Yesterday in Paris, France, Dr. Tilman Drueke conducted a forum featuring three other scientific experts on various aspects of salt and health. The event was organized by EuSalt, the trade association of European salt producers. An audience of salt producers and news reporters heard presentations by Drueke of Necker Hospital, Paris; Dr. Jens Titze from Erlangen, Germany; Dr. David A. McCarron from the U.S.; and Niels Graudal from Denmark.

Dr. Drueke noted that scientific investigation of the relationship of dietary salt and health outcomes has a distinct "political aspect" and represents an "ongoing hot debate on the pros and cons of a generalized salt restriction." He referenced Gary Taubes' article in Science: "The (Political) Science of Salt ." Drueke declared:

In any case, high blood pressure is nothing more than a surrogate marker of outcome. What is really important is outcome itself. Surprisingly, the medical community has started only recently to examine this issue, namely a possible relationship between salt intake and cardiovascular or all-cause mortality. No prospective randomized controlled trials have been done to address this question. Only observational studies are available and their results led to contradictory conclusions."

He postulated that "the solution...may reside in the notion of salt sensitivity." Salt sensitivity, he explained differs from person to person and for a given person can vary from time to time based on other factors, including diet. He concluded:

"...the main focus on salt restriction is erroneous. In addition, although reducing sodium intake has many effects, either by its own or in interaction with other dietary components, we know nothing about their unintended consequences on human health."

Dr. Titze introduced data that completely call into question the evidence on sodium intakes over the past century. It has been well-accepted, he recounted, that the "gold standard" surrogate for dietary sodium intake is a 24-hour urine specimen, based on the well-understood notion that the body has a fixed store of sodium and daily additions are excreted to maintain sodium balance. He continued:

"Startling data from recent long-term balance studies, where healthy human subjects accumulated large amounts on Na+ without significant changes in their body water content, have challenged this traditional view....Subsequent experiments in animals have confirmed tht large amounts of Na+ can be accumulated without commensurate water retention in the organism."

This, in turn, led to the hypothesis that the skin and skeletal muscle could contain reservoirs of sodium which totally confound previously accepted measures of dietary sodium intake and that "...these Na+ reservoirs might 'buffer' the relationship betwen total body Na+ excess and blood pressure. This hypothesis has been supported in experiments...." This research clearly has major scientific and public health nutrition policy implications.

Dr. McCarron emphasized that evidence shows "that dietary patterns rather than salt should be the focus of public health nutritional recommendations to reduce BP" (blood pressure). He pointed out that the two DASH (Dietary Approaches to Stop Hypertension) studies showed the importance to blood pressure of diets rich in calcium, magnesium and potassium (fruits, vegetables and dairy products), and that the Trials of Hypertension Prevention showed that the blood pressure lowering effect even of significant salt reduction disappears over three years. He noted that

"the intoduction of fruits, vegetables and low-fat dairy (DASH diet) essentially eliminated salt sensitivity even in hypertensive individuals....the DASH-Sodium investigators (and) government agencies, without justification, have used this trial to argue for universal sodium restriction, regardless of blood pressure status....This position has occurred even though numerous meta-analyses and the results of the DASH-Sodium trial itself do not support the conclusions that sodium restriction is effective for normal individuals or for most hypertensive subjects."

Dr. McCarron then warned:

Sodium restriction has a variety of effects beyond blood pressure on other risk factors for CVD. These include weight, insulin resistance, angiotensin II, the sympathetic nervous system, diet quality and physical activity. For each of these risk factors, the preponderance of the evidence indicates that moderate or greater sodium restriction is associated with an adverse impact. Weight control is impaired, insulin resistance increases, angiotensin II levels are raised, sympathetic activity is increase, diet qualityis harder to achive, and maximal exercise capacity may be impaired. None are improved with sodium restriction. Thus, while BP may be decreased in 30-40% of individuals with sodium restriction, the impact on these other CVD risk factors in both salt-sensitive and salt-resistant individuals may offset any potential benefit."

Concluding the Forum, Dr. Graudal reviewed the mass of medical literature for which he has published one of the foremost meta-analyses. He declared:

"The fact is that today supporters of sodium reduction and sceptics do not diasgree about the effect size (BP reduction on reduced salt diets). Furthermore, they agree that sodium reduction can be useful in individuals with elevated BP. The controversial question is: Does an effect of 1-2 mm Hg in normotensive persons justify a general recommendation of sodium reduction in the whole population? The sceptics think not. The supporters think that any small decrease in BP will result inan improved survival and less morbidity. However a recent meta-analysis of the effect anti-hypertensive beta-blockers indicates that this is not necessarily the case....You must have proof and this does not exist, as also shown by a recent review of epidemiological studies which like teh clinical trials could not relate dietary sodium to to cardiovascular disease and death."

Thanks to the organizers of this valuable Forum.