Is Salt Really So Bad?
Experts disagree about its role in high blood pressure
Sept. 25, 2003 -- If you have high blood pressure, you've probably been told
to reduce the salt in your diet, but new findings are challenging the idea that
sodium is a major culprit in promoting high blood pressure.
Researchers who have argued against the salt-blood pressure link for almost
two decades presented new data Thursday suggesting that high blood pressure is
much more closely linked to a diet low in minerals such as calcium, potassium,
and magnesium than sodium intake. The data were presented at the American Heart
Association's (AHA) 57th annual high blood pressure research conference in
But don't toast the news with a round of salt-rimmed margaritas just yet. An
AHA spokesman tells WebMD that the findings are based on shaky science that is
much less convincing than another large study published two years ago, which
found a strong link between salt and high blood pressure.
"The best trials we have had clearly indicate that sodium intake does
impact blood pressure," says Daniel Jones, MD, who is dean of the school of
medicine at the University of Mississippi Medical Center.
Poor Diet May Be to Blame
In the newly reported study, roughly 33,000 people had their blood pressures
recorded and answered dietary questions.
Researchers divided the participants' sodium, calcium, and total mineral
intake into four groups and found that while blood pressure did not vary
significantly according to sodium intake, higher calcium intake was associated
with lower blood pressure. In one of the most recent surveys, higher mineral
intake was also linked to lower blood pressure.
"We believe that as a rule, high sodium intake is a marker of a poor
quality diet," says lead researcher David McCarron, MD. "The [new
study] data indicate that it is not the sodium per se that affects blood
pressure, but the lack of calcium, magnesium, potassium, and probably some
other minerals and vitamins." McCarron is a longtime paid consultant for
the salt industry.
But Jones counters that surveys such as this present an incomplete and
potentially flawed picture of nutritional status because they rely on
participants to remember the foods they have eaten. He says the clinical trial
known as the Dietary Approaches to Stop Hypertension (DASH) sodium study was
much more convincing.
In that trial, 412 participants ate either a typical diet or a highly
controlled diet that was low in sodium and fat and high in calcium, fruits, and
vegetables. Researchers found that reducing the salt in the diet had a direct
impact on blood pressure levels, even when the participants did not have high
McCarron has challenged the latest DASH findings. He tells WebMD that the
government and Harvard University researchers who published the study did not
include information on subgroups who did not benefit from lowering their salt
intake, such as men younger than 45 with normal blood pressure.
"The recommendations from the DASH sodium trial are that all Americans
should reduce their sodium intake to 1,500 mg a day," he says. "The
previous recommendation was 2,300 mg a day, and nobody could do that. All I'm
saying is show me the data that proves this is necessary."