We have long believed that all the available evidence demonstrated a clear link between low-salt diets and insulin resistance, the condition that is a precursor to Type 2 Diabetes. In fact, the Salt Institute has published a Salt and Health Newsletter on that very subject. Insulin helps the body utilize a key energy source, blood glucose. When insulin is low or absent, cells cannot absorb glucose and the body starts to use fat as an alternative energy source. Insulin resistance leads to Type 2 diabetes, which is characterized by suppression of lipolysis (breakdown of fats) and poor regulation of energy intake in the liver, muscle, adipose tissue, and the central nervous system. It is also strongly associated with other components of poor health including dyslipidemia (an abnormal concentration of lipids in the blood), inflammation and hypertension, all leading to serious cardiovascular disease.
Dogmatic low-salt diet recommendations have ignored all the medical literature which warns that low salt intakes are associated with increased CVD deaths among those with CV conditions as well as those with elevated insulin resistance. Low-salt diets trigger production of other hormones and result in elevated aldosterone levels. Insulin resistance was always considered to be an unanticipated consequence of low salt intakes in humans and animals. Low-salt diets also increase sympathetic nerve activity and decrease tissue perfusions, two other factors contributing to insulin resistance.
The most recent research by investigators Rajesh Garg, Gordon Williams, Shelley Hurwitz, Nancy Brown, Paul Hopkins and Gail Adler from Brigham and Women's Hospital, Harvard Medical School, Vanderbilt University and the University of Utah confirm this negative health impact resulting from low-salt diets. In their article entitled, "Low-salt diet increases insulin resistance in healthy subjects ," published in the journal, Metabolism - Clinical and Experimental on November 1, 2010, they report on testing the low-salt/insulin resistance hypothesis in subjects that were healthy. These healthy individuals were tested after 7 days of a low salt diet (1.2 g salt/d) and 7 days of high-salt diet (9 g salt/d) in a random order. Insulin resistance was measured after each diet and compared statistically. There was no question that a low-salt diet was found to be significantly associated with an increase in insulin resistance, while the high salt diet showed no negative consequences.
It is time that the health authorities in this country, such as the National Institutes of Health , the Institute of Medicine , the CDC and the AMA pull their collective heads out of the sand (or wherever they have them lodged), stop acting like wannabe thoughtless consumer activists and start doing their jobs. Any policy related to salt and health in this country must be based upon real, verifiable, clinical evidence. Were not living in some place where a few zealots should be able to dictate health and diet policy based upon antiquated anti-industry ideology and a perverted sense of self-importance. This is not an intellectual banana republic. We have competent scientists and we have large bodies of evidence that have repeatedly demonstrated that the negative salt myth promulgated by our health institutions is baseless.
The modern version of the Hippocratic Oath states:
"I will respect the hard-won scientific gains of those physicians in whose steps I walk, and gladly share such knowledge as is mine with those who are to follow."
It is time our medical authorities demonstrate the courage of their alleged convictions.
Following yesterday's blog, I just came across another article attributing "salt-sensitivity" to abnormally high levels of aldosterone . Admittedly, this research was carried out on mice, but their mamallian renin-angiotensin-aldosterone system works similarly to that of humans. The report states that mice lacking normal components of circadian clock controls (the 24-hour cycle of biochemical, physiological, or behavioral processes) show salt-sensitive hypertension due to the production of abnormally high levels of aldosterone by the adrenal glands. In fact, the authors recommend this to be a new hypertension risk factor in mice. Based upon the evidence, high aldosterone levels should move way up the chain of risk factors for humans as well.
This is another example where salt-sensitivity is not an independent medical condition, but an overt manifestation of a more profound physiological disturbance resulting in excessive aldosterone production. It is control over aldosterone levels which will be the critical strategy for treatment.
The evidence continues to build....
One of the most misunderstood phenomenons related to hypertension is commonly termed “salt-sensitivity.” It has never been explained to everyone’s satisfaction, it is complicated to characterize and most people who are diagnosed with it are unaware they have it. Why is that? Could it be that salt-sensitivity is not an independent medical condition per se but rather a coupled overt manifestation of a far more profound physiological disturbance?
