What is the relationship between fat and the risk of mortality? Recently, a study was published questioning the beneficial effects of unsaturated fat. However, this study has some limitations, so there is no reason to avoid unsaturated fats.
The researchers re-analyzed data from a study conducted in the 1960s and 70s. This study involved more than 2,000 people in psychiatric hospitals or care homes. Over the course of a year, they were given diets rich in either unsaturated fat or saturated fat.
During this study, it was observed that blood cholesterol levels decreased in the group that consumed a diet high in unsaturated fats (such as linoleic acid).
In the new analyses of this study, the researchers not only looked at cholesterol levels but also at cardiovascular effects. They found no evidence that the group consuming unsaturated fats experienced fewer cases of atherosclerosis or heart attacks. In fact, mortality was higher among those whose cholesterol levels dropped the most. This result was unexpected.
So what are the limitations of this study?
Although it was a large study, a period of one year is not representative enough to properly assess mortality due to cardiovascular disease. In addition, it is unclear whether other factors — such as medical history, medication use, or smoking — may have influenced the results.
Advice from the Health Council
Recently, the Dutch Health Council evaluated all studies on fats in relation to LDL cholesterol and cardiovascular disease. The conclusion: it has been convincingly demonstrated that diets rich in unsaturated fats reduce the risk of cardiovascular disease. This conclusion is based on several controlled studies showing that LDL cholesterol is lowered by replacing butter with margarine and by substituting saturated fats with unsaturated fats. Replacing saturated fats with unsaturated fats also reduces the risk of heart disease.
For this reason, the Health Council has issued the following guideline:
“Replace butter, hard margarine, and solid cooking fats with soft margarines, liquid cooking fats, and vegetable oils.”
The Netherlands Nutrition Centre (Voedingscentrum) has incorporated this guideline into the new Schijf van Vijf (the Dutch food guide).