Noting that New York City has announced a campaign to reduce dietary salt in the Big Apple, nurse-blogger Sandy Szwarc laments that the "significance of this initiative may have been lost on media" and capsulizes why people should care:
It deserves to be out in the open, though, because the best science for nearly half a century — including the government’s own findings on examinations reflecting 99 million Americans; more than 17,000 studies published since 1966; and even a recent Cochrane systematic review of the clinical trial evidence — fails to support the hypotheses that salt reductions offer health benefits for the general public. Cochrane’s reviewers specifically concluded that such interventions are inappropriate for population prevention programs.
It’s not just that the salt reductions being proposed will be costly programs that won’t be of much help to people, but that they could hurt people. Even more troubling, the public health messages in this new campaign appear to be most targeting minorities, fat people, the elderly and poor.
Szwarc sums the NYC campaign quoting from the New York Times : “Dr. Frieden says a quiet, mass reduction in sodium levels — stealth health, they like to call it around the department — might be more effective.” She then continues to skillfully excoriate the city health department's scientific summary: "None of these claims can be scientifically supported," she declares.
She then explains how heart disease rates are improving, how population blood pressure has been unchanged over the past 20 years and how salt usage, also, has not increased over the past 20 years. Then she turns to health outcomes, summarizing the findings by a team at the Albert Einstein Medical College who studied the biggest and best federal government database, the National Health and Nutrition Examination Survey (NHANES):
The lowest sodium intakes — the 1500 mg/day that the New York health department says everyone should be eating — were associated with an 80% higher risk of cardiovascular disease compared with those consuming the highest salt diets. The lowest salt intakes were also associated with a 24% higher risk of all-cause mortality. Clearly, low-salt diets are not associated with lower risks for the general population. Conversely, the Albert Einstein researchers were unable to show that even the highest salt intakes were associated with increased risks for developing cardiovascular disease or high blood pressure or for premature death.(emphasis in original)
She explores the "unintended risks" of low-salt diets, the many scientists who question universal salt reduction and queries: "What is it all about?" answering:
As the New York City-led nationwide low-salt initiative is clearly not founded on a true health crisis, on the medical evidence, or on proven health interventions for the primary prevention of high blood pressure or heart disease, what might it really be about?
As the New York Times pointed out today, the target is going after packaged foods and chain restaurant meals. Reducing salt to levels unpalatable to their consumers appears to primarily be about getting people to eat less of foods these public officials don’t think people should eat or others should sell.
Szwarc rarely deals with salt. She's been a consistent and effective proponent of evidence-based health decisions on a broad range of nutrition issues. Her insights earned Junk Food Science "silver medal" runner-up recognition for the best medical/health issues blog for 2008. This could vault her to "gold" in 2009!
President George W. Bush's first director of his White House Office of Information and Regulatory Affairs (OIRA), Harvard professor John Graham, exercised an activist role in promoting better science in federal decision-making. President Obama's OIRA choice, another Harvard professor, Cas Sunstein, could do the same.
Graham directed the Harvard Center for Risk Analysis. Sunstein has been on the faculty of the Harvard Law School and directs its Program of Risk Regulation. He taught earlier at the University of Chicago and is the author of a recent book, Nudge.
A devout liberal who writes for New Republic regularly, he also advocates some positions (judicial minimalism and support of such Bush nominees as now-Chief Justice John Roberts, among them) that have worried left-leaning environmentalists like Chris Mooney, author of the anti-Bush diatribe The Republican War on Science. Mooney admits he's impressed with Sunstein's intellect. "I'm interested to hear whether any environmentalists are going to be rattled by this choice. Sunstein is an ingenious scholar, and continues the whole "best and brightest" motif of the Obama administration...Important question: Will he roll back the Bush administration's overuse of the Data Quality Act?"
Good question. Our concern was that, after Graham’s departure, the Bush Administration failed to push the Data Quality Act far enough. But Sunstein is a believer in behavioral economics and its contention that the theoretical assumptions of law and economics should be modified by new empirical findings about how people actually behave. This might lead to the kind of confident assumption that government policy manifestos to change Americans’ diets will trump human physiology. Stay tuned.