We have long known that many people of African decent have a heightened tendency towards hypertension. In what has become almost a knee-jerk reaction, these individuals are routinely prescribed a low-salt diet with highly variable degrees of success. Now, researchers Kammerer and Pratt have looked more closely onto the matter and have determined that many Africans have a genetic predisposition to high aldosterone levels, which is a significant contributor to hypertension.
The rennin-angiotensin-aldosterone system (RAAS) evolved as a means of physiologically controlling the amount of sodium in the blood. When we consume sufficient sodium (salt), the excess is simply excreted in the urine. When we do not consume sufficient sodium, several receptor systems in the body are stimulated to activate the RAAS, which produces aldosterone, which in turn signals the kidneys to start recouping the sodium that was destined to be excreted in the urine and send it back to the circulatory system. That is the sodium control mechanism that has evolved for humans and many other animal species. For most people, the RAAS begins to be activated when our consumption of salt falls below 6-8 g per day.
While aldosterone plays this very important sodium-control function, its presence at elevated levels in our blood is not benign. High levels of circulating aldosterone are associated with several negative consequences including hypertension, degeneration of arterial epithelium, metabolic syndrome and Type II diabetes.
Of particular interest is the combination of elevated aldosterone and normal to high salt consumption which routinely results in increased blood pressure.
Researchers Kammerer and Platt believe the genetic tendency for Africans to have elevated aldosterone levels is the evolutionary result of coming from an environment that was traditionally low in salt, thereby necessitating a continual need to conserve all available salt within the body. This chronically elevated level of aldosterone has resulted in high rates of hypertension and a symptomatic sensitivity to salt.
The conventional first course of treatment – severe reduction of salt in the diet – may have a positive impact on reducing some of the blood pressure, but it does nothing to reduce the chronically-high levels of aldosterone. On the contrary, reducing salt may stimulate even more aldosterone production with all the attendant negative consequences.
Salt reduction is a very poor and somewhat thoughtless strategy in this circumstance and the most likely reason for its inevitable selection is the dogmatic attachment to the concept of “salt-sensitivity.”
Labeling chronic elevated aldosterone as “salt-sensitivity” is a bit like calling the genetic tendency to accumulate cholesterol as “schmaltz-sensitivity.” The basic problem is neither the salt nor the schmaltz – it is the genetically-moderated tendency to produce excessive amounts of harmful metabolites.
Just as we routinely treat cholesterol conditions with statins, we have to consider our first treatment strategy for chronically-elevated aldosterone to be ACE inhibitors and aldosterone blockers such as spironolactone. Rather than treating only one of the manifestations of the conditions, by going after the real culprit all of the consequences of elevated aldosterone will be managed.
Well, at long last the data are in. In a paper published in the American Journal of Clinical Nutrition (pdf 135.14 kB) , Harvard researchers Adam Bernstein and Walter Willett found that the amount of sodium consumed by Americans over the past 4 decades has remained unchanged, while the rates of high blood pressure have increased greatly. The result, based upon the most reliable form of data - the 24 hour urinary sodium analysis - was a real shock. So upsetting was this data that the authors parsed it in the following way:
"Sodium intake in the US adult population appears to be well above current guidelines and does not appear to have decreased with time."
No statement can be more reflective of a fixed ideology than that. In the first instance, they fully expected to see a significant increase in salt - but they did not - salt consumption has remained unchanged - why did they not simply say salt has not increased with time? If high blood pressure increased significantly but salt consumption did not, then it is obvious that the Dietary Guidelines regarding salt are totally baseless, yet once again they remain entrapped in a flawed doctrine that has proven to be wrong time and time again.
In fact, their most telling, but grudging admission comes near the end of their publication:
"Thus, despite the increase in processed foods in the US marketplace over the past 50 y, total caloric imbalance and the resultant epidemic of obesity may be a more important determinant of the increased prevalence of hypertension than sodium intake."
In other words, the sodium-hypertension link is not what it was quacked up to be!
