Refining advice about dietary fat and heart disease, from the July 2014 Harvard Heart Letter

Published: July, 2014

Decades of well-meaning advice to not eat much fat (especially saturated fat) led food manufacturers and consumers to replace fat with refined carbohydrates and sugar. But low-fat chips, cookies, and other highly processed foods aren't necessarily a better choice, reports the July 2014 Harvard Heart Letter.

"Many foods that are low in fat and saturated fat, such as bagels, fat-free desserts, and low-fat processed turkey breast, are more harmful than foods that contain some saturated fat or cholesterol, such as eggs, nuts, and avocados," says Dr. Dariush Mozarrafian, associate professor of epidemiology at the Harvard School of Public Health who was recently named Dean of the Friedman School of Nutrition Science and Policy at Tufts University in Boston.

Several major studies have questioned whether saturated fats are as harmful as once believed. When researchers compared people who ate the most saturated fat with those who ate the least, they found no clear differences in heart disease risk.

Compared with carbohydrates, saturated fat raises harmful LDL cholesterol, but it also raises "good" HDL cholesterol and lowers triglycerides. But replacing saturated fat with refined carbohydrates does not—and appears to actually raise risk. Eating sweet or starchy foods causes blood sugar to rise, along with triglycerides, insulin, and other hormones thought to contribute to obesity, diabetes, and the formation of artery-clogging plaque. By comparison, replacing saturated fat with polyunsaturated fat (the type found in soybean or canola oils, for example) lowers heart disease risk.

Media coverage of the saturated fat research suggested that people could eat hamburgers every day and slather butter on their morning toast with no health implications. "People are so fat-focused, they're missing the bigger picture. The toast is actually the worse part; it's high in sodium and usually made from highly processed, refined grains," says Dr. Mozaffarian. A better breakfast would be an egg cooked in extra-virgin olive oil with spinach and mushrooms, he says.

Read the full-length article: "For a heart-healthy diet, don't fixate on fat"

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