In an excellent attempt to provide a balanced view of the salt and health debate, Kevin Lomangino, editor of Clinical Nutrition Insight reviews several sides of the matter in the May 20, 2008 edition of the bulletin . He correctly states that a number of physicians feel strongly that the reduction of salt intake would provide significant benefit to the overall health of the population. However, he immediately follows on to say that there are other well-known physicians that dissent from this point of view.
But while the maneuverings on the political and media fronts would suggest that the science on salt settled, a thorough search of the literature shows that this is not yet the case.
Lomangino goes on to quote Doctor Alexander Logan, professor of medicine at the University of Toronto, Ontario, who stated in an introduction to the 2006 Journal of the American College of Nutrition supplement about dietary salt:
Until better information is available, evidence supports a public-health dietary policy that focuses on improving diet quality in the entire population and recommends a different target intake levels for sodium based on individual susceptibility to salt.
The article describes that several influential medical practitioners would like to see a major study on the impact of sodium restriction on health outcomes while, on the other hand, some believe that it is unnecessary and expensive. Dr. Michael Alderman, professor of medicine at the Albert Einstein College of medicine and Past President of the American Society of Hypertension believes that proceeding to implement a salt reduction policy without such a study is very risky.
To experiment on 300 million people on issues that might cause harm... it's just not sound scientific policy.
The article went on to say that Dr. Alderman was very concerned that people have stopped looking at the paucity of evidence supporting salt reduction policy and that they are simply looking at the means of implementing one.
With the US presidential campaign focusing so much on character (Obama's embrace of his racist preacher, Clinton's embellished "experience," McCain's unpredictable "maverick" tendencies), one can lose track of some very real issues that divide the candidates. These aren't limited to the economic issues, but that's today's focus. This week Congressional Democrats tied themselves squarely to the anti-free trade crowd with Speaker Pelosi refusing a vote on the Columbian free trade agreement (which Bill was for before Hillary was against). Hovering just under the radar is, aguably, the biggest divide: the Bush tax cuts. Democrats only accepted the cuts because they included in the package a provision that automatically restores the original tax rules and rates at the end of 2010 unless another law supersedes the one on the books. Democrats have loudly proclaimed the tax cuts as a Republican give-away of the federal treasury while Republicans crow that the cuts ended the recession that began in the last year of the Clinton presidency and is needed to sustain our economic growth.
The April 21 edition of National Review (subscription required) examines the historic tax take of the national governments of the US and its OECD partners. An excerpt illustrates, but please keep reading because I'd like to draw a parallel to an issue regarding salt. NR's Kevin Hassett wrote:
As reporters sort through these debates, they must write at a far lower level of sophistication than that of the studies in question. Since New York Times readers don't know econometrics, they are instead offered pseudo-analysis. The economists who agree with supply-side economics are generally described in terms to suggest that they are nut jobs. Those who disagree with supply-siders are "distinguished professors" or "senior fellows" at "nonpartisan" institutes. We are invited to judge, not the arguments, but the reasonableness of those who make them - and it is clear what our judgment is supposed to be. But interestingly enough, it's possible to determine with some precision whether a policy has been formulated by nut jobs. To see how, consider the following statement: "U.S. fiscal policy in recent years has deviated wildly from fiscal policy in other developed nations." If that's true, one can presumably make the case that U.S. policymakers have ignored policy norms. (This is of course just what one would expect nut jobs to do.) If the claim is false, however, then it's rather harder to claim that American fiscal policy is in the hands of kooks.
Let's apply that method to the question of income-tax cuts. The nearby chart depicts recent trends in the share of GDP that governments collect through income taxes. The purple line represents the U.S.; the blue line represents the average for large developed nations in the OECD, excluding the U.S. And the story is clear: For most of recent history, the U.S. share was about equal to that of the OECD generally. It did deviate wildly at one point - in the second term of President Clinton, when the U.S. was collecting a markedly higher percentage of its GDP in income-tax revenue than were its fellow OECD members. But the Bush tax cuts returned us to normalcy.
The "salt" issue? The policy debates over whether the entire population should be encouraged to reduce dietary salt often comes across as a debate with an empty chair. Proponents of this intervention are content to point to their accepted "expert" status and insist that their informed opinion should determine the policy question. These are the "distinguished professors" etc of Mr. Hassett's narrative. By no means all, but some of these activists have tried to marginalize the equally-distinguished experts who argue that no evidence shows low salt diets will improve public health. They duck the issue and try to dismiss opposing scientists as somehow less informed or, surely, more biased -- in short, akin to the "nut jobs" Mr. Hassett describes (though none of them have stooped that far to date).