Not surprisingly, Dr Graham MacGregor (University of London, UK), the spiritual father of WASH (World Action on Salt and Health) feels there must be something wrong with the data . The man behind the worldwide campaign to denigrate salt, has typically tried to cast doubt upon the data because it blows away his anti-salt agenda and his lifelong work.
One thing we know for certain. These data are real and confirms that on a population-wide basis, salt does not contribute to high blood pressure except for a minority of the population that is salt sensitive. I await the day when researchers shake loose from their arbitrary dogma and willingly admit the truth. We will all be better off.
Researchers at the Medical College of Georgia have documented a chain of events showing that excess fat can cause the body to retain more sodium and, consequently, more fluid resulting in higher blood pressure.
Their findings point toward a biomarker in the urine that could one day help physicians identify the most effective therapy for these patients.
Team leader Yanbin Dong said, "It's well established that obesity increases inflammation, salt sensitivity and high blood pressure," referring to the study in the American Journal of Physiology Regulatory - Integrative and Comparative Physiology .
Dong's team outlined the process that appears to start with fat producing more inflammatory factors, such as interleukin-6, or IL-6.
When he and his colleagues exposed mouse kidney cells to the fat inflammatory factor, interleukin-6, they found increased salt reabsorption.
Whether the mouse reactions function the same way in humans remains to be seen, but it appears Dong may have found a way to gauge this activity in humans. Dong already is measuring obese people with and without hypertension as well as normal-weight individuals. A simple urine test could one day help identify those at risk for or experiencing this type of inflammation-based hypertension, he said.
We live in interesting times. As you can imagine, the last week was a very busy one filled with numerous television, newspaper and radio interviews. After the IOM press conference to release their report on "Strategies to Reduce Sodium Intake," a key message that we felt was necessary to get out, was the admission on the part of the lead author that the Committee studying the matter never considered the science behind the salt and health issue - but only the strategies required to reduce salt in foods. This was a rather strange admission, since the major part of the IOM Committee consisted of epidemiologists and physicians rather than industry professionals who actually had some knowledge about food formulation. The centerpiece of the IOM 'Strategy' was the recommendation for the FDA to start regulating the salt contents of processed foods and foods prepared in restaurants and foodservice establishments. This would be a dramatic reconsideration of what is an essential nutrient and the oldest and most ubiquitous food ingredient known to humankind. One would expect that a move of this magnitude would be based upon a substantial body of uncontested scientific evidence, but that is very far from the case.
One of the interviewers from a Los Angeles radio station asked me how I might dare to challenge the medical authorities on this matter. I thought it best to ask him for a clarification. Was he referring to the medical authorities that recommended hormone replacement therapy for women and 30 years later admitted that such a strategy had disastrous consequences for women? Or was it the medical authorities that emphatically stated that the consumption of any more than one egg a week would lead to a very ugly and early death from cholesterol-blocked arteries - only to completely recant this advice 20 years later? Or perhaps he was referring to the medical authorities that decreed that frequent PSA measurements were the answer to prostate cancer, only to come out with their most recent recommendations that perhaps it's best not to do PSA tests at all because they can be misleading? Precisely which medical authorities was he referring to? The interviewer admitted that he got the message and dropped the question.
During the course of the actual press conference, I pointed out to the senior author that the impact of salt on health has been reviewed on a number of occasions over the years with mixed results. The latest meta-review of the evidence was commissioned by the German Ministry of Health just last year and concluded that population-wide salt reduction was not justified from a public health point of view. Indeed, it would have been wise for the US to do the same before going ahead with strategies to reduce sodium. Because of the controversial nature in which the evidence has been interpreted, I went on to ask if the international trade implications of salt regulation in food was ever considered in the deliberations of the IOM ‘Strategies’ Committee. The lead author appeared stunned at this question and admitted that the question of trade never entered into their deliberations.
