We often receive conflicting information on the role of dietary fats and heart risk. A new study released this month is attempting to clarify this link, since it is one of the largest studies ever conducted on dietary fats and overall long-term health risk. It was performed by the well-respected Harvard School of Public Health, and used a database of over 126,000 men and women followed for 32 years. These were healthcare workers who are in good health, and the dietary habits were followed closely with detailed questionnaires. Their rates of death over 32 years were then tracked carefully.
Here are some of the key findings:
1. Eating more saturated fat and trans-fats (“Bad” fats) was indeed associated with an increase in overall mortality (death rates).
2. Eating more polyunsaturated and mono unsaturated fats (“good” fats) did reduce the overall risk of death. For example, replacing just 5% of your total calories of bad fats with good (polyunsaturated) fats, would reduce the risk of death by 27%.
3. Simply replacing the bad fats with carbohydrates did not show any protective effect. (I call this the “Snackwell Cookie” effect)
4. In addition to lower heart and vascular disease, subjects who ate more healthy fats also had a lower risk of dying from neurodegenerative and respiratory disease. So, a healthy diet may protect against a variety of chronic diseases.
Polyunsaturated fats contain essential fats your body can’t produce by itself, such as omega-6 and omega-3 fatty acids. Some of the best sources are nuts, seeds, fatty fish, and leafy greens. They are also found and vegetable oils such as canola, soybean, and safflower oil. In this particular study, monounsaturated fats were also protective but less so than polyunsaturated fats. The most common example of a monounsaturated fat is olive oil.
Of course, this was a retrospective review, so the findings are not as powerful as a randomized study. Nevertheless, the study appears to support the recommendation that we should reduce saturated fats in our diet, and emphasize polyunsaturated fats instead. We should also be careful not to increase our carbohydrate intake to compensate, emphasizing the role of total calories. We still have a lot to learn regarding the optimal diet for disease prevention, but studies like this continue to shed light on the subject.
This article from CNN Online has a very nice summary of the findings, along with an excellent summary of the various types of good and bad fat, and examples of each in the diet: Good fats can cut risk of death by 27% @CNN