Harvard Heart Letter

Latest thinking on a "cardioprotective" diet

The focus is on foods, not on food components like fat and fiber.

Scientific research often advances our understanding of health and disease. Sometimes, though, it leads to dead ends. The latter is what happened to several decades of nutrition research that focused on individual nutrients like cholesterol, saturated fat, fiber, and antioxidants. Although that work shed ample light on how nutrition affects health and disease, it unintentionally complicated and often confused the concept of healthy eating.

A new emphasis on foods rather than nutrients aims to simplify recommendations for healthy eating, making them easier to understand and put into action. A trio of nutrition experts have applied this food-based approach to a "cardioprotective diet."

The whole is healthier

Food, like the living things from which it comes, is a complex substance. An apple, a fish fillet, a cup of coffee — each contains hundreds of chemical compounds. Many of the compounds work together and depend on each other for their biological activity.

One way to study complex systems is to break them into their parts and study each part in isolation. Nutrition research has taken this tack for more than a century. In the late 1800s, researchers began discovering that deficiencies in certain nutrients caused particular diseases: vitamin C and scurvy, vitamin D and rickets, vitamin A and night blindness, and iodine and goiter, to name a few.

That focus on nutrients continued into the mid-20th century as nutrients were tied to chronic conditions like heart disease and cancer. This research was eventually translated into public health messages to limit cholesterol, saturated fat, sugar, and sodium, and to get more calcium and fiber.

One problem with this approach is that we don't make meals and snacks out of nutrients. We eat foods. Calculating how much cholesterol, saturated fat, sodium, fiber, and calcium is in your food, or gauging how many calories you take in, can be a daunting task.

Another problem is that we don't eat nutrients in isolation. When you eat "protein" — say, a spoonful of peanut butter — you also get some fat (mostly unsaturated but some saturated), vitamins, minerals, carbohydrates (including sugar), fiber, and more.

Eat food

A shift away from nutrient-based recommendations to ones based on food slid into public view in 2008 through journalist Michael Pollan's influential book, In Defense of Food, with its seven-word answer to the question "What should we eat?" Eat food. Not too much. Mostly plants.

Three nutrition experts who have long focused on cardiovascular health have applied a food-based approach to a heart-healthy diet. We've summarized the recommendations from their paper, "Components of a Cardioprotective Diet," in the table below (Circulation, June 21, 2011).

"Until now, most dietary recommendations told us what we shouldn't eat," says Dr. Dariush Mozaffarian, a cardiologist at Harvard-affiliated Brigham and Women's Hospital, associate professor at the Harvard School of Public Health, and a coauthor of the Circulation paper. "For most people, though, getting more of what's missing from their diets — fruits, vegetables, whole grains, and healthy fats — will have a larger health benefit than limiting certain nutrients."

Food-based dietary recommendations for cardiovascular health

This table lists heart-healthy foods that you should eat more of (blue) and heart-harmful foods you should eat less of (red). It comes from nutrition experts at the Harvard School of Public Health, Johns Hopkins University, and Northwestern University (adapted from Circulation, June 21, 2011).


One Serving Equals...


Consume more


4 to 5 servings per day

1 cup of raw leafy vegetables; cup of cut-up raw vegetables, cooked vegetables, or 100% vegetable juice

Spinach, kale, and other green leafy plants; broccoli, peas, carrots, onions, peppers. Don't include potatoes, corn, and other starchy vegetables in this category.


