we truly care about, and on that all-important metric, it found that saturated fat in the diet has virtually no effect.

That meta-analysis is hardly the only study that has found saturated fat innocent of any direct involvement in cardiovascular disease. In the fall of 2011, a new study came out in the
Netherlands Journal of Medicine
titled “Saturated Fat, Carbohydrates, and Cardiovascular Disease.” Like the above-discussed meta-analysis, its purpose was to examine the current scientific data on the effects of saturated fat, looking at all the controversies
as well as the potential mechanisms for the role of saturated fat in cardiovascular disease.

Here’s what the researchers wrote:

“The dietary intake of saturated fattty acids is associated with a modest increase in serum total cholesterol, but
not
associated with cardiovascular disease [italics ours].”
²

As we’ve been saying throughout this book, cholesterol is only used as a marker. (In other words, it’s a stand-in answer for what we
really
want to know—namely, what is the likelihood of developing heart disease?) But if you’re looking for a metric to predict who is and isn’t going to get heart disease, cholesterol—as we’ve seen in this book—is a lousy choice for a marker. If cholesterol really predicted heart disease (wrong belief number one), and if saturated fat really did terrible things to your cholesterol (wrong belief number two), then that might be reason to eliminate saturated fat from your diet.

But it turns out neither of those two things is true.

Let’s take those two notions one by one, because they are the bedrock beliefs of fat theology.

Researchers in Japan examined the first of those beliefs—that cholesterol is a good predictor of heart disease—with another meta-analysis. They searched for all studies that had examined the relationship of cholesterol to mortality, excluding any done before 1995 and any that had fewer than five thousand subjects. Nine studies met the criteria, but four had incomplete data and so were excluded. The researchers then performed a meta-analysis on the remaining five studies, which together involved more than 150,000 people followed for approximately five years.

The researchers placed everyone into one of four groups depending on their cholesterol levels: less than 160 mg/dL, 160 to 199 mg/dL, 200 to 239 mg/dL, and higher than 240 mg/dL. (These categories mirror the American Heart Association guidelines, which state that 200 mg/dL or lower is “desirable,” 200 to 239 mg/dL is “borderline high,” and higher than 240 mg/dL is bad news indeed.)

Which group do you think would have the worst possible outcomes?

According to everything we’ve heard from the cholesterol zealots, the answer is simple: Those whose cholesterol readings were the highest (240 mg/dL and over), and even those with cholesterol readings in the “borderline” category (200 to 239 mg/dL), should be expected to die at a higher rate than those with a cholesterol level of 160 to 199 mg/dL. And those in the under 160 mg/dL category should live longest of all!

That is precisely and exactly what did
not
happen.

In fact, the group with the
lowest
cholesterol levels died at the
highest
rate.

In scientific terms, the risk for dying from any cause whatsoever (called “all-cause mortality”) was highest in the group with low cholesterol. Compared with the reference group (160 to 199 mg/dL), the risk of dying from any cause whatsoever was significantly decreased in the group having “borderline high” cholesterol of 200 to 239 mg/dL and even further
decreased in the group having “high” (greater than 240 mg/dL) cholesterol. In contrast, your risk of dying from any cause was the highest of all if your cholesterol was under 160 mg/dL!
³

Total cholesterol is so irrelevant as a metric that in 2007 the Japan Atherosclerosis Society stopped using it in any tables related to the diagnosis or treatment criteria in its guidelines.

So
high ch
olesterol is associated with a
reduced
risk of death? Not exactly what you might expect but exactly what the study found.

Total cholesterol is so irrelevant as a metric that in 2007 the Japan Atherosclerosis Society stopped using it in any tables related to the diagnosis or treatment criteria in its guidelines.
⁴
It’s not that the society abandoned the cholesterol theory, mind you. It just now relies entirely on LDL levels to determine who should be classified as having “high cholesterol,” reasoning that if total cholesterol is high simply because you’ve got a terrifically high HDL level, that shouldn’t be counted as a bad thing. Many American doctors—even the most conservative ones—would probably agree that the LDL number is the important one, even if they don’t fully embrace the notion that it is the
type
of LDL—not the LDL number—that matters the most.

But is the LDL level a better predicator of heart disease or mortality than the total cholesterol level?

Once again, let’s go to the videotape.

Researchers in Japan set out to answer this question in something called the Isehara Study.
⁵
The Isehara Study was based on data collected from annual checkups of residents in Isehara, a smallish city (population: 100,000) located in the central Kanagawa Prefecture in Japan. A database of 8,340 men (average age sixty-four) and 13,591 women (average age sixty-one) was mined for cholesterol readings, and the 21,931 people were divided into seven groups ranked from lowest to highest LDL cholesterol levels (in mg/dL): <80, 80 to 99, 100 to 119, 120 to 139 (reference group), 140 to 159, 160 to 179, and >180.

