Let’s look at cholesterol, which has enjoyed the status of being the number-one dietary supervillain for at least the past 50 years. Our interpretation of its role has gone through a dramatic change over the last several decades. The fact that we’re still unsure what cholesterol’s functions are and what significance low and high levels may mean should indicate that we still have a very long way to go to full understanding.
Common wisdom regarding cholesterol, whether total or LDL cholesterol, has been that if it’s high, you’re at increased risk for cardiovascular disease. Certainly, there is a great deal of scientific theory to back that up. Much of the research comes from associational studies that look at populations and compare rates of heart disease with corresponding cholesterol levels. The evidence includes a number of animal studies, and drug trials have demonstrated that lowering cholesterol can decrease the incidence of disease.
Many of these studies have been repeated multiple times with similar results; therefore, perhaps the theory should stand. Indeed, often when someone’s blood test comes back with an elevated cholesterol level, the doctor almost automatically offers a drug to lower cholesterol. Heck, I remember when I was a medical student many years ago, I often overheard the attending physicians joking about how popular cholesterol-lowering statin drug Lipitor should be placed in the water supply because all the lazy, fat patients needed to be on it. That’s how commonplace treating high cholesterol with drugs had become.
So, let me make a simple observation about conclusions that come from an associational study. Let’s assume you have a study that says people with elevated levels of cholesterol have a higher risk of heart disease. Fair enough—certainly there’s data to support that. But what if you ask, “Does that association hold up in all people in all situations?” That’s a simple question, but it drives a lot of thought and gets at the heart of some of the problems with this type of science. Suppose I could gather a subset of people who have elevated cholesterol but who also are profoundly insulin sensitive; they’re also very lean and have low levels of systemic and vascular inflammation. Does the association still hold? Or if it does, is it so small, in light of those other factors, that it’s rendered insignificant?
Let’s use some arbitrary numbers and say that risk of heart disease goes up 20 percent if you have an LDL higher than 130, but it goes down 150 percent if your insulin is lower than 3. Heart disease goes down another 85 percent if your waist is smaller than your height, and it goes down a further 120 percent if you have a C-reactive protein (a marker of inflammation) level lower than 1.0. In this theoretical situation, your risk for heart disease would be very favorable in the big picture. Now, many would be tempted to suggest that we should lower the risk even more by getting the cholesterol down by using drugs or perhaps a low-fat diet. Certainly, that strategy might be beneficial if all the other factors also remain favorable. But what happens if they don’t? What happens if going on the low-fat diet causes your insulin to rise or your C-reactive protein to go up? What happens if you take a drug and the side effects cause you to gain weight, and your waist expands? Those are questions we need to ask.
Also, we have a mounting pile of evidence that shows that heart disease risk is more influenced by other factors, including things like hyperinsulinemia, inflammatory status, and triglyceride levels, than it is by cholesterol levels. One interesting group of people that have been studied are those who have a genetic variant that leads to something called familial hypercholesterolemia. Basically, many of these people walk around with sky-high cholesterol levels, but they don’t die of heart disease any more frequently than anyone else; people with this condition have normal life expectancies. If they have unfavorable insulin levels, the story is different: heart attack city. This implies that high cholesterol by itself is insufficient to cause cardiovascular disease, which should be no surprise because we are complex systems that are affected by myriad interrelated variables.
Dave Feldman, a wonderful citizen scientist, has been demonstrating that our cholesterol levels can change by up to 100 points in a matter of a few days based on nothing more than what that person has eaten in the preceding few days. An interesting study shows that cholesterol rises by about 36 percent when a person fasts for one week. Now, under the assumption that meat is bad for us because it can cause cholesterol to rise (which it can) then does that also mean that eating nothing is equally bad for us?
The assumption is that low cholesterol is always a good thing when it comes to preventing heart disease; because heart disease is our number-one killer, that’s where our focus should be. Plus, we have some pretty cool drugs that lower cholesterol and are worth billions of dollars. (But I’m sure no one was concerned about the money to be made from those drugs, right?) However, what about the role of cholesterol outside the discussion of heart disease? What part does it play in our bodies? What effect does it have on things like all-cause mortality? What about diseases like cancer and certain neurodegenerative diseases? Entire books are dedicated to this stuff, but I’ll touch on it briefly here. (Believe me, I really want to get back to talking about steaks, but I need to at least mention this stuff.)
Your entire body—every single cell you have—contains cholesterol. That’s the major difference between defining a plant cell and an animal cell. (I used to laugh when I’d see advertisements on plant products pointing out the fact that they were “cholesterol free.” Well, duh; of course—because they’re plants.) Your brain uses something like 25 percent of your body’s cholesterol, and many of your hormones are made from it. Cholesterol is integral to the structure of every cell in your body. You can easily find studies that link low cholesterol to depression, violence, suicide, and neurodegenerative diseases. Some studies report that people tend to die younger if they have low cholesterol. Some cancers have been linked to low cholesterol. Infectious disease can be more difficult to fight when cholesterol levels are low.
If you list some of the major associative factors that are believed to be a contributor to heart disease, you will find the relative effect of cholesterol level to be relatively lower on that list. If you then stratified those factors by things that can be most efficiently adjusted with drugs rather than through lifestyle changes, you would see cholesterol at the top of that list. Not surprisingly, billions of dollars have been focused on the factor that’s drug-modifiable, whereas the lifestyle factors largely receive lip service.
Suffice it to say that I don’t think that low cholesterol is necessarily a good thing. High cholesterol may be problematic in certain cases, but that doesn’t necessarily mean it always is. Some people will continue to be concerned about this particular particle or that particular subfraction of this or that lipid, and perhaps that concern and the knowledge it spawns will lead to the answer to immortality. Or perhaps we’ll just replace heart disease with cancer, dementia, or some other equally awful way to die.
The bottom line is this: You and I will likely die of heart disease or cancer regardless of the diet we choose. For example, data on vegan and vegetarian mortality indicates the number-one and number-two killers for that group are cancer and heart disease. Heart disease kills a lot of people, and most people die with so-called normal cholesterol.
It saddens me to see almost daily that so many people are examined with a simple annual blood lipid test and then offered a drug to lower their cholesterol based only on that test and no further investigation. The overprescribing of cholesterol medications largely comes down to a lack of time and education on the part of physicians. You can literally walk into your doctor’s office after having lost every ounce of fat on your body, feeling the best you have in decades, sporting excellent blood pressure and otherwise perfect metabolic markers, but if your annual blood test reveals high cholesterol, you’ll still leave the office with a prescription for some medication without any further discussion. In my view, that’s unacceptable, and it’s a sign of systemic laziness. We have to remember that our physiology is an incredibly complex system with far more going on than we can hope to find out with a snapshot of what’s traveling in our blood at one particular instant.
Today, it’s encouraging to see more and more patients challenging some of the knee-jerk reaction of their doctors, and the patients are asking for more information. Remember that no one has more at stake regarding your health than you do. Be a pain in the ass; ask for more details and more testing. Challenge your physician to up his game. I’ve learned more from patients than I ever learned from any textbook.
Excerpted from The Carnivore Diet, By Dr. Shawn Baker.
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