Evidence-based politics of salt and blood pressure

Representation and misrepresentation of scientific evidence in contemporary tobacco regulation: a review of tobacco industry submissions to the UK Government consultation on standardised packaging

BACKGROUND

Standardised packaging (SP) of tobacco products is an innovative tobacco control measure opposed by transnational tobacco companies (TTCs) whose responses to the UK government's public consultation on SP argued that evidence was inadequate to support implementing the measure. The government's initial decision, announced 11 months after the consultation closed, was to wait for 'more evidence', but four months later a second 'independent review' was launched. In view of the centrality of evidence to debates over SP and TTCs' history of denying harms and manufacturing uncertainty about scientific evidence, we analysed their submissions to examine how they used evidence to oppose SP.

METHODS AND FINDINGS

We purposively selected and analysed two TTC submissions using a verification-oriented cross-documentary method to ascertain how published studies were used and interpretive analysis with a constructivist grounded theory approach to examine the conceptual significance of TTC critiques. The companies' overall argument was that the SP evidence base was seriously flawed and did not warrant the introduction of SP. However, this argument was underpinned by three complementary techniques that misrepresented the evidence base. First, published studies were repeatedly misquoted, distorting the main messages. Second, 'mimicked scientific critique' was used to undermine evidence; this form of critique insisted on methodological perfection, rejected methodological pluralism, adopted a litigation (not scientific) model, and was not rigorous. Third, TTCs engaged in 'evidential landscaping', promoting a parallel evidence base to deflect attention from SP and excluding company-held evidence relevant to SP. The study's sample was limited to sub-sections of two out of four submissions, but leaked industry documents suggest at least one other company used a similar approach.

CONCLUSIONS

The TTCs' claim that SP will not lead to public health benefits is largely without foundation. The tools of Better Regulation, particularly stakeholder consultation, provide an opportunity for highly resourced corporations to slow, weaken, or prevent public health policies.

Salt and hypertension

Current salt intake is too high. Current evidence documents that salt is crucial to the genesis of hypertension.

Salt restriction and practical aspects to improve compliance

Salt as a commodity to preserve and flavor food and to treat ailments has been in existence for hundreds of years. Sodium (salt) restriction to treat hypertension and fluid retention has been practiced for several decades. More recently, evidence-based best practice guidelines have been developed and published on websites to guide medical and healthcare practitioners to treat patients with hypertension, heart disease, chronic kidney disease, and other sodium-sensitive conditions. As the consequences of hypertension affect many people around the world, the World Health Organization is involved in helping to prevent the development of hypertensive risk factors by advocating a global reduction in salt and a healthy lifestyle. Many governments have or are in the process of adapting these recommendations for local implementation. This paper provides information about existing guidelines for healthy individuals and patients with chronic kidney disease and practical aspects to achieve a lifelong change in dietary habits.

Salt restriction in kidney disease--a missed therapeutic opportunity?

The importance of salt restriction in the treatment of patients with renal disease has remained highly controversial. In the following we marshal the current evidence that salt plays a definite role in the genesis of hypertension and target organ damage, point to practical problems of salt restriction, and report on novel pathomechanisms of how salt affects blood pressure and causes target organ damage.

Non-pressure-related effects of dietary sodium

After the demonstration of a positive correlation between sodium intake and arterial pressure in large population studies, the effect of short-term reduction in sodium intake demonstrated the efficacy of this nonpharmacological therapy. In addition, a positive relation between urinary sodium (the most reliable estimate of salt intake) and left ventricular hypertrophy was found; and in recent years it was shown that cardiovascular morbidity clearly progressed with increasing sodium intake, despite one contradictory study. The role of non-pressure-related effects of dietary sodium is discussed in order to bring more arguments for a large-scale attempt to reduce sodium intake by 30% to 50%.