Low cholesterol increases stroke risk
Part 3: Low cholesterol also increases ischemic stroke risk
There is no doubt the risk of hemorrhagic stroke is increased by low cholesterol levels, but that still leaves ischemic strokes. Although the effect is similar to a hemorrhagic stroke, the cause is different. Instead of a blood vessel leaking in the skull, in this case, an artery is blocked by a clot.
For the same reason that heart attacks are blamed on cholesterol blocking coronary arteries, so are ischemic strokes blamed on a fatty diet. But the theory that eating too much saturated fat increases the risk of a stroke, also seems to have no foundation. In 1997, we got a Christmas present from the long-running Framingham study when it published findings that for every 3% more calories from fat, ischemic stroke risk went down by 15%.[1]
Confirmation came 6 years later in yet another study. This time, scientists at the Department of Nutrition, Harvard School of Public Health, studied 43,732 men aged 40-75 years who were free from cardiovascular diseases and diabetes in 1986 and followed them for 14 years.[2]
During that period they studied intakes of every conceivable type of fat: animal fat, fish oil, vegetable oil, saturated, mono-unsaturated, polyunsaturated, trans fat, as well as the amounts of each that were consumed. They found that none of them made any difference whatever and conclude:
'These findings do not support associations between intake of total fat, cholesterol, or specific types of fat and risk of stroke in men.'
To sum up, the published evidence refutes the accepted wisdom that high levels of cholesterol and a fatty diet lie at the root of strokes. It turns out that the opposite is true. Low cholesterol increases the risk of both types of stroke. Which is probably why the number of cases has been increasing — and being seen in ever younger people — since we were introduced to 'healthy eating'.
References
1. Gillman MW, et al. Inverse association of dietary fat with development of ischemic stroke in men. JAMA 1997; 278: 2145-50.2. He K, et al. Dietary fat intake and risk of stroke in male US healthcare professionals: 14 year prospective cohort study. BMJ 2003; 327: 777-782
