Salt Shakeup:
Study Links Low-salt Diet with Higher Risk of Death

By Emma Ross
Copyright 1998 The Associated Press
March 12, 1998

LONDON (AP) -- A low-salt diet may not be so healthy after all. Defying a generation of health advice, a controversial new study concludes that the less salt people eat, the higher their risk of untimely death.

The report does not necessarily mean Americans should suddenly lunge for the salt shaker -- but it does cast doubt on an item of standard dietary wisdom.

The study, led by Dr. Michael Alderman, chairman of epidemiology at Albert Einstein School of Medicine in the Bronx and president of the American Society of Hypertension, suggests the U.S. government should consider suspending its recommendation that people restrict the amount of salt they eat.

"It is possible that the harm of a low-sodium diet may outweigh its benefit," the study said.

The study, published in The Lancet, a British medical journal, suggests that no single level of sodium will be appropriate for every person in all circumstances. It said the data provide no support for a blanket recommendation regarding dietary sodium.

"The lower the sodium, the worse off you are," Alderman said. "There's an association. Is it the cause? I don't know. Any way you slice it, that's not an argument for eating a low-sodium diet."

Alderman examined the relationship between sodium intake and death among 11,346 Americans evaluated in the 1970s by the U.S. government's National Health and Nutrition Examination Survey.

By 1992, 3,923 of them had died. He found there were 19 deaths for every 1,000 years of life in the people with the highest salt intake, compared to 23 in those who ate the least salt.

Overall, a 1,000 milligram increase in dietary salt was associated with a 10 percent reduction in mortality.

The link between low-salt diets and death held up even after the researchers factored in people's blood pressures, cholesterol levels, age, gender, economic status and mineral deficiencies.

The study was denounced by some who said the salt consumption information in the original government survey on which the research is based was too inaccurate because participants had underestimated the amount of salt they were eating.

"There are major methodological flaws which makes meaningful interpretation of this paper virtually impossible," said Dr. Paul Elliott, an epidemiologist at London's Imperial College and one of the authors of a key study on which conventional wisdom is based.

Dr. Graham MacGregor of St. George's Hospital in London agreed, saying he believed the link could have been a statistical fluke.

MacGregor and Elliott also noted Alderman's past association with the food industry -- until a few years ago, Alderman served on a policy advisory committee for the Salt Institute.

Alderman responded that he saw no conflict of interest in his association with the institute, and that he gave all the fees involved to charity.

Dr. John H. Laragh of Cornell University Medical School defended the study, saying the criticism was unfair and "irrational."

Calling the study "very ingenious," he said the salt intake information is "not perfect, but it can't be taking you in the wrong direction."

Health officials, however, said the study does not persuade them they need to reconsider policy.

Based on several studies showing a restricted sodium diet can lower blood pressure, U.S. health officials recommend Americans restrict the amount of salt in their diets to no more than 6 grams, or one teaspoon, per day.

The average person eats about 12 grams of salt a day, and about 80 percent of that comes from processed foods.

"We have a preponderance of evidence that cannot be ignored. There are lots of clinical trials that show lowering blood pressure saves lives," said Edward Roccella, coordinator of the National High Blood Pressure Education Program at the National Institutes of Health.

Low-sodium proponents say ample indirect evidence exists that lower-salt diets save lives through lowered blood pressure.

High blood pressure is associated with a higher risk of stroke and heart attack. About 80 percent of the Western world's population has higher blood pressure than it should, MacGregor said.

But Alderman said focusing on blood pressure misses the point.

"That's not good enough. You've got to look at the end point study," Alderman said. "There's no evidence that a low-sodium diet makes you live longer."

Besides lowering blood pressure, cutting salt also raises blood renin, a hormone that constricts blood vessels and raises risk of heart attack, Alderman said. Low-salt diets also increase insulin resistance and nerve activity, he said.

Dr. David McCarron of Oregon Health Science University agreed with Alderman's call for the government to suspend its dietary salt recommendation.

"This is a very important issue and the data now are becoming very consistent," McCarron said. "Some people could actively be doing harm to themselves."

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