The Cholesterol Myth - It Doesn’t Cause Heart Disease
Some time during the 20th century cholesterol become the scape goat for the rapidly escalating heart disease rates that the western world was experiencing at the time. Despite what may be reported in the mainstream media about the importance of lowering cholesterol levels by limiting consumption of dietary cholesterol and saturated fat, the evidence from actual clinical trials and studies paints a different picture.
While it is true that high blood cholesterol (known as serum cholesterol) levels and a lower ratio of high density lipoprotein (HDL) to low density lipoprotein (LDL) are associated with a higher incidence of heart disease, many myths exist as to what actually increases cholesterol in the blood.
Myth 1: Eating high cholesterol foods increases blood cholesterol, therefore high cholesterol foods increase coronary heart disease risk.
There is actually little correlation between dietary cholesterol consumption and cholesterol levels in the blood.
One of the biggest studies into the effects of cholesterol intake on blood cholesterol levels was the Framingham heart study which began in 1948 and followed over 5,000 adults aged 30 to 62. The study found that dietary cholesterol had no correlation at all with blood cholesterol. Men both above and below the median cholesterol intake had the same average blood cholesterol level of 6.16 mmol/L. Women consuming below the median cholesterol amount had a blood cholesterol level of 6.37 which interestingly was higher than that for the group that consumed more than the median amount of cholesterol who had an average level of 6.26 mmol/L.
The researchers concluded that there was no evidence of a relationship between dietary cholesterol and the development of coronary heart disease.
These findings are backed up by other studies that suggest healthy individuals blood cholesterol levels are unlikely to be significantly effected by dietary cholesterol consumption. In a 2005 study, Yale researchers fed 49 adult participants two eggs a day for six weeks. Despite eggs being very high in cholesterol, neither “bad” LDL cholesterol, nor total cholesterol increased amongst the participants.
Myth 2: Eating food high in saturated fat increases both blood cholesterol levels and heart disease risk.
Again there is little evidence pointing to a direct link between high saturated fat intake and either heart disease or high blood cholesterol levels.
The Tecumseh study was a research study that attempted to find a correlation between fat and/or cholesterol consumption and the amount of cholesterol in the blood. The study involved over 2,000 adults in Tecumseh, Michigan - participants recorded all food consumed in the 24 hour period prior to a blood cholesterol test. The study found no correlation between total fat intake or saturated fat intake and blood cholesterol. Furthermore no correlation was found between dietary cholesterol intake and blood cholesterol.
In the last 100 years, despite a significant rise in coronary heart disease rates, there has been little change in total fat consumption and there has actually been a significant decrease in saturated fat consumption (which are generally animal fats) and an increase in polyunsaturated fat consumption (plant based fats in general).
So if dietary cholesterol and saturated fat intake don’t increase cholesterol what does? Exercise, weight loss, and not smoking are all associated with decreases in both blood cholesterol and increases in the ratio of “good” to “bad” cholesterol. It is interesting to note that over the last 100 years, obesity rates have increased dramatically and sedentary lifestyles have become much more common suggesting these are more likely to blame for increased coronary heart disease rates.
