This week's Journal of the American Medical Association included an editorial by editor-in-chief Dr. Catherine D. DeAngelis announcing the prestigious journal's tightening of its conflict-of-interest policy in response to scientists' failure to disclose all financial ties to pharmaceutical companies. Said DeAngelis:
Authors are expected to provide detailed information about all relevant financial interests and relationships or financial conflicts within the past 5 years and for the foreseeable future (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony,royalties, or patents filed, received, or pending), particularly those present at the time the research was conductedand through publication, as well as other financial interests (such as patent applications in preparation) that represent potential future financial gain.
Avoiding conflicts of interest is obviously a good thing and disclosure of funding relationships is certainly important in that regard. But JAMA's new rules don't get the job done.
JAMA's new rules are fundamentally flawed. They limit consideration of financial conflicts of interest to those with funding ties to private industry, totally ignoring the fact that many researchers sustain their professional careers fulfilling the agendas of government health agencies. Major studies can bring in nine-figure grants or contracts and lead to career-enhancing publications, professional visibility -- and more grants. Public health agencies have their favored strategies and their own special interests. JAMA would do well to have these conflicts disclosed too.
Harvard professor Thomas Stossel made much the same point in an op ed in the Washington Post July 2nd where he pointed out that journal editors play favorites, imposing (entirely appropriate) rigorous peer-review standards on academic researchers while exempting public interest groups from such scrutiny despite the fact that they often receive grants from parties at interest too.
Today's Boston Globe has a balanced article on the ongoing controversy about the health aspects of dietary salt. Unlike many journalists, however, Globe reporter Judy Foreman focuses on the right question: "Is lowering salt consumption important for health." After the obligatory quoting of an anti-salt advocate, in this case Dr. Lawrence Appel of Johns Hopkins who pointed out 1) lowering salt can reduce blood pressure and, 2) loweirng dietary salt is "easier for morst people than ... making other dietary changes", Foreman states that "lowering blood pressure by salt reduction may not translate to a survival advantage, quoting Dr. Hillel Cohen of New York City's Albert Einstein College of Medicine who explained the most recent study: "people who reduced salt actually had a 37 percent greater risk of death than those who didn't." Foreman makes it clear that "The Salt Institute did not pay for the study." Actually, Foreman neglects to mention, the data Dr. Cohen analyzed is from the federal government's own NHANES II database.
Congratulations to the Globe and Ms. Foreman for recognizing that the proper question is the health outcome of any intervention (e.g. survivability or, in this case, it might be incidence of heart attacks) not impact on an intermediate variable like blood pressure. There are many metabolic changes that occur when a person reduces dietary salt. Blood pressure is one. Dangerously increasing insulin resistance is another. Yet another is stimulation of the renin-agiotensen system; high plasma renin activity has been shown to produce dramatically higher rates of heart attacks. Next time someone tells you that reducing salt can lower your blood pressure (it can, though in a minority of the population), remind them that none of the 13 reported studies of whether reducing dietary salt actually improves health outcomes, none, has suggested a lower salt diet is healthier. None.
After a busy spate, I'm catching up. Perhaps you saw articles published last week (for example, in the Boca Raton News , June 15) discussing a recent study by the National Academy of Sciences on teh question of whether teh flavanol in cocoa reduces the incidence of cardiovascular events.
Boca Raton News writer Nicol Jenkins, interviewed eminent Harvard researcher Norm Hollenberg who had published earlier work in this area in 2003 and 2004 , describing the study results:
Researchers provided participants with a cocoa drink that was either high or low in certain cocoa flavanols. Only the group consuming the flavanol-rich cocoa experienced increased blood vessel relaxation.
"Pinpointing specific nutrients responsible for the observed cardiovascular effects, as we are seeing here with (-) epicatechin, opens up new possibilities for the development of dietary or therapeutic interventions for cardiovascular disease," said co-author Norman Hollenberg, MD, PhD, professor of medicine at Harvard Medical School.