In establishing the Sanitary and Phytosanitary Agreement (SPS) on trade, the United States was one of the leading countries to insist that unjustified measures could not be used to limit trade between countries. Countries would not be able to ban products for public health or safety issues unless it was proven beyond doubt that these measures were fully justified on a sound, scientific basis. For example, because Italians and Greeks have excellent cardiovascular health, exporters of many traditional high salt foods from these countries may find full justification under the World Trade Organization SPS Agreement to declare the regulation of salt in food as a non-tariff barrier to trade and launch an action against the US at the WTO. Since the US has never carried out a large-scale trial on the overall health impacts of salt reduction, and since the sum of evidence remains controversial, the WTO is likely to consider such a complaint valid.
As I said, we live in interesting times.
During the 2008 presidential campaign, candidate Obama complained about how scientists and policymakers in the George W. Bush Administration were perverting the free expression of science. While our choice of examples may have differed, we were in hearty agreement that the government had turned its back on science in the one area we track intensively: science pertaining to salt and health. In fact, the Salt Institute was forced to ask the federal courts to prevent the executive branch from ignoring the data quality standards of the federal Data Quality Act – and the courts demurely determined that the executive branch was immune to judicial oversight in the way it uses scientific data – the final arbiter of its own DQA compliance.
Unsurprisingly, one of President Obama’s early initiatives was to issue, in March 2009, a Memorandum on Scientific Integrity with a promise to have a plan in place to correct the problem by mid-2009. The plan has not yet been released. Examples of impaired integrity in government use of science continue.
One of the most vocal proponents of improving scientific integrity has been Bush-bashing investor George Soros (disclosure: at one time, Mr. Soros was a part-owner of a Venezuelan salt production facility). Soros’ Open Society Institute funded a study to document the threat to scientific integrity within the federal government (“The Scientists in Government Project”) run by George Washington University . The Federation of American Scientists , Government Accountability Project , Scientists & Engineers for America and Union of Concerned Scientists also provided support.
The Project just released its report, Strengthening Science in Government: Advancing Science in the Public’s Interest , and it makes the case that citizens should be very concerned about the integrity of science as portrayed by government scientists. And, we would add: and science controlled and funded by those same government scientists.
The Report takes as its theme Albert Einstein’s observation about the duty of scientists: “One must not conceal any part of what one has recognized to be true.” Tellingly, the Report also quotes a senior manager at the Centers for Disease Control and Prevention (CDC) complaining that “We need supervisors who have the courage to speak up for the science.” (Indeed, when the agency head assiduously leads in the opposite direction).
The Report effectively articulates the challenge:
The (Einstein quote) statement above serves not only as a guiding principle of good science, but as a framework for effective, science-based policy-making. The best public policies are built on a foundation of rigorous data and analyses, widely shared among scientists and the public. The fundamental obligations of a science-based society – advancing the public health, protecting the workforce, safeguarding the environment, developing appropriate energy technologies, defending the nation, and much more – depend on a full and open exchange of ideas, methods, findings, and interpretations.
New scientific knowledge constantly builds on existing scientific knowledge. When information is readily shared, new findings can be analyzed and new hypotheses vetted in an ongoing process that continually generates opportunities for further study and analysis. Science flourishes when scientific ideas are given a fair hearing by colleagues, debated on their merits, tested through replication and further research, and revised in light of new understanding.
Beyond the merits of advancing science, the open exchange of ideas is also cherished because it is concordant with the ideals of a democratic society. Freedom of information is a core belief in the American system.
An analysis of the approach to science taken by the five White House administrations that preceded that of President Barack Obama explains, “It is naïve to believe that scientific findings are the sole determinant of policy . . . Much of the funding, direction and use of American science is determined by the federal government and the political biases of the dominant party invariably influence the decisions that get made.
Policy decisions may be based on science, but they are not purely scientific. Preferences and political considerations shape decisions about regulation, research priorities, service delivery, and program development and evaluation. Nonetheless, the integrity of the science and the validity of the data that informs these decisions must be preserved.
But the report then goes on to explain the "pressures on scientists" employed by government (or hired by government scientists, we'd add):
A "unique challenge" for them is that "they may be expected to represent and advocate for official agency positions, regardless of their personal perspective on an issue. Conversely, they may be barred from presenting conclusions or analyses that are inconsistent with an agency’s stance, even if they are speaking as private citizens."
