From Ronald Hoffman, MD
HDL is the “good cholesterol”, in contrast to LDL, the “bad cholesterol”. Generally, healthy lifestyle measures like exercise and maintenance of healthy weight via a low-refined carb diet are associated with better HDL numbers.
By now I’m familiar with the refrain: “Doc, I know my cholesterol’s high, but so’s my HDL. So I get a free pass from heart disease, right?”
Thus went the conventional wisdom for a long time. It wasn’t so much your total cholesterol, but the ratio between your cholesterol and your HDL cholesterol that determined risk.
In fact, data from the landmark Framingham Heart Study in the 1970s showed that, for a given level of LDL, the risk of heart disease increases 10-fold as the HDL varies from high to low.
For example, a person with a cholesterol of 240 mg/dL—which is considered high—but with an HDL of 80 mg/dL, constituting a total cholesterol to HDL ratio of 3:1, might be considered to be at lower risk of heart disease than someone with a much lower “satisfactory” cholesterol of 180 mg/dL, but with an HDL of 30 mg/dL, yielding a 6:1 ratio (a ratio of 4:1 or lower has been considered favorable).
This is a dogma that I uncritically accepted until some new research findings forced me to adopt a more nuanced approach.
First, I had to acknowledge that there were some outliers. When I started to routinely order coronary calcium scans on my patients, that actually revealed the presence or absence of calcium in their coronary arteries—highly predictive of the eventual risk of heart attacks or need for stents or bypass—I noticed that, while most with high HDLs were indeed free of plaque, some had considerable evidence of incipient atherosclerosis.