Dialysis Unplugged: No Eating Out!

Reducing salt intake is recognized as an important intervention in treating hypertension and managing volume in patients with kidney failure. Dialysis patients have 2 large intakes of salt: the diet and the dialysate (especially during sodium modeling). 

The FDA regards salt as “generally recognized as safe” (GRAS), but some groups are trying to have salt re-classified as an "additive". For example, the Center for Science in the Public Interest (CSPI) in tandem with the American Heart Association (AHA), is concerned about the serious health risks posed by overconsumption of sodium, such as heart disease and stroke. CSPI has been pushing for front-label symbols identifying high-sodium foods, posting nutrition disclosures on chain restaurant menus and brochures, encouraging manufacturers to make foods with less sodium, establishing a “division of sodium reduction” at the FDA, and spearheading a major heart-healthy education initiative. 

A report in Morbidity and Mortality Weekly Report (MMWR) published October 21, 2011 is a sobering read because it reinforces the concerns of CSPI and the AHA that most Americans are eating much more salt than they should. However, what’s striking in the report – at least to me – is that 75% of this salt that is consumed is added to commercial foods during processing or to restaurant foods during preparation; only about 25% occurs naturally or is added at the table or in cooking by the consumer (1).

Bottom line - We need to emphasize to our patient’s with kidney disease, especially dialysis patients, that commercially prepared food: restaurant and processed foods are packed full of salt. In other words, if you really want to avoid salt then no more eating out! We spend a lot of time telling our patients to restrict salt in their diet by not adding salt to food or by avoiding salty foods – that may not be where the problem is.

Details on the study

The Center for Disease Control (CDC) and the National Institutes of Health analyzed data for 2005–2008 from the National Health and Nutrition Examination Survey (NHANES).

The key findings are:

• In individuals aged ≥51 years, blacks, and those with hypertension, diabetes, or chronic kidney disease, further reducing sodium intake to 1,500 mg daily is recommended. 47.6% aged ≥2 years meet these criteria to limit daily sodium intake to 1,500 mg, but the usual daily sodium intake for 98.6% was >1,500 mg.
• The Dietary Guidelines for Americans, 2010 (2) recommend that healthy individuals aged ≥2 years should limit daily sodium intake to <2,300 mg. In 88.2% of the U.S. population, daily sodium intake was greater than the recommended <2,300 mg.

The MMWR study has several limitations, but the most important are that the assess­ment of sodium intake excluded table salt and sodium from dietary supplements and antacids, underestimating intake by approximately. Also, dietary data are self-reported.

References

1. Institute of Medicine. Strategies to reduce sodium intake in the United States. Washington, DC: The National Academies Press; 2010.

2. US Department of Health and Human Services, US Department of Agriculture. Dietary guidelines for Americans, 2010. 7th ed. Washington DC: US Department of Health and Human Services, US Department of Agriculture; 2011. Available at http://health.gov/dietaryguidelines/2010. asp. Accessed October 18, 2011.