David B. Hipgrave, Suying Chang, Xiaowei Li, Yongning Wu. Salt and Sodium Intake in China. JAMA. 2016;315(7):703–705. doi:10.1001/jama.2015.15816
Noncommunicable diseases are increasing globally, with major socioeconomic implications.1 The World Health Organization2 proposed 9 noncommunicable disease–related targets, including 30% reduction in salt/sodium intake to reduce risk of hypertension.
In China, hypertension prevalence is rising3 and salt intake is high (12 g/person/d).4 However, this estimate derives from 2002, and China’s dietary habits are changing.
We compared salt and sodium consumption in China in 2000 with 2009-2012.
The National Centre for Food Safety Risk Assessment Ethics Committee approved China’s total diet studies. All participating householders provided oral consent. Total diet studies include weighed food intake and laboratory analysis of prepared foods representing dietary intake, using a standardized design.5 They are designed to assess food consumed and its biochemical content, accounting for losses during processing, preparation, and storage. By 2011, 30 countries, including 5 in Europe, had conducted total diet studies.5
Total diet studies were undertaken in 2000 and 2009-2011 in 12 of China’s 31 mainland provinces. These provinces were selected to represent its geographic regions and dietary habits, and housed approximately 50% of its population. Eight additional provinces housing 29% of the population were studied in 2009-2012, expanding geographic coverage; only China’s far west region was not studied.
In each province’s total diet study, 1 urban district and 2 rural counties were randomly selected from lists of nonpoor districts and counties, representing typical dietary intake. Within each district or county, 2 communities or townships, then 5 neighborhoods or villages, and then 30 households were randomly selected. Study personnel recorded all residents’ dietary intake by recording food consumption and weighing ingredients, including salt, during 3 consecutive daily visits. No households refused to participate. Using local ingredients, matching foods were prepared and analyzed at China’s national reference laboratory. Using the age, weight, sex, and occupation of those surveyed, the daily salt and sodium consumption of a standard person (man, aged 18–45 years, weighing 63 kg, and engaging in light activity) was calculated for each province, to represent a value around which the sampled householders’ salt/sodium consumption varies. Meals consumed outside the home were excluded from the calculation.
Salt consumption, based on household measurements, and laboratory-analyzed sodium in prepared food samples were analyzed. We compared salt and sodium intake in the 12 provinces surveyed twice using a 2-sided t test (P < .05 for significance) in SPSS Statistics (IBM), version 13. To derive national estimates, we calculated population-weighted intakes. To verify previous research on dietary salt intake in China, we also compared calculated sodium intake, based on salt consumption, with laboratory-analyzed sodium intake.
In 2000, 1080 households participated (n = 3725; mean age, 34.7 years [SD, 19.6]; 49% men); from 2009 through 2012, 1800 households participated (n = 6072; mean age, 42 years [SD, 20.1]; 47% men). Five percent of data was missing.
Among 20 provinces surveyed from 2009 through 2012, the population-weighted, mean weighed salt intake of a standard person was 9.1 g per day and laboratory-analyzed sodium intake was 5.4 g per day (Table). Among 12 provinces surveyed twice, salt intake decreased 22.2% between 2000 (11.8 g/d) and 2009-2011 (9.2 g/d) (t = 2.53, P = .03). However, the 12.3% decrease in sodium intake (from 6.4 g/d in 2000 to 5.6 g/d in 2009-2011) was nonsignificant (t = 1.21, P = .25). Weighed salt consumption yielded a calculated sodium intake (4.6 g/d in 2000 vs 3.5 g/d in 2009-2011) much less than laboratory-analyzed sodium intake (see Table footnote).
All provinces exceeded the recommended daily maximum intake of salt (5 g/d) and sodium (2 g/d). Although salt added during food preparation has decreased over time, total sodium intake has not (noting the large increase in Guangxi).
These findings update studies using different methodologies in the 1990s6 and 20024 and confirm that simply weighing dietary salt intake underestimates sodium consumption in China.6
Limitations of the total diet studies include the small samples, but China’s ethnic and socioeconomic homogeneity suggests mostly uniform dietary habits within provinces. For the same reason, clustering and studying different households in 2000 and 2009-2011 should not have affected the findings. Inclusion of meals consumed outside the home was impracticable; they may be more highly seasoned. Poor communities were excluded, but their number is small.
China’s diet is changing and refrigeration is replacing salt for food preservation. High sodium intake persists due to addition of salt and other seasonings during food preparation, and increasing consumption of processed food. Further efforts are needed to limit salt/sodium intake, and regular monitoring is needed to assess progress.2
Corresponding Author: Yongning Wu, PhD, Key Laboratory for Food Safety Risk Assessment, China National Centre for Food Safety Risk Assessment, Bldg 2, No. 37 Guangqu Rd, Chaoyang District, Beijing, 100022, China (firstname.lastname@example.org).
Author Contributions: Drs Wu and Hipgrave had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Hipgrave, Chang, Li, Wu.
Acquisition, analysis, or interpretation of data: Hipgrave, Chang, Li, Wu.
Drafting of the manuscript: Hipgrave, Li.
Critical revision of the manuscript for important intellectual content: Hipgrave, Chang, Li, Wu.
Statistical analysis: Hipgrave, Chang, Li.
Obtained funding: Wu.
Administrative, technical, or material support: Hipgrave, Chang, Li, Wu.
Study supervision: Wu.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Funding/Support: This work was supported by the National Natural Science Foundation of China (grant 21537001; 2007 and 2009 surveys), the National Basic Research Program of China (973 Program 2012CB720804; 2009 survey), the China Ministry of Health (grant 200902009; 2009 survey), and UNICEF (2009 survey). The authors were entirely funded by their institutions.
Role of the Funder/Sponsor: UNICEF played a role in the design and conduct of the study, collection, management, analysis and interpretation of the data, preparation, review and approval of the manuscript, and the decision to submit the manuscript for publication.