Take Sodium Advice With a Grain of
Salt. Low Salt Crusade: Fact or Fiction?
by
governmentrico on August 27, 2010 By Paul J. Rosch, M.D. The “diet dictocrats” are at it again.
The latest NHLBI (National Heart Lung and Blood Institute) warning is that
Americans are eating too much salt and are therefore at increased risk for
hypertension, stroke and heart attacks. Others claim that excess sodium is a
poison that can also cause cancer and osteoporosis. NHLBI recommends that not
only high blood pressure patients but all Americans should sharply reduce their
sodium intake, regardless of age, gender or race. This is another example of
the same, stupid “one size fits all” cookie cutter approach of treating
population statistics and laboratory measurements rather than people. This latest ban on sodium seems strange
since salt has always been viewed as being very valuable. In ancient Greece,
slaves were traded for salt – hence the expression “not worth his salt.” Roman
soldiers were sometimes paid in salt (salis) and their salarium is the origin
of our word “salary”. “Soldier” actually comes from the Latin (sal dare), which
means, “to give salt”. How Did the Low Salt Crusade Start? If salt was believed to be so valuable
and useful in so many ways for so many thousands of years by so many million
people from so many different cultures, why is it that we have only recently
discovered that it is dangerous? Like the conspiracy against cholesterol and
fat intake, the denunciation of sodium began little more than 50 years ago. ewis Dahl was able to develop a strain
of salt sensitive rats who routinely developed hypertension to support his firm
belief in the value of salt restriction. This was widely heralded and cited by
other low salt proponents as proof of the role of salt in hypertension. What
they often neglect to mention is that these rats would have to be fed an amount
of salt equivalent to over 500 grams daily for an adult human. Dahl also
demonstrated a linear relationship between salt intake and blood pressure in
different populations as noted below: This surely confirmed the dangers of
salt for everyone and prompted the 1979 “Surgeon General’s Report on Health
Promotion and Disease Prevention” condemning salt as a clear cause of high
blood pressure. Since then, the government has spent untold millions in a vain
attempt to justify this claim. Their expensive and lengthy crusade to prove a
link between sodium and hypertension began in 1984 with the $1.3 million
INTERSALT study of 10,000 subjects in 52 centers around the world. As
anticipated, researchers reported that societies with higher sodium intakes
also had higher average blood pressures. A similar relationship was also
allegedly shown in individuals, thus clinching the government’s case. The Art of Mining Salt
Study Statistics The INTERSALT study seemed to confirm
Dahl’s findings. However, when the four primitive societies with both extremely
low sodium intake and very low blood pressures were excluded no such
correlation was found in the other 48 groups. This was reminiscent of Ancel Keys’
famous study where he “cherry picked” seven countries out of 15 around the
world and demonstrated a straight-line relationship between animal fat and
cholesterol consumption and deaths from coronary heart disease. Had Keys
selected data from the eight other countries that were available to him the
results would have been exactly the opposite. The INTERSALT researchers conveniently
neglected to mention that the population of the four countries responsible for
skewing the total figures to coincide with their preconceived conclusion also
had less stress, less obesity, ate far less processed foods and much more fiber
from fruits and vegetables. They also tended to die at younger ages from other
causes and often too soon to have developed any significant degree of coronary
atherosclerosis. Critics complained that these four
societies that distorted the average figures for sodium intake and hypertension
were so different from the rest of the groups, especially those in the U.S.A.
and U.K., that it was “like comparing apples with stringbeans rather than
oranges.” The Yanomami Indians in the rain
forests of Brazil had mean blood pressures of 95/61 and equally low urinary
sodium levels. These primitive people had no evidence of hypertension, obesity
or alcohol consumption and their blood pressures did not rise with age. When the available data from the other
more civilized societies was reviewed, statisticians found that as sodium
intake increased there was a decrease in blood pressure, just the opposite of
what had been reported. The lowest salt intake seemed to be in a subgroup of
Chicago black males despite the fact that their incidence of hypertension was
above average. Conversely, high blood pressure was relatively rare in
participants from China’s Tianjin Province even though this study group had the
highest salt intake. When confronted with these
discrepancies, the researchers reanalyzed their data in an attempt to justify
their conclusions. However, the only thing they could come up with was that a
higher sodium intake could be correlated with a faster rise of blood pressure
as people grew older. This is referred to as “mining the data” since a
relationship between blood pressure and aging was never a goal of the study.
