Recent studies that examine links between sodium consumption and health outcomes support recommendations for Americans consuming high levels of sodium to reduce their intake. However, a report released this week by the Institute of Medicine says evidence from these studies does not support a reduction in sodium intake to less than 2,300 milligrams per day. These findings could have a significant impact on the 2015 Dietary Guidelines for Americans.
Despite efforts over the past several decades to reduce dietary intake of sodium, the average American adult still consumes 3,400 mg or more of sodium a day. The current Dietary Guidelines for Americans urge most people ages 14 to 50 to limit their sodium intake to 2,300 mg daily. People ages 51 or older, African Americans and people with hypertension, diabetes or chronic kidney disease – groups that together make up more than 50 percent of the U.S. population – are advised to follow an even stricter limit of 1,500 mg per day.
These recommendations are based largely on a body of research that links higher sodium intakes to certain “surrogate markers,” or markers for disease progression such as high blood pressure, an established risk factor for heart disease. In the IOM report, the committee of experts reviewed recent studies that examined how sodium consumption affects actual health outcomes, like heart disease, rather than the surrogate markers.
The report indicates that reducing sodium intake from very high to moderate levels provides health benefits. However, the authors concluded there is no indication that the general population should lower sodium intake below 2,300 mg, or that special populations need separate recommendations.
This report comes just before the Dietary Guidelines Advisory Committee will begin work on the 2015 Dietary Guidelines for Americans. This new analysis could affect the sodium recommendations of the Advisory Committee, especially related to the very low limits recommended for special populations. Since cheese is a contributor to sodium in the American diet, past recommendations to severely restrict sodium intake could have had a significant impact on Dietary Guidelines recommendations on cheese consumption.
Analysis and Conclusions
While cautioning that the quantity of evidence was less than optimal and that the study designs also somewhat limited the results, the committee made several conclusions.
- The evidence supports a positive relationship between higher levels of sodium intake and risk of heart disease, which is consistent with previous research based on sodium’s effects on blood pressure.
- The studies on health outcomes are inconsistent in quality and insufficient in quantity to conclude that lowering sodium intake levels below 2,300 mg a day either increases or decreases the risk of heart disease, stroke or all-cause mortality in the general U.S. population.
- The evidence indicates that low sodium intake may lead to risk of adverse health effects among those with mid- to late-stage heart failure.
- Limited evidence exists for addressing the association between low sodium intake and health outcomes in population subgroups (i.e., those with diabetes, kidney disease, heart disease, hypertension or borderline hypertension; those 51 years of age and older; and African Americans). The studies on health outcomes provide some evidence for adverse health effects of low sodium intake (in ranges approximating 1,500 mg to 2,300 mg daily) among those with diabetes, kidney disease or heart disease. However, the evidence for both the benefit and the harm is not strong enough to indicate that these subgroups should be treated differently from the general U.S. population. The evidence on direct health outcomes does not support recommendations to lower sodium intake within these subgroups to or below 1,500 mg daily.
- Further research is needed to shed more light on associations between lower levels of sodium (in the 1,500 mg to 2,300 mg a day range) and health outcomes, both in the general population and the subgroups.
For more information, contact Michelle Matto, IDFA consultant on nutrition and labeling, at amfoodnutrition@gmail.com.