The parallel? Mr. Hassett graphs the data. That's what we should be doing too: looking at the data. Those data can tell us a lot more than the "expert" opinion of those who cannot or won't deal with the real evidence. Let's stop talking with the empty chair. The public deserves better.
The April 10 issue of the Harvard Medical School 's HealthBeat offers "diet tips for lower blood pressure." We wish they'd wake up that the real issue isn't "blood pressure," but "improved health." Still, the glimmerings of awakening are discernible. Let me add boldface to the relevant parts of the complete text for the tip: "Consume less salt":
Doctors first noticed a link between hypertension and sodium chloride - the most common form of dietary salt - in the early 1900s, when they found restricting salt in patients with kidney failure and severe hypertension brought their blood pressures down and improved kidney function.
Federal guidelines advise people to limit sodium intake to 2,300 milligrams (mg) per day - about the amount in 1 teaspoon of table salt. Yet Americans typically consume 1 to 3 teaspoons, or as much as 7,200 mg a day. This fact, coupled with the high prevalence of hypertension in the United States, led researchers to assume that salt overload was the culprit.
As it turns out, this may or may not be true. Nearly 50% of people who have hypertension are salt-sensitive, meaning eating too much sodium clearly elevates their blood pressure and puts them at risk for complications. In addition, people with diabetes, the obese, and older people seem more sensitive to the effects of salt than the general population. However, the question of whether high salt consumption also puts generally healthy people at risk for hypertension is the source of considerable debate. Regardless of whether high salt intake increases blood pressure, it does interfere with the blood pressure-lowering effects of antihypertensive medications.
Baby steps forward.
Newspapers today reported on work being carried out at Glasgow University on the relationship of aldosterone to blood pressure . The research was presented at the annual Society for Endocrinology BES meeting in Harrogate , UK. The initial research indicates that in older people, higher levels of aldosterone in the bloodstream are associated with high blood pressure .
In a paper entitled, "Aldosterone and cardiovascular function: a lifetime of damage ," Dr. John Connell , who is Professor of Endocrinology at the University of Glasgow and Head of the of the Medical Research Council's Blood Pressure Group, based in the British Heart Foundation's Cardiovascular Research Centre in Glasgow described how an excess of aldosterone greatly increases the risk of stroke and heart failure, thus explaining the results of several previous research studies that revealed more cardiovascular patients dying on low salt diets than on regular diets.
Professor Connell said:
"Aldosterone is a key cardiovascular hormone. The higher the level of aldosterone in your blood, the more likely it is that you will suffer from high blood pressure, which will increase your risk of suffering a heart attack or a stroke."
The research revealed that in older people, higher levels of aldosterone in the extracellular fluid are associated with high blood pressure. In young adults, high aldosterone levels predict that they will be more likely to develop hypertension later in their lives. There are a number of factors that determine elevated aldosterone levels in humans, including low birth weights, genetics and diet. More specifically, insufficient salt intakes will stimulate the renin-angiotensin-aldosterone system (RAAS) to produce more aldosterone in order to conserve the body's cache of sodium in order to retain osmotic balance.
Elevated aldosterone levels mean that throughout life, certain individuals will be more prone to developing high blood pressure, arterial stiffness and cardiovascular disease. Connell's previous research indicated that aldosterone may be a causal factor in 10% of UK patients with high blood pressure*.
It is difficult to understand why the UK Food Standards Agency, the EU Commission and the Health Canada are all deliberately ignoring this research in their drive to reduce the levels of salt consumed. The mechanistic research work on the malignant role of elevated aldosterone levels upon the cardiovascular system brings far more weight to the salt and health outcomes question than the highly promoted, yet scientifically flawed epidemiological studies on salt and blood pressure.
The human body is an organism governed by biological mechanisms and no amount of bias, hype or imprudent policies will change this. ______ *Connell, J.M.C., Davies, E. 2005. Journal of Endocrinology, 186, 1-20.
