Feb 22, 2006 — In yet another blow to conventional medical wisdom, researchers at the Albert Einstein College of Medicine of Yeshiva University have found that lower salt diets are significantly linked to an increase in risk of dying from cardiovascular disease (CVD): the nation’s leading cause of death that includes coronary heart disease.
In fact, those who had a diet in line with the current federal recommendation to consume less than 2300 mg of sodium per day were 37 percent more likely to have died from CVD and 28 percent more likely to have died from any cause, compared with higher-sodium-intake individuals.
This is the third study this month to challenge prevailing medical thought. Earlier, a study from the federally funded Women’s Health Initiative found that low-fat diets don’t reduce a woman’s risk for developing heart disease or breast cancer. Then, in another WHI study, calcium-and-vitamin-D supplements were shown to be of little help in preventing hip fractures in older women.
In the new Einstein study, published in the February 22 online edition of The American Journal of Medicine, researchers led by Dr. Hillel W. Cohen analyzed data from the second National Health and Nutrition Examination Survey (NHANES II). In the federally funded NHANES II survey, more than 20,000 Americans from childhood to 74 years old were interviewed and examined between 1976 and 1980. Participants were asked to recall their dietary intake over the previous 24 hours, which allowed their salt (sodium) intake to be calculated.
In 1992, NHANES II looked at the mortality status of participants who had been between 30 and 74 on entry to the study, to learn which of these people had died and what they died from.
In the new Einstein study, the researchers examined the data for a sample of 7,154 of these individuals, to see if there were links between sodium intake and risk of death.
People with lower sodium intakes were found to have a significantly greater risk of dying from cardiovascular disease (CVD) than people who had consumed greater amounts, even after accounting for caloric intake, age, smoking and other known risk factors. (This inverse association between salt intake and CVD mortality was consistently observed in 24 subgroups but not in people who were younger than age 55 at the beginning of the NHANES II study, in non-whites, nor in obese people).
“We found significant associations between lower sodium intake and CVD mortality—and found no subgroup that actually benefited from a lower-sodium diet,” said Dr. Cohen, associate professor of epidemiology and population health at Einstein. “This was an observational study and not a clinical trial, so we can’t really conclude from our findings that low-sodium intakes are harmful. But our study certainly doesn’t support the idea of a universal prescription for lower salt intake.
“The current recommendations are based on several short-term studies showing that reducing salt intake can lower blood pressure—which is not the same as mortality. What we clearly need,” Dr. Cohen concludes, “are long-term clinical trials that move beyond intermediate outcomes like blood pressure so that we can convincingly establish the relationship between salt intake and the risk of dying.”