Saturated Fat and Heart Disease
The saturated fat found mainly in meat and dairy products has a bad reputation, but a new analysis of published studies finds no clear link between people's intake of saturated fat and their risk of developing heart disease.
Research has shown that saturated fat can raise blood levels of "bad" LDL cholesterol, and elevated LDL is a risk factor for heart disease and stroke. Because of this, experts generally advise people to limit their intake of fatty meat, butter and full-fat dairy.
The American Heart Association (AHA) suggests that adults get no more than 7 percent of their daily calories from the fat; for someone who eats 2,000 calories a day, that translates into fewer than 16 grams of saturated fat per day.
But in the new analysis, which combined the results of 21 previous studies, researchers found no clear evidence that higher saturated fat intakes led to higher risks of heart disease or stroke.
The findings, published in the American Journal of Clinical Nutrition, may sound like good news for steak lovers, but a past AHA president cautioned against "over interpreting" the results.
"No one is saying that some saturated fat is going to harm you...people should enjoy their food," said Dr. Robert H. Eckel, a professor of medicine at the University of Colorado School of Medicine in Denver.
But, he pointed out, many studies have shown that dietary saturated fat can raise people's cholesterol, and the new analysis is not going to change recommendations to keep saturated fat intake in check.
Perhaps more importantly, though, Eckel said that the thinking on diet and heart health is moving away from a focus on single nutrients and toward "dietary patterns."
A number of studies have linked the so-called Western diet to greater heart disease risks; that diet pattern is defined as one high in red and processed meats and saturated fats -- but also high in sweets and other refined carbohydrates like white bread.
On the other hand, diets described as Mediterranean or "prudent" -- generally high in fruits and vegetables, whole grains, fish, unsaturated fats from vegetable oil -- may help lower the risk of heart disease and stroke.
It's that type of eating pattern that people should strive for, Eckel said.
For the current study, researchers led by Dr. Ronald M. Krauss, of the Children's Hospital Oakland Research Center in California, pooled data from 21 studies that included a total of nearly 348,000 adults.
Participants, who were generally healthy to start, were surveyed about their diet habits and then followed for anywhere from five to 23 years. Over that time, 11,000 developed heart disease or suffered a stroke.
Overall, Krauss and his colleagues found, there was no difference in the risks of heart disease and stroke between people with the lowest and highest intakes of saturated fat.
The analysis included what are known as epidemiological studies -- where the researchers looked for associations between people's reported diet habits and their risk of heart disease and stroke. These types of studies have inherent limitations, like depending on people's recollection of their eating habits.
In addition, the study could not address whether saturated fat intake has different effects on heart disease and stroke risk for different age groups. Nor could it look at the effects of replacing saturated fat in the diet with polyunsaturated fats -- like those found in vegetable oils and fish -- or with carbohydrates.
Some other studies, the researchers write, have shown that consuming polyunsaturated fats in place of saturated ones may lower heart disease risk.
Robert H. Eckel, et al.
Study fails to link saturated fat, heart disease
American Journal of Clinical Nutrition
University of Colorado School of Medicine