Choosing a Healthy Diet

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Atkins, Flexitarian, F-Factor, Flat Belly, Paleo, South Beach, TLC—these are just some of the numerous diets to choose from. Which is best for you?

Every year, US News & World Report attempts to address that seemingly simple question. A panel of experts ranked 40 popular diets on factors such as weight loss, heart health and ease of adherence. The diets ranked best overall were a Mediterranean eating pattern and the Dietary Approaches to Stop Hypertension (DASH) diet.

Both candidates topped the rankings because of scientific evidence supporting them. “People can claim anything they want about a diet, but is there any evidence for it, that is the first question to ask,” says Susan B. Roberts, PhD, director of Tufts’ HNRCA Energy Metabolism Laboratory, who was among the 25 experts who analyzed the diets.

In addition to providing some objective facts to help you choose a diet, “rankings can also be helpful in establishing whether a diet is safe,” Roberts says. “Are the calories unreasonably low? Is it nutritious in general? And then there is behavior change—a key issue. Without giving you help to change how you think and behave about food, the diet is unlikely to last very long.”

So, what should health-conscious Americans choose—Mediterranean or DASH or something else? For overall benefit, out of the diets that were ranked, Mediterranean and DASH did well because they both provide diets that are overall healthy and safe.

Evidence-Based Eating: Unlike some of the diets evaluated in the rankings, Mediterranean and DASH options are both grounded in substantial nutritional research on the healthfulness of the foods they recommend.

The National Heart, Lung and Blood Institute supported a series of clinical trials to evaluate a diet rich in nutrients expected to lower blood pressure, mainly potassium, calcium, magnesium, protein and fiber, termed a DASH diet. Mediterranean eating patterns have also been the subject of numerous and continuing studies. A key clinical trial demonstrated that a Mediterranean diet typical in Spain reduced the risk for cardiovascular disease—particularly stroke—and diabetes.

Both a Mediterranean pattern and the DASH diet share some key features, which echo recommendations of the Dietary Guidelines for Americans:

-A variety of vegetables, including dark green, red and orange, and other types, as well as legumes (beans, peas)

-Fruits, especially whole fruits

-Grains, at least half of which should be whole grains

-Dairy, including milk, yogurt, cheese and/or fortified soy beverages

-A variety of protein foods, including seafood, lean meats and poultry, eggs, legumes, nuts and seeds

-Unsaturated plant oils

-Limit red and processed meats, added sugars and salt.

Mediterranean vs DASH and OmniHeart: At the same time, there are some notable differences between the Mediterranean and DASH diets—starting with the fact that the Mediterranean “diet” is actually an overall pattern with a range of styles. There are many variations on Mediterranean-style eating. These differ mainly in their flavors and food varieties across Mediterranean regions and cultures.

In contrast, DASH calls for specific numbers of daily servings from various food groups, based on your total daily calorie intake. It limits sodium to a specific threshold, offering both a low-sodium (2,300 milligrams) and very low-sodium (1,500 milligrams) option. If you choose to, you can obtain detailed guidelines to help you plan meals “by the numbers.”

Another difference between Mediterranean and DASH is their perspectives on dietary fat. In clinical trials, the DASH diet limited total fat intake to 27% of total daily calories and saturated fat to 6%. Mediterranean-style diets do not have any specific limits on these fats and indeed often exceed 35% to 40% of calories from total fat, largely from unsaturated plant oils and fats.

Since the original DASH research was conducted, nutrition scientists have realized that reducing total fat is less important than a person’s overall food choices and diet pattern, and that actually mono- and polyunsaturated fats from plants and fish are quite healthy. So, Mediterranean patterns do not restrict fat and favor liberal use of plant oils like extra-virgin olive oil, regular consumption of seafood and nuts and keeping red meat to an occasional meal.

In response to this new evidence, the original DASH researchers decided to test a variety of DASH diets, including versions much higher in either plant oils and fats or plant protein, in a study called OmniHeart. As reported in JAMA in 2005, the researchers discovered that partly substituting starch (carbohydrate) with either plant-derived protein or unsaturated fat was superior to the low-fat DASH diet. “The OmniHeart study showed that a Mediterranean-style DASH diet was even better than the original,” says Dariush Mozaffarian, MD, DrPH, Dean of the Friedman School and editor-in-chief of Tufts Health & Nutrition Letter. “When combined with all the other new science in the last decade, to me a ‘high-fat Mediterranean diet’ is the quickest shorthand for a healthy diet.”

The choice of diet—and how you implement it—depends on your personal tastes. “You have to customize it to what you are going to enjoy,” says Alice H. Lichtenstein, DSc, director of Tufts’ HNRCA Cardiovascular Nutrition Laboratory and executive editor of Tufts Health & Nutrition Letter. “The only way somebody is going to stick to a good dietary pattern is if they customize it to their own personal preferences.”

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