Aldosterone is the primary mineralocorticoid hormone in humans. The mineralocorticoids are those steroid hormones, secreted by the adrenal cortex that regulate the balance of water and electrolytes in the body. Working at the distal tubule and collecting ducts of the kidney, aldosterone increases the permeability of their inner membranes to sodium and potassium and is responsible for reabsorbing sodium (Na+) ions and water from the urine back into the blood, while secreting potassium (K+) ions into the urine. Aldosterone is responsible for the reabsorption of virtually all the sodium content in human blood under normal kidney filtration function. Aldosterone also acts on specific receptors in the brain to conserve water and salt by controlling renal tubular resorption.
Unfortunately, chronic high levels of aldosterone in the blood can have major negative consequences for the cardiovascular system, including to induce myocardial fibrosis, renal damage and stiffening of the arteries.
After its discovery more than 50 years ago, the medical interest in aldosterone has been dramatically renewed because of it's immense impact on the cardiovascular system. Aldosterone is now considered to be the most important cardiovascular hormone in the human body.
As an integral part of the renin-angiotensin-aldosterone system (RAAS), a key function of aldosterone is to conserve salt (sodium chloride), when an insufficient amount is consumed. The latest research published in Clinical Endocrinology indicates that for most healthy humans, anything less than 6 g/day of salt (2300 mg sodium) will be insufficient to prevent the RAAS system from kicking in. That's right - anything less than 6 grams of salt a day!
But the Dietary Reference Intakes recommends that an adequate intake of salt is 3.8 g/day of salt - not 6 g/day. In fact, the dietary reference intakes state that 6 g/day of salt is the tolerable upper limit of salt intake. How can one recommendation state one figure for a maximum intake while the scientific research indicates that very same figure is a minimum intake?
Perhaps the answer lies in the paper given at the Institute of Medicine workshop "The Development of DRIs 1994-2004: Lessons Learned and New Challenges" held in Washington September 18-20, 2007 by Dr. Peter Greenwald, Director of Cancer Prevention at the National Cancer Institute of the National Institutes of Health. Dr Greenwald described how most of the figures behind the recommended dietary intakes were based upon expert opinion (the lowest quality evidence) rather than randomized controlled double blind clinical trials (the highest level of evidence).
"Little research of the most useful type (randomized clinical trials) is available, whereas there is an enormous amount of information that is not very meaningful. This needs to be reversed."
Later Dr. Greenwald goes on to say:
"To underscore the importance of "getting the science right," we need only turn to a recent article in the New York Times Magazine written by a respected science reporter. It was entitled "Why can't we trust much of what we hear about diet, health and behavior-related diseases?" (Taubes, 2007). The reporter includes several examples, many in nutrition epidemiology, where there is so much conflicting evidence that people do not believe it. Clearly, we have a serious problem, and we must push for the conduct of definitive studies before we make pronouncements on public health."
As noted in an earlier article, the latest evidence reported by Shapiro, Boaz et al from the Tel Aviv University Medical School reveals that healthy young adults who have been asked to limit their salt intake to 6 g/day (2300 mg sodium) were found to have elevated aldosterone levels indicating that their bodies were in a salt conservation mode. Unfortunately, these elevated levels of aldosterone quickly led to stiffening of the arteries. The conclusion was that for healthy young adults, the Dietary Guideline tolerable upper limit for salt was insufficient to prevent stimulation of aldosterone production. What would happen if the population actually consumed the level of salt recommended by the Guidelines? Would we be condemning an entire population to premature arterial stiffening? Would the government take responsibility for this or would it somehow contrive to blame the food industry for this problem?
In Europe, the EU Commission, led in large part by the UK and its Food Standards Agency has decided that public policy to reduce salt intake will trump basic human physiology. Charging forward pell-mell, the EU Commission, deliberately ignoring the latest scientific evidence, believes that they could not possibly go wrong on this issue because of the support of medical advocates, who have long ago given up any pretence of scientific objectivity.
The world has seen, time and again, that we ignore the science at our peril and as usual, consumers will end up being the victims.
The EU Commission has set the stage for the largest nutrition experiment ever carried out in history with the half billion citizens of the European Union expected to serve as the guinea pigs. When the compulsion to be seen as a driving force for change grabs policy makers by the throat, there is little left to do but allow that change to take place, regardless of the potentially disastrous consequences.
