July 16, 2004
Kathryn
McMurry
HHS Office of Disease Prevention and Health Promotion
Room 738-G
200 Independence Avenue, SW
Washington, D.C. 20201
Dear
Kathryn:
As
the Dietary Guidelines Advisory Committee prepares for its final meeting next month, we
would take this opportunity for a few “closing” thoughts.
Congratulations
to the Committee for its obvious recognition of the importance of addressing the
population’s calcium, magnesium and potassium deficiency status. We read the evidence to show that overcoming these
deficiencies (as through the DASH Diet) will virtually eliminate “salt
sensitivity” and eliminate need to accept the risks inherent in the Committee’s
unfortunate continuation of a recommendation of universal sodium restriction.
We
are perplexed as to why the Committee did not adopt an “evidence-based”
approach. Of course, everyone uses
“evidence” as the basis for recommendations.
An “evidence-based” approach, however, is more than that: it is the discipline of defining in advance the
quality of evidence that will be required to make population-level recommendations and
then evaluating the evidence against that yardstick.
It is clearly distinguishable from the “expert opinion” approach employed
by the Committee – a missed opportunity.
We
are concerned that the Committee did not examine the health outcomes of the
recommendations being made. With regard to
restriction of dietary sodium, the relevant health outcomes are the incidence of
cardiovascular events; does reducing dietary sodium cut heart attacks and strokes? The evidence on this point is not robust, to be
sure, but it is consistent. Not one of
the ten studies examining the health outcomes of restricting a population’s dietary
sodium has identified a population reduction in the incidence of cardiovascular events. In fact several have identified additional risks
of following the advice that the Committee seems determined to include in its final
report. It is regrettable that the Committee
chose to ignore the only ten studies bearing directly on the question it sought to answer:
will reducing dietary salt reduce the risk of heart attacks? While the Committee’s faith in salt reduction
has been widely repeated; we believe the question should be empirically tested. Ignoring inconvenient evidence is unacceptable
public policy.
The
Committee should be cautious in its use of the DASH-Sodium conclusions as presented by its
investigators. While the conclusions are
exciting and the methodology compelling, DASH-Sodium is, after all, a single 30-day
feeding trial. Moreover, the investigators
have promised to publish key data that are needed to verify their conclusions that
virtually all Americans – those with elevated blood pressures as well as those with
normal pressures, young and old – would benefit by reducing dietary sodium. To us, that conclusion seems unlikely, but without
the data neither interpretation can be properly tested.
As you know, those data are the subject of a complaint filed earlier this
year in federal court.
As
we informed you earlier, the dissemination of the DASH-Sodium investigators’
conclusions as government policy must, by law, be consistent with the federal Data Quality
Act. Just yesterday, the Salt Institute and
the U.S. Chamber of Commerce filed our most recent brief with the federal district court
in Alexandria, VA, requesting the court to compel HHS/NHLBI to produce the information
upon which their (and your) recommendations are based. I’ve enclosed a copy of that brief for your
information. The oral argument is scheduled
for August 13th.
One
of the major remaining questions for the Committee is to fashion a recommended research
agenda that would provide critical information for the 2010 revisions of the Guidelines. We have a few recommendations for your
consideration; they include:
“… members of the (2004) FDA Food Advisory Committee responded to the question, ‘Does the current scientific evidence suggest a relationship between total fat intake and risk of coronary heart disease?’ with a resounding no. They were quoted as stating there is essentially no relationship between dietary fat and CHD and that the emphasis on total fat was distracting attention from saturated and trans fat.”
Sounds
familiar to me. The protracted effort to
reduce dietary sodium has distracted us from more important and fruitful interventions. The editorial continues and quotes a Food
Chemical News article that reported “that most panel members regarded the low-fat
fad as an example of what can happen when industry and regulators embrace a scientific
concept too quickly and fail to ponder the possible consequences.” While I cannot speak to whether industry jumped
“too quickly” to respond to dietary recommendations to reduce dietary fat, I
know that the food industry has been trying mightily for a quarter-century to follow the
Guidelines’ sodium recommendation by reducing the salt content of its foods. And it has. But,
when we get the DASH-Sodium data and when a clinical trial of the health outcomes of salt
restriction is finally tested, will the food industry that has asked for a scientific
rationale for salt reduction be blamed if the story changes? Will salt restriction turn out like hormone
replacement therapy? The flat earth? The
universe of Ptolemy?
If
you must proceed with a salt reduction recommendation, at least please forcefully advocate
investing in the research needed to guide the next Advisory Committee. With that new information, future committees will
be better able to assess whether the recommendation is doing more harm than good. If that proposition turns out to be the case, the
distracting advice to lower salt intake will no longer compromise more effective
recommendations to improve the quality of the American diet.
Sincerely,
Richard
L. Hanneman
President
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