Perhaps you saw the headlines like "salt reduction benefits go beyond blood pressure." We did, so we read the study by Kacie Dickinson et al, "Effects of a low-salt diet on flow-mediated dilation in humans ." The study of 29 overweight and obese Australians in this month's American Journal of Clinical Nutrition is being portrayed as yet another reason to reduce dietary salt.
Not so fast. We recognize that there are many changes that occur when dietary salt is reduced, some well understood (e.g. renin, aldosterone, insulin resistance, blood pressure), others less so. So it may be that this study adds to our understanding.
Keep in mind one key finding: "There was no correlation between change in FMD (flow-mediated dilation) and change in 24-h sodium excretion or change in blood pressure. No significant changes in augmentation index or pulse wave velocity were observed."
As we push for risk factors of risk factors, let's not lose sight of the other competing mechanisms that are activated by lowering dietary sodium and reaffirm our commitment to examining the sum total, the net outcome of all these interventions in terms of cardiovascular health.
Forecast for New York City: flurries. While many New Yorkers may worry more about whether salt is being used to keep their streets safe, city health commissioner Thomas Frieden is concocting a plan to put less of it in their diets.
Today's New York Times carries a story by Kim Severson, "Throwing the book at salt " which describes Frieden's effort to reduce salt in packaged foods and restaurant meals with an aim to reduce salt intake by 25% over the next five years. He's talked to the food industry (mentioned) and the Salt Institute (unmentioned) and warns: "If there's not progress in a few years, we'll have to consider other options, like legislation."
Severson continues to point out the campaign will be "difficult for Dr. Frieden, both practically and politically."
It's actually more difficult than Frieden and his cardiovascular advisor Sonia Angell imagine. Severson quotes Angell presuming that salt intake is a matter of taste: "We've creatd a whole society of people accustomed to food that is really, really salty. We have to undo that." The plan is for "stealth" reductions in the salt content of processed foods "based on one in the United Kingdom (where) targets for sodium reduction will be set for certain food categories."
All this in blithe ignorance of the evidence. Well, not really ignorance, self-deception. Last week, the Salt Institute met with Dr.Frieden and his senior staff and laid out the problems he's facing, none of them "political" but all "practical" since the campaign is based on pseudo-science. The Institute confirmed its representation in a letter, as usual, posted on its website . The letter warns that Frieden's disregard of the science amounts to "using the citizesn of New York as a grand experiment of this generally-believed but as-yet untested hypothesis."
The Institute told Frieden that sodium-reduced diets raise the blood pressure in a significant number of people and will increase in most people insulin resistance, sympathetic nervous system activity and activate productin of renin and aldosterone, well-demonstrated to increase their risk of teh very cardiovascular events your program is intended to reduce." Bottom line: "Salt reduction may actually increase the risk of a significant portion of those New Yorkers who adopt your recommendations since teh lower sodium intake stimulates these known physiologic factors for heart attacks, congestive heart failure and metabolic syndrome."
The Institute lamented the predictable but "unintended consequences" since the medical literature is discovering more and more adverse impacts of salt reduction. "Since it is your mandate to improve the public health of the citizens of New York, we remind you that it si these physiological facts, not political policies that will ultimately determine health outcomes," the Institute warned.
Frieden's campaign also ignores strong evidence that the UK model has been a total waste of money and has achieved no sodium reduction and that medical evidence shows that humans' salt appetite is "hard-wired" in the brain, not a behavioral choice. Unmentioned in the letter was a new study released just yesterday showing that the "human brain makes snap decision on fat content" -- the headline on a new study in NeuroImage .
NHLBI scientists and their taxpayer-funded university researchers released a follow-up study for the important Trials of Hypertension Prevention trial . The authors claimed "a higher soidum to potassium excretion ratio is associated with increased risk of subsequent CVD (cardiovascular disease)." Headline writers fell in line.
