David Merritt Johns

Salt And Public Health: Contested Science And The Challenge Of Evidence-Based Decision Making

For more than four decades, starting in the late 1960s, a sometimes furious battle has raged among scientists over the extent to which elevated salt consumption has adverse implications for population health and contributes to deaths from stroke and cardiovascular disease. Various studies and trials have produced conflicting results. Despite this scientific controversy over the quality of the evidence implicating dietary salt in disease, public health leaders at local, national, and international levels have pressed the case for salt reduction at the population level. This article explores the development of this controversy. It concludes that the concealment of scientific uncertainty in this case has been a mistake that has served neither the ends of science nor good policy. The article poses questions that arise from this debate and frames the challenges of formulating evidence-based public health practice and policy, particularly when the evidence is contested.

Why do we think we know what we know? A metaknowledge analysis of the salt controversy

BACKGROUND Although several public health organizations have recommended population-wide reduction in salt intake, the evidence on the population benefits remains unclear. We conducted a metaknowledge analysis of the literature on salt intake and health outcomes. METHODS We identified reports--primary studies, systematic reviews, guidelines and comments, letters or reviews--addressing the effect of sodium intake on cerebro-cardiovascular disease or mortality. We classified reports as supportive or contradictory of the hypothesis that salt reduction leads to population benefits, and constructed a network of citations connecting these reports. We tested for citation bias using an exponential random graph model. We also assessed the inclusion of primary studies in systematic reviews on the topic. RESULTS We identified 269 reports (25% primary studies, 5% systematic reviews, 4% guidelines and 66% comments, letters, or reviews) from between 1978 and 2014. Of these, 54% were supportive of the hypothesis, 33% were contradictory and 13% were inconclusive. Reports were 1.51 [95% confidence interval (CI) 1.38 to 1.65] times more likely to cite reports that drew a similar conclusion, than to cite reports drawing a different conclusion. In all, 48 primary studies were selected for inclusion across 10 systematic reviews. If any given primary study was selected by a review, the probability that a further review would also have selected it was 27.0% (95% CI 20.3% to 33.7%). CONCLUSIONS We documented a strong polarization of scientific reports on the link between sodium intake and health outcomes, and a pattern of uncertainty in systematic reviews about what should count as evidence.

The FDA and Graphic Cigarette-Pack Warnings — Thwarted by the Courts

The Obama administration has decided not to appeal a court ruling that found the FDAs mandated graphic warnings for cigarette packs unconstitutional. Clearly, efforts to limit commercial speech in the United States face strong constitutional and political constraints.

Beyond Bioethics: Reckoning With the Public Health Paradigm

In the wake of scandal over troubling research abuses, the 1970s witnessed the birth of a new system of ethical oversight. The bioethics framework, with its emphasis on autonomy, assumed a commanding role in debates regarding how to weigh the needs of society against the rights of individuals. Yet the history of resistance to oversight underscores that some domains of science hewed to a different paradigm of accountability--one that elevated the common good over individual rights. Federal officials have now proposed to dramatically limit the reach of ethical oversight. The Institute of Medicine has called for a rollback of the federal privacy rule. The changing emphasis makes it imperative to grapple with the history of the public interest paradigm.

When open data is a Trojan Horse: The weaponization of transparency in science and governance

Openness and transparency are becoming hallmarks of responsible data practice in science and governance. Concerns about data falsification, erroneous analysis, and misleading presentation of research results have recently strengthened the call for new procedures that ensure public accountability for data-driven decisions. Though we generally count ourselves in favor of increased transparency in data practice, this Commentary highlights a caveat. We suggest that legislative efforts that invoke the language of data transparency can sometimes function as “Trojan Horses” through which other political goals are pursued. Framing these maneuvers in the language of transparency can be strategic, because approaches that emphasize open access to data carry tremendous appeal, particularly in current political and technological contexts. We illustrate our argument through two examples of pro-transparency policy efforts, one historical and one current: industry-backed “sound science” initiatives in the 1990s, and contemporary legislative efforts to open environmental data to public inspection. Rules that exist mainly to impede science-based policy processes weaponize the concept of data transparency. The discussion illustrates that, much as Big Data itself requires critical assessment, the processes and principles that attend it—like transparency—also carry political valence, and, as such, warrant careful analysis.

Controversial salt report peppered with uncertainty.

A recent Institute of Medicine (IOM) assessment ([ 1 ][1]) provoked controversy by concluding that there is a lack of evidence for health benefits of reducing sodium intake to the very low levels recommended by some authoritative groups (“Report reignites battle over low-salt diets,” K.

Was there ever really a “sugar conspiracy”?

Twists and turns in science and policy are not necessarily products of malevolence Over the past quarter-century, historical research has revealed how major industries from tobacco to lead to petroleum have meddled in science to conceal the hazards of their products. Drawing on secret industry documents, these studies have shown how special interests have used financial incentives to influence scientists, fabricate doubt, and delay regulation (1). Recently, similar allegations have been made against the sugar industry, with claims that prominent industry-backed researchers in the 1960s downplayed or suppressed evidence linking sugar and heart disease. Building on a newly popular narrative holding that the low-fat campaign of the 1980s was not based on solid science, these allegations have suggested that if not for the machinations of the sugar industry and its cadre of sponsored researchers, the history of U.S. dietary policy might have unfolded very differently. In this article, we argue that the historical evidence does not support these claims. Although we do not defend the sugar industry and cannot address every aspect of this history, we believe recent high-profile claims come from researchers who have overextended the analogy of the tobacco industry playbook and failed to assess historical actors by the norms and standards of their time. Our analysis illustrates how conspiratorial narratives in science can distort the past in the service of contemporary causes and obscure genuine uncertainty that surrounds aspects of research, impairing efforts to formulate good evidence-informed policies. In the absence of very strong evidence, there is a serious danger in interpreting the inevitable twists and turns of research and policy as the product of malevolent playbooks and historical derailments. Like scientists, historians must focus on the evidence and follow the data where they lead.

Response—The sugar industry's influence on policy

Kearns et al. suggest that our critique is based on news stories rather than their peer-reviewed papers, and they claim that they did not conclude that a sugar industry–backed review published by Harvard nutritionists in 1967 meaningfully shaped the course of dietary science and policy. Our Policy