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Salt and rhetoric

Recently I heard sharp exchanges on radio between medics firing salvos of data at each other from their respective ammo dumps of evidence. Spectacular though these skirmishes were, I heaved a sigh of nostalgia for the era when doctors’ opinions were received unchallenged by a respectful public and unseemly medical squabbles were confined behind closed doors. Then I thought … nah, this is better.

Nobel laureate Prof Harold Urey (1893−1981) yearned in 1964 for a return to a past that exerted greater control over scientific publication: “Science,” he fumed, “has always been aristocratic.” I learnt this from historian of science Steven Shapin writing in the London Review of Books (8 November 2012, p.38). Shapin’s response to Urey: “In a society insisting on its democratic character, that was not a wildly popular position ….”

Today, mediated largely through the Internet, some wildly popular positions are adopted by medical scientists one minute and others consigned to outer darkness the next. At present a brouhaha rages around white powders and fats, which, many argue, are freighted with such lethal potential as to place the public in clear and present danger. The white powders in question are, of course, salt and sugar, both of which exercise the medical profession to such an extent that hardly has one set of recommendations on their dietary consumption appeared online than another – contradictory – one hoves into view.

As for fats, the decades-long medical establishment view has been that low-fat diets, especially those limiting intakes of saturated fats and cholesterol, are good for health in general and heart health in particular. But low-carbohydrate/high-protein and fat (LCHF) diets are now gaining traction. One proponent is South African heart surgeon Dr Otto Thaning, whose early career was guided by transplant pioneer Dr Christiaan Barnard. In September 2014, aged 73 years, Thaning became the oldest person to swim the English Channel, preparation for which included switching to the LCHF diet, something he now recommends to his patients. “The surprising thing,” he told me, “is that on this diet the serum lipogram actually improves. There is also an improvement in the body-mass index and in their tendency to be pre-diabetic or frankly diabetic. All these changes are protective to vascular health, and thus predictive of an improved quality-of-life.”

But the LCHF approach isn’t new. Writing in The Lancet (29 October 1960), Yudkin and Carey described, “The treatment of obesity by the ‘high-fat’ diet,” noting both that it worked (albeit in only six subjects they investigated) and that “… the phrase ‘high-fat’ in relation to weight-reduction is sufficiently startling to have made a deep impression both on the public and on the medical impression …”. It still does.

However, the current flux which dietary opinion is undergoing within the medical profession is healthy. After all, as Sir Humphry Davy stated in a lecture in 1810: “Nothing is so fatal to the progress of the human mind as to suppose our views of science are ultimate ….”

One of the best ways to test our views of science – and life in general – is through debate and argument, which can generate both heat and light. The process may create controversies, but it’s often through their resolutions that progress is made.

So I was puzzled by a recent editorial in The Lancet (published online 20 May, 2016) by Prof Eoin O’Brien of University College Dublin, the title of which asks, “Salt – too much or too little?” Prof O’Brien, addressing the issue of population strategies for salt consumption, states: “When apparent dogma is challenged, we should speak not of controversy but rather accede to the all-encompassing expression of so-called scientific uncertainty, so as to avoid unbecoming rhetoric.”

Perhaps the professor’s advice was offered only in relation to the particular context he outlined, namely the idea that, “… reducing sodium intake across populations will be beneficial to all, has been challenged with the assertion that doing so might indeed be harmful”. My inference, however, is that it was intended as a general principle and I disagree.

Sometimes it is necessary to challenge and expose dogma, even if it causes controversy, rather than “accede to the all-encompassing expression of so-called scientific uncertainty”. To stick with salt, the sports drinks industry and its medical scientist apologists and employees have long peddled the dogma that extra sodium should be consumed during exercise. For example, Montain et al in the British Journal of Sports Medicine (2006, 40: 98-105) claimed: “Contributing factors to exercise-associated hyponatraemia [EAH] include over drinking of hypotonic fluids and excessive loss of total body sodium [my emphasis].” Significantly, the authors had associations with the sports drink industry. But Prof Tim Noakes in Waterlogged (2012) brushed “scientific uncertainty” aside by rejecting their reference to total body sodium with a blunt: “There is no scientific basis for this statement.”

Nuance is one thing, but to cloak published work that is plain wrong with the mantle of “scientific uncertainty”, when unequivocal condemnation is required, confers too much politesse upon those who don’t deserve it. The definition of rhetoric that I favour – Prof O’Brien doesn’t offer one – is the art of using language to persuade or influence others. On occasion it is appropriate to deploy rhetoric, unbecoming or not.

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