Not wanting to be perceived as being left out of this salt-reduction policy wave, Canada is set to follow suit - again totally ignoring the science and putting Canadian citizens at an elevated risk. One would think that some caution would be in order, but once again, backed by medical advisors and institutions that have done far more advocacy than homework, the government believes it cannot lose on this issue. Since when does ignoring the science and putting a population at an elevated risk give the Government a free pass?
So here we are, in the early part of 2008, with the drumbeat of scientific evidence piling up that the dietary guideline recommendations for sodium are largely irrelevant for the general population and insufficient to prevent production of elevated levels of aldosterone. For the majority of the people, salt, like water is a self-limiting nutrient. We know that aldosterone, chronically maintained at elevated levels as a result of reduced salt intake, will have major negative consequences on the integrity of our cardiovascular system. Like the mythical lemmings that march inexorably over the cliffs to their watery demise, it appears that the EU and Canada are on a track guided by what they don't know, rather than by what they know - by urban myth and prejudice rather than science.
It is hoped that the new Committee selected to establish the Dietary Guidelines for 2010 will not feel obliged to make poor quality, knee-jerk decisions based upon subjective opinion and search out the most current scientific data upon which to establish their recommendations. Our health is at stake here.
Today's Washington Post "word of the day" is "un-an-tici-pat-ed" which staff writer Paul Farhi defines as "lacking foresight in hindsight."
Examples abound. He notes the U.S. military's missteps in Iraq, the D.C. treasurer's problem with escalating bond interest rates, UCLA's point guard's observations about the shooting accuracy of the Mephis Tigers' basketball team in the Final Four semis, Barack Obama's 20 year association with his fiery minister and Hillary Clinton's faulty sniper fire memory. Best, it seems:
While he was press secretary for President Bush, Tony Snow was constantly fending off media questions that implied that officials should have anticipated the unforeseen, he says. "Everyone plays that game," Snow says. "It's always taken as a sign of your incompetence, cupidity or callousness if you didn't anticipate a million different reactions."
Snow says he tried to avoid we-didn't-anticipate responses to questions about the administration's policies because "it probably sounds defensive." Instead, he says, he tried to explain the context in which decisions were made -- what the facts, goals and priorities were at the time -- and let others engage in "retroactive perfectionism."
As toxic as is "retroactive perfectionism," so is our inability to recognize that our understanding DID err and our perspective should become more "perfected." So we don't exactly agree with Farhi who rejects the Tony Frost worldview. He quotes Grant Barrett, the editor of the Oxford Dictionary of American Political Slang.
It's a buck-passing maneuver and a tacit admission of failure"...
"It really means that you didn't have foresight, that you didn't plan well, that you were ignorant before and that you're confessing that you're not ignorant now," Barrett says. "You're basically providing your opponents with the wedge in which they'll place their hammer and chisel to chip away at your credibility. You might as well draw up your letter of resignation."
Often, Barrett says, we-didn't-anticipate can give the perception that you just ignored someone else's anticipation.
We're big into transparency and accountability, but we cannot agree with Farhi. Sure, in many decisions we make, the easy-out of "unanticipated consequences" must be rejected. After all, how "unanticipated" is it that our social values have demographic consequences? That economic mobility in America re-shuffles the poverty "quintiles" every decade? That earmarks "buy" Congressional votes? That disparaging certain foods results in diminished intakes of not only the complained-of nutrients, but all those in that food? The list is endless and reinforces George Santayana's observation that "Those who cannot learn from history are doomed to repeat it."
Unanticipated consequences, however, are also how we learn. Particularly in science, the discovery that the hypotheses is NOT confirmed shouldn't be an occasion for mourning; celebrate the advance -- one less dead end to pursue. Truth is like an onion being stripped away layer by layer, so disposing of the discarded layer of only partially-understood truth is an advance.
So is it, for example, with our understanding of the role of dietary salt and health. We know all healthy bodies require salt. We know that salt is related to blood pressure. We know that populations with lower blood pressures have less risk of cardiovascular events and mortality. Our investment in studies to examine the question of whether lowering intakes of salt will lower the rates of heart attacks and strokes have been worthwhile -- even if they've produced the contrary, "unanticipated consequence" that the evidence does not support a link of lower sodium diets to improved health. Rather, the resesearch has unmasked other "unanticipated consequences" that we now know well occur when dietary salt is reduced: insulin resistance rises, the kidney produces the hormones renin and aldosterone. "Unanticipated" at one point, they have been predictable for a couple decades now. So, let's face facts and get on with our pursuit of truth. It doesn't look like reducing dietary salt is going to reduce cardiovascular risk. Don't believe it? Fine. Let's test the proposition -- a solution we suggested to HHS nearly two years ago, "up close and personal" after having voiced the recommendation publicly even earlier.
