Last fall, New Yorker science writer and former NY Times correspondent Michael Specter released an important book entitled Denialism: How Irrational Thinking Hinders Scientific Progress, Harms the Planet, and Threatens our Lives . In the NY Times book review, Janet Maslin captured the essence his thesis: "Firing Bullets of Data at Cozy Anti-Science ."

When the IOM produced its report earlier this week on how to implement salt reduction, questions at the news conference about the impacts on health and international trade in processed foods evoked artful non-answers. The authoring panel's chair conceded that the group had not examined the science on whether such a policy would improve public health. And she admitted that the group had not considered how the U.S. would defend its action against the World Trade Organization should FDA be so foolish as to adopt the IOM recommendation.

Though Specter's book deals with a myriad of junk science issues, it is silent on salt. Specter takes jab at celebrity know-nothings like Britain's Prince Charles and targets Dr. Andrew Weil's promotion of vitamin supplements as raising a larger concern -- undermining valid science by equating it with pseudo-science. Says Specter: “The idea that accruing data is simply one way to think about science has become a governing tenet of the alternative belief system....When Weil writes about ‘a great movement toward evidence-based medicine’ as if that were regrettable or new, one is tempted to wonder what he is smoking.”

We expect that a scientist with the appropriate credentials will act like a scientist, not a shaman. But on salt, the quasi-religious fervor has an unstable foundation of pseudo-science and the denialism of the politico-medical establishment -- as rendered in the IOM report -- is, indeed, "hindering scientific progress" and, arguably, "threatening our lives."

Let's "fire bullets of data at the cozy anti-science" behind the IOM report and ask ourselves what data are available to explore the two key questions:

1. While salt intake is related to blood pressure, the relationship is heterogeneous and, more importantly, blood pressure is only one of several important health risk factors impacted by changes in salt intake (others being insulin resistance, plasma renin activity, aldosterone production, sympathetic nervous system activity,etc.) so the proper end point is not BP but rather some "hard" end point like cardiovascular mortality or all-cause mortality or incidence of heart attack, etc. Dr. Alderman, former president of the International Society of Hypertension and current editor-in-chief of the American Journal of Hypertension , summarized this argument in a JAMA piece a couple months ago. The only controlled trial of this question showed low-salt diets had worse outcomes. The observational studies are split with most showing no health benefit of reducing dietary salt.
2. Any health impact of dietary salt depends not on the amount of salt (sodium) in any particular food, but rather on the amount of sodium in the diet. No studies have been done to establish that persons choosing diets replete with "low-salt" foods instead of those foods with "regular" sodium content are able to reduce and sustain their total sodium intake. On the other hand, evidence by Drs. Joel Geerling and David McCarron have found a physiological signal for "salt appetite" based on the body's need for sodium and that this "need" results in sodium intake levels within a relatively narrow range which is unchanged over time and independent of government dietary guidance.

So, to quote the McCarron-Geerling paper's title: "Can Dietary Sodium Intake Be Modified by Public Policy?" Let's get the evidence before we launch a madcap -- and anti-scientific -- effort to make a massive, untested change in our national diet.

Back to the larger point and in conclusion, this from Kevin Shapiro's review of the Specter book in Commentary magazine:

In Specter’s parlance, “denialists” are those who reject the substantive technological benefits of modern science—medicines and vaccines to treat and prevent illnesses, or techniques to enhance the quality and quantity of agricultural yields. At the same time, they cling to an unsubstantiated faith in the advantages of “natural” alternatives such as vitamins, supplements, and organic foods. The term e-ncompasses a diverse array of quacks and crackpots, ranging from New Age celebrities like Andrew Weil to reactionary patricians like Charles, Prince of Wales. What unites them is a hostility to reason that, when amplified in society, threatens the ability of scientists to pursue real solutions to such problems as disease, hunger, and malnutrition.