Lewis Jones’ article “Cholesterol-shmesterol” is so full of distortions I hardly know where to start. He confuses the dietary cholesterol-heart connection with the blood cholesterol-heart connection, fails to differentiate between primary prevention (in healthy people) and secondary prevention (in those who already have heart disease), and he refers to “good” and “bad” cholesterol as dodgy data mining, a characterization that is laughable to anyone familiar with the extensive research on HDL and LDL cholesterol.
He quotes Richard Peto. He might be surprised to find Peto’s name on the December 2007 Lancet study that concluded
Total cholesterol was positively associated with IHD [ischemic heart disease] mortality in both middle and old age and at all blood pressure levels. The absence of an independent positive association of cholesterol with stroke mortality, especially at older ages or higher blood pressures, is unexplained, and invites further research. Nevertheless, there is conclusive evidence from randomised trials that statins substantially reduce not only coronary event rates but also total stroke rates in patients with a wide range of ages and blood pressures.
Peto’s name is also on a 2005 Lancet studythat concluded
Statin therapy can safely reduce the 5-year incidence of major coronary events, coronary revascularisation, and stroke by about one fifth per mmol/L reduction in LDL cholesterol, largely irrespective of the initial lipid profile or other presenting characteristics. The absolute benefit relates chiefly to an individual’s absolute risk of such events and to the absolute reduction in LDL cholesterol achieved. These findings reinforce the need to consider prolonged statin treatment with substantial LDL cholesterol reductions in all patients at high risk of any type of major vascular event.
He cites a quotation by Petr Skrabanek about blood cholesterol having “no predictive value for the risk of future heart attack” and that lowering blood cholesterol “has no effect on overall mortality.” To anyone keeping up with current medical literature, it’s hard to imagine how anyone could still believe either of those assertions. Study after study has shown that lipids are a significant risk factor, that lowering blood levels reduces the incidence of cardiovascular events and reduces total mortality at least in some high-risk groups, and that lipid-lowering statin drugs are even safer than we once thought. The degree of lipid lowering correlates with the degree of reduced risk.
It is true that reducing cholesterol in the diet has very little effect on blood cholesterol levels. We used to recommend a low cholesterol diet, then a low fat diet, then a low saturated fat diet, and now we are more concerned about trans-fats. We are refining our knowledge, and recommendations are changing accordingly.
Some elderly people have artificially low cholesterol levels as a result of inadequate diet and chronic illness, which explains the higher death rate in this group in some studies. But it has been established that cholesterol levels are correlated with risk in every age group. Women are at less risk than men, but the higher their cholesterol, the greater their risk. It is simplistic to talk about total cholesterol alone, because an increased risk from high LDL (low density lipoprotein or bad cholesterol) can be offset by a decreased risk from a high HDL (high density lipoprotein or good cholesterol).
Good physicians don’t just have a knee-jerk reaction to lower everyone’s cholesterol. They are conscientiously trying to interpret the best evidence to choose the best treatment for their patients. A recent article in American Family Physician reviewed the evidence and made the following practice recommendations (the A and B ratings refer to high standards of evidence behind the recommendations):
|Primary prevention of cardiovascular disease|
|Patients with elevated cholesterol levels should reduce dietary fat consumption. However, this step may lead to only a small reduction in cardiovascular events.||A|
|Statin medications are indicated to decrease cardiovascular events in patients with elevated cholesterol levels, although a decrease in cardiovascular and
all-cause mortality has not been demonstrated.
|Following a Mediterranean diet may reduce all-cause mortality.||B|
|Secondary prevention of cardiovascular disease|
|Statin medications should be used for aggressive lipid control in patients with CHD to decrease cardiovascular events, cardiovascular mortality, and overall mortality.||A|
|Cholesterol-lowering medications prevent disease progression and improve symptoms in patients with lower limb atherosclerosis. Statins can decrease cardiovascular events and all-cause mortality in these patients.||A|
|Cholesterol-lowering medications should be used to reduce the risk of stroke
in patients with a history of CHD and average-to-high cholesterol levels.
Much of what Lewis Jones says echoes the distorted information being spread by a group called the International Cholesterol Skeptics. They cherry-pick the literature to find studies that seem to support their agenda. Good science is not furthered by activist groups of this sort. We didn’t need an International X-Ray Skeptics group to convince us to stop doing routine annual chest x-rays on healthy people. The evidence speaks for itself.
Reducing the risk of heart disease and stroke is a complex proposition. Cholesterol is only part of the equation. Good doctors consider the individual patient and all the other risk factors, such as family history, sex, age, weight, exercise, blood pressure, previous heart attacks, and smoking. If you are otherwise healthy and have few risk factors, you can indeed “keep doing what you’re doing.” But if you are at high risk, lowering your cholesterol might just save your life – or at least prevent a non-fatal heart attack or stroke.
Prospective Studies Collaboration, Lewington S, Whitlock G, Clarke R, Sherliker P, Emberson J, Halsey J, Qizilbash N, Peto R, Collins R. Blood cholesterol and vascular mortality by age, sec, and blood pressure: a meta-analysis of individual data from 61 prospective studies with 55,000 vascular deaths. Lancet. 2007 Dec 1; 370(9602):1829-39.
Baigent C, et al. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet.2005 Oct 8:366(9493):1267-78.
Lockman A, et al. Treatment of Cholesterol Abnormalities. American Family Physician, 2005, March 15, 71:6:1137-42.
This article was originally published in Skeptical Briefs, a publication of the Committee for Skeptical Inquiry.