“Fresh Insight” and “Support For Skeptics” In New Blood Pressure Report

Alexandria, VA (Mar. 9)…The world’s leading salt industry association issued the following reaction statement to publication in The American Journal of Hypertension of an article, “Low Mineral Intake Is Associated with High Systolic Blood Pressure in the Third and Fourth National Health and Nutrition Examination Surveys: Could We All Be Right?” by Marilyn S. Townsend, et. al. Salt Institute President Richard L. Hanneman issued this statement:

While most medical researchers accept that dramatically reducing dietary sodium will result in modest lowering of population blood pressure, they are divided as to whether this overall “benefit” is worth the accompanying risk of increasing blood pressure in a significant minority of the population and whether there may be healthier dietary advice. The Salt Institute has been among the skeptics arguing for improving overall dietary quality rather than focusing on reducing dietary sodium. We’ve questioned the government’s primary focus on reducing sodium intake.

The largest federally-funded survey of health and nutrition, analyzed in a new study by Townsend, et al, offers fresh insight and strong support to skeptics like us. The study reconfirmed that there is no difference in sodium intake levels regardless of whether a person has normal or elevated blood pressure. The fresh insight is that individuals with “top number hypertension” (systolic blood pressure, SBP, more than 140 mmHg), have very different intake levels of dietary minerals than those with normal blood pressure or those with elevated diastolic blood pressure (DBP) or whose hypertension involves both SBP and DBP. Researchers agree that systolic hypertension is the most important risk factor for heart attacks and strokes. “Top number hypertensives” are 60% of the total.

For this 60% of hypertensives, lower mineral intakes – sodium, calcium, potassium and magnesium – are associated with higher systolic blood pressure. In fact, dividing up those with high blood pressure into these two groups finds that these “top number hypertensives” already have, by far, the lowest intakes of dietary sodium.

To us, the message is clear: we need to focus on increasing the intake of minerals for this large at-risk group, not reducing already-lower sodium levels. The authors report: “There is substantial collateral evidence that those at greatest cardiovascular risk, older participants with systolic hypertension, will benefit from interventions that emphasize a dietary pattern that ensures adequate mineral consumption (calcium, potassium, and magnesium), regardless of sodium intake.”

Those with “bottom number hypertension” have exactly the opposite pattern. This lower risk group consumes higher amounts of all the minerals – sodium, potassium, calcium and magnesium. Those with normal blood pressure also consume greater amounts of all these minerals.

Clearly, advising both groups to reduce dietary sodium is inappropriate. We have been remiss in not assigning high priority to increasing mineral intake levels of “top number hypertensives” though such means as the DASH Diet – high in mineral-rich fruits, vegetables and dairy products without regard to sodium levels.

The authors conclude:

“Our findings have several important implications for the prevention and management of hypertension, and for future research initiatives. Clearly, the development of hypertension guidelines should be tailored to individual patients, as has generally been the approach with pharmacologic management, and not applied uniformly across all BP categories or groups at increased risk for hypertension. Furthermore, the emphasis of national nutrition policy on sodium restriction for hypertension is not consistent with these findings, identified in the federally funded NHANES databases and warrants careful scientific evaluation.”

This becomes a second key question that should be pursued with a clinical trial. The first priority research trial, however, remains the critical need to examine the health outcomes of the current advice to restrict dietary sodium. Blood pressure is only an intermediate variable. We really want to prevent heart attacks and strokes. A trial of whether reducing dietary sodium reduces cardiovascular events is long overdue. All ten population studies of whether the government’s advice to reduce sodium will actually improve health have come to the opposite conclusion: there is either no benefit, or cutting back salt will actually increase the risk of heart attacks and strokes.

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Note: The article is online: http://journals.elsevierhealth.com/periodicals/AJH/current. The article invites follow-up with co-author Dr. David A. McCarron (503-432-4650; dmccarron@academicnetwork.com. Please visit our web page “Especially For Journalists”: http://www.saltinstitute.org/55.html. For additional information about the role of systolic blood pressure, see other articles in the AJH: Franklin, Stanley S. “Systolic Blood Pressure: It’s Time to Take Control” (2004;17:49S-54S) and Joffres, M.R. et al, “Distribution of Blood Pressure and Hypertension in Canada and the United States” (2004;14:1099-1105).

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