Low Total Cholesterol and Mortality Rates

This is an exploration of mortality rates associated with low cholesterol. The review was published in Circulation: Journal of the American Heart Association. In this review, the National Heart, Lung, and Blood Institute held a conference seeking to understand why lower total cholesterol (TC) levels are associated with some cancers, respiratory and digestive diseases, trauma, and residual deaths.

Apparently, men are more susceptible to this correlation than women. They examined 19 cohort studies from the U.S., Europe, Israel, and Japan. TC is a calculation of cholesterol measurements of LDL, HDL, and triglycerides.  The review noted high rates of cerebral hemorrhage with lower average TC. The rate of cerebral hemorrhage decreased as average TC went up in prospective populations. This was true in the Multiple Risk Factor Intervention Trial (MRFIT) in addition to increased incidence of colon cancer with lower TC. This may be related to what I wrote in an earlier post.

For women, 6 of the 11 studies showed no variation in cancer death rates across all spectrum of TC levels. There was an increased cancer risk in men when their TC levels fell below 180 mg/dL. In non-cancer and non-cardiovascular death rates, both men and women had similar risk findings. When TC was below 160 mg/dL there was a 40% increase of mortality compared to 160-199 mg/dL levels. Risk was also reduced by 10% when TC levels were between 200-240 mg/dL compared to the reference class (TC between 160-199 mg/dL levels).

This increase in non-cardiovascular deaths raises the issue of the dangers associated with taking cholesterol lowering drugs. These dangers are real and should not be taken likely (as mentioned in the study). Once again, when the data was pooled together, TC below 160 mg/dL was associated with highest risk of mortality.

Unfortunately, some of the data did not differentiate between age or sex but we can assume that having TC this low for anyone is quite risky. The review did take into account people with diabetes, smokers, CVD, alcohol intake, and other possible factors that might skew the data. Some of the research also separated participants further by age and gender.

Findings for all-cause mortality (ACM [death from any cause]) for those with TC between 200-240 mg/dL had the lowest incidence. The rate of death increased the TC went down below 199 mg/dL (are you seeing a trend yet?). Interestingly enough, the American Heart Association, the journal's parent organization, say that total cholesterol should be below 200 mg/dL. This is the range that has been demonstrated by the AHA to increase risk death from all causes. The standard protocol for primary care providers is to prescribe statin medication when TC is above 200 mg/dL which will place patients well within the range of increased risk of death. 

There are also other health risks associated with direct effect of statin use in addition to health benefits not associated with TC lowering mechanisms. Statins act on many mechanisms in addition to reducing cholesterol synthesis in the liver. A benefit-risk analysis of statin use will be explored in a future post.

It is safe to say that total cholesterol levels appear safest when they remain in the range between 200-240 mg/dL. This is my target. Unless you have a very rare disease, it is completely controllable through diet which will be discussed later. Don't forget exercise will increase your total cholesterol level (by increasing HDL) as it improves your health.