To assess the long-term benefits of a flavanol-rich diet, the researchers further studied two populations of Kuna Indians of Panama. A previous study has shown that hypertension is rare among the indigenous Kuna Indians living on the islands compared to those living on the mainland. The island-dwelling Kuna Indians traditionally consume large quantities of flavanol-rich cocoa (an average of 3-4 cups daily), while those who live in the suburbs of Panama City consume very little cocoa. This supported the idea that cocoa flavanols may be responsible for lower blood pressure in the island dwellers.
Every time I read about Hollenberg's research on the Panamanian Kuna Indians, my mind recalls his findings that so clearly resolved a long-standing contention of the anti-salt crowd that when primitive peoples migrate from their customary isolated, rural homelands to settle in urban centers their blood pressure increases. Of course, they conclude, this is because their primitive diet was low in sodium and their city-dwelling diet is substantially higher. And usually that is the salt consumption pattern of migrants. But, of course, one could argue that many things change in the migration. Instead of avoiding snakes, they have to dodge taxis and buses; instead of a relatively simple and slower-paced lifestyle, they have to function in high-energy and fast-paced urban settings. Even in the diet, a lot changes, not just salt.
So what did Hollenberg do regarding these Kuna Indians? He studied two groups, one that stayed at home on their remote, isolated islands and another group that migrated to Panama City and published his findings in a 1997 article in the American Heart Association's Hypertension magazine . What did he find? Migrants had a significant increase in hypertension when they moved from their home islands to Panama City -- so what? That's what other migrant studies have found. What is different about the Kuna is that, at home on their isolated island homes, they consume salt in about the same amounts as Americans do. Thus, it is some other aspect of their personal urbanization that contributes to their increased blood pressure -- not salt! Perhaps rush hour traffic? Job stresses? Simple adjustment to a lot of new things? No one knows, but we know it wasn't higher salt intake levels. For the record, Hollenberg doesn't buy the "stress " theory either.
Thanks for making that clear, Dr. Hollenberg.
A recent article in the Medical Journal of Australia should have received more US media attention than it has.
On June 5, the MJA ran an article "Media reporting on research presented at scientific meetings: more caution needed" (HTML PDF ). Dartmouth Medical School professors Dr. Lisa Schwartz write that because "the public has a strong appetite for medical news and scientific meetings provide the media with an easy source of provocative material" oral presentations (and the news releases that accompany them) usually omit key disclaimers and key study facts. For example, one-third did not report the study size and 40% did not quantify the main result, only 6% of animal studies noted that the results might not apply to humans and only 2 or 175 stories admitted that the data were not (peer reviewed or) published.
It's easy to fault honest researchers and reporters for failure to disclose the limits of these studies. What is more bothersome, and unmentioned in the article, is the practice of research project sponsors like the National Heart, Lung and Blood Institute which, for example, put out a news release the day before its funded researchers supported the DASH-Sodium Study. NHLBI has stated that they have no access to the underlying data, yet their news release claimed the study showed every American would benefit by reducing dietary sodium. Reporters called me for reaction and, in fact, I did attend the presentation of the paper at the American Society of Hypertension meeting the next day, but what could I "react" to? The paper was not only not peer-reviewed or published, it hadn't even yet been presented! Not only that, but now that the data have dripped out over the past couple years, it shows that in six of eight subgroups (collectively including well over three-fourths of the population) there was no statistically significant association at all. So don't just blame resume-sensitive researchers or headline-hunting reporters.
The fish-based, high-salt, low-fat Japanese diet, probably the saltiest in the world due to massive amounts of seafood, soy sauce and pickled vegetables, is credited with a major role in making the Japanese the world's longest-lived population.
Researchers at Tohoku University recently reported to the Japanese Society of Nutrition and Food Science in Shizuoka the superiority of Japanese fare to that ingested by Americans.
More than four in five Americans believe if the federal government pays for health-related research the results should be freely availalbe both to other medical researchers and to the general public according to a Harris Poll announced May 31.
Yet a week earlier an editorial in Kidney International criticized the Salt Institute for employing the Data Quality Act with its requirement that data disseminated by federal agencies had to be available for independent review and verification. In this case, the data in question were from a federally-funded study and used by the federal government to make policy and issue public health guidelines.
