Harvard Heart Letter

New dietary guidelines offer sketch for healthy eating

These evolving guidelines continue to get better and more helpful.

Every five years, the federal government revises the Dietary Guidelines for Americans. The 2010 edition (issued a few months into 2011) was more a facelift than a makeover — a few wrinkles removed here, some definition added there.

It did, though, break a little new ground. For the first time, the guidelines actually urge Americans to eat less. And they mention a few foods by name, like pizza and fries and sugary beverages, rather than talking in generalities.

This document is important for several reasons. It sets the standards for all federal nutrition programs, from school lunches and food stamps to the food services for the armed forces. It can influence the foods and food products that Americans buy, and so affect how billions of dollars are spent each year. In 2005, for example, the guidelines recommended eating more whole grains and fewer refined ones. Stroll down your grocery store's breakfast cereal and bread aisles today and you'll see many more whole-grain choices than were available then. The 2010 edition takes aim at reducing salt, something that companies are trying to do with their processed and prepared foods.

On a personal level, the guidelines offer pretty good guidance about healthy eating. We'll summarize the main messages here. But if you are interested in healthy eating, reading or even browsing the 112-page report is a worthwhile undertaking. For one thing, it's free — part of your tax dollars at work. (You can download a copy at www.health.harvard.edu/170). For another, Dietary Guidelines for Americans is a treasure trove of diet tips and interesting — sometimes jaw-dropping — information, such as the table listing Americans' top sources of calories (baked desserts, pizza, and soda are three of the top five.)

Overarching concepts

The latest edition of the dietary guidelines is organized around what the authors call two "overarching concepts":

Maintain calorie balance over time to achieve and sustain a healthy weight. Translation: Eat and exercise in ways that keep your weight in the healthy range or move it in that direction.

Focus on consuming nutrient-dense foods and beverages. Translation: Eat more vegetables, fruits, whole grains, beans, seafood, lean meat and poultry, nuts, seeds, and other foods that deliver nutrients, not just calories. Nutrients include protein, vitamins, minerals, phytochemicals (potentially beneficial plant compounds), healthy fats, fiber, and more. Consume fewer foods and beverages that contain mostly sugar, such as sugary breakfast cereal or sweetened soda and juice.

The emphasis on nutrient density is important. This term is a useful way of looking at food and food products. Let's compare extremes: a can of soda sweetened with sugar or high-fructose corn syrup versus 12 walnut halves. Both provide 150 calories of energy. The soda gives you nothing besides water and sugar. It has low nutrient density or, put another way, a lot of empty calories. The walnuts deliver protein, healthy fats, some fiber, vitamins, minerals, and other phytochemicals. They have high nutrient density.

SoFAS

A euphemism introduced in the 2010 guidelines is the term "solid fats and added sugars," abbreviated as SoFAS.

Solid fats include beef, poultry, pork, and other animal fats; butter; lard; stick margarine; shortening; and much of the fat in milk, cheese, and other dairy foods. Added sugars include white sugar, high-fructose corn syrup, brown sugar, honey, molasses, and more exotic sources such as agave nectar.

More than one-third of all calories in the average American diet come from solid fats and added sugars, but they contribute few if any essential nutrients.

Key recommendations on foods

Dietary Guidelines for Americans 2010 offers these recommendations for a healthy diet:

Foods and nutrients to increase

  • Eat more vegetables and fruits.

  • Eat a variety of vegetables, especially beans, peas, and vegetables that are dark green, red, or orange.

  • Get at least half of your grains from whole-grain sources, such as whole-wheat bread or pasta, brown rice, oatmeal, and cracked wheat.

  • Choose fat-free or low-fat milk and dairy products.

  • Choose a variety of protein sources, such as seafood, lean meat and poultry, eggs, beans and peas, and nuts and seeds. The most healthful protein packages are low in saturated fat and sodium and often contain healthy fats.

  • Eat fish or other seafood more often, in place of red meat.

  • Use oils whenever possible in place of solid fats like butter, margarine, and shortening.

illustration of plate showing suggested food portions

Foods and food components to reduce

  • Reduce daily sodium intake to less than 2,300 milligrams (mg), or to less than 1,500 mg if you have high blood pressure, diabetes, or chronic kidney disease, are in your 50s or older, or are African American.

  • Consume less than 10% of calories from saturated fats (mainly in red meat and dairy products).

  • Consume less than 300 mg of cholesterol per day.

  • Try not to get any trans fats by limiting your intake of foods made with partially hydrogenated oils.