4 to 5 servings per day

1 medium-sized fruit; cup of fresh, frozen, or unsweetened canned fruit; + cup of dried fruit; cup of 100% juice

Blueberries, strawberries, apple, grapes, kiwi, grapefruit, avocado, mango

Whole grains

3 or more servings per day, in place of refined grains

1 slice of whole-grain bread; 1 cup of high-fiber, whole-grain cereal; cup of cooked whole-grain rice, pasta, or cereal

Brown rice, whole-grain bread, oats, bulgur, whole-wheat couscous, barley

Fish and shellfish

2 or more servings per week

3.5 ounces (about the size of a deck of cards)

The best choices are oily fish such as salmon, tuna, mackerel, trout, herring, and sardines

Nuts and seeds

4 to 5 servings per week

1.75 ounces (the proverbial "handful")

Almonds, walnuts, peanuts, hazelnuts, cashews, pecans, Brazil nuts, sunflower seeds, sesame seeds

Dairy products

2 to 3 servings per day

1 cup of milk or yogurt; 1 ounce of cheese or sour cream

Reduced fat or nonfat milk or yogurt, buttermilk, cottage cheese

Vegetable oils

2 to 6 servings per day

1 teaspoon oil, 1 tablespoon vegetable spread

Canola oil, olive oil, safflower oil, peanut oil, soybean oil; "tub" spreads made with vegetable oils

Consume less

Any food containing or made with partially hydrogenated vegetable oil

Don't eat

Stick margarine, commercially prepared baked foods (cookies, pies, donuts, etc.), snack foods, and deep-fried foods

Processed meat

No more than 2 servings per week

1.75 ounces

Bacon, sausage, hot dogs, pepperoni, salami, processed deli meats

Sugar-sweetened beverages, sweets, grain-based desserts, and bakery foods

No more than 5 servings per week

8 ounces of beverage; 1 small sweet, pastry, or dessert

Sugar-sweetened soda, fruit drinks, sports drinks; candy bars, packaged sweets; cookies, donuts, pie, cake, ice cream

What foods can do for you

In the Circulation paper, the researchers lay out the evidence from clinical trials and other studies for the benefits (and hazards) of various types of food. Here are some of the ways foods affect health.

Fruits and vegetables. Provide vitamins, minerals, fiber, and a host of other nutrients. They are filling without delivering too many calories.

Whole grains. Deliver slowly digested carbohydrates along with vitamins, minerals, fiber, and more.

Fish and shellfish. Good sources of omega-3 fats and vitamin D. A good alternative to red meat as a protein source.

Nuts. Full of healthy fats, minerals, and protein.

Vegetable oils. Provide polyunsaturated and monounsaturated fats needed by arteries, the brain, the immune system, and other parts of the body.

Dairy products. Good sources of calcium and vitamin D. Since dairy foods are naturally rich in saturated fat, low-fat choices are best. Calcium and vitamin D supplements are good alternatives.

Trans fats. Found in products made with partially hydrogenated vegetable oil, like stick margarine, many commercially prepared baked goods, and deep-fried foods. Trans fats elevate harmful LDL cholesterol, depress beneficial HDL, and increase inflammation.

Processed meats. Contain a lot of salt, saturated fat, and preservatives.

Sugary beverages and foods. Deliver rapidly digested carbohydrates and little else.

Carbohydrate confusion

Until challenged by the "low-carb" craze, carbohydrates like bread, rice, and pasta were long promoted as the healthful base of daily food intake. But as with fats, some sources of carbohydrate are good for health and others aren't. The worst carbohydrate sources are those the body rapidly breaks down into sugar, causing quick, high spikes in blood glucose. These are foods made from highly refined grains, such as white bread, bagels, and cornflakes and many other breakfast cereals, as well as those with a lot of added sugar.

At the other end of the spectrum are intact whole grains, like wheat berries or whole oats; foods made with minimally processed whole grains; beans; and vegetables. Carbohydrates from these foods are digested slowly, causing steady, manageable rises and falls in blood sugar. They also contain the mix of nutrients and compounds found in the plant from which they came.

One way to tell a good carb source from a not-so-good one is to compare the amount of carbohydrate and fiber. Divide the grams of carbohydrates per serving by the grams of fiber. An answer less than 10 is good for bread or pastry; aim for less than 5 for cereals.

Because grains and other carbohydrates often provide about half of the average person's daily calories, improving the quality of the carbohydrates you eat can make an important contribution to improving health, says Dr. Mozaffarian.