Harvard Heart Letter

For a heart healthy diet, don't fixate on fat

Instead, eat a variety of whole or minimally processed foods.

Since the 1970s, food packages have trumpeted fat-focused statements such as "no cholesterol," "fat-free," and "low in saturated fat." These well-meaning claims were intended to help us avoid suspected dietary culprits. After all, eating too much saturated fat can raise levels of unhealthy LDL cholesterol, a key contributor to cardiovascular disease.

But as we've learned over the past few decades, the story isn't quite that simple. When food manufacturers and consumers took the fat out of their products and diets, they often replaced it with refined carbohydrates; namely, white flour and sugar. People munched freely on low-fat chips and cookies, fat-free sweetened yogurt, refined cereals, bread, and white rice, as well as low-fat deli meats.

Refining the long-held advice on fat?

Experts now believe that diets high in refined carbohydrates are fueling the nation's rising tide of diabetes and obesity, both of which also boost cardiovascular disease risk. Yet perhaps the most persistent heart-related dietary advice, still championed by the American Heart Association and U.S. Dietary Guidelines, is to limit red meat, cheese, and full-fat dairy products, our main sources of saturated fat.

"As a whole, just knowing the amount of saturated fat in a food or in your diet doesn't provide very much useful information. You have to consider your overall diet," says Dr. Dariush Mozaffarian, dean of the Friedman School of Nutrition Science and Policy at Tufts University in Boston. In fact, 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 such as nuts and avocados, he says.

Building a heart-friendly diet

Don't focus on avoiding specific nutrients like saturated fat. Composing your diet around these foods is a better strategy.


How much to eat *


2 to 2½ cups (4 to 5 servings) per day


2 to 2½ cups (4 to 5 servings) per day

Whole grains

3 servings of whole grains per day; one serving is one slice of whole-grain bread, 1 cup of cooked whole-grain cereal, or ½ cup cooked brown rice.

Fish and seafood

At least two servings (3–4 oz each) per week, including at least one serving of oily fish, such as salmon, tuna,
or mackerel.

Vegetable oils

5–6 teaspoons per day, including oil found in foods


4 to 5 servings (1 oz each) per week, with a serving equaling ¼ cup nuts or 2 tablespoons of peanut butter

Dairy products

2–3 servings per day, with 1 serving equal to 1 cup of unsweetened yogurt or milk, or 1 oz of cheese

* Serving amounts and sizes are based on a 2,000-calorie diet.

Images: Thinkstock

Sizing up saturated fat

In recent years, several major studies have questioned whether saturated fats are as harmful as we've been led to believe. The latest one (published in Annals of Internal Medicine and co-authored by Dr. Mozaffarian) pooled data from 72 studies to gauge how different fats influence the risk of a heart attack or related problem. 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 does raise LDL cholesterol, but it also raises "good" HDL cholesterol and lowers triglycerides. Several trials and observational studies have shown that replacing saturated fat with polyunsaturated fat (the type found in soybean or canola oils, for example) lowers heart disease risk. 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.

Some of the media coverage of the Annals study questioned whether people could now eat hamburgers—or even slather butter on their toast. "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.

A whole-diet focus

Don't want to toss your toast? Spreading on a little butter isn't bad, but
a healthier choice would be a vegetable oil–based spread. If you enjoy red meat, have a freshly made burger or small steak once in a while. But don't choose a low-fat processed deli meat instead. There is no benefit to the lower fat content and plenty of harm from the sodium and other preservatives.
A better choice would be fatty fish like salmon.

"Nutritional science is starting to focus more on the overall dietary pattern rather than specific nutrients," says Dr. Mozaffarian, who stresses the importance of eating whole or minimally processed foods (see "Building a heart-friendly diet" for a guide). "If something has a food label, it's perhaps not the best choice. We need to move away from the idea that we can manufacture an artificially healthy diet," he says.