Low cholesterol associated with higher mortality

Most readers here are aware that cholesterol is the substrate for all steroid hormones and a component of all cell membranes, so that when too low it is a contributing factor to a range of disorders. A study just published in the Journal of Epidemiology provides more evidence for the association between low cholesterol and death from all causes. The authors state:

"We investigated the relationship between low cholesterol and mortality and examined whether that relationship differs with respect to cause of death."

They conducted their study using 12,334 healthy adults from 12 rural areas in Japan. They correlated serum total cholesterol with total mortality, noting sex and cause of death. The average follow-up period was 11.9 years. What did their data show?

"As compared with a moderate cholesterol level (4.14-5.17 mmol/L)[161.5-201.5 mg/dL], the age-adjusted hazard ratio (HR) [risk] of low cholesterol (<4.14 mmol/L)[161.5 mg/dL] for mortality was 1.49 [50% increase in mortality]... High cholesterol (≥6.21 mmol/L)[≥242 mg/dL] was not a risk factor. This association was unchanged in analyses that excluded deaths due to liver disease... The multivariate-adjusted HRs [hazard ratios = risks]...of the lowest cholesterol group for hemorrhagic stroke, heart failure (excluding myocardial infarction), and cancer mortality [were] significantly higher than those of the moderate cholesterol group, for each cause of death."

Numerous lines of reasoning, documented in a broad accumulation of scientific evidence (of which a small 'taste' is reported in this venue) converge on the assertion that inflammation, rather than cholesterol per se, is the primary villain in cardiovascular disease. Clinicians and patients alike should bear in mind the authors' conclusion:

"Low cholesterol was related to high mortality even after excluding deaths due to liver disease from the analysis. High cholesterol was not a risk factor for mortality."