Stroke and heart disease are caused by damaged blood vessels. A common cause of blood vessel damage is the build up of plaque on the inside wall of the blood vessel. High cholesterol levels in your blood contribute to this build up. It is a commonly held belief that a high-fat diet can increase your cholesterol levels. In particular, saturated fats, from animal fats, have been blamed as one of the biggest culprits for increasing cholesterol and risk for heart attacks and strokes. But is there really proof that this link exists?
Researchers from California combined the results from several studies to examine the direct effect of saturated fat intake on heart disease. The study, published in American Journal of Clinical Nutrition, did not find a significant link between high dietary saturated fat and increased risk of heart disease or stroke.
This systematic review and meta-analysis examined 21 previous studies. Sixteen of these studies evaluated the risk for heart disease with increased dietary saturated fat, while eight studies examined the risk of stroke with high dietary saturated fat. The analysis included a total of 347,747 people. Over follow-up periods between 5-23 years, 11,006 people developed heart disease or stroke. Only two out of the 16 studies looking at heart disease found significant associations between dietary saturated fats and disease risk. An analysis combining all of the studies found the intake of saturated fats was not significantly associated with the development of stroke or heart disease.
The review also accounted for other factors that can impact the risk of stroke or heart disease, such as age or sex. After accounting for these factors and the quality of the studies, there was still no significant association between high dietary saturated fats and risk of heart disease or stroke.
A meta-analysis combines smaller, and sometimes conflicting, studies. The larger pool of participants leads to more reliable outcomes. In this case, the large study appears to contradict popular guidelines that a diet high in saturated fats is directly linked to higher levels of heart disease or stroke. While major guidelines that advise lowering your intake of saturated fats will probably not disappear due to this study, it may lead to reconsiderations of diets that severely restrict or eliminate fats.
The results of this analysis do not mean it is time to stock up on donuts or eat all the saturated fat you want. As with any nutritional element, moderation is important. A well-balanced diet needs a balance of carbohydrates, proteins, and fats, with healthy amounts of fruits and vegetables. Lowering your risk of heart disease also includes staying physically active, reducing stress, and monitoring your blood pressure and cholesterol levels.
Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010 Mar;91(3):535-46.
Last reviewed 4/28/2010 by Brian P. Randall, MD
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