Changing views about saturated fat and cardiovascular disease
For generations, the consumption of dairy products has been positively associated with the health and wellness of families and communities. Nevertheless, the recent shift in dietary trends has focused on "what not to eat" instead of emphasizing "what to eat," resulting in demonizing the naturally occurring fats in dairy, while overlooking its many essential nutrients.
However, the long-held beliefs about the impact of saturated fatty acids (SFA) on the risk of cardiovascular disease (CVD) are being challenged by a new perspectives paper from an international symposium, held at the University of Copenhagen in May, 2010 and chaired by Professors Arne Astrup and Walter Willet. The paper in the American Journal of Clinical Nutrition, currently available online, addresses "The role of reducing intakes of saturated fat in the prevention of cardiovascular disease. Where does the evidence stand in 2010?"
This first of its kind meeting brought together many of the world's leading scientists to debate and discuss this controversial topic. The experts concluded that "single risk factors have limitations when considered on their own because the effects of diet on CVD risk are mediated by many pathways, with blood lipids being only one." Further, the ratio of total cholesterol to HDL cholesterol is a better predictor of the effect of saturated fatty acids on CVD risk than LDL- and/or total cholesterol, as individual fatty acids have differential effects on various blood lipids. When it comes to determining the correlation between CVD and food, the entire components comprised within the food matrix may be more important than concentrating solely on fatty acids content. As an example, the paper points out that the protein, calcium and other nutrients within cheese, including certain fatty acids, may offset the effects of its SFA content on blood lipids and overall CVD risk.
According to the experts, current evidence only suggests that substitution of SFA by polyunsaturated fatty acids (PUFAs), but not carbohydrates, results in a lowering of total and LDL cholesterol. "However, even this conclusion isn't the last word, as there is growing recognition that individual fatty acids within the PUFA category have different physiologic effects," said Dr. Cindy Schweitzer, Technical Director, Global Dairy Platform, referring to a recent analysis published in the British Journal of Nutrition which reported that substitution of certain PUFA for SFA and trans fatty acids increased risk of coronary heart disease (Ramsden BJN 2010).
When viewed in totality, the expert group concluded that the effect of a specific food on risk of cardiovascular disease (CVD) cannot be determined on the basis of its SFA content alone and outlined specific issues that need to be addressed in future research.
A similar view is echoed in the 2010 Dietary Guidelines for Americans, released on January 31, which states "Moderate evidence shows that intake of milk and milk products is linked to improved bone health, especially in children and adolescents. Moderate evidence also indicates that intake of milk and milk products is associated with a reduced risk of cardiovascular disease and type 2 diabetes and with lower blood pressure in adults."
"We commend the efforts of Astrup et al in enriching our understanding of the complex relationships between diet and health. The importance of this symposium cannot be overstated in focusing attention on this topical area of dietary recommendations and the contribution of dairy products to the intake of nutrients essential for good health," said Dr. Schweitzer.