Since this article was published, the study it is based on has been retracted by the journal . Some of the data researchers used in their meta-analysis appeared to be duplicate data, rendering the findings suspect.
Things we thought we knew about sodium may need to be taken with a grain of…salt. A new report from the Institute of Medicine (IOM) has health experts shaking their heads and health organizations issuing peppery statements of disagreement.
Sodium is not a harmful substance in and of itself. This mineral is a nutrient essential to the functioning of every cell in your body.
There is no good reason for Americans to reduce their sodium intake below 2,300 mg/day, and in fact, it could be harmful to health. This is the conclusion of the newly issued report by the IOM. The recommendations stand in stark contrast to the government-issued Dietary Guidelines for Americans, and contradict the recommendations of the American Heart Association and several medical groups.
The health warnings over the years have given salt a bad rap. Sodium is not a harmful substance in and of itself. This mineral is a nutrient essential to the functioning of every cell in your body. Adverse health effects occur with sodium intakes that are too high and too low.
Then the American Heart Association weighed in and tightened the rein on sodium intake even further.
Even with the new recommendations, the average American consumes too much sodium — about 3,400 mg/day or the equivalent of 1½ teaspoons of salt. Sodium causes the body to retain extra fluid, making the heart work harder. High intakes have been associated with an increased risk for heart failure, stroke, stomach cancer, kidney disease, and osteoporosis. It is estimated that high sodium consumption may be linked to a third of the cases of high blood pressure in the US.
In 2005, the IOM set the minimum amount of sodium required for adequate nutrition at 1,500 milligrams, and 2,300 milligrams as the maximum amount that could be consumed each day without raising blood pressure.
These ranges were behind the 2010 Dietary Guidelines for Americans which recommend people consume no more than 2,300 mg/day, except for those who face greater health risks from excess sodium consumption: adults over 50, African-Americans, and those with high blood pressure, diabetes, or chronic kidney disease. People in these groups, who make up over half the population, were advised to limit their sodium to 1,500 mg/day per day.
Then the American Heart Association weighed in and tightened the rein on sodium intake even further. It said that everyone, regardless of age, race, or ethnicity, should limit their sodium intake to 1,500 mg/day per day. Their thinking was that keeping sodium intake this low would help prevent heart attacks and strokes. The only problem was there were no data on the health benefits of such a sodium restriction.
It was widely accepted in 2005 when the IOM report came out that when people ate less salt, they had a slight drop in blood pressure. But more rigorous studies since then showed that low sodium consumption produced a number of negative effects in people who had mid-to-late stage heart failure and that there was little evidence that low sodium intake helped the subgroups of the population who are encouraged to keep their intake down to the 1,500 mg/day level.
The new IOM report concludes that, “Studies on health outcomes are inconsistent in quality and insufficient in quantity to conclude that lowering sodium intake levels below 2,300 mg/day either increases or decreases the risk of heart disease, stroke, or all-cause mortality in the general US population. ” In fact, some recent studies suggest that sodium intake might affect the risk of heart disease via pathways other than high blood pressure.
“These studies make clear that looking at sodium's effects on blood pressure is not enough to determine dietary sodium's ultimate impact on health. Changes in diet are more complex than simply changing a single mineral. More research is needed to understand these pathways,” Dr. Brian Strom, chairman of the IOM committee, said in a statement.
Americans should still limit their sodium intake to 2,300 mg/day, as there is good evidence that this level decreases the risk of heart disease. The new report does not recommend a “healthy” range; more research is needed to determine an association between low sodium intakes (1,500 and 2,300 mg/day) and health outcomes.
The new recommendations are not a signal that it's OK to stock up on chips. The American Heart Association disagrees with the conclusion of the IOM report and stands by its 1,500 mg/day recommendation, and the Center for Science in the Public Interest, a nonprofit organization, said they hope this report will not stop the government, food industry, health professionals, and consumers from pushing for lower sodium levels.
Another committee will take on the task of revising the Dietary Guidelines for Americans. New recommendations will be released in 2015. Perhaps by then we will better understand the biology behind the contradictory findings.
Regardless of what numbers ultimately evolve, the majority of Americans consume significantly more sodium than the 2,300 mg/day recommendation. While it is useful to continue to question and revise nutritional recommendations in light of new research, for most of us, using less salt on our food and paying attention to the sodium content of processed foods, eating out less often, and eating more fresh fruits and vegetables, meat, poultry, and fish, beans and peas, unsalted nuts, eggs, and low-fat or fat-free dairy is likely to be more important than setting a number that the average consumer probably won’t understand or pay attention to anyway.