A summary analysis of the article published in the January 12 Archives of Internal Medicine would have been more accurate had it stated: There was no statistically significant relationship between sodium excretion and cardiovascular risk and even the reported non-significant association evaporated when the researchers adjusted for known confounding factors. A "p-value" (calculating the likelihood that the reported association was accurate) is usually considered valid when it is 0.05 or less, meaning a 95% chance that the result is accurate. The sodium:blood pressure "p-value" for men was 0.49 and for women 0.98. This means that there was only a 51% chance of a valid relationship between sodium among men and a miniscule 2% chance in women. Hardly the conclusion drawn by the authors or the headline writers.
With the Dietary Guidelines for Americans up for review, we can hope the process deals more with data than headlines. But don't hold your breath.
Salt is so basic to our existence we often forget its life-saving role as an essential nutrient; consider oral rehydration therapy which has saved millions of lives, particularly in Africa. But salt is not only essential to life, it plays a key role combatting mental retardation; consider the enormous achievement of iodized salt.
New York Times columnist Nicholas D. Kristof does just that. In today's paper, he reviews the enormous paybacks of salt iodization, "Raising the World's I.Q ."
Salt does have a real downside, Kristof admits -- "it's so numbingly boring, few people pay attention to it or invest in it. (Or dare write about it!)." I guess we here at the Salt Institute are so insensate we didn't realize that salt was boring or unworthy of attention so count us among the few.
Thankfully, Kristof is one of the few as well. With his proselytizing, perhaps the few will become many.
Although the study was conducted in an at-risk population being treated for congestive heart failure (CHF) and, therefore, not directly comparable to healthy populations, yet another study has found reduced-sodium diets creating health risks.
A study by an Italian research team led by Salvatore Paterna and Pietro Di Pasquale on "Normal-sodium diet compared with low-sodium diet in compensated congestive heart failure " in the October issue of Clinical Science asks: "Is sodium an old enemy or a new friend?"
Friend, according to the data. Lowering dietary sodium stimulated plasma renin activity (PRA) and aldosterone production.
The normal-sodium group had a significant reduction, P less than 0.05, in readmissions. BNP values were lower in the normal-sodium group compared with the low sodium group (685±255 compared with 425±125 pg/ml respectively; P
When PRA and aldosterone levels are high, multiple studies have shown subjects have significantly higher incidence of heart attacks and cardiovascular mortality.
Thus, the study concluded: "a normal-sodium diet improves outcome, and sodium depletion has detrimental renal and neurohormonal effects with worse clinical outcome in compensated CHF patients."
The 2010 Dietary Guidelines Advisory Committee has begun its five-year review of the science behind the government's recommendations for U.S. food consumers -- all of us!
In its latest Salt and Health newsletter, the Salt Institute examines "The Evidentiary Foundation of our Dietary Gudelines " and finds that foundation is built on sand, not rock. The article recounts a 2007 review of the process by the Institute of Medicine of the National Academy of Sciences which confirmed that the scientific review of the diet and disease data was based on the opinions of respected authorities -- the lowest level of evidence -- rather than on controlled trials of dietary interventions. That review drew on a New York Times Magazine story on "Why can't we trust much of what we hear about diet, health and behavior-related diseases?" The Salt Institute endorses an "evidence-based" approach as opposed to the "opinion-based" recommendations produced in the current process.
It appears that we finally have something that we can agree upon with the Center for Science in the Public Interest (CSPI) . According to a recent article prepared by Merrill Goozner of the at CSPI, and repeated by Marion Nestle in her blog , nearly half the new 2010 Dietary Guidelines Advisory Committee's 13 members have taken funding from the food and pharmaceutical industries. Of common interest is the Chairperson of the Committee, Dr. Linda van Horn, professor of preventive medicine at the Northwestern University Feinberg School of Medicine in Chicago. We are not aware of any conflict of interest involving research funding, however, during the first public meeting of the DGAC, Dr. van Horn recalled an experiment that she had done as a graduate student, which she stated proved without doubt that children who were fed reduced salt diets ended up abhorring the typical salt levels in many foods. Thus, she revealed the personal bias she brings with her as she assumes the chair of a committee tasked with the 'objective' evaluation of all the data on salt and health to be used as a base for future recommendations.
