Researchers in the Clinical Trial Service Unit found that lowering cholesterol by 1 millimole per litre (mmol/L) – an easily achievable difference – led to a 56 per cent drop in deaths from ischaemic heart disease (the type of heart disease that usually causes attacks) in the 40–49 age group. This mortality drop was 34 per cent in the 50–69 age group and 17 per cent in the 70–89 age group.

The drops in risk were seen throughout the main range of cholesterol in most developed countries – in other words, whatever your level of blood cholesterol, even normal or low, reducing it still reduces the risk of heart attack.

The Prospective Studies Collaboration reanalysed information from 61 existing prospective observational studies, mostly in Western Europe and America, involving almost 900,000 adults without previous ischaemic heart disease. The findings are published in The Lancet.

The researchers were puzzled, however, by their findings on the relation between stroke and cholesterol. Both stroke and ischaemic heart disease are vascular events, in other words, related to blood vessels, so both would be expected to occur less with lower cholesterol.

Indeed, there is extremely good evidence, much of it from Oxford studies, that statins – which lower cholesterol – lower the risk of both heart attack and stroke. However, this study did not find a clear association with stroke – in fact, at older ages (ie 70–89 years), particularly for those with high blood pressure, higher cholesterol was associated with somewhat lower stroke mortality.

‘We cannot explain this surprising finding’, says Dr Lewington, ‘but irrespective of the explanation, treatment should be guided principally by the definitive evidence from trials that statins substantially reduce strokes and heart attacks, in patients with a wide range of ages and blood pressures. In other words, don’t stop taking the statins.’

Source: Oxford University