Perhaps we should simply conclude that HHS is thumbing its nose at the public in sitting on these data. But perhaps another well-known phenomenon is taking place. When pollsters ask the public their opinion about Congress, not only this year, but generally over the past generation, Congress scores poorly (lower than George W., and that's not good), but when asked whether they think their own Congressman is doing a good job, most say "yes." It's a question of the trees and the forest.
Perhaps the public hasn't focused on the fact that when a bureaucrat locks up federally-funded research, the question should be on access, not on whether the individual being polled agrees with the opinion of the bureaucrat on what the undisclosed data really mean.
When six of eight subgroups of the DASH-Sodium study show no statistically significant relationship of salt and blood pressure -- and don't address at all the paramount question of whether a health benefit is realized -- then we all are losers when HHS refuses to abide by the Data Quality Act and allow independent verification of its interpretation that "every American" benefits by cutting back salt.
The public "gets it" on the macro level. Now we need to get down to cases.
The May 17 edition of National Review Online contained an article entitled "Salt Sense" by Bruce Bartlett. The article makes the point that budget deficits and immigration (legal and illegal) "are benign up to a point." So far, so good. But Mr. Bartlett introduces the concept comparing it to dietary salt intake.
Analogy is a powerful tool. Painting mental pictures embeds thoughts into memory. Mistaken analogies either perpetuate error or undermine the author's argument. Since Paracelsus, we've all understood that "the dose makes the poison" and that all organisms can tolerate sub-toxic exposures (perhaps we should exempt the State of California's Proposition 65 from this generous assessment). But Mr. Bartlett's "favorite example" is mythologic. "Too much salt," he says, can be problematic. Sure. "Too much" of anything, by tautologous definition, is excessive. His implication is clear: above some amount that humans might ingest, "salt can create physical problems such as high blood pressure." That may be Mr. Bartlett's opinion, but not a medical consensus. He continues that "a large quantity of salt consumed within a short time will kill you." Misleading at best. If a human were fed any substance intravenously, such as increasing the concentration of the perfectly safe saline used in emergency medical procedures, doubtless it could be fatal, but humans cannot ingest such amounts; their intolerant stomachs would rebel and regurgitate such amounts. As for blood pressure, we've known for four millenia of the relationship of salt and blood pressure, but there is no consensus that salt intake "causes" hypertension ("high blood pressure," a defined medical term). Hypertension is an important indicator of "physical problems" but, itself, only a risk factor, not a health outcome. We are rightly concerned that blood pressure is a strong predictor of adverse health outcomes such as heart attacks, but there are other risk factors involved. Not a single study examining the relationship between the amount of salt consumed in the American diet and either heart attack rate or to how long people live, has found that "excessive" salt intake is associated with higher rates of heart attacks or with lower mortality . In fact, the latest study, by the current president of the International Society of Hypertension, published in the March issue of the American Journal of Medicine , found that Americans who ingest the government-recommended amount of salt, actually had a 37% higher mortality. Low-salt dieters died more frequently. This is because salt serves multiple metabolic purposes and reducing salt, for example, increases insulin resistence, a risk factor for diabetes, and plasma renin activity, a strong predictor of myocardial infarction. There is no controlled trial showing that reducing dietary salt improves health outcomes. None of this, of course, should impune Mr. Bartlett's logic: the dose, indeed, makes the poison. It's unfortunate that his easy adoption of a popular myth in his "favorite example" might tend to undermine the credibility of his argument.
Frank Greve of Knight Ridder Newspapers just did a syndicated story on "20 things we could do to be healthier ." As Sherlock Holmes would have observed, it was notable for "the dog that didn't bark": despite the drumbeat of advice from publc health officials, former US Surgeon General David Satcher led an alliance of health insurers, state health departments, academics and trade groups as they tried to answer the question of which preventive measures could keep us healthiest for the least money. They reviewed more than 8,000 preventive-medicine studies.
Before announcing the results, keep in mind that universal salt reduction is touted as providing its benefits at virtually no cost. Now, the envelope, please: Unmentioned in the "Top 20" was anything about salt.
Academics, public health experts and association leaders met yesterday at the National Press Club to discuss "The World Health Organization: How can the United Nations agency fight disease inthe 21st century. " The event was sponsored by the Hudson Institute.