Even worse that the mea culpa that US preventive medicine couldn't have foreseen the "unintended consequences" of low salt diets that has neutered the expected benefits (and perhaps even reversed them such that a number of studies have found greater risk for those who cut back salt ), is the unexcusable insistence on pursuing this discredited strategy and pretending that the "unanticipated consequences" aren't actually happening.
That's what prevented the Bush Administration from recognizing the need for its new strategy in Iraq and what sent UCLA's basketball team home last Saturday. Things may not turn out the way we believe going in. Get over it. Move on.
A cogent op ed piece in yesterday's Washington Times by Elizabeth Whelan, president of the American Council on Science and Health , voices an observation often registered in this blog: all research reflects the "agenda" of the agency that funds it; the important thing is the quality of the science and the evidence supporting its findings. In "'Conflict' chills research ," Whelan concludes:
A new scientific McCarthyism is alive and well in America today...
The current trend toward cleansing government panels of scientists with any taint of industrial support will leave scientific debate in the hands solely of those who pass the politically-correct test. Credentials, accomplishments, and expertise will be superseded by a candidate's anti-business credentials and leanings. Their adherence to an anti-chemical, anti-business philosophy and the precautionary principle will bring progress to a grinding halt. Is that how we really want crucially important scientific decisions to be made?
In reaching these conclusions, she identifies four reasons why a false "dichotomy of 'good' science versus 'suspect' science based on funding is not only misguided and hypocritical, but - if allowed to dominate the peer-review process - will have an insidious effect on future collaboration between academic scientists and corporations, collaborations that would benefit all of us." Her rationale is right on target:
(1) The decision to regard industry funding as some uniquely corrupting force overlooks the reality that bias can be introduced into science in many forms - not just through corporate funding. Why would a consulting history with Pfizer or DuPont be more a source of potential bias for a researcher than a history of membership in environmental-activist groups like Greenpeace or the Natural Resources Defense Council? Why is corporate funding more suspect than funding from innocuous-sounding but agenda-driven private foundations, such as those committed to ridding the nation of what they perceive to be nasty industrial chemicals? These ideologically fueled foundations are rolling in endowment money and happy to support anti-business researchers in publishing junk science in their custom-made, obscure journals.
(2) There are myriad nonfinancial factors that can influence scientists and impair their objectivity, from strongly held political convictions to the desire for glory in a given field to a "cognitive dissonance factor," which causes a researcher who has spent years trying to prove a point to skew data to yield the desired conclusion. Even a well-meaning scientist operating with no knowledge at all of his financial base of support can be misled by his lifelong, passionate commitment to a given theory and his desire to prove it correct.
(3) The current obsession with corporate ties as a "conflict of interest" is not harmless. It has led to regulations and restrictions in government and academia that have restricted scientists, preventing collaboration with external scientific experts and slowing development of new technologies. Such arbitrary guidelines stifle the progress of public health. Government agencies are being denied access to the best available scientific advice if only those who can claim an "industry-free" resume are left in the candidate pool.
Corporations choose the top scientists when they seek advice - and it is often the less-accomplished scientists, those never sought as consultants or whose beliefs made them averse to contact with corporations, who are left as panel candidates.
(4) Finally, the obsession with "transparency" regarding funding sources has come to obscure what is truly important about scientific research: the quality of the research process and the legitimacy of the findings. If a study is done meticulously and accepted for publication in a peer-reviewed journal, why does it matter who funds it? Does the mere fact a study is funded by a corporation (even an odious corporation) make its conclusions invalid?
There's a new public recognition of the link of salt and health, a "saline solution." As described in our blog back in January, salt-lined "caves" are the latest "in thing" in this week's Time Magazine's Living section. Reporter Jennine Lee-St. John seems to be on a mission to convince Time's readers that the halotherapy in Chicago's Galos Caves replicates the longstanding success of treating Eastern Europeans suffering respiratory ailments with recuperative sessions in salt mines. But it's stress relief that attracts US Midwesterners, not relief from air pollution. Lee-St. John describes the attraction as a "quest for holistic relaxation."
