A Swedish-led group of European researchers set off to document the relationship between dietary electrolytes (magnesium calcium, potassium and sodium) and stroke risk. The ended up documenting the lack of an association of sodium and risk of stroke, adding to the lengthening list of "health outcomes" studies which are remarkably consistent in their conclusion: reducing dietary salt won't improve health.
Published in the March 10 issue of the Archives of Internal Medicine , the researchers studied 26,556 older Swedes; all were smokers. Over the 13.6 years of the study, the group recorded 579 stroke events. The population had extemely high salt intakes; the average sodium intakes for the five quintiles of sodium ranged from 3,909 mg/day to 5,848 mg/day (the U.S., by comparison averages about 3,500 mg/day -- lower than the lowest 20% of the Swedes in the study).
The findings: stroke incidence was nearly identical in all five quintiles and not only was there no trend in the pattern, but of the 30 separate analyses performed, not a single subgroup had a significant relationship between sodium and stroke incidence. Add this study to the list.
A long plane ride today afforded the opportunity to read an Anthony Daniels review of Ibn Warraq's new book , Defending the West: A Critique of Edward Said's Orientalism. Daniels uses what Benjamin Franklin in the play 1776 said of Thomas Jefferson's writing skills: "a peculiar felicity of expression."
That expression, offered in the context of refuting Said's famous book, was offered as printed:
Some might say that Ibn Warraq has picked an easy target: Said's work would not have been worth refuting had it not been so phenomenally successful in creating what Auden called, with regard to Freud, "a whole climate of opinion."
Whatever you think about the Said/IWarraq contention, our attention was captured by the strong parallel of Said's conventional wisdom versus Warraq's critique to the Salt Institute's recurrent attempts to engage federal public health nutrition leaders in a discussion of the weakness of the scientific data offered in support of the contention that lowering dietary salt will improve health.
To paraphrase: if the federal anti-salt advocacy campaign hadn't been "so phenomenally successful" in creating a "climate of opinion" condemning salt, it would, in Warraq's appropriate words "would not have been worth refuting." Of the fifteen studies of health outcomes of salt-reduced diets , nearly every one has found no benefit and many have found additional risk.
We need a controlled trial to sort out the issues raised in these studies; all of them are merely observational. But the lack of any likelihood that a controlled trial would validate the notion of a health risk of current levels of dietary salt is trumped by the obvious fact that this unsubstantiated policy is already in place. So, even though the "hypothesis generating" studies would suggest the negative hypothesis, that lowering dietary salt would NOT improve health outcomes, the existence of the current policy based on the contrary assumption, though ostensibly "not worth refuting" is actually well worth examining.
Let's let the science guide our policy, not the momentum of obsolete assumptions. Secretary Leavitt, fund a health outcomes study of salt-reduced diets. Please.
NPR (National Public Radio) hit the nail on the head with this just-out story: "Doctors' 'Treat the Numbers' Approach Challenged ." As correspondent Richard Knox explains:
It can take scientists a decade or more to determine whether a drug actually works. In the meantime, doctors rely on other measures, like testing blood pressure and cholesterol levels, to determine whether a drug is having positive effects. But recent studies challenge the practice of prescribing medicine based on certain test results.
Doctors call it "treating the numbers" - trying to get a patient's test results to a certain target, which they assume will treat - or prevent - disease.
Knox quotes Dr. Steve Atlas of Mass General hospital: "It's a big deal because it reminds us of something that we often forget: the number isn't the outcome. And this raises concerns that just lowering the number doesn't get you where you want to be," (emphasis added)
This is, of course, exactly what our public health nutrition policy on salt is doing: treating the number. We need to look at outcomes (see numerous earlier posts to this blog).
Knox also quotes Dr. Ned Calonge on cholesterol-lowering drugs based on the recent diabetes trial disaster , saying:
"Now, what's open is - is lower better? And I think a lot of people believed it would be, and there are many of us that were saying, 'You're going to need to show me,' " he says.
Lately, studies have also challenged other cherished assumptions - like lowering blood sugar. For a long time, doctors have believed that getting diabetic patients' blood sugar as close to normal as possible would prevent heart attacks. A drug called Avandia lowers blood sugar very well.
It was approved in 1999 and was heralded as "one of the newer and greater drugs for the treatment of diabetes," says Dr. Cliff Rosen. Rosen is the chairman of a Food and Drug Administration advisory panel that concluded unanimously last year that patients taking Avandia actually had more heart attacks and strokes.
Rosen says the Avandia story is a caution against treating millions of patients on unproven assumptions.
It's the same story for salt -- but, so far, a largely-untold story. Still, just as public health policy cannot change human physiology, neither can news coverage. But it can slow down our quest for the truth and our ability to base policy on evidence rather than opinion. Please, someone tell HHS! Outcomes matter.
USA Today published a story today echoing the CASH/WASH mantra that children eat too much salt. Our reply:
Kim Painter's article ignores two important points of science. First, salt reduction in children and adults may be related to blood pressure, but because salt reduction triggers other reactions , it has not been shown to lower the rate of heart attacks or cardiovascular mortality. That cherished assumption has been demolished by evidence over the past 13 years. Second, humans and other animal species eat salt in predictable amounts when they can get it; our salt intake is unchanged over the past century. Research published in the February issue of Experimental Physiology explains that the brain's neural system system provides multiple, redundant systems to make sure our salt appetite ensures we get enough salt. Salt is an essential nutrient. We die unless we eat salt.
Let's let the science guide this policy. The U.S. Preventive Services Task Force , the government's in-house advocate for evidence-based policy, has found evidence insufficient to advise the general population to reduce dietary salt. Ditto the Cochrane Collaboration , the global inventor of "evidence-based" decision-making in medical science.
For more information, check the Salt Institute website, http://www.saltinstitute.org/28.html. .
Dick Hanneman President, Salt Institute
Britain's Food Standards Agency asks: "Are we 'bad science' junkies?" Well, yes you are. The regulators, of course, aimed their barbed inquiry at what they perceive is an insufficiently alert public that can't separate fact from fiction with regard to the scientific basis for dietary recommendations. In their mind, salt is the exception; they aver: "There was good awareness of the risks associated with eating too much salt."
Well, no there isn't "good (public) awareness of the risks associated with eating too much salt." The public has followed FSA down the "bad science" pathway and been convinced that science supports general salt reduction. Wrong. Any fair-minded reading of the literature addressing the question "will reducing dietary salt improve health" shows scant evidence for a health benefit and far more data suggesting actual increased risks.
FSA conducted the survey for the launch of the first meeting of the independent General Advisory Committee on Science (GACS) which will open its proceedings with a panel debate to look at the question 'Should we trust what scientists say about food?'.
Our suggestion: let's query the data, not the scientists. Good science is empirical, not expert opinion. Evidence-based medicine considers expert opinion only a Class D level of evidence.