Feature Article
Cholesterol Does What?
Last time, we discussed saturated fat and the lack of evidence
that it leads to cardio-vascular disease (CVD). More than that, that it's really
poor evidence, especially considering how it's been
demonized so thoroughly that it's now "artery-clogging" saturated fat (even though it's not). As that post mentioned, the beef (get it?) against
saturated fat is largely predicated on its effect on cholesterol; specifically, that it raises cholesterol and that's a sure sign of impending CVD. But is it?
In the olden days--about 25 years ago--checking cholesterol was simple. There was one number, and if it was above 200, there was trouble afoot. But then it
was discovered that there's more than one kind of cholesterol. Instead, it was divided into HDL, or "good" cholesterol, and LDL, or "bad"
cholesterol. So tests started measuring both, but still considering the total as well.
And to anyone who knows anything about math, this should raise a question: why are we adding one number that we want to be high (HDL) and one that we want
to be low (LDL)? How can that possibly make sense?
Well anyway, math aside, further research discovered that there's more than one kind of LDL. Now they're differentiated by size, with the small, dense LDL
being nasty and the large, "fluffy" LDL being benign, at worst. But that's hard (read, "expensive") to test, so we're typically left
with total cholesterol and the ratio of HDL to LDL, regardless of the type of LDL. Progress!
Now back to saturated fat raising cholesterol. The part that gets conveniently left out is that while it raises LDL, much of that increase is the
benign "fluffy" LDL. And
saturated fat can raise HDL,
so much so that it can improve the HDL/LDL ratio, even while raising total cholesterol. Oh, how we long for the simplicity of the 80s!
Let's step back for a moment and take a look at cholesterol. What is it, anyway? It's
"a waxy steroid of fat. It is an essential structural component of mammalian cell membranes and is required to establish proper membrane permeability
and fluidity." It's also essential to the hormonal system, and other bodily functions. And in an interesting twist, HDL and LDL are not cholesterol;
they're proteins ("HDL" stands for "high-density lipoprotein") that carry cholesterol in the body.
So where does most of our cholesterol come from? If you said "eggs" that would be a good guess, since it's been demonized for being a
high-cholesterol food. But that's wrong. The correct answer is the liver. No, not liver we eat. Our own livers. So while we're being advised to
avoid eating foods with too much cholesterol, our own bodies are making up the difference by manufacturing it. Stupid livers!
OK, as I mentioned last time, I'm not a doctor nor do I play one on TV. But doctors aren't always a great source of information. For some reason, I
saw Dr. Sanjay Gupta, CNN's chief medical correspondent (he's not only a doctor, he
also plays one on TV!), on Anderson Cooper's
show (the only time I ever saw any of his show...coincidence?) talking about diet and dissing meat. To emphasize the benefits of vegetarianism, he
said that
broccoli has more protein per gram than chicken. It doesn't. Not even
close. But now there's an "expert" saying it so it must be true! <sigh> Nonetheless, this is my understanding of the way cholesterol
relates to CVD.
Arteries can become damaged or inflamed. Causes for this are uncertain, but stress is one likely culprit. In any case, when this happens, the body sends
cholesterol, via LDL, to make repairs. As the cholesterol does its work, HDL carries it away for excretion. (This is, of course, a simplified explanation.)
So while high cholesterol is often blamed for causing trouble, it can actually be just a symptom of underlying inflammation. In any case, everything's
still fine until something bad happens to the small LDL and they become oxidized and penetrate the wall of the blood vessel. Then it can no longer be
carried away by HDL, so it accumulates, forming arterial plaque and voila! CVD. So unlike the old concept of saturated fat clogging up blood vessels,
the buildup is actually within the blood vessel wall and happens when something goes wrong with the natural response to inflammation. (For more information,
you can check out
this post
at Mark's Daily Apple, although he's not a doctor either.)
Research continues, of course, and our understanding of what's really happening and why will certainly improve. But the point is that the cholesterol
story that most people know--eating cholesterol (and fat) gives you high cholesterol which leads to heart disease--is, at best, not quite right and at
worst is totally wrong. You can find all kinds of studies online challenging the story
(like
this) as well as studies challenging
the idea that
HDL
lowers your risk of CVD. There's clearly still a lot we don't know.
The fat/cholesterol link to CVD won't go away any time soon, no matter what research shows. There's too much money to be made treating symptoms and
selling
heart-healthy logos to "foods" like Cocoa Puffs. Oh well. And the media will of course continue their fear-mongering
("
Fear Me!") because that sells, too. What are
you buying?
Be seeing you.
-gary
Tonight is our second Kickboxing Class, for guys only, at 7:30. You can sign up online in 
