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Dietary Sources of Sodium in China, Japan, the United Kingdom, and the United States, Women and Men Aged 40 to 59 Years: The INTERMAP Study

https://doi.org/10.1016/j.jada.2010.02.007Get rights and content

Abstract

Public health campaigns in several countries encourage population-wide reduced sodium (salt) intake, but excessive intake remains a major problem. Excessive sodium intake is independently related to adverse blood pressure and is a key factor in the epidemic of prehypertension/hypertension. Identification of food sources of sodium in modern diets is critical to effective reduction of sodium intake worldwide. We used data from the INTERMAP Study to define major food sources of sodium in diverse East Asian and Western population samples. INTERMAP is an international, cross-sectional, epidemiologic study of 4, 680 individuals ages 40 to 59 years from Japan (four samples), People's Republic of China (three rural samples), the United Kingdom (two samples), and the United States (eight samples); four in-depth, multipass 24-hour dietary recalls/person were used to identify foods accounting for most dietary sodium intake. In the People's Republic of China sample, most (76%) dietary sodium was from salt added in home cooking, about 50% less in southern than northern samples. In Japan, most (63%) dietary sodium came from soy sauce (20%), commercially processed fish/seafood (15%), salted soups (15%), and preserved vegetables (13%). Processed foods, including breads/cereals/grains, contributed heavily to sodium intake in the United Kingdom (95%) and the United States (for methodological reasons, underestimated at 71%). To prevent and control prehypertension/hypertension and improve health, efforts to remove excess sodium from diets in rural China should focus on reducing salt in home cooking. To avoid excess sodium intake in Japan, the United Kingdom, and the United States, salt must be reduced in commercially processed foods.

Section snippets

Participants and Methods

This report is based on data from the INTERMAP Study, a cross-sectional basic epidemiologic investigation. The general aim of the INTERMAP research program as a whole is to advance knowledge on influences of multiple dietary factors—macro and micronutrients—on blood pressure of individuals, and on the role of these factors in the etiology of epidemic prehypertension and hypertension in adults of diverse geographic, ethnic, and socioeconomic backgrounds. Detailed study methods have been reported

Results

Mean age of participants was 49 years (Table 1). Mean body mass index was lowest in the People's Republic of China (23.1) and highest in the United States (28.9). Mean systolic blood pressure ranged from 117 mm Hg in Japan to 121 mm Hg in the People's Republic China. Prevalence of hypertension ranged from 13% (Japan) to 27% (United States). Mean 24-hour urinary sodium excretion ranged from 3,702 mg (United Kingdom) to 5,633 mg (People's Republic China); mean dietary sodium intake ranged from 3,

Discussion

INTERMAP is the first study to use standardized methods for systematic concurrent measurement of salt intake in four countries. For every person, total sodium intake was estimated from both two timed 24-hour urinary excretion and four 24-hour dietary recalls. There was general concordance of mean findings by country, except for the People's Republic of China where the dietary estimate was lower than the urinary. Our primary findings on foods/food groups supplying dietary sodium are that

Conclusions

Excess sodium intake has been linked to increased risk of cardiovascular diseases and such adverse conditions as prehypertension/hypertension, renal stones, gastric cancer, asthma, and osteoporosis. To prevent and control prehypertension/hypertension and improve health, efforts to remove excess salt from diets must be enhanced. Our findings of much lower salt intake in southern than northern Chinese, with associated lower blood pressure, indicate this is feasible and efficacious; the emphasis

C. A. M. Anderson is an assistant professor of epidemiology, Johns Hopkins University Bloomberg School of Public Health, and Welch Center for Prevention, Epidemiology, and Clinical Research, Baltimore, MD.

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      Citation Excerpt :

      The recent SSaSS first showed that effective control of discretionary sodium intake at the individual level could significantly lower the CVD incidence in Chinese participants.11 Our results indicate that an effective control of discretionary sodium (adding salt) intake in a Western diet may also produce significant health benefits, although the total sodium intake in the UK population is not as high as in the Chinese diet.26 We found heterogeneous associations between the frequency of adding salt to foods and 3 major subtypes of CVD, and the strongest association was with heart failure.

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    C. A. M. Anderson is an assistant professor of epidemiology, Johns Hopkins University Bloomberg School of Public Health, and Welch Center for Prevention, Epidemiology, and Clinical Research, Baltimore, MD.

    L. J. Appel is a professor of medicine, epidemiology, and international health (human nutrition), Johns Hopkins Medical Institutions, and Welch Center for Prevention, Epidemiology, and Clinical Research, Baltimore, MD.

    N. Okuda is an assistant professor, Department of Health Science, Shiga University of Medical Science, Otsu, Shiga, Japan.

    H. Ueshima is a professor, Department of Health Science, Shiga University of Medical Science, Otsu, Shiga, Japan.

    K. Miura is an associate professor, Department of Health Science, Shiga University of Medical Science, Otsu, Shiga, Japan.

    I. J. Brown is a research associate, Department of Epidemiology and Public Health, School of Medicine, Imperial College London, UK.

    Q. Chan is a senior research officer, Department of Epidemiology and Public Health, School of Medicine, Imperial College London, UK.

    P. Elliott is a professor, Department of Epidemiology and Public Health, School of Medicine, Imperial College London, UK.

    L. Zhao is an associate professor, Department of Epidemiology, Fu Wai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences, Beijing, China.

    H. Kesteloot is a professor, Division of Epidemiology, Katholieke Universiteit Leuven, Leuven, Belgium.

    J. D. Curb is a professor of geriatric medicine and internal medicine, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu.

    K. Yoshita is leader, Project for the National Health and Nutrition Survey, Nutritional Epidemiology Program, National Institute of Health and Nutrition, Tokyo, Japan.

    M. E. Yamamoto is an assistant professor, Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA.

    J. Stamler is a professor emeritus, Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL.

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