Promising "diagnosis and prognosis," the experts delivered some valuable insights and advice for WHO, culminating in a powerful address by Dr. Gail Wilensky, a member of the WHO Commission on Social Determinants of Health and head of Pres. George H.W. Bush's Medicare and Medicaid program and one of America's "Top 25 Women in Health."
The group intended to catalogue ideas, not produce concensus and, indeed, opinions were disparate. Some highlights:
Amir Attaran, PhD of the University of Ottawa, decried WHO's focus on visible problems at the expense of public health realities, urging the agency to show more respect for science and confine its activities to its areas of competence (avoiding "mission creep").
Nicole Bates of the Global Health Council outlined the importance of partnerships, particularly with the private sector, a point reinforced by Jean-Luc Poncelet, M.D. from the Pan American Health Organization (PAHO) who also reminded the group that the real work gets done at the country level, not in Geneva. I added that involvement of private sector partners enhances the likelihood that program initiatives will be real-world and sustainable, using the example of the salt industry's active partnership to combat Iodine Deficiency Disorders. Several responses credited the salt industry with enlightened and effective leadership.
Mary Pendergast, FDA deputy director under Dr. David Kessler under Presidents Bush and Clinton, suggested WHO focus on eradicating infectious diseases where it has enjoyed success rather than tackle chronic diseases where its record is spotty (or worse). I added that perhaps the true dichotomy was not infectious versus chronic, but rather interventions for which well-accepted interventions were being applied (as is the case in infectious diseases and some chronic conditions such as smoking) versus interventions recommended for chronic diseases which remain controversial due to lack of health outcomes trials of the specific interventions such as restricting dietary salt.
My take-away message for reforming WHO for the 21st century:
1. Make a concerted effort to identify the best science and confine intervention initiatives to those well-supported by the evidence.
2. Conduct honest consultations and actively engage with private sector partners to fashion sustainable program responses to health challenges.
3. Become more involved in providing assistance to the 192 member health ministries to create and maintain FDA-type regulatory bodies in their countries.
Thank you Hudson Institute and program chairman Dr. Carol Adelman, director, (Hudson Institute) Center for Science in Public Policy .
I'm sure it's reported elsewhere, but yesterday's Boston Globe carried a story of House Appropriations Committee approval of an amendment by Rep. Rosa DeLauro (D-CT) to the FY07 agriculture appropriations bill scheduled for House debate next week. DeLauro's amendment would give the US Food and Drug Administration authority to compel drug makers to conduct clinical trials of drugs after they've been made available for consumer use. The amendment stemmed from a recent General Accounting Office report criticizing FDA's post-marketing drug safety efforts.
FDA has requested post-approval trials for 73% of new drugs the Agency approved from 1988-2003, but two-thirds of those trials have not been completed, GAO found. Over the past decade, there have been a number of FDA-approved drugs that have been determined to have unexpected adverse side-effects forcing their approval to be rescinded or to have been found to be ineffective.
While Congressmen can disagree whether FDA has enough authority already, and PHARMA may counsel patience in awaiting the results of these long-term trials, it's pretty much agreed that government health regulators are human and despite their expertise, they cannot always make the right call in recommending approval of a particular pharmacologic intervention. Some system of reconsidering the safety and effectiveness of the approved pills must be done afterwards to make sure they work as intended and improve health outcomes.
If it's true for pills, why not, then, for policies?
Of course, the example is salt. A quarter century ago, FDA led the charge encouraging a non-pharmacologic intervention for every American -- eat less salt. It was a policy, not a pill, but the question remains: was FDA approval of this non-pharmacologic intervention safe and efficacious? What post-approval clinical trials have been done to show that it has worked and improved health outcomes as predicted -- lowering the incidence of heart attacks and reducing cardiovascular mortality? After all, it was deemed so important that no trials could be undertaken at the outset -- "everyone" knew it would work and repeatedly proclaimed "at least it can't hurt anyone."
So, what now, post-approval?
