Today’s Wall Street Journal reports a recent study on “The Preventable Causes of Death in the United States: Comparative Risk Assessment of Dietary, Lifestyle, and Metabolic Risk Factors ” published online by the Public Library of Medicine. With scientists from major institutions and high powered statistical techniques, the study addresses the public health burden of a dozen “modifiable dietary, lifestyle, and metabolic risk factors” including dietary salt. Putting aside evidence that salt intake may not be “modifiable,” the authors tip off readers as soon as Table 1, footnote h that they’ve failed to take advantage of their opportunity to address this important question of mortality related to salt intake.

The footnote reads:

The effect of reduction in salt intake on SBP and the effect of subsequent decline in SBP on the relevant disease outcomes, were estimated at the individual level to account for possible correlation between salt intake and SBP.

Actually, there’s no need to read any further. The authors confine their concern for dietary sodium to extrapolated “benefits” based solely on blood pressure, totally ignoring both the two published studies of a randomized trial of the health outcomes of reducing dietary sodium and the entire literature of observational health outcomes studies which does not support the conclusion that SBP is the only relevant variable in determining disease outcomes. The authors term blood pressure a “disease outcome,” further weakening their credibility as examiners of mortality.

Even employing a fundamentally and fatally flawed methodology, they employ high powered statistics to examine the same question addressed earlier in the week by the Center for Science in the Public Interest which claimed salt caused 150,000 American deaths each year. This study puts the figure about 35,000 – wrong, but underscoring how fast and loose CSPI and NHLBI have been in playing with these projections.

Unfortunately, as has become the pattern, journalists pick up the news release and run with the story line. For example, Daniel Akst in the WSJ story reports:

Too many of us appear to be bent on slow-motion suicide. Consider smoking; if we could get every American to stop, we'd save 467,000 lives annually. Solving high blood pressure (much of it arising from unhealthy lifestyles) would save 395,000. And if we could get everyone to slim down to an appropriate body weight, we'd save 216,000 lives.

Great headlines. Lousy science.

Generals are often accused of preparing to fight the last war, not recognizing that events have moved on. The grand strategy of reducing the global burden of chronic diseases should remain our mission, to be sure, but we need to understand whether we’re using the right weapons in our battlefield tactics. The “last war” mentality is represented in the simplistic, one-size-fits-all campaign against blood pressure. Now we know there are many ways to reduce blood pressure. Some improve health; others, don’t. We used to bleed patients to improve their health. That certainly reduced their blood pressure. And many died. We used to urge pregnant women to reduce salt intakes; today that would be medical malpractice. Some interventions work to advance our mission of improving human health, other well-intended tactics have proved counterproductive, creating “unintended consequences,” like the 37% greater cardiovascular mortality among Americans consuming (recommended) low-salt diets. Think of salt reduction as waterboarding. Extreme, for sure. Some would argue unethical. But, bottom line, ineffective and possibly counterproductive.

Headlines across the country , and the world , alerting the public that the DASH Diet reduces the rate of heart failure. As champions of the DASH Diet for the past dozen years, we feel vindication. It was distressing, therefore, to read the authors’ news release declaring their study provides support for salt reduction among the dietary improvements. It doesn’t. Actually, it’s just the reverse.

Lead author Emily Levitan et al, explains about the findings published in the Archives of Internal Medicine , as reported by Science Daily :

"High blood pressure is always of concern because it has the potential to lead to major adverse events, including strokes, heart attacks and heart failure," explains senior author Emily Levitan, ScD, a research fellow in the Cardiovascular Epidemiology Research Center at BIDMC. She and her coauthors, therefore, hypothesized that the DASH diet (short for Dietary Approaches to Stop Hypertension) would also reduce a woman's risk of heart failure through its blood pressure lowering effects as well as its secondary effects on cholesterol and other heart-disease risk factors. The DASH diet, which has been shown to lower blood pressure in randomized clinical studies, is plentiful in fruits, vegetables, low-fat dairy products and whole grains. "These foods are high in potassium, magnesium, calcium and fiber, moderately high in protein, and low in saturated fat and total fat," explains Levitan.

So far, so good, but a news release referenced by Cardiology Today continues:

Emily Levitan, ScD, a research fellow at Beth Israel Deaconess Medical Center, said the women’s diet did not have to exactly mirror the DASH diet to have a benefit. “Very few of the women we looked at had diets that shared all aspects of the DASH diet,” she said in a press release. “But we found that the closer they were, the lower their risk of HF.

“This suggests that making even moderate adjustments to your diet to include more fruits, vegetables, whole grains and low-fat dairy products, and less salt and sugar and less red meat and processed meats, can help improve cardiac health,” she said.

Levitan ignores her own data. Like previous studies that have shown higher quality diets are not lower in salt, this new study does the same. The original DASH Diet, of course, held salt constant to eliminate the possibility that its results might be confounded by salt reduction. The ensuing DASH-Sodium trial added a salt reduction intervention and its (salt reductionist) authors refuse to divulge the data for analysis, but what has been reported suggests any salt effect applies only to a small number of people , at most. But this new study found the DASH Diet – high in fruits, vegetables and low-fat dairy products – had double digit changes to typical diets in terms of fat, saturated fat, cholesterol (all down) and potassium, calcium, magnesium and fiber (all up). That’s what you’d expect. The salt intake was virtually unchanged (<2%). The study also reports that the “high quality” NHLBI diet, which does recommend reduced salt intakes, had the same magnitude double-digit changes to fat, saturated fat (both down) and potassium calcium, magnesium and fiber (all up) and, in addition, recorded double digit increases in protein and sodium. Repeat, a double digit increase in sodium, not a cut. This was the actual diet of those adhering most closely to the recommended diet.

So, this further evidence confirms exactly the opposite point the authors’ report: the Archives study shows no link of reduced-salt diets with heart failure rate.

Until a year ago, that would have been surprising. Until last year, heart failure patients were routinely placed on low-salt diets. “Everyone” knew low-salt diets would be medically helpful. Except that “everyone” was wrong. The first-ever clinical trial of the health outcomes of low-salt diets was done among congestive heart failure patients . Guess what? Those on the low-salt diets had far worse health outcomes . They died and were re-admitted to the hospital much more frequently. A year later, you’d think researchers who found no association of salt intake with heart failure would have referenced the only two studies on this very point. Peer reviewers missed it.

Unfortunately, most of the reading public did too, according to the media play of the authors’ news release.