When the federal government set up its program to ensure the safety of American foods, it recognized that some ingredients had been used safely for years -- for some, for centuries and for a few, like salt, for millennia. They prioritized their resources and accorded these proven-safe ingredients recognition as Generally Recognized as Safe (GRAS). The decision was reviewed and affirmed in 1982. The process is about to be re-run.
Arguing that salt affects blood pressure, a number of advocacy groups endorse removing GRAS from salt and having FDA set food-by-food limits on salt content on the assumption that this would produce lower sodium intakes and lower blood pressure. Defenders of GRAS for salt (SI, food manufacturers, some health groups and prominent hypertension researchers, argue that blood pressure is an "surrogate" risk factor -- and not a very good surrogate at that! There are other surrogate candidates to predict chronic disease risk: insulin resistance, plasma renin activity and more. Salt affects them as well. Salt's defenders -- like the Salt Institute -- have insisted the right test isn't blood pressure, but rather actual disease outcomes like heart attack incidence or, better still, mortality rates.
FDA is conducting a hearing Nov. 29th to air the controversy with prominent proponents of both views delivering oral testimony to an FDA panel in College Park, MD.
The Salt Institute will be testifying, renewing its call for a controlled trial of the health outcomes of low-salt diets and challenging FDA to help fund the study. Read the news release or the full testimony .
For a good review of the issues, see JunkFoodScience's story "The good-bad salt debate gets a hearing at the FDA ."
We're an equal opportunity critic of cooking the books on medical studies. As an FDA panel this week will (again) examine the relationship of salt and health, JunkfoodScience reminds us of the games-playing in the "gold standard" ENHANCE trial, "Even gold can be tarnished." Don't miss it. Let's hope the FDA panel reads it too!
It's a deadly double play combining the Big Lie with the Devil in the Details. But this is no game.
Epidemiological studies are often used inappropriately for common illnesses like cardiovascular disease and cancer, according to British cardiologist Guy Lloyd.
Randomized controlled trials are more reliable. Epidemiology is most effective in identifying large risks in rare diseases. Just in the field of cardiology, the results of observational studies are often seriously flawed.
Observational studies of the cardioprotective effects of female sex hormones, the usefulness of antioxidants or homocysteine lowering strategies, and rhythm control for atrial fibrillation suggested a clear treatment effect and greatly influenced practice. But subsequent randomised trials refuted each hypothesis.
The main problem, he explained, is all of the interacting factors among cohorts that can't be statistically accounted for in an epidemiological study.
Concerns with the reporting of medical studies are multiplying. A recent blog on Junkfoodscience highlights the efforts of a new project, STROBE (Strengthening the Reporting of Observational Studies in Epidemiology). We wish them all success.
Since the early 1950s the health promoting qualities of the Mediterranean diet have been universally acknowledged. The Mediterranean diet "is characterized by abundant plant foods (fruit, vegetables, breads, other forms of cereals, beans, nuts and seeds), fresh fruit as the typical daily dessert, olive oil as the principal source of fat, dairy products (principally cheese and yogurt) and fish and poultry consumed in low to moderate amounts, zero to four eggs consumed weekly, red meat consumed in low amounts, and wine consumed in low to moderate amounts, normally with meals. This diet is low in saturated fat (less than or equal to 7-8% of energy) with total fat ranging from less than 25% to greater than 35% of energy throughout the region." In fact, the famous DASH diet was designed using the Mediterranean diet as the model. What is never revealed, however, is that the level of salt in the Mediterraneam diet is considerably higher than that the levels recommended for the US diet.
Drs. Leclercq and Ferro-Luzzi of the WHO Collaborating Centre for Nutrition, at the National Institute of Nutrition in Rome, Italy reported in that males consumed 4400mg sodium per day based upon 24 hr Urinary excretion, equivalent to 11grams of salt per day . It was also observed that the discretionary intake of salt for adults varied from 36% (males) to 39% (females) of the total intake. The discretionary intake alone, of salt in Italy amounts to almost 75% of the total sodium recommended in the US (2300 mg). Since many of the Mediterranean foods are naturally well salted (cheeses, olives, salted fish (cod, anchovies), fish eggs, etc., it is natural to expect that a majority of the discretionary salt is used to improve the palatability of the variety of vegetables that are such a conspicuous and essential part of the diet.