Nor did this observation address the major purpose of determining whether
increased dietary sodium was related to higher rates of illness or death for
everyone. While it may be true that “figures
don’t lie,” liars can still figure. The first law of statistics is that if the
statistics do not support your theory you obviously need more data. The second
is that if you have enough data to choose from, anything can be proven by
statistical shenanigans. A good example are the numerous “risk factors” for
coronary heart disease like a deep earlobe crease or premature vertex baldness
that are really “risk markers.” These simply represent statistical associations
rather than competent causes. You can’t use a statistic to prove another
statistic. However, the anti-salt statisticians
had a field day with the data from the 1999 follow-up study of NHANES (National
Health and Nutrition Examination Survey) which began tracking 20,729 Americans
in 1971. They reported that participants who ate the most salt had 32 percent
more strokes, a whopping 89 percent more deaths from stroke, 44 percent more
heart-attack deaths, and 39 percent more deaths from all causes. This finally seemed to prove precisely
what the government had been preaching all along. In addition, the study’s
conclusions were seemingly credible due to the large number of subjects and a
19-year average period of observation, enough time to determine whether people would
have increased mortality rates or a higher incidence of illness from consuming
too much salt. As the lead author proudly proclaimed,
“Our study is the first to document the presence of a positive and independent
relationship between dietary sodium intake and cardiovascular disease risk in
adults”. Pouring Salt in
Low-Sodium Wounds However, when independent researchers
reanalyzed the data they discovered that dietary sodium intake was associated
with higher rates of illness and death only in participants who were
overweight. There was no correlation between sodium and increased
cardiovascular disease risk in the remainder. Undaunted, another study author
continued to claim that the conclusions were valid since statistics showed that
more than one in three Americans were overweight and most ate too much salt. He admitted that the NHANES research
“was not specifically designed to answer” the question of sodium and health –
in other words, more mining of the data. In addition, the entire study depended
on just one 24-hour recall of sodium intake. When questioned about the dubious
value of such information he was forced to concede that “At best, the estimate
for sodium is imperfect”. He also agreed that measuring the concentration of
sodium in a 24-hour urine specimen would have provided more accurate
information about dietary habits and excess consumption. Statistics are somewhat like expert
witnesses in that they can be used to testify for either side depending on what
you want to prove. When Michael Alderman, a highly regarded epidemiologist and
past president of The American Society of Hypertension scrutinized the same
data in patients who were not overweight he reported that “the more salt you
eat, the less likely you are to die.”–(from heart disease or anything else). Alderman has long been critical of the
government’s low sodium diet advice for large populations and their focus on
sodium intake as it relates to blood pressure rather than to the overall
health, quality and length of life of individuals. He examined the relationship
between sodium intake and health effects in 3,000 patients with mild to
moderate hypertension. In addition, his group measured sodium excretion, which
is much more accurate than estimating dietary intake. At the end of four years,
they found that those who consumed the least sodium had the most myocardial
infarctions and other cardiovascular complications. The reason for this is that when you
restrict vital nutrients like salt (or cholesterol) all sorts of strange things
can result. Low sodium diets can increase levels of renin, LDL and insulin
resistance, reduce sexual activity in men and cause cognitive difficulties and
anorexia in the elderly. Tasteless and dull low sodium diets can cause other
nutritional deficiencies. Lowering sodium with diuretics to treat hypertension
can cause similar problems. Renin is possibly the most powerful and
dangerous blood pressure raising substance known. Indeed, the study done by
Alderman’s group found that for every two percent increase in pretreatment
plasma renin activity there was a 25 percent increase in heart attacks. No such
correlation was found with increased sodium intake. There are no research reports that
justify putting everyone on a low-sodium diet. A meta-analysis of 83 published
studies that included people who had been randomly assigned to follow a high or
low sodium diet found that in those with elevated blood pressures, a low sodium
diet was able to lower systolic pressure 3.9 mm Hg and diastolic pressure by
1.9 mm Hg. However, in others with normal
pressures, cutting salt intake reduced blood pressure by only 1.2 mm systolic
and 0.26 mm diastolic. I don’t know how many of you have ever taken a blood
pressure but it is almost impossible to detect such minute differences. If you
use the standard method and take repeated blood pressures over a few minutes
each reading often varies by 5 mm. or more and it is extremely difficult to
detect a diastolic measurement difference of 2 mm. These figures were arrived at because