In both men and women, overall mortality was significantly higher in the group with the lowest LDL cholesterol levels (under 80 mg/dL).

Although it’s true that in this study mortality from heart disease was greater in the group with the highest LDL levels (over 180 mg/dL, which is, admittedly, pretty darn high), this was only true in men. In women the opposite was so—fewer women died of heart disease in the group with the highest LDL levels. In any case, this increase in heart disease in the high LDL group of men was apparently more than offset by the increase in deaths from other causes.

Okay, hopefully this information will get you, and your doctor, to at least question the notion that cholesterol is an important marker or predictor of heart disease. But let’s say for the sake of argument that you, or your doctor, is not quite willing to throw out the cholesterol theory. Fine, no problem. After all, you, like most of us, have been indoctrinated with the idea that anything that raises your cholesterol is bad news, and that’s a hard thing to let go of, especially when you’ve been hearing it for your entire adult life.

But before you go back to demonizing saturated fat, let’s examine the second belief that constitutes the bedrock of fat theology, the idea that saturated fat does really bad things to your cholesterol.

When cholesterol was assessed in the old-fashioned way—”total,” “good,” and “bad”—this idea might have made sense, because a number of studies show that saturated fat does raise total cholesterol and LDL cholesterol. And if you bought into the theory that cholesterol is a big cause of heart disease, this would be a good enough reason to give up the butter. But saturated fat actually raises HDL (“good”) cholesterol more than it does LDL cholesterol, leaving the ratio between total cholesterol and HDL cholesterol—a ratio that’s accepted as a measure of heart disease risk by just about everyone—unchanged or even improved.

If you eat less saturated fat and your cholesterol goes down as a result, your doc may think that’s a good thing and stop looking any further. But that’s the point: You can’t just look at your LDL number and stop there. The reduction in LDLs that you may get from cutting out saturated fat, and the reduction in LDLs that makes everyone jump for joy and celebrate your newfound “health,” comes with a hefty price: a big decrease in precisely the LDL molecules that you want more of—the “good citizen” LDLs, those big, fluffy LDL particles that, when they’re predominant, make up a pattern A cholesterol profile.
⁶
When the number of big, fluffy particles goes down, the proportion of your LDL population shifts in favor of the nasty, angry, atherogenic, BB gun pellet–type particles, giving them a kind of “majority rule.” Sure, your LDL number will go down and your doctor will be happy, but meanwhile, because of the shift in makeup of your LDL population, your risk for heart disease goes
up
.

Conversely, when saturated fat intake goes up—and carbohydrate intake goes down—the opposite happens. Now you’ll see a significant shift to more of those big, fluffy, harmless LDL particles and less of those small, dense, angry LDL particles. Your LDL population has just shifted, and the big, fluffy, harmless particles are now in the majority, leaving you in a significantly better place in terms of your heart disease risk. Sure, your overall LDL level may go up a bit, but what’s actually happened is that there are now many
more “good citizens” among your LDL population and far fewer “bad” ones. In other words, you’re much better off.

For decades, most health professionals have told us that we’d be doing ourselves a huge favor if we just cut out saturated fat and replaced it with carbohydrates. And that’s exactly what most people did. After all, this idea fit nicely with the prevailing ethos: Saturated fat is bad, and “complex” carbohydrates are good. If we just swap ‘em, everyone will go home happy, and all will be right with the world.

So, as our old friend Dr. Phil might say, “How’s that working for you?”

The answer is, “Not so well.”

One important study shed light on the whole “carbs for saturated fat” swap but raised a lot of eyebrows because of its unexpected results. The study, titled “Dietary Fats, Carbohydrate, and the Progression of Coronary Atherosclerosis in Post-menopausal Women,” was conducted by the distinguished researcher Dariush Mozaffarian and his associates from Harvard Medical School.
⁷

As the study title suggests, Mozaffarian set out to investigate how various fats—saturated, polyunsaturated, and monounsaturated—influenced the progression of heart disease in postmenopausal women who ate a relatively low-fat diet. Noting that standard dietary advice has always been to eat less saturated fat, the researchers wondered exactly what terrific things would happen if you replaced terrible saturated fat with other food substances. According to the standard advice, replacing saturated fat with good stuff (e.g., carbs or “good fats” such as vegetable oils) should substantially reduce your risk for heart disease.