It is interesting to note that CSPI, Marion Nestle, and the preponderance of professionals in the medical community choose to define conflict of interest almost exclusively in terms of funding received from outside (particularly industry) sources. What they seem to totally ignore is the overwhelming bias resulting from personal ego, and a lifelong investment in a particular point of view on a subject. Such an all-consuming passion usually results in a conflict of interest greater than any motivated by research funding. Clinical researchers who have promoted a particular theory for decades are very unlikely to change their minds easily. Many brazenly belong to advocacy groups that publicly espouse their positions. How can they be expected to objectively evaluate data that may make decades of their investment worthless? Yet, there they are - fully prejudiced by preconceived positions - and placed in a position of public trust to make objective evaluations.
Thus, we have one of the greatest hypocrisies in modern medicine - biased researchers sanctimoniously pointing their fingers at the 'conflicts of interest' of others.
Physician, heal thyself.
As we pointed out in an earlier article, the chairman of the sub-committee for Fluid and Electrolytes for the 2010 Guidelines is Larry Appel. Dr. Appel is one of the world's most outspoken anti-salt advocates and is listed as a member of World Action on Salt and Health (WASH) , an advocacy group whose singular aim is: "to achieve a reduction in dietary salt intake around the world." In their justification for salt reduction , WASH focuses almost exclusively on hypertension to the virtual exclusion of all other risk factors and biomarkers responsible for overall health outcomes. They systematically ignore all data (including the Cochrane review and its latest reissue - ) as well as the most recent evidence that demonstrates the net negative health outcomes from reduced salt diets. How any member of such an advocacy group could possibly be selected (much less lead) what is supposed to be an objective advisory group is quite astonishing and black mark on the Institute of Medicine as well as our National Academy of Sciences under which it operates. It is not as if the IOM were unaware of this conflict of interest. They simply choose to ignore it, confident in the belief that they can pass anything off as legitimate science.
And why not? When has the medical establishment ever been called out, no matter how egregious their behavior or advice has been? How many people marched on the IOM or the AMA offices to protest the countless deaths resulting from the hormone replacement therapy fiasco. When it comes to medicine, people suffer silently - and the establishment gets a free pass.
Such hypocrisy does not bode well for the future of objective medical science in this country.
Recently, the Department of Health and Human Services launched their first Physical Activity Guidelines for Americans . This was in direct response to the national obesity epidemic whose effects can be seen everywhere. The U.S. Centers for Disease Control have stated that adult obesity rates doubled since 1980, from 15 percent to 30 percent while childhood obesity has almost tripled during the same time period, from 6.5 percent to 16.3 percent.
While it is great that these new guidelines are here, it is fair to ask why it took so long for them to be published. The answer to that is clear. The responsibility for carrying out physical activity is almost entirely in the hands of individuals. If individuals don't make the effort to do physical exercise, then there is no one to blame but themselves. This is, of course, much more related to adults than children. For children, it is both the home and school environment that is largely responsible for the amount of exercise they do.
Because of the great degree of personal responsibility associated with physical exercise, there has been little attention paid to this issue on the part of consumer advocacy groups, whose political capital is largely the result of finding businesses and large institutions to blame for problems. With reference to the obesity epidemic, consumer advocacy groups invariably blame the food industry for producing high fat, empty calorie foods, and, to a lesser extent, they blame the government for not regulating the industry. It is a very rare occurrence when a consumer advocacy group calls on consumers to bear their share of the responsibility for managing their lifestyle and matching their food consumption with energy expenditure through physical activity.
Thus, while the Physical Activity Guidelines for Americans has just been published, the Dietary Guidelines for Americans is in the process of preparation of its sixth iteration since 1980.
It is strange that it is only since the first iteration of the Dietary Guidelines for Americans that we have experienced the obesity epidemic. This does not say much about the effectiveness of the Dietary Guidelines and the people or institutions that have developed them. Considering what has happened to our physical condition in the last quarter century, one wonders if Americans would have been better off without the Dietary Guidelines. Is it possible that this could have been corrected if the Physical Activity Guidelines were issued at the same time? Not likely.