Okay. We agree on the statement of the problem. And we hope the supporters of the report are sincere. Let’s see if the “solution” is more government-knows-best or whether the new Administration is willing to be measured by the metrics of its lofty rhetoric.
Early indications from CDC on the salt issue haven’t been encouraging, but hope springs eternal.
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:
- 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.
- 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.
Data may be just another “four letter word” to some. And for some advocates, data gets in the way of a good story. That’s what’s been happening as evidence unfolds about the bogus “salt hypothesis” where blood pressure-based computer modeling projecting health benefits from cutting back on dietary salt have been crushed by peer-reviewed studies showing worse outcomes and questioning even the physiologic possibility of modifying salt intakes .
Well, data is happening in other areas, too.
Recently, the American Heart Association journal Circulation published an analysis of 30 million Medicare beneficiaries’ data (repeat, 30 million Americans’ actual experience, not a computer projection). The data clearly documented that (surprise!) heart attack rates are in decline – just the opposite of what computer projections and prominent public health “experts” have claimed.
Dr. Harlan Krumholz of the Yale University of Medicine and principal investigator for the study told the Wall Street Journal that the findings “breathtaking” and attributable to evidence-based prevention strategies. The same results are found in the general population, he claimed.
Of course, the new data came after the fear-mongers’ success in enacting a government takeover of healthcare arguing the current situation was deteriorating. And consider a second point: these same big-government-knows-best “experts” are telling us we have a crisis in salt intake causing, according to recent headlines, a half million heart attacks a year based on their computer projections – when salt intake levels are unchanged over many decades and now we know that heart attack rates are in decline.
As Jeff Stier of the American Council on Science and Health notes: “This isn’t consistent with their storyline that we need more government intervention like fast food bans to keep us healthy.”
So, who to believe? The “experts” or the data?
On January 11 of this year, you announced an ambitious program dubbed the "National Salt Reduction Program." This program was patterned after the Food Standards Agency salt reduction program in the UK, which you characterized as a success. Considering the economic, social and infrastructural problems that New York City faces, you clearly believe that a population-wide reduction of salt intake is a very high priority issue. Yet, the issue of population-wide salt reduction remains deeply mired in controversy. The majority of meta-analyses on the subject do not conclude that population-wide salt reduction is warranted. Some even state that there may be an unintended consequence resulting from such an action.
As you are so devoted to this program, I believe that you should have an opportunity to openly demonstrate the depth of this commitment. It would certainly not be the first time that political leaders have stood up to demonstrate the courage of their convictions. In 1991, in an effort to stave off international criticism regarding Peru's polluted fishery, President Alberto Fujimori dined on local ceviche in front of news cameras to demonstrate his faith in the quality of their fish. It is of no consequence that he came down with cholera the next day - the important thing is he had the courage to stand up for what he believed in.
As a public leader, I feel that you should have the same opportunity and hope that you would demonstrate the same degree of courage. I propose that you go on a 1,500 mg sodium/day diet, as recommended by the CDC and I will maintain my 3,500-4,500 mg sodium/day level for a full month. During that time, we should have our blood chemistry (renin, aldosterone, cortisol, etc.), blood pressure, arterial pulse wave velocity (a measure of arterial stiffness) and urinary sodium levels checked weekly. I would further invite Drs. Larry Apell, Chairman of the Dietary Guidelines Sub-Committee on Electrolytes and Michael Jacobson of the Center for Science in the Public Interest, two individuals who have repeatedly stated that humans do not require more than 500 mg of sodium/day to join in this demonstration by consuming that 500 mg sodium/day for one month as well and undergo the same tests.
Finally, I propose that Dr. Mehmet Oz use his good facilities to manage the clinical tests and report the results on his television program.
Mr. Mayor, I have no doubt that you wish to do what is right. I do as well, however, we are operating from a totally different set of peer-reviewed data. A task as simple as the one I suggest may well resolve this issue to everyone's satisfaction and will set the salt and health debate upon a course that should benefit all citizens.
