Sodium content of processed foods: 1983–

Center for Science in the Public Interest
1875 Connecticut Avenue, NW, Suite 300
Washington, DC 20009
E-mail: mjacobson{at}cspinet.org

Dear Sir:

In a recent issue of the Journal, Khaw et al (1) provided convincing evidence that sodium intake correlates with blood pressure, and they cited the need for public health action to reduce intakes. Unfortunately, no such action has been undertaken in the United States, and the sodium content of processed foods has not declined.

We have been monitoring the sodium content of processed foods, which provide 80% of the sodium in the average American diet, since 1983 (2, 3). We identified 100 commonly consumed foods and used labeling or manufacturer's data to ascertain the sodium content of each food. In 1994, we examined the sodium content of the same 100 foods, 94 of which were still being marketed. The average sodium content per serving (adjusted for any changes in serving size) decreased by 15% over the 11 y. In 2004, 69 of those foods were still being marketed. Between 1983 and 2004, the average sodium content per serving of those foods decreased by 5% (from 592 to 564 mg), or 0.3%/y. The greatest increase in the sodium content of a food was 82%, and the greatest decrease was 71%. However, from 1994 to 2004, the average sodium content per serving increased by 6% (from 533 to 564 mg).

Modest reductions in the sodium content of certain foods and the introduction of some reduced-sodium products have not been sufficient to reduce sodium consumption. Indeed, according to national food-recall surveys (which underestimate food intake and exclude salt added at the table), daily sodium consumption increased from 2262 mg in 1971–1974 (4) to 2819 mg in 1976–1980 (5) and to 3427 mg in 1988–1994 (6); it decreased slightly, to 3375 mg, in 1999–2000 (7). The increases were due to both the consumption of higher-sodium foods and increased energy intakes. The Institute of Medicine recommends a daily adequate intake of 1500 mg Na (1300 mg for persons 50–70 y old and 1200 mg for those >70 y old) and a tolerable upper level of 2300 mg (2). The Dietary Guidelines for Americans 2005 recommends that Americans consume 2300 mg Na/d and that a sodium intake of 1500 mg/d be the target for hypertensive persons, African Americans, and middle-aged and older adults (8).

Clearly, the recommendations by the Institute of Medicine and others have failed to reduce sodium consumption. The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure has recommended reducing sodium consumption by 50% over 10 y, a change that could save an estimated 150 000 lives per year (9, 10). It appears that more effective measures, such as front-label warnings on food packages, restrictions on the sodium content of foods that currently contribute the most sodium to the diet, and well-funded and aggressive education campaigns (such as those sponsored by the British Food Standards Authority), are needed to achieve that goal.

ACKNOWLEDGMENTS

The author had no conflict of interest with regard to the article by Khaw et al or to their study.

REFERENCES

1. Khaw KT, Bingham S, Welch A, et al. Blood pressure and urinary sodium in men and women: the Norfolk Cohort of the European Prospective Investigation into Cancer (EPIC–Norfolk). Am J Clin Nutr 2004;80:1397–403.
2. Institute of Medicine. Dietary reference intakes: water, potassium, sodium, chloride, and sulfate. Washington, DC: National Academies Press, 2004.
3. Jacobson MF, Liebman BF. Sodium in processed foods. Am J Clin Nutr 1996;63:138 (letter).
4. Abraham S, Carroll MD. Fats, cholesterol, and sodium intake in the diet of persons 1–74 years: United States. Adv Data 1981;54(February 27):1–11.
5. US Department of Health and Human Services. Dietary intake source data: United States, 1976–1980. Vital Health Stat 11 1983;231:1–488.
6. Centers for Disease Control and Prevention. Dietary intake of macronutrients, micronutrients, and other dietary constituents: United States, 1988–94. Vital Health Stat 11 2002;245:1–159.
7. Centers for Disease Control and Prevention. National Health and Nutrition Examination Survey, 1999–2000. Adv Data 2003;334(April 17):1–4.
8. US Department of Health and Human Services and US Department of Agriculture. Dietary Guidelines for Americans 2005. Washington, DC: Government Printing Office, 2005.
9. Chobanian AV, Bakris GL, Black HR, et al. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. JAMA 2003;289:2560–72.
10. Havas S, Roccella EJ, Lenfant C. Reducing the public health burden from elevated blood pressure levels in the United States by lowering intake of dietary sodium. Am J Public Health 2004;94:19–22.