As much as the Department of Health and Human Services (HHS) and the Department of Agriculture (USDA) assure us that the Dietary Guidelines are evidence-based, they are about the worst example of this that anyone might choose. The Dietary Guidelines are predominantly based upon opinion - the absolutely lowest level of evidence in the hierarchy of acceptable evidence. In fact, some of the evidence upon which the Guidelines are based is so subjective, there have been complaints that certain of the Guidelines should never have been issued. Unfortunately, there are certain segments of our society that have an burning desire to provide guidance, no matter how ill-advised.
If you consider both the Dietary and Physical Activity Guidelines, you will see that they don't really relate to one another. (It is interesting to note that the Physical Activity Guidelines are issued by the HHS alone, while the Dietary Guidelines are issued jointly by HHS and USDA - are there some issues at play here?) While food products carry labels that indicate the energy content (calories) of each serving, it is almost impossible for consumers to easily translate this into the amount of physical activity required to expend the energy taken. People who watch their weight and exercise regularly are an exception. They have a good idea of what extra energy will have to be burned off in order to make up for extra food consumption. If they treat themselves to a few extra chocolate chip cookies, then they put in the effort to jog for an extra half hour in order to burn the calories off.
Instead of putting calories on the food label, why don't they put the physical activity equivalent on, so that people will have an idea of what they have to do to get rid of that additional intake. That is the sort of thing that will link the Dietary and Physical Activity Guidelines together - calories by themselves simply don't convey the energy input/output message to consumers.
Getting consumers to relate their diet to physical activity and energy expenditure is not rocket science. It does, however, require a sensitivity to the needs and awareness of consumers rather than a focus on political expediency and a compulsion to give advice by a medical establishment that has still to learn what food and nutrition are all about.
Britain's Food Standards Agency (FSA) has a target to reduce average salt intakes across the population to 6g per day by 2010. It selected its targets, it says, on surveys from 2000-2001 claiming British men consume 11 g/salt/day and women, 8.1 gpd. The agency announced July 22nd the publication of a survey of Britons' urinary sodium -- the "gold standard" measure for salt intake, "which shows the UK's average daily salt consumption has fallen from 9.5g to 8.6g since 2000." FSA termed the results "an encouraging decline in salt levels," but conceded its pace would fail to achieve the 6 gpd target in 2010 so it unveiled a consultation to "make its voluntary 2010 salt reduction targets, for 85 categories of food, stricter, and set more challenging 2012 targets, for 80 categories of food."
Entitled "An assessment of dietary sodium levels among adults (aged 19-64) in the UK general population in 2008, based on analysis of dietary sodium in 24 hour urine samples," the methodology explains the care taken to secure accurate samples and analysis. So, we can be pretty sure that the 2008 number is sound. The study actually didn't find 8.6 grams, but rather 8.728 grams; it is expressed as 148 mmol Na (a millimole of sodium being equal to 23 milligrams; this assumes, as they mistakenly do, that all the sodium comes from salt, which it doesn't -- no matter). So they misled on the achievement, but still, reduction from 9.5 grams salt (161 mmol Na) would be an impressive achievement. Indeed, FSA continues to boast that it "is encouraged that action to reduce the average amount of salt we are eating on a daily basis is clearly having a positive impact." This, of course is not the proper metric: salt reduction isn't an end it itself. The "positive impact" would be reduced incidence of heart attacks or better than projected cardiovascular mortality -- no matter, here.
The deception arises in the 9.5 gram (16 mmol) "starting point" which turns out to be a phone survey, not a carefully controlled collection of 24-hour urine samples with quality analysis (as was done in 2008).
Fortunately, we have another exceptionally well-done survey of a representative British population. And from a good deal more vantage point so we can see just how much improvement has been recorded. Its size is nearly comparable, 754 in the 2008 survey and 598 in the Intersalt Study published in the British Medical Journal, July 30, 1988. Intersalt sampled three British populations, carefully collected 24-hour urine samples and had them analyzed in a single laboratory. The results? One population had 149.9 mmol; one 150 mmol; and the third, 151.8 mmol. A far cry from the FSA's claimed 2000-01 starting point of 161 mmol. Instead of a 13 mmol reduction to 148 mmol, over the past 20 years Briton's have changed their salt intake virtually not at all (2 mmol, probably within the margin of error).