Alexandria, VA 22314
This year has brought an avalanche of salt reduction papers in the medical journals, together with supporting editorials and letters from well-known and influential anti-salt activists. The effort appears to have been coordinated and I would not be at all surprised if WASH (World Action on Salt and Health) and CSPI (Center for Science in the Public Interest) were associated with it.
The rather odd thing is, despite all the published text calling for stronger regulatory action to reduce salt due to all the projected morbidity, mortality and health care costs this would result in, not a shred of actual new evidence was published. The papers published were simply statistical models based upon evidence we know was highly flawed. Obviously, the laudatory op eds and letters that followed were more a show of desperation trying to shore up the flimsy house of cards.
I sent a letter to the Annals of Internal Medicine criticizing the current state of affairs, where leaders in public health policy appear to have become so political that they no longer demand evidence to develop public policy. It is a sorry state of affairs when academics resort to statistical models with fancy nine dollar words instead of simply going out and getting the data which is easily available. The letter can be seen here . Scroll down the page to the letter and click the "more" link to see the full content.
Caught up in this frenzy of scientific folly and compulsion to regulate, New York Assemblyman Felix Ortiz introduced Bill A10129 stating that no restaurant should be allowed to add salt to the food they prepare. I blogged this item and he is apparently rethinking his position coming out with the inevitable statement that he was totally misunderstood by all – that’s not what he meant…..he really meant…..not too much salt…..maybe not on Tuesdays or Thursdays…..only at Happy Hour……or no more rice in the salt shaker…… or something equally stupid!
In fact, Ortiz was highly criticized by Bloomberg for his bill with Bloomberg saying he was only working with manufacturers to gradually reduce salt over time. You know, “slowly, slowly, catchee monkey.” That way no legislation has to be developed and if it all goes south and people start exhibiting signs of cardiovascular illness, metabolic syndrome or stress or reduced cognition or alzheimer’s (all possibilities described in the medical literature), then no one has to take responsibility for it. He can simply say “We were only suggesting salt reduction – it was the industry that actually did it!”
Years ago, when “GAO” stood for “General Accounting Office,” that arm of Congress focused its reviews on how well government agencies were spending taxpayers’ resources. A new GAO report suggests FDA should expend more resources on substances earlier determined to be safe, some, like salt, of proven safety since before the founding of FDA or even the founding of the United States. GRAS has been a prime achievement in wise use of taxpayer monies in that it has allowed the agency to accept substances in foods which had been used safely for centuries, enabling FDA to focus on substances with unproven food safety.
Salt was the original, archetypical GRAS substance.
No one should doubt the safety of salt. The petitioners would have FDA regulate the amount of salt allowed in each serving of food. There is no evidence that this would produce either of the benefits the petitioners assert. No studies have been done that show that those consuming diets incorporating low-salt foods result in lower overall salt consumption. Evidence shows that salt appetite responds to an individual’s physiologic need. Neither is there any controlled trial of whether diets lower in salt or sodium produce better health outcomes. Nearly every one of the few studies that have been done show either no benefit or even increased risk. In fact, the two controlled trials reported to date both show worse outcomes for those on lower sodium intakes.
GAO should go back to serving the taxpayers in assessing whether government agencies are using good judgment in prioritizing limited resources on real problems. The GRAS status of salt is a PR sideshow unworthy diverting FDA from its vital mission of ensuring the safety of America’s food supplies. GAO would be well served to ask why NHLBI continues to fund PR-oriented studies offering computer models of blood pressure impacts of low-salt diets when that question is well-studied and by NHLBI continues to frustrate efforts, including those of the 2005 Dietary Guidelines Advisory Committee, to have the federal government conduct a meaningful controlled health outcomes study of whether lower sodium diets would improve public health. Until that study is done, FDA is right to prioritize its resources to questions where evidence suggests the public will get better bang for its buck.
