December 27,
2002
Mr. Jeff Allder
Scientific Advisory Committee on Nutrition
Room 808C Aviation House
125 Kingsway
London WC2B 6NH
United Kingdom
RE: Consultation on SACN Draft Salt Review
Dear Mr.
Allder:
On behalf of
its global membership of salt producing companies, particularly those in Europe and,
specifically, in the United Kingdom, the Salt Institute strongly endorses the SACN’s
identification of the “key issues” with regard to the public health implications
of nutrition guidance for consumption of dietary sodium.
Salt is the source of an estimated 85% of the sodium in the British diet.
The Salt
Institute also endorses the British salt industry’s critique of the draft report as
submitted by the Salt Manufacturers Association. We
believe the entire draft should be rewritten and offer our additional comments as
suggestions to focus more effectively the SACN’s advice and recommendations on the
“key issues” its Salt Subgroup has identified.
These “key
issues” are set forth in the draft in Section 1.4 as follows: “(T)he Salt Subgroup identified some of the
key issues for consideration. These were: physiological requirements for sodium; salt
sensitivity; and morbidity and mortality outcomes.”
All are important, but the final “key issue” – health
outcomes – represents the breakthrough in understanding that can resolve the
continuing controversy that has plagued our efforts to resolve this larger issue. In recognizing as one of the three “key
issues,” that of health outcomes, the SACN perceptively accepts the evolving
consensus that Britons’ health outcomes are the legitimate public health concern, not
a focus on intermediate variables such as blood pressure.
It has been this mistaken focus on blood pressure to the exclusion of hard
end points of cardiovascular disease and all-cause mortality that has confused scientists
for the past 30 years, distracted public health leaders and stalled an effective attack on
dietary therapy and public health nutrition interventions to reduce the incidence of heart
attacks and strokes.
Unfortunately,
the draft then goes on to focus virtually all its discussion on non-“key issues”
and misses its opportunity to contribute to advancing the public health agenda. Its discussion of the “key issues” is
incomplete, biased and omits crucial available evidence.
As a prime example, although the draft references the recent Hooper et. al.
meta-analysis published in the September 30, 2002 British Medical Journal, it
entirely omits that study’s conclusion that evidence does not support a conclusion
that sodium reduction reduces the incidence of cardiovascular events.
We urge the
SACN to begin afresh rather than risk transmitting the current draft which fails in its
attempt to address these “key issues” and, in fact, represents a highly-biased,
inappropriately-focused and arbitrarily-interpreted commentary resulting in misdirected,
if commonplace, dietary recommendations. The
Food Standards Agency deserves better advice from its advisors.
Blood pressure
is certainly important. Lowering blood
pressure is certainly a priority health concern. What
is required, however, is not a simplistic focus on the level of systolic (and, to a lesser
extent, diastolic) blood pressure, but a simple recognition that while blood pressure
levels do matter, how blood pressure reduction is achieved also matters. The objective of lowering blood pressure is not
less blood pressure, but, instead, improved health.
Since
publication of the SACN draft, the final report of The
Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack (ALLHAT) Trial has been published. This massive U.S. trial compared the health
outcomes of various pharmacologic interventions for their ability to reduce cardiovascular
events and all-cause morbidity. It accepts
the premise that blood pressure reduction, alone, is an insufficient metric to determine
the suitability of an intervention. The principal
objective of ALLHAT was to identify differences in coronary heart disease morbidity and
mortality; it found no significant differences. Of
course, all-cause mortality is probably what most public health officials care most about. But even though a large trial and, particularly,
since active agents were used to lower blood pressure equally, since the ALLHAT Trial was
an intervention designed to only effect cardiovascular disease, it was never anticipated
that all causes of mortality would change in a 5 year study. Surprise! The
significant findings were that the drugs did differ significantly in different components
of end points. Thus, for example, the calcium channel blocker produced more congestive
heart failures than diuretics, and the converting enzyme inhibitor recorded more strokes
than diuretics. The bottom line is that neither
of the newer drugs beat a diuretic in any category, and the diuretic beat each of its
competitors in a least one important outcome for of CVD.
ALLHAT demonstrated just how dramatically real evidence on health outcomes
can affect decisions on selecting the proper pharmacologic intervention.
Likewise, the
SACN now has the ability to redraft its advisory to incorporate this rationale and
identify the health outcomes of potential non-pharmacologic interventions on improving
cardiovascular health and reducing all-cause mortality.
