For something that hardly anyone had heard of 20 years ago, cholesterol has become something of a phenomenon. We are encouraged to keep a lid on our cholesterol levels the recommended amount of which in the blood seems to be in perpetual decline. And this is there is quite a lot of political pressure put on individuals to bring their cholesterol levels into line. This week, for instance, saw the publication of a report which highlighted the fact that only 47 percent of women with a history of heart problems had their cholesterol ‘under control’, compared to 56 percent of men. Tut tut.
Despite our collective neurosis about cholesterol, there is a considerable body of evidence to suggest that this fat is not the killer it is so often made out to be. While there is indeed some evidence that high cholesterol levels are associated with an increased risk of heart disease and death, a close look at the available evidence shows that this association only seems to be true for individuals up to the age of about 50 or so. After that time, plenty of evidence shows ‘raised’ cholesterol levels in later life are not associated with adverse effects on health [1-15]. Indeed, there is even some evidence that higher cholesterol is actually associated with enhanced longevity and survival [16-19].
Now it’s worth bearing in mind that the vast majority of cases of conditions said to be related to raised cholesterol levels (namely heart attacks and strokes) occur in middle age and beyond. As the science shows that cholesterol is not a risk factor, and indeed may even be beneficial, in people of this age, then this should perhaps cause us to question the current appetite to paint cholesterol as the culprit.
As with saturated fat, if we really want to make a judgment of the true impact cholesterol has on health, we need intervention studies ” studies in which cholesterol levels are lowered and the effect of this assessed. In 2005 a meta-analysis which combined the results of 17 similar studies in which subjects made dietary changes explicitly to reduce blood cholesterol levels was published in the Archives of Internal Medicine [20]. Overall, these studies brought about a 10 per cent lowering of cholesterol levels. Despite this, the amassed results showed no reduced risk of death, neither in healthy individuals, nor even in high-risk individuals who had a history of heart attack or stroke. Basically, taking dietary steps to reduce cholesterol levels simply does not seem to save lives yet more evidence that cholesterol is not as important a factor in health as it is so often said to be.
Apart from diet, the other major way to quell cholesterol levels is through drug therapy. Currently, the most popular type of medication used for this purpose are known as the ‘statins’ which include atorvastatin (Lipitor), rosuvastatin (Crestor) and simvastatin (Zocor). A huge stash of cash has been made out of these drugs, but is their life-saving reputation deserved?
Statins do seem to have the capacity to save lives, though the benefits of them seem to be largely confined to individuals who already have diagnosed cardiovascular disease (e.g. heart disease or previous stroke). This evidence is often used to support the notion that cholesterol causes heart disease. However, in additional to reducing cholesterol, statin drugs also have other effects in the body that would be expected to reduce the risk of cardiovascular disease. For instance, it is well recognised that statins have anti-inflammatory effects, and current evidence suggests that inflammation is an important underlying process in the development of cardiovascular disease. This has raised the question that statins’ apparent ability to reduce the risk of cardiovascular disease may have nothing at all to do with cholesterol.
I suppose this wouldn’t matter too much if the recommendations to lower cholesterol upper limits were based on good science. However, a review in the Annals of Internal Medicine published in 2006 concluded that there was no high-quality clinical evidence to support current treatment goals for cholesterol. The authors of this review went on to say that the recommended practice of adjusting statin dose to achieve recommended cholesterol levels was not scientifically proven to be beneficial or safe [21].
It is perhaps interesting to note that the most recent recommendations regarding cholesterol levels in the USA came from a panel of nine scientists, eight of whom had financial links with drugs companies making statin drugs. And this clear conflict of interest only emerged after their report had been published.
It seems that the impact of cholesterol on health might have been seriously overstated. For those of you keen to learn more, I heartily recommend to you a The Great Cholesterol Con by British medic Malcolm Kendrick. Read it, and I reckon it’s unlikely that you may find the interest in your cholesterol and any fear you have about this wanes somewhat.
References:
1. Scientific steering committee on behalf of the Simon Broome Register group. Risk of fatal coronary heart disease in familial hypercholesterolaemia. British Medical Journal,1991; 303: 893-896
2. Forette F, et al. The prognostic significance of isolated systolic hypertension in the elderly. Results of a ten year longitudinal survey. Clinical and Experimental Hypertension. Part A, Theory and Practice, 1982; 4: 1177-1191
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17. Forette B, et al. Cholesterol as risk factor for mortality in elderly women. Lancet, 1989; 1:868-870
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20. Studer M, et al. Effect of different antilipidemic agents and diets on mortality. Archives of Internal Medicine. 2005;165:725-730
21. Hayward RA, et al. Narrative review: lack of evidence for recommended low-density lipoprotein treatment targets: a solvable problem. Ann Int Med 2006;145:520-530