Arguing that TV chef Delia Smith's recipes are "loaded with salt," Dr. Graham MacGregor and his Consensus Action on Salt and Health have attacked them as unheathy. MacGregor's crocodile tears flowed as he declared "It's a real pity she seems to be unaware of the dangers of eating too much salt."
What is truly pitful is the easy acceptance of the flawed underlying premise that foods (even diets) "high" in salt -- meaning the diets freely chosen by 6 billion inhabitants of this planet -- are "unhealthy." But don't get us started. See other posts on this blog, the Salt Institute summary or the presidential address at the International Society of Hypertension if you prefer the non-fiction version of this book.
Now's no time for jokes about the taste of British food. Apparently it's not John Bull, but John bullied.
Our society -- and our government -- puts itself at a disadvantage when it substitutes political judgments for scientific evidence (on this see numerous past quotes in this blog). In the areas of human and ecological health, we can certainly apply human judgments and expend lots of taxpayer resources, but, ultimately, nature has its own way, whether in human physiology or the natural laws governing the ecology of Mother Earth.
That's not to say we always understand why our bodies do what they do or how nature will respond to our interventions. Sometimes there are unintended consequences. Sometimes they're serious. Often they're precipiated by the same kind of hubris as some judge has prompted American interventionism abroad: a confidence that our policies can overcome all the world's ills (or all our bodies' infirmities). And often the prescription is to take a step back, look at the problem at hand with the greatest humility we can muster and sort out fact from fiction about what we "know." Painful experience has taught us that worse than a policy grounded on ignorance is a policy grounded on error because we employ our powerful resources and worsen the inintended effect.
For that reason, the integrity of the process we employ to ascertain scientific truth in our public health and our environmental policies is of paramount importance.
And for that reason, we should give attention to the challenge announced in today's Washington Post , that Congressional leaders are probing the actions of the U.S. Environmental Protection Agency which removed as chairman of a science advisory committee a scientist accused of having pre-judged the evidence and openly advocating one of the policy options before her advisory committee.
Congressmen John Dingell (D-MI) and Bart Stupak (D-MI) have defended the principle of scientific objectivity and bashed the Bush Administration for heeding a complaint by the American Chemistry Council that the panel chair's activist agenda undermined the public interest in an objective scientific inquiry. We should all embrace with enthusiasm the principle being articulated that science should be insulated from politics and the tyranny of conventional wisdom that so often cloaks its minions. So, we should read beyond the headlines and try to understand what's going on.
If the Congressional overseers are taken at their word, their dedication is to scientific truth and their complaint is the interference of "politics" in the process. Kudos. On the other hand, the industry advanced the same arguments in its complaint of prejudice -- the ACC sought elimination of an crusader from a position that would seem well-served to preserve the neutrality of scientific inquiry. So, strip away this veneer of rhetoric and look for other clues. Surely, the industry group didn't like the advocacy position of the now-deposed chair; that's a given. And, likewise, busy Congressmen don't have time to meddle into bureaucratic decisions they agree with, so Messers Dingell and Stupak are registering their views on the other side of the policy divide on this particular action. But what of the process? How can we create a process that elicits for the public good the best, most objective science to help us understand issues and fashion policy?
Beneath the veneer of the Congressional assault is a second justification that seems to illuminate the issue perfectly. The Congressmen, joined by the activist Environmental Working Group, complain bitterly that other panelists (presumably those taking the contrary viewpoint) have had their research funded by private industry. The implication is that the deposed chair didn't. Since scientific stature is constructed on the foundation of published research and that costs money, the chair must have derived her research support elsewhere, probably from the federal government which is the other large funder of research. So, if the thinking is to take the Wooodward & Bernstein approach of "follow the money" the agenda or policy bias of the funder becomes paramount. But we should accept the principle that every funding source has an objective and interests. The Congressmen apparently aren't bothered by the chair's source of funding, perhaps because it's the very funding source that they have provided as they authorize and appropriate. So it's really THEIR interest, perhaps, or the bureaucracy's, that's behind "public" money.
The better solution is transparency and, even more, the integrity of the process. We need standards such as those, in the medical science area, advocated by process-oriented watchdogs like the government's U.S. Preventive Services Task Force. Industry funding and government funding are both facts of life, both have inherent potential bias. The integrity of the process is assured by the quality of the science at the end of the pipeline. That's why we've always embraced the Data Quality Act as a means to overcome politicizing science.