Well, short answer: there's been no controlled trial. There have been 13 observational studies of the health outcomes of those who followed FDA's advice. Funny thing, though, none of them showed the American public to be better off. Heart attacks weren't reduced (some studies say the low-salt group had more heart attacks), mortality for low-salt dieters wasn't reduced (in fact, the latest study says those eating the FDA-approved 2,3000 mg/day of sodium actually died 37% more). Dreadful news for an FDA whose drug approval record is already under attack.
So, if salt reduction were a pill and not a policy, the DeLauro Amendment would compel FDA to come clean and move immediately to withdraw its approval of this intervention until a controlled trial could prove that it works and improves health. So far there's no evidence that such a trial would validate FDA's hoary determination 25 years ago.
Elected members of our legislative and executive branches of government sometimes leave office at the low point of their careers as a direct result of the process of public accountability. Federal judges hold their posiitons with a lifetime tenure and news of their retirement usually merits little comment. Not so with 4th Circuit Court of Appeals Judge J. Michael Luttig who announced this week he will step down at age 51.
A year ago, Judge Luttig was on President Bush's short list for nomination to the U.S. Supreme Court. Passed over twice in the past year for that appointment and, then, almost exactly two months ago, the author of an embarrassing opinion in Salt Institute v. Leavitt , the trajectory of Judge Luttig's starred career turned down and is now history. Celebrated for strong defense of limited government (the Wall Street Journal editorialized that "his opinions have been prominent in setting the limits of executive and judicial power...."), Judge Luttig's Salt Institute opinion swung 180-degrees from that record and reversed clear Congressional intent that federal agencies be required to ensure that data used in their policy pronouncements meet high quality standards, be fully disclosed and succeptible of being reproduced by outside experts. Judge Luttig's opinion, rather, declared that agencies could make their own decisions about whether they'd met their obligations under the Data Quality Act. He put the fox in charge of the henhouse.
No doubt, Judge Luttig rendered valuable service through most of his 15 years on the appelate bench. It's too bad one of his final decisions was probably his worst ever.
By unhappy coincidence, today's news included two otherwise-unrelated stories: an outstanding article from Elizabeth M. Whelan, Sc.D., M.P.H., president of the American Council for Science and Health, "Public Health's Credibility Crisis " (from the Skeptical Inquirer) and a real life example confirming her worst fears.
First, Dr. Whelan:
"As society grapples with a possible avian influenza epidemic, threats of biological and chemical terrorism, AIDS, cigarette smoking, drug abuse, obesity, and more, it is vital that public health professionals present reliable scientific information and that the credibility of the public health profession be beyond reproach. In recent years, however, a worrisome trend has emerged: many in the public health community appear to be promoting politics and ideology over sound science. The slippage of public health science into pseudoscience and agenda-driven initiatives has been going on for some time."
She has her own examples offered as evidence of the threat. Let me offer my own recent disappointment.
As I reported earlier on the Salt Institute's "water conditioning" RSS feed, last week, the World Health Organization sandbagged the water treatment industry and plans to produce guidelines that would have public drinking water systems ensure that the water they provide contains at least minimum amounts of calcium and magnesium, two nutrients under-consumed in the U.S. and much of the world. No one disputes the need for calcium and magnesium, but drinking water is hardly the best delivery vehicle.
Experts in nutrition and drinking water gathered in Baltimore, MD, April 24-26 to discuss whether remineralizing drinking water with low amounts of calcium and magnesium would advance public health. I attended the symposium and participated in the discussion.
The symposium was organized by the National Sanitation Foundation and the International Life Sciences Institute on behalf WHO. WHO had been asked by its Middle East office whether water from reverse osmosis or distillation desalination plants was unhealthy because nutrients had been removed.
The experts agreed on several key points: 1) calcium and magnesium are vital nutrients and generally under-consumed and it is necessary to remineralize water from desalination plants in order to prevent it from aggressively attacking the pipes by which it is delivered to homes and businesses. They also agreed that ecologic studies (observational studies of the relationship between variables such as nutrients in drinking water and the incidence of cardiovascular (CV) events, are an inappropriate and under-powered analytic tool to use in determining public health policy.
