Tuesday, November 30, 2010

LDL: It Ain't All Bad

When considering cholesterol numbers, most people -- doctors included -- use a simple but flawed shorthand:
  • High HDL: Good!
  • High LDL: Bad!
  • High total cholesterol: Bad!
When you get your blood cholesterol analyzed, these numbers are often all that come back from the lab. But we know that the reality’s not quite that simple. After all:
LDL cholesterol can no longer be identified as the single source of all heart trouble. Those pamphlets adorning your doctor's waiting room may portray LDL as a kind of lone gunman taking a bead on your heart, but they hide a basic fact of science: "Bad cholesterol" is at best a poor shorthand for four major types of independently behaving LDL, each with its own implications for heart disease. We ignore the distinctions at our peril.
In fact, some types of LDL are pretty innocuous, while other forms are dangerous. The big, fluffy LDL particles are generally benign -- they don’t affect heart health. But small, dense LDL particles are bad news, triggering the inflammation that causes cardiovascular disease. People typically have a mix of large, small, and medium-sized LDL particles, but you’re obviously better off if the bigger, fluffy stuff predominates.

And here’s the thing:
A diet high in saturated fat mainly boosts the numbers of large-LDL particles, while a low-fat diet high in carbohydrates propagates the smaller forms.
Sadly, “[t]he typical LDL test doesn't distinguish between large and small LDL particles -- it can't even spot the difference.” And as a result, even today, most doctors don’t concern themselves with this critical distinction, relying instead on total LDL numbers or total cholesterol numbers to indicate what course of medical action to take. But by lumping all the forms of LDL together, “[w]e may be medicating many people who have no clear need for medication, using drugs that don't target the right particles, and replacing foods that are benign with foods that are anything but.”

Thankfully, not too long ago, Ronald Krauss of Children’s Hospital of Oakland and his colleagues developed a device capable of distinguishing between and precisely measuring LDL and other lipoproteins to provide a much more accurate picture of cardiovascular health. Krauss and his partners have also identified the best predictors of cardiovascular disease. In order of most predictive to least, they are:
  • High levels of small and medium-sized LDL particles combined with low HDL (pretty darn predictive of heart disease!)
  • Low HDL levels (kinda/sorta predictive!)
  • High total LDL levels (not very predictive!)
And utterly not predictive at all? Total cholesterol.

BUT: The test that Krauss developed isn't widely available. Most doctors are still going by the old standby measurements, and looking solely at total cholesterol, HDL, and LDL numbers. Ugh.
The upshot: If you’re like me -- a Paleo convert whose diet contains relatively large quantities of saturated fat and cholesterol -- you might get lab results that, on their face, look a little baffling:
  • Total cholesterol: 261 mg/dL (Yikes -- that's super-high!)
  • HDL: 100 mg/dL (But wait -- HDL is fantastic!)
  • LDL: 97 mg/dL (Just barely within the range of “optimal,” right?)
I have no idea whether my LDL particles are large or small, but given my diet, I’m assuming the former. (Probably not a bad assumption, given that M and I eat almost exactly the same diet, and her LDL particle size was recently tested and confirmed as predominantly Type “A”: big and fluffy.) And my HDL is through the roof. I'm not at risk for cardiovascular disease.

But if you were to ask my doctor, he'd probably tell you another story based on my total cholesterol.

Science can sometimes be slow to progress, but we've got to get more sophisticated testing out there. Otherwise, the problem is that lowering your total cholesterol or LDL -- without knowing the type of LDL particles you have -- can cut both ways:
Just because you have less of the symptom (statin users take note) doesn't mean you'll have less of the disease. A drop in your total LDL cholesterol might mean nothing at all. A higher LDL cholesterol reading, for that matter, could simply mean you are a healthy person who has learned how to build an amazing sauce out of wine, garlic, shallots, butter, and heavy cream.
Or, if you’re M, a fantastic dish of sous vide pork chops seared in melted lard.