Guidelines recommend that nearly half of US residents should follow low-sodium recommendations, but most do not. (Image: Eric Delmar/iStockphoto.com)
The study in today’s Morbidity and Mortality Weekly Report (MMWR) tried to get a handle on the proportion of US residents who should restrict their sodium intake, according to the federal government’s Dietary Guidelines for Americans, 2010. Overall, the guidelines recommend no more than 2300 mg of sodium daily. But they also say that some people—those aged 51 years or older, blacks, and people with hypertension, diabetes, or chronic kidney disease—are particularly sensitive to sodium’s ability to increase blood pressure. The guidelines advise them to restrict daily sodium intake to 1500 mg.
Investigators reported that 47.6% of US residents aged 2 years or older fall into 1 or more of those groups. More specifically, the data show that 57.1% of adults and 16.2% of children should follow the low-sodium recommendation. According to race and ethnicity, 100% of blacks, 44.1% of whites, and 23.7% of Mexican Americans also should restrict their sodium intake.
The study is based on data from 18 823 US residents aged 2 years or older who participated in the 2005-2008 National Health and Nutrition Examination Survey (NHANES). Participants provided blood and urine samples for testing, had their blood pressure measured, and answered questions about what they ate over 2 separate 24-hour periods.
Data on their sodium consumption as measured in the study painted a very different picture than what’s recommended in the guidelines. On average, people who should restrict their intake to 1500 mg daily actually consumed 3264 mg daily. People aged 51 years or older consumed 3111 mg and blacks’ intake was 3198 mg daily.
Investigators noted that the Institute of Medicine last year proposed that mandatory sodium target levels be set for processed and restaurant foods to help US residents lower their sodium intake. Federal agencies have developed programs to help state and local governments as well as schools to promote low-sodium foods, according to the study.
“If, as this study says, nearly half the population would be healthier eating less sodium, personal choice isn’t going to fix the problem. Neither is medical advice,” said Marion Nestle, PhD, MPH, professor of nutrition, food studies, and public health at New York University in New York City, who was not involved with the study.
“Individuals can’t do this without help. This study is clear indication of the need for policies to reduce the amount of sodium in the food supply,” Nestle said in an e-mail.
But another expert said policy changes may not be justified because current scientific evidence doesn’t show that reducing dietary sodium intake decreases cardiovascular disease. “This is not settled science,” said Michael Alderman, MD, editor of the American Journal of Hypertension (AJH) and emeritus professor of epidemiology and population health at Albert Einstein College of Medicine, Bronx, New York.
Alderman noted that studies published in July in the Cochrane Library and AJH did not show that reduced sodium consumption decreased the risk of cardiovascular disease or death from any cause in people with normal or high blood pressure. A study in May in JAMA linked low sodium intake with a higher likelihood of dying of cardiovascular disease.
NHANES data show that sodium intake in the United States has remained consistent for the past 50 years, Alderman said in a telephone interview. During that time, he added, deaths from heart disease have decreased by about 50%.
“There are no good data linking sodium intake to cardiovascular outcomes,” he said. “Lowering sodium by the amount required to reduce blood pressure has a lot of other effects.” Among them is decreased insulin sensitivity.
“We’re walking into this whole experimental world,” he said “Is sodium reduction good? We still don’t know.”