It remains hard to believe, when the daily newspapers are screaming for action to curtail population sodium intakes, that until this month, only one controlled trial has ever examined the actual health outcomes of salt reduction . Sure, we've seen computer models based solely on blood pressure projections that predict fewer heart attacks and lower cardiovascular mortality. But this fantasy has been "mugged by reality" as the data begin to appear in the peer-reviewed literature.
This month's Clinical Journal of the American Society of Nephrology published the results of a second health outcomes study of low salt diets in a vulnerable population. The first study found low-salt diets caused more hospitalizations and greater mortality among congestive heart failure patients. This new study, by a Chinese research team headed by Dr. Jie Dong, "Low dietary sodium intake increases the death risk in peritoneal dialysis." It's conclusion:
This study revealed that low dietary sodium intake independently predicts the high overall and cardiovascular mortality in dialysis patients.
The researchers suggested a J-shaped curve as described by Dr. Michael H. Alderman in his presidential address to the International Society of Hypertension . Dong et al termed it "another example of 'reversal epidemiologic phenomenon," continuing:
In the case of dialysis patients, harm may outweigh benefit ... Low sodium intake is significantly related to overall and CVD mortality. Sodium restriction did generate undesirable effects in previous studies including increased insulin resistance, activation of the renin-angiotensin system and increased sympathetic nerve activity. ... We reveal for the first time that low sodium intake is not necessarily a good thing....
Hyponatremia is a far more serious condition than was originally thought. While reviewing some of the standard therapies associated with symptoms, I came across some facts that caused me to do a double take. As anyone who has ever been admitted to hospital for treatment knows, the intravenous saline drip is standard therapy and the fastest way to deliver fluids and medications throughout the body. Normal saline drip is the commonly-used term for a solution of 0.91% salt (sodium chloride). The amount of saline infused depends largely on the particular needs of a patient, but on average is typically between 1.5 and 3 liters a day for an adult. So, in order to maintain an average adult in optimum health during a hospital stay, somewhere between 13.7 – 27.3 grams of salt per day is administered. Of course, that doesn't even include the salt that is consumed along with the food. If the hospital dieticians were able to provide meals that corresponded to the current recommended levels, this would add an additional 6 grams of salt for a total of somewhere between 20 and 33 grams of salt a day. And don't forget, every four hours or so, they come by to check on your blood pressure.
I wonder how hospitals will comply with the salt intakes recommended by the Dietary Guidelines Advisory Committee? After all, the Dietary Guidelines recommend 4 - 6 grams of salt per day, about 1/5 of what is currently administered in hospitals!!
Today's NY Times (free subscription) carries an opinion column by science editor John Tierney, "Salt Wars." It recounts the exchanges between medical experts over the advisability of asking the general population to reduce dietary salt and hits both of the key issues, which are:
- Is salt reduction even possible or is "salt appetite" a hard-wired physiological response by the body to its need for this necessary nutrient?
- If population salt reduction were achieved, would public health be improved?
The most interesting aspect of this debate among medical professionals is that those advocating for population salt reduction want to skip over these two questions. Tierney blows the whistle on them, quoting America's leading salt reductionist, Dr. Larry Appel, conceding that the data a "murky" and that there is no evidence of any change in American salt consumption, up or down, in recent decades. Said Appel: “We just don’t have great data on sodium trends over time. I wish that we did. But I can’t tell you if there’s been an increase or decrease.”
To oblige Dr. Appel, while the data on any putative benefit of salt reduction is clearly all over the map with some studies supporting a benefit but more finding no benefit or even heightened risk, the data on the immutability of salt appetite is rather consistent and compelling -- government policies do not move salt consumption among people eating normal amounts of sodium (the U.S. intake is absolutely dead center among nations around the globe).
Recognizing the volatility of the issue, Tierney invited his readers to comment:
You’re welcome to weigh in on any of these issues, especially the question of what scientists really know about the effects of restricting salt. Should Washington follow New York City’s lead in pressuring food companies to take salt out of their products? Or has New York gone beyond what the evidence warrants, as argued by Elizabeth Whelan of the American Council on Science and Health ?