No consensus emerged, however, on the key policy question of whether drinking water system operators should meet minimum mineral standards just as they now control for "maximum contaminant levels" (MCLs). Experts lamented the weak research in the area. Dr. Martha Sinclair from Australia, for example, noted the need for "substantial improvements on the evidence" and Dr. Richard W. Morris who directed the British Regional Heart Study said his large database offered no support for the conclusion that having calcium and magnesium in drinking water improved CV risk. Purdue University's Dr. Connie Weaver said a more effective strategy would be to increase dairy intake. Swedish professor Ragnar Rylander summed up: "We cannot prove that a small increase in calcium or magnesium consumption will have beneficial health effects." Leading opposition to the WHO initiative, Joe Harrison of the Water Quality Association (a speaker at this year's Salt Institute annual meeting), pointed out that buffering chemicals are needed to protect pipe systems, but that any health concerns about soft water pertain only to naturally soft water - as found in a quarter of U.S. cities - and water softened in an ion-exchange water softener. Softened water does not attack pipes, he noted. Other engineers pointed out that failure to ensure proper buffering to control pH would result in drinking water being contaminated with heavy metals from the pipes. WHO sequestered selected scientists on April 27-28 to draft a report on the subject. At that meeting, WHO staff pushed through a "consensus" report endorsing the staff's determination to recommend minimum amounts of calcium and magnesium for drinking water.
Much as it did in "managing" objections to its interventionist staff priorities, the World Health Organization (WHO) is on the path to establishing a guideline that all drinking water would be deemed "healthy" if it contains minimum amounts of calcium and magnesium. One quarter of U.S. cities don't have the target minimums, though federal law does not allow consideration of such minimum standards so at least Congress can protect us, right? Symposium participants were promised a look at the draft recommendations, but my personal experience testifying to WHO in Geneva is that the staff routinely ignore "public" comments inconsistent with the staff-driven policies they favor.
The scenario sounds like WHO's Report 916 all over again. Report 916 of two years ago was an attempt by WHO staff to create policy advocating salt (and other dietary) restrictions in the name of combating obesity. That report was so controversial it was not endorsed by the World Health Assembly composed of the 182 health ministers of United Nations countries. Could be a replay.
Many U.N. initiatives -- and many public health initiatives -- have foundered as they pursue objectives inconsistent with political realities or with, in this case, the science and engineering of public water supply systems. It seems such a waste of precious credibility
This weekly commentary piece by Anthony Fletcher in foodnavigator.com contends that the public may loose a proper focus on the iinherent danger of dietary salt in the current debate in the UK over sodium reduction targets in various foods. Mr. Fletcher is right to worry about missing the forest for the trees -- but, overall, is only half right.
I totally agree with him that it would be a dangerous public policy mistake to re-focus the "salt debate" on the UK Food Safety Agency's targets for foods away from the scientific rationale for reducing dietary salt. The public deserves to know what medical science informs us of the prospective benefits that achieving compliance with these targets will deliver, not just how hard it will be to accomplish.
Where we part company becomes apparent in his cheery contention: "The vital important message that salt consumption must be reduced will be lost in detail and voluntary detail at that." Wrong. The vital important message that would be lost in detailing the FSA target debate is the crucial and paramount question of whether reducing dietary salt will improve public health. You jump too quickly to the conclusion that "everyone knows" salt should be reduced.
In fact, there have been only thirteen studies reported which examine the amount of salt in the diet with relation to the incidence of cardiovascular events or mortality. All of them are observational studies; none is a controlled trial. If all thirteen were consistent in finding a health benefit for lower-salt consuming populations, perhaps we would have a strong argument that we should do a controlled trial of salt reduction to confirm that the postulated benefits would be realized. Recent trials of hormone-replacement therapy, calcium supplementation and low-fat diets have failed to confirm benefits suggested by observational studies of these questions even though the hypotheses were eminently plausible. Not only is there no controlled trial of the health outcomes of salt reduction, but all thirteen observational studies that have been reported turn out to be consistent in their findings -- but consistently find that there is no health benefit of reducing dietary salt. Four of the thirteen studies, including the Scottish Heart Health Study, have shown that low-salt consuming populations, in fact, showed a higher risk of adverse cardiovascular outcomes. The current, March edition of the American Journal of Medicine, for example, contains the latest of these studies. That research, by the current president of the International Society of Hypertension, documents that those on low-sodium diets have a 37% greater cardiovascular mortality.