All evidence suggests that sodium/salt intakes are largely unchanged in most populations over the past century. The high-salt consuming Finns and Japanese claim signficant reductions, but it does lead one to wonder if the "starting points" are valid in those cases.
So, when FSA makes these bold pronouncements of their "progress" in reducing cardiovascular disease in the UK by cutting salt intake, take it with a grain of salt. Ask whether beating up food manufacturers about reducing salt in their foods is really working. Is a 1.3% reduction over twenty years (even if true) worth the effort? Even using the much-lower "real" starting point, the current pace would have Britons' achieving a 6 gpd target not in 2010, but a bit further down the road -- in 2205 if the current trend can be sustained. That is, another 197 years, not two, before reaching the target of 100 mmol (6 gpd of salt). They admit they're behind schedule, but that may just be classical British understatement, right?
Let's be honest in interpreting the data. FSA has made NO PROGRESS despite the enormous pain it has inflicted on British food manufacturers and diverting resources to supporting "Sid, the Slug" has postponed real progress in improving Britons' health. No wonder FSA prefers to make up number about salt intake than face the proper challenge of improving public health.
The UK Food Standards Agency (FSA) conducts mini surveys amongst consumers on a quarterly basis in order to monitor changes in consumer attitudes towards food related issues. The latest survey was just published and there were some interesting surprises.
Despite a costly public relations campaign demonizing salt, including many television ads, which named and shamed manufacturers for the salt content in their foods, the latest mini survey revealed that consumer concerns over salt has dropped dramatically. In fact, consumer concens with salt are at their lowest level since December 2003 - years before the FSA began its aggressive anti-salt campaigns, including "Sid the Slug " and "Your Food is Full of It ."
Bravo to the British consumer. It is a fitting tribute to the quote, "You can fool some of the people…."
Terri Coles of Reuters (Toronto) recently wrote an interesting article on the new Dietary Guidelines. Coles is one of the few writers who wisely made reference to the Yeshiva University study , written by Marantz, Bird and Alderman, from the Albert Einstein College of Medicine and published in January, 2008 in the American Journal of Preventive Medicine. The authors wrote that the members of the Dietary Guidelines Advisory Committee should use explicit standards of evidence in making their nutritional recommendations. If not, their recommendations could end up producing unintended consequences that may have a negative impact on public health.
Most importantly, the authors proposed that there should be alternative and more rigorous standard for evidentiary support, and went as far as to state that when adequate evidence is not available, the best option may be to issue no guidelines . Now, how courageous is that?
Imagine - saying that you should not make any recommendations until you have reliable data - extraordinary!
The New York Times, like the Washington Post, loves to "blow the whistle" on bad actors, be they corrupt politicians, greedy businessmen or hypocritical "public interest" groups. Yesterday's Science column by John Tierney on "'Misleading' Research From Industry ?" revisits a subject of repeated comment in our blogs. We've pointed out that every funding agency has an agenda when it ponies up to support health-related research. The solution: examine the methodology and the integrity of the analysis. Too often, industry-funded studies are dismissed for bias while government-funded studies are given a free pass (despite numerous examples of why they shouldn't).
Tierney briefly reviews the disparagement of industry-funded studies, lamented by the British Medical Journal as creating a "hierarchy of purity among authors," and reports:
Now some researchers have looked to see what kind of hierarchy actually exists. After analyzing weight-loss research conducted over four decades, they've found that the quality of data reporting in industry-sponsored research does seem to be different from that in other research: It's better.
The study, published in the International Journal of Obesity , concluded: "while continued efforts to improve reporting quality are warranted, such efforts should be directed at nonindustry-funded research at least as much as at industry-funded research."
Ironically, the article appeared concurrent to the first meeting of the new 2010 Dietary Guidelines Advisory Committee whose salt subcommittee chair has enjoyed millions of research dollars leading to reports that endorsed the official government policy of universal sodium reduction while specifically opposing release of the data in those studies for independent expert analysis. So, if the Gray Lady wants another whistle-blowing target there are surely many choices.