On February 18, 2008 we reported that less than 20% of US adults with high blood pressure eat foods in line with the government guidelines for controlling hypertension (the DASH diet). Now, the of major dietary trends in US food consumption from 1972 - 2005 carried out by the Economic Research Service of the US Department of Agriculture indicates that this poor dietary pattern is reflected throughout the whole of the population.
The Dash diet, which was specifically designed as a dietary approach to reduce hypertension is, in essence, a well balanced diet. It is high in fruits and vegetables as well as low-fat dairy products and whole grains. The amounts of high fat foods (particularly those with saturated fats) and refined carbohydrates are limited.
This type of diet has long been consumed in the Mediterranean and to a lesser extent the Asian regions, with clearly positive health outcomes. Unfortunately, the latest USDA study indicates that the majority of Americans consume too few fruits, vegetables, low-fat dairy and whole grain products.
A large part of our dietary pattern is influenced by the messages we receive from those institutions we perceive to be authoritative. However, organizations such as the American Heart Association (AHA), the American Medical Association (AMA) and the National Heart Lung and Blood Institute (NHLBI) in their approach to the reduction or prevention of hypertension have all chosen to focus their attention on salt reduction far more than the promotion of a good, balanced diet. Even the most well-known food advocacy groups prefer to lay blame on one nutrient or food group rather than to promote the benefits of a balanced diet.
Until we come to a general understanding that it is far more beneficial to promote the benefits of a whole, well-balanced diet, rather than to isolate and malign single nutrients or foods out of context, results such as those from the USDA/ERS report should not come as a great surprise.
This month's issue of Physiological and Biochemical Zoology (you all do read that, dont' you?) carries an important story of enduring signficance about how curtailed dietary intake compromises the immune systems of deer mice. Researchers Lynn Martin et al of The Ohio State University report that cutting back just 30% of dietary intake "reduces secondary antibody responses in deer mice (Peromyscus maniculatus), functionally representing a cost of immune memory." Ohio State's been doing some good work in nutrition recently.
The results are another recurring reminder of this lesson long-taught and repeatedly-reminded: there are very real physiological costs in terms of unintended consequences in reducing "normal" dietary intakes. It's been more than 20 years, for example, since Dr. Mark Cook of the University of Wisconsin published results that curtailing salt intake in chickens impaired their immune system function . That's before most of the world woke up to the AIDS catastrophe.
Today's news services ran an interesting story regarding the recommended dietary intakes for water of 9 - 13 cups as highlighted in the Institute of Medicine's Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2004) . CBS , NBC , ABC , the BBC, the Guardian , the Telegraph and Daily Mail , among others have all featured articles saying that there is not a single drop of evidence behind the myth of drinking eight glasses or more of water a day.
It turns out that the dietary recommendations from noted medical authorities as well as self-appointed health gurus to drink two or more liters of water per day are totally unsupported by any scientific evidence. Doctors Dan Negoianu and Stanley Goldfarb from the University of Pennsylvania in Philadelphia reviewed all the published clinical studies on the subject and concluded that no data exists for average healthy individuals regarding the amount of water they should consume on a daily basis.
Indeed, it is unclear where this recommendation came from," the University spokesman added.
Their research also debunked the myth that drinking water makes the skin more supple and made it easier to lose weight. "There is simply a lack of evidence in general," they reported in the Journal of the American Society of Nephrology .
Reuters reports that this was not the first time such a conclusion was made since Dr. Heinz Valtin of Dartmouth Medical School found the recommendations to drink that amount of water to be totally lacking in scientific merit.
Because we all have specific individual needs for water, Goldfarb recommended, "If you're thirsty, drink. If you're not thirsty, you needn't drink."
This most recent article highlights the specificity of an individual's metabolic need, a situation paralleled by salt intake. The human body has an ability to excrete 250 times the maximum recommended intake of salt - an amount of salt that is virtually impossible for anyone to consume. In other words, our salt consumption is not limited by our ability to excrete it, but rather by our innate senses - sensory perception and biological feedback mechanisms. Both of these mechanisms are specific for every individual, just as water is.
For this reason, it is the very same folly to apply a "one size fits all" set of policy recommendations to salt consumption as it is for water consumption. Salt consumption is self-limiting and regulated by nature's biology, not by shortsighted dietary recommendations.