So I agree with the commentary that "The current debate about the levels at which the UK's food regulator has set its salt reduction targets misses the point about how healthier eating habits can be achieved." "Healthier eating" will not be achieved by reducing dietary salt. We believe that the "healthier eating habits" should be based on the Dietary Approaches to Stop Hypertension (DASH Diet) with greater emphasis on consumption of fruits, vegetables and dairy products and which is salt-neutral. Let's not let the "details" of the scientific underpinning for the entire enterprise be lost in the discussion to the detriment of both consumers' understanding and, more importantly, improving consumers' health.
We know salt masks bitter flavors. The reason for the bitter taste of the salt debate is the lack of a crucial, missing ingredient -- mixing in a generous portion of health outcomes data. For more, see http://www.saltinstitute.org/28.html.
BestSyndication.com just ran an article with this title authored by Dan Wilson. Wilson argues that the proper test of a dietary intervention is not its affect on an intermediate factor like blood pressure, but whether the dietary change has been shown to extend life.
We agree.
Unfortunately, Wilson makes a few errors and omissions that undermine the argument. He compares a low-calorie diet to the DASH Diet. The only tests of the DASH Diet are for blood pressure; longevity was not measured -- it was, after all, a 30-day trial of a special population (e.g. 60% African American). He states that a "goal (of the DASH Diet) was to reuce sodium intake." This is an error. The DASH Diet held sodium constant -- a major distinguishing feature of this from other interventions. Thus, he concludes in puzzlement asking why advocates of a purportedly low-sodium DASH Diet would continue to recommend sodum reduction in the face of evidence "that showed people who said they limited their salt intake were 37% more likely to die from coronary heart disease or stroke when compared with those who ate more than the US recommended daily allowance of 2,300 milligrams a day (of sodium, he forgot to add)."
We have no quarrel with advocates of calorie restriction. But let's not set up straw men. And let's play square with the facts. The facts are: the DASH Diet is not sodium restricted and the DASH Diet never claimed to reduce mortality (although some of its advocates would have you believe that).
Bottom line: The headline is correct: Aim at extending life, not any intermediate risk factor like blood pressure (or insulin resistance, plasma renin activity, etc.).
This story in the March 14 Washington Post captures pretty well the issues underlying the discussion about whether American consumers should believe the massive new federal study that found no health outcome benefit of reducing dietary fat.
Authors Lisa Schwartz, Steven Woloshin and Gilbert Welch capture public anxiety over what to believe when headlines trumpet stories that diet can prevent cancer and counter-punch with other stories saying just the opposite.
In the recent Women's Health Initiative (WHI), researcher reported "the latest apparent flip-flop...about low-fat diet and breast cancer. The story describes the new 50,000, eight-year WHI trial and the 2005 Women's Intervention Nutrition Study (WINS) with about 5% that number. Helpfully, the authors point out that the two studies "differed in two major ways. First, they studied different groups of women: one with prior breast cancer (WINS) and one without (WHI). Women with breat cancer are substantially more likely todevelop a new breast cancer than women without breast cancer....And this is exactly what happened....The second major difference ...was in how statisticians judged the findings. This difference was profound. Based on conventiaionl statistical practices, the effect of the low-fat diet in women with breast concer was deemed to be real--the result of more than chance. But in women without breast cancer, the effect of diet was judged to be statistical noise."
The authors go on to explain the importance of statistical significance, the difficulty of compliance -- especially by the subgroup that derives no benefit and, importantly, the crucial difference between observational studies (that show diet affecting cancer risk) and intervention trials which don't.
"In fact, most of the diet flip-flops come from observational studies that suggest a benefit (or harm) from diet that is not subsequently confirmed in randomized trials." See where I'm headed? With regard to salt, we have policy based on an intermediate variable (blood pressure) and only observational studies of health outcomes. While the observational studies offer no comfort to low-salt interventionistsl, we can only insist on a controlled trial of low sodium diets to see if they will reduce risk. The early betting is that they won't.
For more, see the author's website, the VA Oucomes Group .