When the DASH-Sodium trial is examined, it is immediately apparent that moving to a DASH-type diet has a far greater impact on blood pressure than lowering salt consumption. Dropping from the current level of sodium consumption to the recommended dietary level dropped the systolic pressure by an average of 2.1 mm Hg. However, simply changing from a regular to the DASH diet, without any changes to sodium consumption, reduced the systolic blood pressure by 5.9 mm Hg, almost three times the drop resulting from the sodium reduction. This clearly explains why Mediterranean people enjoy an excellent cardiovascular status despite their high salt consumption. With a DASH diet, the impact of sodium on the blood pressure of hypertensives is minimal (and of no significance to normotensive people - the majority in the population).
Considering that significantly increased fruit and vegetable consumption is a key element to the DASH/Mediterranean diet models, it is entirely realistic to question whether the current recommended daily intake of sodium (2300mg/day) is realistic, given the Italian example above. Amongst the most important foods are the bitter cruciferous vegetables. While they have so much nutrition to offer, without salt, they are not palatable to adults or children (who are even more sensitive to bitterness). In addition to the benefits of the DASH/Mediterranean diet for cardiovascular disease outcomes, all other health parameters are significantly improved. Based on all the scientific evidence we have available, fruits and vegetables are the cheapest, most readily available, and most beneficial foods we can consume to give a significant degree of protection from the modern health challenges we face. Considering the hierarchy of positive health impacts, maintaining the DASH/Mediterranean diet is far more significant than reducing salt - the one safe condiment that has traditionally made this diet so agreeable.
Three weeks ago, at the GMA/FPA and CSPI Salt Conference, Michael Jacobson of CSPI categorically stated in his opening remarks, "The debate on sodium is over. There is no longer a debate whether salt is good or bad." He was followed by Steve Havas of the AMA who stated that he did not believe any additional research was necessary to prove the beneficial impacts of a dramatic sodium reduction in the diet. This attempt to stifle discussion and pronounce, as if by imperial fiat, that there was no longer any debate concerning the benefits of salt reduction in the diet backfired.
When the audience, which was composed of professional food scientists, nutritionists, dieticians, epidemiologists and policy makers split into working sessions to consider all that was said, they concluded that the benefits of salt reduction to health outcomes had yet to be proven scientifically and that that a singular focus on salt reduction was not a viable solution. Indeed, the delegates unanimously stated that a more holistic approach was needed to improve overall dietary quality.
Almost as it on cue, within two weeks of the Salt Conference, two peer-reviewed medical journal articles appeared, both demolishing Michael Jacobson's assertion that "the debate on sodium is over." In a paper published in the October issue of the European Journal of Epidemiology , prominent Dutch scientist D.E. Grobbee and colleagues in the Rotterdam Study concluded that urinary sodium is not significantly associated with myocardial infarction, stroke, or overall mortality, adding: "The absence of a relationship between salt intake and mortality in our study corroborates the findings from the large Scottish Heart Health Study among almost 12,000 middle-aged subjects with 24-h urine samples."
Shortly thereafter, in the Journal of Interactive Cardiovascular and Thoracic Surgery , Drs. Jay Walker, Alastair MacKenzie and Joel Dunning of the Department of Cardiothoracic Surgery at James Cook University Hospital, in Middlesbrough, UK reported their in-depth review of all available evidence to determine if restricting dietary salt intake would provide protection from adverse cardiovascular events or mortality. They found it impossible to find a link between salt and heart disease due to a "lack of adequately powered randomized trials or observational studies conducted with sufficient rigor." Dr Dunning went further - he dismissed the theory that salt can cause strokes and heart attacks as,
...an argument of hope over reason....
These two publications reinforce the conclusions of the recent evaluation of the health outcomes study from Finland's three decade long salt reduction program.
Today saw a scathing denunciation of the poor science that has gone into the UK's public health policies . Dr. Phil Peverley, a GP from Sunderland in Northern England is this year's Magazine Journalists and Designers Association Columnist of the Year. Last year, he won the Press and Periodical Association's columnist of the year award. In his article, "A Very Large Pinch of Salt," Dr. Peverly criticizes
those doctors and politicians who have for years promoted the nannying theory that we should be forced to eat less salt in our diets. The obvious lack of a correlation between elevated blood pressure and salt intake should have been good enough for them.
He goes on to describe Public health minister Dawn Primarolo, who was recently quoted as saying that a low salt intake was an essential part of a healthy diet.
