Cholesterol Doesn't Mean What You Think It Means

Many new studies are complicating our understanding of the role cholesterol plays in heart disease. And last month, a group of researchers published the results of a study showing that what you thought you knew about "bad" cholesterol is probably wrong — or at least far too simplistic.

Over at KQED, Liza Gross has the story:

Most of us know that too much cholesterol promotes heart disease. And many know that cholesterol comes in good and bad forms. "Bad" (low-density lipoprotein, or LDL) cholesterol clogs the arteries that pump blood to the heart and feed the brain, raising the risk of heart attack and stroke. "Good" (high-density lipoprotein, or HDL) cholesterol removes excess cholesterol and fat from the bloodstream, keeping arteries healthy.

But a little knowledge can be a dangerous thing: this good versus bad scenario offers a simplistic view of cholesterol's role in heart disease.

Doctors assess cardiac health with routine blood tests that estimate LDL and HDL cholesterol levels along with total cholesterol and triglycerides. But cholesterol is just one component of the lipoprotein particles (spherical balls made of proteins and other lipids) that transport the water-phobic molecules through the blood. Most blood tests reflect how much cholesterol the particles carry but don't provide any information about the particles themselves.

"But it all starts with the particle," says Ronald Krauss, senior scientist and director of Atherosclerosis Research at Children's Hospital Oakland Research Institute. "The LDL particles go into the artery wall and carry the cholesterol with them. So we see the cholesterol in the plaque but it's the particle concentration and the number of particles that really determine the process."

Smaller LDL particles carry less cholesterol than larger LDL particles, yet it's the smaller particles that are most strongly associated with heart disease risk.

That's because smaller particles are more likely to glom on to artery walls and do so more often because they circulate in the blood longer. Once they get stuck, they undergo chemical changes that make them more toxic to arteries.

So if you have mostly small LDL particles, your cholesterol levels could be normal, but you may still be at risk for heart disease, Krauss says. "It turns the cholesterol story upside down."

Krauss and his colleagues point out that the connection between small LDL particles and heart disease is "rock solid." And avoiding saturated fat doesn't help. Instead, we need to think more about how to avoid sugars.

"Taking away eggs and milk has virtually no effect on the bad guys," Krass told KQED. "But you can make a really big improvement if you cut the sugar out."

Read the full article at KQED

Chocolate Fountain image by Moyan Brenn