Japanese experts question the evidence for the cholesterol hypothesis
Posted Aug 09 2012 1:24pm
Last year saw the Japan Society for Lipid Nutrition hold its 20th annual meeting. A panel discussion during the event was held entitled ‘Rethinking Cholesterol Issues’. Recently, the Journal of Lipid Nutrition published an account of that panel discussion , and it makes for interesting reading.
The panel was made up of six experts from both sides of the debate: some who believe in the supposed dangers of cholesterol and the need to lower ‘raised levels’, as well as those who doubt the wisdom of and evidence-base for these assertions.
Part of the conventional view came from an expert who quoted data from the so-called ‘Framingham Study’, which found links between higher cholesterol levels and increased risk of heart disease. However, this data revealed that beyond the age of 50, ‘raised’ cholesterol is not associated with an increase in the overall risk of death (the best overall marker of health). Plus, The Framingham data revealed that cholesterol levels falling over time was associated with an increased of dying from cardiovascular disease (such as heart attack and stroke).
The case for the hazardous nature of cholesterol was also supported with evidence in the form of statin trials (statins reduce cholesterol and reduce the risk of cardiovascular disease). However, this evidence is on shaky ground indeed, because statins don’t just reduce cholesterol, but have several mechanisms of action (including anti-inflammatory effects) that might reduce the risk of cardiovascular disease. This means that statins beneficial effects might have nothing to do with their impact on cholesterol.
In fact, there’s some evidence to support this idea in the form of studies which show, for instance, that statins can reduce risk of cardiovascular disease in individuals with normal or low levels of cholesterol, as well as the fact the statins significantly reduce stroke risk despite the fact that cholesterol is a weak risk factor for stroke, if a risk factor at all.
Against this, I think the case against the traditional cholesterol hypothesis was put much more robustly. Experts, for instance, cited evidence which shows that in most Japanese studies, lowest overall risk of death was seen in those with higher levels of total cholesterol or (supposedly unhealthy) LDL-cholesterol.
Those arguing against the cholesterol hypothesis also point out that the impact of statins on overall risk of death is small, if it exists at all. It should be noted, I think, that in individuals with no previous history of cardiovascular disease (a group that makes up the vast majority of people taking statins), statins do not reduce overall risk of death.
The dissenters also draw our attention to the fact that up to the mid-noughties, published literature on statins was overwhelmingly positive, with study after study lauding the ‘benefits’ of these drugs. Since then, the evidence has been overwhelming negative. It is perhaps not a coincidence that in 2005–2006 European legislation came into play which required clinical trial results to be published even if the data were ‘not favorable’. In other words, drug companies could not now so easily bury unfortunate data and selectively publish the stuff that supported their products. The authors of the summary of this paper state: “…the results published before the regulation were questionable and should not be used as the basis for recommendations for treatment with cholesterol-lowering medications.”
It is interesting to note that the Japan Atherosclerosis Society (an organization which takes a conventional view on cholesterol) was invited to send experts to participate in the panel, but declined to do so. I wonder if members of the Society know more that they’re letting on.
1. Rethinking Cholesterol Issues – Summary of the Cholesterol Panel Discussion at the 20th Annual Meeting of the Japan Society for Lipid Nutrition 2011. J Lipid Nutr 2012;21(1):67-75