Ms Primarolo's only qualification to spout off on this subject is a six-year pre-MP career as a 'mature student', so I would always have regarded her pontifications as profoundly suspect…
Delving deeper, he states:
However, my remit is a wider one. This is further evidence that it is us, the medical profession, who don't know what we are talking about. I never fell for the bollocks about salt, but I have been as guilty as the rest of spreading disinformation and inaccurate advice about a whole manner of other medical subjects. It is becoming embarrassing.
Bravo Phil Peverly! There are not many like you, but hopefully there will be enough to drive away the fog, so we can get back to the science.
Writing for the American Council on Science and Health , Kathleen Meister offers sound advice for medical and science writers. Available in PDF , here's the executive summary :
• Scientific studies that show an association between a factor and a health effect do not necessarily imply that the factor causes the health effect. Many such studies are preliminary reports that cannot justify any valid claim of causation without considerable additional research, experimentation, and replication.
• Randomized trials are studies in which human volunteers are randomly assigned to receive either the agent being studied or an inactive placebo, usually under double-blind conditions (where neither the participants nor the investigators know which substance each individual is receiving), and their health is then monitored for a period of time. This type of study can provide strong evidence for a causal effect, especially if its findings are replicated by other studies. Such trials, however, are often impossible for ethical, practical, or financial reasons. When they can be conducted, the use of low doses and brief durations of exposure may limit the applicability of their findings.
• The findings of animal experiments may not be directly applicable to the human situation because of genetic, anatomic, and physiologic differences between species and/or because of the use of unrealistically high doses.
• In vitro experiments are useful for defining and isolating biologic mechanisms but are not directly applicable to humans.
• Observational epidemiologic studies are studies in human populations in which researchers collect data on people's exposures to various agents and relate these data to the occurrence of diseases or other health effects among the study participants. The findings from studies of this type are directly applicable to humans, but the associations detected in such studies are not necessarily causal.
• Useful, time-tested criteria for determining whether an association is causal include:
- Temporality. For an association to be causal, the cause must precede the effect. - Strength. Scientists can be more confident in the causality of strong associations than weak ones. - Dose-response. Responses that increase in frequency as exposure increases are more convincingly supportive of causality than those that do not show this pattern. - Consistency. Relationships that are repeatedly observed by different investigators, in different places, circumstances, and times, are more likely to be causal. - Biological plausbility. Associations that are consistent with the scientific understanding of the biology of the disease or health effect under investigation are more likely to be causal.
• New research results need to be interpreted in the context of related previous research. The quality of new studies should also be assessed. Those that include appropriate statistical analysis and that have been published in peer-reviewed journals carry greater weight than those that lack statistical analysis and/or have been announced in other ways.
• Claims of causation should never be made lightly. Premature or poorly justified claims of causation can mislead people into thinking that something they are exposed to is endangering their health, when this may not be true, or that a useless or even dangerous product may produce desirable health effects.
We hope this gets to be a popular site.
Whether it's the health of the planet or of its human inhabitants, it seems we have to learn every generation about the pain and suffering inflicted when we act on improperly-understood "science" -- and, thus, the need to employ a cautionary, evidence-based approach to basing public policy on boldly-asserted scientific truth.
An article in the current American Thinker deals with global warming, but it's not my intent to explore the validity of the scientific clash on that issue, only to "steal" an anecdote to make a further point. Author James Lewis shares this story:
Trofimko Lysenko is not a household name; but it should be, because he was the model for all the Politically Correct "science" in the last hundred years. Lysenko was Stalin's favorite agricultural "scientist," peddling the myth that crops could be just trained into growing bigger and better. You didn't have to breed better plants over generations, as farmers have been doing for ages. It was a fantasy of the all-powerful Soviet State. Lysenko sold Stalin on that fraud in plant genetics, and Stalin told Soviet scientists to fall into line --- in spite of the fact that nobody really believed it. Hundreds of thousands of peasants starved during Stalin's famines, in good part because of fraudulent science.
He then provides context:
When the scientific establishment starts to peddle fraud, we get corrupt science. The Boomer Left came to power in the 1970s harboring a real hatred toward science. They called it "post-modernism," and "deconstructionism" --- and we saw all kinds of damage as a result. Scientific American magazine went so far as to hire a post-modern "journalist" to write for it. John Horgan became famous for writing a book called The End of Science, but never seemed to learn much about real science. It was a shameful episode. ....
Pathological science kills people and ruins lives. Such fake science is still peddled by the PC establishment in Europe and America. ...