This report of the Salt Subgroup could become the basis for a broader
reassessment by the SACN of its dietary recommendations to reduce adverse consequences of
chronic disease.
We would
recommend that a new draft of this report from the Salt Subgroup confine its discussion to
such key issues as:
·
What evidence establishes the level of
physiological need for sodium, including factors affecting the range of individual
variation and considering developmental requirements (e.g. cognitive function), emotional
impacts and metabolic side-effects?
·
Is there reproducible evidence from
randomized control trials that reducing sodium intake reduces morbidity and mortality in
the general population?
·
Is there reproducible evidence from
randomized control trials that reduced sodium intake has no adverse health outcomes?
·
Is there reproducible data from randomized
control trials that sodium restriction is a cost effective public policy that justifies a
health intervention in the general population?
·
Is there reproducible evidence from
randomized control trials that the recommended levels for sodium intake for the age
specific populations are optimal?
·
Is there reproducible data from randomized
control trials that sodium restriction is sustainable over three months or longer and
cardiovascular outcomes are related to the degree of sodium reduction?
All the rest of
the content of the extant draft report except for those portions, which address these
points or could address them were they included and fairly presented, are not germane to
the properly-understood public policy goals of the SACN.
Blood pressure does not matter if there are no discernable improvements in
morbidity and mortality.
Our enthusiasm
for the SACN’s identification of health outcomes as the “key issue”
drastically diminished when we read the draft’s actual discussion. Our concerns include the following:
·
Section 4.66 is so consumed with
criticising the Alderman paper (1998) that it fails to report his finding that, in the
general population, there is a 20% greater incidence of MI for those on low-sodium diets
as on normal/high sodium diets. The published
exchanges of letters are certainly appropriate to mention, but this section is unbalanced
as drafted.
·
Likewise, Section 4.67 is overtly biased. The draft should be revised to point out that
there was no association in the He study between sodium intake and CV events in the
general population, though some subgroups were identified at additional risk directly
related to sodium intake levels (suggesting, perhaps, that other subgroups would be at
additional risk inversely related to sodium intakes).
·
Again, in Section 4.68, the discussion of
Dr. Alderman’s 1995 paper is incomplete and biased.
It focuses on criticism and limitations on the analysis rather than
reporting the key finding: a 430% greater
incidence of MI among hypertensives on low sodium diets compared to high sodium diets. A balanced report is required. Without question, the study is not definitive; but
it is highly suggestive.
·
Section 4.69 discusses the Scottish Heart
Health Study, but never mentions it found increased risks of low-sodium diets. These results of a critical and quality study (of
a British population) need greater attention.
·
Section 4.70 is disingenuous and
misrepresentative. Quoting the abstract when
the full report is on record – and substantially different from the abstract, is poor
scholarship at best, purposefully manipulative at worst.
The report as delivered at the American Heart Association meeting should be
fairly presented, including the author’s sincere apology for his misleading abstract
and recognition in the SACN draft that his final conclusions were that his data show no
health outcome benefit from reducing dietary sodium.
·
Section 4.71 misses the point entirely. As in He et al, a subgroup had identified risks on
a very high sodium diet (220 mmol average), but even at this very high consumption level
no health benefit was found in the general population.
An expanded, balanced critique is needed.
·
The draft omits discussion of other health
outcomes studies, most prominently that by Hooper et. al. published in BMJ
September 21, 2002, referenced in Annex 3, but not discussed here.
In short, we
recommend that the SACN direct the Salt Subgroup to consider these comments and those of
the SMA and “go back to the drawing board” to produce an entirely new – and
doubtless, shorter – report focused on the health outcomes of various intake levels
of dietary sodium. Food manufacturers have
tried valiantly to cooperate with the government as science developed on this issue. Many individuals have struggled to count
milligrams of sodium in their diets and reduce their sodium intake. Now is the time to face the fact that the entire
basis for encouraging universal sodium restriction has been called into question by the
consistent findings of health outcomes studies of the relationship of sodium intakes to
health outcomes – that is: there is
consistent evidence that there is no relationship between reduced-sodium diets and
improved health outcomes. We commend
the SACN Salt Subgroup for identifying the “key issue” and urge the SACN to
rewrite its report reflecting this breakthrough understanding.
Sincerely,
Richard L.
Hanneman
President
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