Op-Ed: U.S. News is wrong about what constitutes the best diet
Critics say the evidence falls short of demonstrating the DASH diet’s significant impact on major nutrition-related diseases.
Dieter beware: U.S. News & World Report, in its high-profile January cover story on “best diets,” calls the DASH and Mediterranean diets tops for health, though these regimens represent the failed nutritional status quo of the last 50 years.
DASH is listed first in the U.S. News rankings, but authoritative reviews have found that it’s been tested on only about 2,000 subjects (mostly middle-aged hypertensives) in studies lasting no longer than six months. Its effects can hardly be generalized to all Americans.
For the record:
2:55 p.m. Jan. 28, 2018An earlier version of this piece said that low-carbohydrate diets have been tested in at least 78 clinical trials; the correct number is 70. It included cheese among the foods that Americans have cut back on, but cheese consumption has not decreased.
In those limited studies, the diet, which promotes fruits, vegetables and low-fat dairy, did lower some cardiovascular risk factors, such as blood pressure. But it usually worsened others, such as HDL cholesterol (the good kind) and triglycerides. And the one and only time it was tested against a higher-fat version of itself, the higher-fat version performed better.
DASH — the acronym stands for Dietary Approaches to Stop Hypertension — has been promoted by our government for more than 20 years, but the evidence still falls far short of demonstrating a significant impact on the major nutrition-related diseases of our time, especially obesity and diabetes. These twin disorders constitute a global public health epidemic of crisis proportions, a “slow-motion disaster,” in the words of the director-general of the World Health Organization. The U.S. News “best of” rankings pay lip service to these diseases, but end up extolling a diet with virtually no demonstrated ability to treat or prevent them.
The Mediterranean diet, listed second for overall healthiness by U.S. News (but formally ranked as tied with DASH), fares little better on the evidence. Highly popular since its formal introduction in 1993 by the Harvard School of Public Health and selected by the U.S. Department of Agriculture in 2015 as one of its three recommended “dietary patterns,” the diet has principally been studied in one 2013 trial, on about 7,500 subjects in Spain. After five years, those on the diet had reduced their risk of cardiovascular events by an underwhelming 2%, in absolute terms. Moreover, the diet had no impact on overall mortality or weight loss. And the trial itself was flawed; it didn’t have an adequate, comparative control group.
It’s clear that U.S. News — which employed an expert panel to rate 40 diets on various criteria — merely recapitulated questionable dietary advice that has gone by a succession of names since the 1970s — “low-fat,” “DASH,” “USDA-style,” “plant-based.” The basic set of recommendations have remained the same, emphasizing plant foods (grains, cereals, fruits and vegetables) over animal products (eggs, regular dairy, meat), and vegetable oils over natural animal fats such as butter.
According to government data, Americans have largely followed these recommendations over the last 50 years, notably increasing their consumption of grains, vegetables and fruits and eating less whole milk, butter, meat and eggs. The outcome? In that time, rates of obesity and Type 2 diabetes have skyrocketed. Something has gone terribly wrong.
Why would 25 doctors, dietitians and nutritionists on the U.S. News panel choose a dietary philosophy that has — so far, at least — failed us? They might be entrenched in their opinions, supported by the industries that benefit from these diets, motivated by non-nutrition agendas such as animal-rights activism, or they might simply have fallen into the easy convenience of groupthink.
The loss to would-be healthy eaters is profound. For instance, diets lower in carbohydrates and higher in fat — called, variously, “Atkins,” “paleo,” “ketogenic” or “South Beach,” and based on the simple idea that carbohydrates are uniquely fattening — were all stiffed in the U.S. News rankings. Indeed, the ketogenic diet, which acutely restricts carbohydrates in favor of fat, came in dead last.
The U.S. News “best of” issue doesn’t measure up.
That’s too bad: Early results of a current trial reported that Type 2 diabetes symptoms can be reversed in just 10 weeks on such a diet. Subjects suffering from diabetes were educated about carbohydrates and coached over the study period. They effectively cured themselves of their disease, something that mainstream medicine does not even believe possible.
These are preliminary results, but many other studies on low-carb diets contain positive results that are similarly encouraging for people with nutrition-related diseases. Low-carbohydrate diets have now been tested in at least 70 clinical trials on nearly 7,000 people, including a wide variety of sick and well populations, mainly in the U.S. Thirty-two of these studies have lasted at least six months and six trials went on for two years, enough time to demonstrate the lack of any negative side effects. In virtually every case, the lower-carb, higher-fat diets did as well or better than competing regimens. The cumulative evidence shows that low-carb diets are safe and effective for combating obesity, highly promising for the treatment of Type 2 diabetes, and they improve most cardiovascular risk factors.
In the midst of a worldwide obesity and diabetes crisis, we don’t need more input from experts who aren’t paying attention to the latest science or who can’t break free from 50 years of conventional thinking about healthy eating. Promoting the same dietary advice over and over again while expecting different results is indeed a kind of insanity, and worse, is doing nothing to combat rising disease and death rates. Consumers need solid information about how to eat for good health. The U.S. News “best diets” issue doesn’t measure up.
Gary Taubes is a co-founder of the Nutrition Science Initiative and the author of “The Case Against Sugar.” Nina Teicholz is the founder of the Nutrition Coalition, an investigative journalist and author of the bestselling “The Big Fat Surprise.”
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