by Stephen Janowsky

Created on: March 23, 2008

"The Cholesterol Paradox"

Is it good to have low cholesterol levels? Surprising as it may seem, the answer is: yes, but not for everybody!

Whereas in the general population high blood cholesterol (a.k.a. "hypercholesterolemia") is universally recognized as a risk factor for cardiovascular disease and mortality, there is clear evidence that low cholesterol levels are also associated with a decreased survival in some people, such as the elderly and those with certain diseases.

Scientific research in older persons from various countries (Reuben, 1999; Shibata, 2001; Casiglia, 2003; Schalk, 2004) found that low cholesterol blood levels predict functional status worsening (defined as an impairment of the ability to perform self-care, self-maintenance and physical activities) and death.

A very recent meta-analysis (i.e. a statistical analysis of combined results of several studies addressing the same issue), published in "The Lancet" in December 2007 by Lewington and co-workers from the University of Oxford, UK, aimed to determine the relevance of cholesterol and blood pressure as risk factors for cardiovascular mortality. This analysis included data from 61 studies (most of these performed in Western Europe and North America), consisting of almost 900,000 adults, aged between 40 and 89 years old. The results showed that lower cholesterol levels diminish the risk of death from coronary heart disease in all people, but, on the other hand, in persons above 70 y.o. (particularly in those with high blood pressure), the risk of death from stroke increases as cholesterol levels decrease. An unexplained apparent paradox!

In 417 patients with chronic heart failure, researchers from London and Berlin (Rauchhaus, 2003) found that the chance of survival increases by 25% for each mmol/l (i.e. 39 mg/dl) increment in total cholesterol serum concentration. In patients with coronary heart disease, cholesterol levels above 5.2 mmol/l (200 mg/dl) are associated with a 92% one-year survival rate and a 72% three-years survival rate, whereas cholesterol levels below that limit are accompanied by only 75% and 50% survival rates, respectively.

The "Euro Heart Failure" survey (Velavan, 2006), conducted on more than 10,000 patients with heart failure, from 115 hospitals in 24 European countries, showed that those with low cholesterol were 1.7 times more likely to die within three months of being hospitalized than people with normal cholesterol. The highest number of deaths was in people with cholesterol

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