All of us know that we need to avoid the bad fats. But nobody is quite certain yet which of the fats are bad for us. A new study of saturated fats helps to clear up the confusion.
Bad fats are those that are bad for our hearts. Nothing is more important for those of us who have diabetes, because heart disease is the most serious and common complication that we face.
The scientific community does agree that one type of fat is quite bad for our hearts. The bad guys are the trans fats that we made in large amounts in the previous century from partially hydrogenated vegetable oil. In 2001 a large study that I reviewed then began to wake us up to the dangers of this artificial fat. These findings and subsequent government pressure on manufacturers and the spread of knowledge has substantially reduced the amounts of trans fats in the American diet.
But widespread belief that saturated fats are bad for us continues, based largely on cherry-picked evidence that Ancel Keys presented in his Seven Countries Study. Saturated fats were his personal demons, but they are neither bad nor good. Recent studies have exonerated saturated fats from having a primary role as the major cause of heart attacks, the hardening and narrowing of our arteries. See, for example, "The role of reducing intakes of saturated fat in the prevention of cardiovascular disease," which The American Journal of Clinical Nutrition published two years ago.
A study that The American Journal of Clinical Nutrition will publish next month goes even further. Publication in this journal is especially important because it is the world's most influential peer-reviewed journal about nutrition.
Dr. Thomas A.B. Sanders of the School of Medicine, King's College London, and three colleagues published their research showing that "SFAs [saturated fatty acids] do not impair endothelial function and arterial stiffness."
They conducted this controlled human study that found no negative influence of saturated fats on blood vessel function or stiffness. This was a relatively large study of 121 insulin-resistant men and women. The study also had a relatively large duration of 24 weeks.
The researchers measured how well the blood vessels of these volunteers worked after they consumed a diet high in saturated fat for a month and then after 24 weeks on a high saturated fat diet or on diets that contained either less than 10 percent saturated fat and were high in either monounsaturated fat or in carbohydrates. Dr. Sanders and his colleagues concluded that the high saturated fat diet did not affect the blood vessels of their subjects.
Measuring arterial stiffness may be the best way to predict heart attacks, according to a recent meta-analysis. The Journal of American College of Cardiology published this study in 2010 as "Prediction of Cardiovascular Events and All-Cause Mortality With Arterial Stiffness."
Most grocery stores in this country and Canada offer few if any whole milk or other full-fat dairy products, like my favorite whole milk Greek yogurt. I discovered this to my chagrin this summer on my extensive road trip to Alaska where I was away from my usual sources at natural foods stores like Whole Foods Markets.
I don't blame the grocers, however, because they sell only what we will buy from them. This too will change as we increasingly recognize that saturated fats aren't bad for us.