It's All About the Carbohydrates

by William Davis, M.D. Health Professional

Here's a common cholesterol scenario:

Total cholesterol 221 mg/dl

LDL cholesterol 150 mg/dl

HDL cholesterol 45 mg/dl

Triglycerides 130 mg/dl

Millions of Americans have cholesterol values in this range.

Next step: Reduce fat, increase grains like whole wheat bread. A few months later a typical response would be:

Total cholesterol 213 mg/dl-down by 3.6%

LDL cholesterol 138 mg/dl-down by 8%

HDL cholesterol 41 mg/dl-down by 8.9%

Triglycerides 172 mg/dl-up by 32%

In other words, reducing fat and increasing grains decreases HDL, increases triglycerides and reduces LDL. Most people would be satisfied with this result. Most physicians would declare this a successful result for diet.

I disagree. I would call it a failure, one that did not decrease risk, but increased risk. The decrease in fat and increase in the dietary carbohydrate load from grains triggered a reduction in protective HDL sufficient to increase risk for heart attack by 8-12%. The increase in triglycerides escalates heart disease risk by 15% in men, 30% in women.

But wait a minute: Isn't LDL cholesterol lower? Shouldn't a reduction in LDL reduce risk?

Yes-if it were true. Recall that LDL cholesterol is not measured, but calculated. The calculation employs a 50-year old equation (the Friedewald calculation) that uses total cholesterol, HDL, and triglycerides to derive LDL cholesterol.

Here's the problem: When you decrease fat in the diet and increase carbohydrates (like grains), the small type of LDL particles-the worst of all-will increase dramatically. If we didn't rely on calculated LDL cholesterol, but used a superior measure, then we would see the number increase, not decrease. Better ways to assess "real" LDL include a measure called apoprotein B (because there is one apoprotein B per LDL cholesterol particle) and LDL particle number (a test provided by the Liposcience laboratory).

But even if you don't have access to one of the superior measured methods of assessing true LDL, don't be fooled by the misleading response of calculated LDL to diets that decrease HDL and decrease triglycerides. While they provide the appearance of reducing LDL cholesterol, they do not if measured. Add to that the HDL-reducing, triglyceride-increasing effect and a low-fat, high-grain diet increases risk for heart disease.

William Davis, M.D.
Meet Our Writer
William Davis, M.D.

William R. Davis is a Milwaukee-based American cardiologist and author. He wrote for HealthCentral as a health professional for Heart Health and High Cholesterol.