  • Eat less solid fat (which we get mainly from whole milk, butter, cream, and red meat) and foods with added sugars (especially sodas and juices sweetened with sugar or high-fructose corn syrup).

  • Try to eat fewer foods made with refined grains (almost anything made with white flour or white rice).

  • If you drink alcohol, do so in moderation — up to one drink per day for women and two drinks per day for men.

Useful direction

Dietary Guidelines for Americans 2010 goes beyond the hard-to-implement "overarching concepts" and gets down to the nitty-gritty of putting them into practice. For example, an entire chapter offers advice about foods you should try to reduce in your diet. Another focuses on foods and nutrients that are worth increasing. ("Key recommendations on foods" lists 14 of the 23 recommendations.) A six-page table in the Dietary Guidelines report offers practical tips (called "potential strategies") for eating more fruits and vegetables, eating out, cutting back on sodium, and more.

Just after the Heart Letter went to press, the USDA announced it was scrapping the food pyramid and replacing it with a new icon called MyPlate. It is a white plate divided into colorful quarters–green for vegetables, red for fruits, orange for grains, and purple for protein. MyPlate was designed to nudge Americans away from meals dominated by meat and starch and towards meals made up mostly of plant-based foods. Additional consumer-friendly advice will be released to the public later in 2011. Examples include:

  • Enjoy your food, but eat less.

  • Avoid oversize portions.

  • Make half your plate fruits and vegetables.

  • Switch to fat-free or low-fat (1%) milk.

  • Drink water instead of sugary drinks.

Hidden vegetables

"Eat more vegetables and fruits" is a key theme running through Dietary Guidelines for Americans 2010. Why? Vegetables and fruits are high in nutrients and low in calories. Diets rich in them have been linked to lower rates of many chronic diseases. But many adults, like many children, aren't particularly keen on vegetables.

Hide 'em, suggest nutritionists from Pennsylvania State University. They explored the effect of surreptitiously adding steamed, pured vegetables to carrot bread, macaroni and cheese, and chicken rice casserole. Forty-one volunteers ate breakfast, lunch, and dinner one day a week for three weeks at a Penn State kitchen. They were told they could eat as much as they wanted. Sometimes the volunteers got regular entres; sometimes the dishes were packed with hidden vegetables.

The volunteers ate the same weight of food, whether or not it contained hidden vegetables. That meant they took in 350 fewer calories on days when they ate hidden-vegetable meals. Daily vegetable intake nearly doubled. And yet the volunteers rated the hidden-veggie and the normal foods the same for taste and satisfaction (American Journal of Clinical Nutrition, April 2011). If you'd like to try this at home, the recipe the researchers used for vegetable-enhanced macaroni and cheese is below.

A few years ago, author Jessica Seinfeld published Deceptively Delicious, a cookbook with 76 hidden-vegetable recipes for children. Based on the Penn State work, it looks like a version for adults could be a big hit, too.

Macaroni and Cheese
(Makes six 1 1/4-cup servings)

8 ounces macaroni (uncooked)

1 tablespoon margarine

2 tablespoons flour

1/2 teaspoon salt

1 cup skim milk

8 ounces reduced-fat shredded cheese, sharp

1 cup pured cauliflower

1 cup pured summer squash

Preheat the oven to 350 F. Spray a glass 8- or 9-inch square baking dish with cooking spray. Cook macaroni in boiling water until tender, about 8 to 12 minutes. Drain. Melt margarine in saucepan over low-medium heat. Stir in flour and salt. Gradually stir in milk. Cook, stirring constantly, until thickened. Add cheese and stir until cheese melts. Add pured vegetables and cooked pasta and stir until mixed. Pour into greased baking dish and bake, covered, at 350 F for 35 to 40 minutes.

Per serving: Calories: 300; Carbohydrates: 36 g; Fat: 11 g; Protein: 17 g; Fiber: 2 g

Recipe courtesy of Alexandria D. Blatt, Pennsylvania State University

Politics and health

Dietary Guidelines for Americans isn't a purely scientific document. It's a political one, too.

The first five editions of the dietary guidelines were created by the U.S. Department of Agriculture (USDA). Its mission, to promote American agriculture, often stands in opposition to advice for healthy eating, such as telling people to eat less or to cut back on red meat. The Department of Health and Human Services joined the USDA for the 2005 and 2010 revisions, which may account for the increase in straight talk.

As compromises go, Dietary Guidelines for Americans 2010 isn't bad. But it would be better for the country's health to see clear recommendations based on the best science rather than guidelines that have been influenced by bureaucrats, policy makers, and lobbyists.