meta-analysis is a technique that allows statisticians to look at studies that
may have been designed for different reasons but contain data on specific items
that can be combined and averaged for whatever purpose you choose. I have never been a great fan of meta-analysis,
since it often illustrates that “statistics are a highly logical and precise
method for saying a half-truth inaccurately.” Low sodium diets may be helpful
for some hypertensive patients by reducing their need for drugs but there is no
proof to support official recommendations that they are good for everybody. Slipping Through Some
Legal Loop-holes As previously noted, low salt diets may
not be as entirely harmless as proponents often claim. In the meta-analysis
survey, which was published in the Journal of the American Medical Association
a few years ago, researchers reported that cholesterol and LDL “bad”
cholesterol increased with sodium reduction. More importantly, blood levels of
renin and aldosterone also rose in proportion to the degree of sodium
reduction. This compensatory response to increase
blood volume would tend to raise blood pressure and possibly the likelihood of
cardiovascular complications. Since the government began promoting sodium
restriction and diuretics three decades ago, the incidence of hypertension and
strokes has increased and the previous declining rate of heart attacks has
leveled off. Investigators from the Salt Institute
also wondered why there would be any dramatic rise with age if population blood
pressures showed no association with dietary sodium intake. Because this was
the only positive finding of the INTERSALT study they asked if an independent
expert could analyze all the data, especially since this was a research project
that had been funded by taxpayer money. The study authors refused claiming
proprietary ownership and that this was only the first in a series of papers.
It would also reveal confidential information about the study participants
which, under INTERSALT’s policies and alleged federal regulations, they were
“obligated to protect from disclosure.” The NIH, which funded the study, was
also petitioned but said that the financial arrangement had been structured
specifically to exclude them from access to the raw data. This seemed strange.
Sensing that some significant information was being withheld and mindful of the
old saying that “the devil is in the data”, the Salt Institute refused to be
stymied. They asked the ORI (Office of Research
Integrity) to determine whether the authors’ findings had been fairly reported.
ORI claimed they could only proceed if it was claimed that the authors had
committed fraud–a Catch-22 situation, since it was impossible to make such an
accusation without access to the raw data. The Salt Institute then sought legal
relief. The law requires that all federal guidelines affecting the public must
be written and promulgated according to the Government Code. This mandates open
meetings and discussions and that the final rules or guidelines must be
published in the Federal Register. It took three years for their attorneys
to finally obtain the raw data dealing with just one of several specific
questions that had been posed. This was enough to bring down the house of
cards. A detailed explanation of how the data had been manipulated to support
predetermined conclusions was published in the British Medical Journal in 1996
and was subsequently endorsed by various authorities. The NIH has consistently circumvented
the Government Code with its cholesterol and hypertension guidelines by claiming
they were written by outside experts not subject to these regulations, even
though they are presented as official policy. The National Heart, Lung and
Blood Institute, Department of Health and Human Services and U.S. Department of
Agriculture have repeatedly referenced the INTERSALT study as justifying sodium
restriction. The FDA even authorized a “sodium and
hypertension” food label health warning that states, “The INTERSALT study
reported a statistically significant relationship between sodium intake and the
slope of systolic and diastolic blood pressure with age.” How can anyone claim
that this is not official policy? In 1998, Congress mandated that federal
agencies make available to the public all such data by broadening the Freedom
of Information Act. It also included other provisions for the Office of
Management and Budget to require all federal agencies to adhere to this new
access-to-data standard. Unfortunately, this is not retroactive. Fifteen years
later we still do not have access to all the INTERSALT data and hundreds of
studies started prior to 1998 are also exempt. Last month, a congressional bill was
introduced mandating that the results of the more than $45 billion spent
annually for research should be freely available to taxpayers. It would also
prohibit all scientists who receive federal funding from holding copyright to
their research. Don’t hold your breath waiting for this bill to become law. The DASH Study-Déja Vu
All Over Again? The NIH funded DASH (Dietary Approaches
to Stop Hypertension) study reported in 1997 that blood pressure could be
significantly reduced by eating a diet rich in fruits, vegetables and low-fat
dairy products. This DASH combination diet was more effective than a typical
American high fat, low fiber, low mineral diet and even one of fruits and
vegetables, particularly in people with elevated blood pressures. All three
diets had the same sodium content and there was no attempt to restrict salt.