Before the age of science, the influence of the classical Greek philosophers was so overwhelming that their simple opinions were taken as divine edicts. Anaximander (610-647 BCE) spent a good part of his life teaching students that animals were miraculously formed out of pure moisture and Aristotle (384-322 BCE) proposed that animals spontaneously arose out of soil, plants or even other species of animals. These opinions resulted in the theory of the 'spontaneous generation' of life, which held sway until the Middle Ages and beyond. Even Van Helmont (1578-1644), the famous Belgian physician and chemist, recorded detailed recipes for the preparation of spontaneously generated mice. For 2,000 years, polemics were the only means of explaining nature, for never once in the history of the debate had anyone ever thought of actually carrying out experiments to prove or disprove the validity of their theories. Francis Bacon (1561-1626) was among the first to seriously question these dogmatic theories and insisted that only careful experimentation and precise observation would lead to the truth. He became the period's most eloquent proponent of methodical experimentation and has often been referred to as the 'Father of the Scientific Method'.
In applying the scientific method to the practice of medicine, the notion of "evidence-based" medicine developed. Although it is not a new concept, it has had a renaissance in recent years, and now everyone refers to their brand of practice as evidence-based medicine. The one institution that rigorously adheres to the strictest principles of evidence-based medicine is the Cochrane Collaboration . Unfortunately, within other organizations, the term "evidence-based" is often used rather loosely and routinely ignores the rigorous discipline upon which the practice is based. What is worse, there is a lack of understanding of what quality evidence actually is. The following is the accepted understanding of the hierarchy of evidence to be used in making evidence-based evaluations:At the very bottom of the quality of evidence pyramid are ideas and opinions. They are exactly the sort of pronouncements that Bacon railed against. Even expert opinion cannot be compared to scientifically generated evidence. Yet, the Dietary Guidelines and the Dietary Reference Intakes (DRIs) upon which the Guidelines are established are predominantly based on opinion - the lowest level of evidence. In fact, when the initial call for comments to the Dietary Guidelines Advisory Committee was announced, our input focused squarely on that issue. Quoting from "The Development of DRIs 1994-2004: Lessons Learned and New Challenges ," our comments (comment ID 000010) highlighted what a number of scientists originally involved with the development of the DRIs were now saying - that we have to get away from expert opinions and start basing our judgments and policies on much more rigorous science.
Unfortunately, that is not what we witnessed at the first meeting of the Dietary Guidelines Advisory Committee (DGAC) meeting held October 30-31, 2008.
As was the case with the 2005 Dietary Guidelines, the chairperson of the sub-committee for Fluid and Electrolytes for the 2010 Guidelines is Larry Appel. As it happens, Prof. Appel is listed as a member of WASH , an advocacy group whose singular aim is: "to achieve a reduction in dietary salt intake around the world." In their justification for salt reduction, WASH focuses almost exclusively on hypertension to the virtual exclusion of all other risk factors and biomarkers that are responsible for overall health outcomes. They systematically ignore all data (including the Cochrane review and its latest reissue - ) as well as the most recent evidence that demonstrates the net negative health outcomes from reduced salt diets . How a member of such an advocacy group could be selected to lead what is supposed to be an objective advisory group is quite astonishing.
At the opening meeting, Appel made his presentation to the Dietary Guidelines Advisory Committee selectively picking all evidence that supported his salt reduction agenda and ignoring all else that didn't. He mentioned a number of NHANES studies, but ignored the most recent one as well as all others that did not agree with his opinion.
When another DGAC member brought up the issue of the possible negative consequences of reduced iodized salt consumption, Prof. Appel repeated a statement he made at a recent FDA hearing. "There is no problem with iodine in this country. We don't have goiter anymore." This was a typical Greek philosopher's statement. As it happens, our iodine values have been dropping steadily during the past 30 years, and although they are not yet at a level that would be considered a public health emergency, they are tending that way . As a result of Appel's pronouncement, there was no further discussion of the iodine issue.
All in all, the first meeting of the DGAC was a great disappointment. It appears that we are once more headed towards a series of recommendations that will result from a process based far more upon opinion than on scientifically-derived evidence. It was like retreating to the notion of spontaneous generation. This is just not on, and we will continue to do whatever we can to ensure that this process get back on track and be the product of objective science, not subjective personal opinion.