Britain is even more vulnerable to politicized science than we are, because medicine is controlled by the Left. That is a huge chunk of all science in the age of biomedicine. But the British Medical Journal and even the venerable Lancet are no longer reliable sources. Their political agenda sticks out like a sore thumb. It was The Lancet that published a plainly fraudulent "survey" of Iraqi civilian casualties a few years ago --- the only "survey" ever taken in the middle of a shooting war. As if you can go around shell-shocked neighborhoods with your little clipboard and expect people to tell the truth about their dead and wounded: Saddam taught Iraqis to lie about such things, just to survive, and the internecine fighting of the last several years did not help. The whole farce was just unbelievable, but the prestigious Lancet put the fake survey into the public domain, just as if it were real science. It was a classic agitprop move, worthy of Stalin and Lysenko. But it was not worthy of one the great scientific journals. Many scientists will never trust it again.
The account continues on global warming, but my point is the broader one: politically-correct science may not be scientifically-correct science and relying on PC science (junk science) risks disasters like that engineered by Stalin. That's true for environmental science. And it's true for nutrition science.
For years, the anti-salt advocates have ducked the scientific evidence and relied on the support of the largest medical and health institutions to prop up their contention that there is an unassailable link between salt intake and cardiovascular disease. This fallacious strategy is known as Argumentum ad Verecundiam - the reliance on known institutions and entrenched doctrines, rather than experimental data - the sort of thing that Francis Bacon grappled against in his struggle to bring us the scientific method.
Predictably, science eventually finds it way to the surface and in this case, the Argumentum ad Verecundiam is showing signs of collapse in the face of mounting evidence against a link between salt intake and cardiovascular disease.
In the most recent issue of the Journal of Interactive Cardiovascular and Thoracic Surgery , Drs. Jay Walker, Alastair MacKenzie and Joel Dunning of the Department of Cardiothoracic Surgery at James Cook University Hospital, in Middlesbrough, UK carried out an in-depth study of all available evidence to determine if restricting dietary salt intake would provide protection from adverse cardiovascular events or mortality. Using reported search parameters, 462 papers were identified of which 14 papers represented the best evidence on the subject. They concluded that restricting sodium intake to levels below 6 g per day as most international guidelines, such as those of the AHA, the US Dietary Guideline Committee and the Scientific Advisory Committee on Nutrition recommend may reduce blood pressure, but found it impossible to find a link between salt and heart disease due to a "lack of adequately powered randomised trials or observational studies conducted with sufficient rigor."
This information corresponds with the recent publication of the Rotterdam Study by Geleijnse et al, as well as the evaluation of the health outcomes from Finland's three decade long salt reduction program .
The myth-information about salt and cardiovascular health outcomes has gone on for a long time and misdirected our focus from more practical and effective approaches to achieving good health. It's time we start devoting our resources to solutions that have scientific merit, such as improving the overall diet through systems and products that encourage greater consumption of fruits, vegetables and low-fat dairy products.
A new Dutch study of 2,896 subjects studied for 5-6 years has concluded that there is no health benefit for healthy subjects to reduce dietary salt. The risk for subjects with cardiovascular disease and diabetes was not reported.
This, the 16th study of the health outcomes of reduced-salt diets, examined the incidence of heart attacks and strokes, cardiovascular mortality and all-cause mortality. Unfortunately, all the studies are observational (this is a case-cohort analysis); a controlled trial is required to address the question. The paper was published in the October issue of the European Journal of Epidemiology .
The research team headed by Diederick E. Grobbee examined a large, high-quality and much-admired database that contains data unavailable to some of the earlier studies. The authors reported:
Urinary sodium was not significantly associated with incident myocardial infarction, incident stroke, or overall mortality. For CVD mortality, however, a borderline significant inverse association was observed (RR = 0.77 (0.60-1.01) per 1-SD, model 3) but the relationship was attenuated after excluding subjects with a history of CVD or hypertension (RR = 0.83 (0.47-1.44) per 1-SD, model 3). In subjects initially free of CVD, the risk of all-cause mortality was also examined across quartiles of 24-h urinary sodium (median values: 45, 87, 125 and 190 mmol, respectively). RR in consecutive quartiles, using the lower quartile as the reference, were 0.80 (0.43-1.49), 0.66 (0.34-1.27) and 0.98 (0.54-1.78), respectively (model 3). In a subgroup analysis of CVD free subjects with a body mass index ≥25 kg/m2, the association of urinary sodium with CVD mortality or all-cause mortality was neither statistically significant (RR = 0.91 (0.44-1.89) and RR = 1.19 (0.86-1.66) per 1-SD, respectively; model 3).