Government officials were anxious to show that restricting sodium would lower
blood pressure even more. This seemed to be confirmed in a
follow-up DASH-Sodium study in 412 subjects with elevated and normal blood
pressures that were randomly assigned to follow the DASH diet or a control
typical American diet. The two groups were further divided into three
categories: those who ate 3.3 grams of sodium/day (the amount in the average
American diet); 2.4 grams/per day (the current recommended level); and 1.5
grams/day. Researchers reported in May 2000 that
reducing sodium intake from the high to low levels resulted in an average
progressive lowering of systolic blood pressure of 6.7 mm Hg for those on the
control diet and drop of 3 mm Hg for Dash Diet subjects. Hypertensive patients
showed a greater response to a low sodium diet in both groups, with an
impressive 11.5 mm Hg reduction for those on the control diet. Thus, sodium restriction lowered blood
pressure in hypertensive and nonhypertensive men and women regardless of race.
The belief that, “the lower the blood pressure the better”, prompted the NHLBI
director to declare that the four-decade-old controversy was now over. Everyone
should adhere to a low sodium diet. Not everyone agreed. The DASH diet was
rich in calcium, potassium, and magnesium, all of which have been found to
lower blood pressure. The study group was not representative of the American
public and all meals had been prepared rather than selected. The available
statistics suggested that for those on the DASH diet with normal blood
pressures, cutting salt intake in half had little effect. Diet was the most important influence
and there was no significant additional benefit in hypertensives who also
restricted salt. Participants were only followed for a month and prior studies
had shown that any blood pressure reductions associated with restricting sodium
tend to disappear after six months as compensatory mechanisms kick in. Since all subjects were fed prepared
meals there was over 95 percent compliance, which would be difficult to achieve
in a real life setting where people choose the foods they want to eat. Almost
60% of the subjects were African Americans and over 40% were hypertensive. Both
of these groups tend to be salt sensitive and are hardly representative of the
general population. David McCarron, a hypertension
specialist argued that the figures suggested that no benefits would be seen in
white men under the age of 45, but here again, all the data were not available.
As in the past, requests to release all the data were denied. McCarron
complained about this in a letter to The New England Journal of Medicine and in
a January editorial in the American Journal of Hypertension, which stated
“critical data from a federally sponsored trial have been withheld.” Nothing
happened. On May 15, the Salt Institute and the
U.S. Chamber of Commerce sought legal relief by invoking the Data Quality Act
that took effect last October. This regulation now mandates that official
agencies promulgating “influential” results that affect large groups must
provide enough data and methods for a “qualified member of the public” to
conduct a reanalysis. Since NHLBI’s latest sodium restriction recommendations
clearly affect a very large group of people and are based on the DASH-Sodium
study, the argument that all subgroup data should be made available seems quite
valid. DASH authors will probably argue that
they plan to publish more papers and, as noted in a response to McCarron’s
editorial, they are concerned that he will “dredge the data” and perform
statistical analyses on groups that are too small to be meaningful. NHLBI has
60 days to respond but based on past experience, will likely continue to
sidestep federal regulations and stonewall concerned scientists. ANOTHER EXAMPLE OF MORE NIH AND HHS
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