Salt Sources Study

Assessment of the Proportion of Sodium Intake From a Variety of Sources - Salt Sources Study

The Centers for Disease Control and Prevention conducted an observational cross-sectional study to obtain information about the amount of sodium consumed from various sources (including sodium from processed and restaurant foods, sodium inherent in foods, and salt added at the table and during cooking) and to examine variability across population subgroups. Data collection will include an observational component as well as a sub-study designed to refine the accuracy of estimates of total sodium intake and discretionary sodium intake.

Information was collected in three distinct geographic regions: 1) Minneapolis/St. Paul, Minnesota, 2) Birmingham, Alabama, and 3) Palo Alto, California. Over a two-year period, a study center in each location recruited 150 participants (total N=450). Overall, an approximately equal number of adults ages 18-74 years by approximately 10-year age groups in each sex-race group, including whites, blacks, Hispanics, and Asians. A sub-study was conducted among a subgroup of 150 of these participants (50 per site). University of Minnesota serves as a study coordinating center.

Study Overview

• Status: Completed
• Conditions: Dietary Sources of Sodium Intake

Detailed Description

The Centers for Disease Control and Prevention conducted an observational cross-sectional study to obtain information about the amount of sodium consumed from various sources (including sodium from processed and restaurant foods, sodium inherent in foods, and salt added at the table and during cooking) and to examine variability across population subgroups. Data collection will include an observational component as well as a sub-study designed to refine the accuracy of estimates of total sodium intake and discretionary sodium intake.

Information was collected in three distinct geographic regions: 1) Minneapolis/St. Paul, Minnesota, 2) Birmingham, Alabama, and 3) Palo Alto, California. Over a two-year period, a study center in each location recruited 150 participants (total N=450). Overall, an approximately equal number of adults ages 18-74 years by approximately 10-year age groups in each sex-race group, including whites, blacks, Hispanics, and Asians. A sub-study was conducted among a subgroup of 150 of these participants (50 per site). University of Minnesota serves as a study coordinating center.

After informed consent and completing a screening process, each participant completed a personal questionnaire, a tap water questionnaire, four 24-hour dietary recalls, and four qualitative food records. In addition, height and weight information on each participant were collected, and each participant collected duplicate portions of their cooking/table salt. A few participants at each site also provided water samples analyzed to produce estimates of the amount of sodium in private sources of tap water.

The Salt Sources Study also included a sub-study to help determine the accuracy of estimates of total sodium intake and discretionary salt intake. About 25 participants at each site used a Study Salt for 11 days instead of their own household salt, provide additional information based on four 24-hour urine collections, four follow-up urine collection questionnaires, and three follow-up questionnaires on Study Salt use. The Study Salt has the same amount of sodium and contains a very small amount of lithium, a metal found in trace amounts in all plants and animals and excreted in urine. Participants are instructed to use the study salt as they would their salt at home and to collect duplicate samples of the amount used at the table and during home cooking. The amount of lithium excreted in the 24-hour urine collection is measured to assess the amount of sodium consumed from discretionary salt use (salt used at the table and during home cooking).

Results from the Salt Sources Study will be used to inform public health strategies to reduce sodium intake, determine if substantial variability in sources of sodium intake exists by social and demographic subgroups, and better inform estimates of salt added at the table used in Healthy People 2020 objectives related to sodium reduction.

• Study Type: Observational
• Enrollment (Actual): 450

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 74 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

A convenience sample of adults aged 18-74 years, able to read and speak English, who have a telephone. Respondents will be excluded if they are pregnant, breastfeeding, have diabetes insipidus, or have chronic kidney disease. Information will be collected from the study participants in three study sites in Minnesota, Alabama, and California.

Description

Inclusion Criteria:

• able to read and speak English, who have a telephone

• live in one of three study sites in the following cities or surrounding geographic areas

  1. Minneapolis, Minnesota
  2. Birmingham, Alabama; Palo Alto, California

Exclusion Criteria:

• pregnant
• breastfeeding
• have diabetes insipidus
• have chronic kidney disease.

Study Plan

How is the study designed?

Design Details

• Time Perspectives: Cross-Sectional

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sodium intake as assessed through four 24 hour dietary recalls	Four 24-hour dietary recalls and duplicate collection of salt added at the table	11 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Discretionary sodium intake from salt added at the table and during cooking as assessed through duplicate salt collection	Collection of duplicated samples of salt added at the table and during cooking on 24-h diet recall days	11 days
Total sodium intake as assessed through laboratory analysis 24-h urine collections	Measured from four 24-hour urine collections in a subset of 150 study participants	11 days
Discretionary sodium intake (from salt added at the table or during cooking) assessed from the amount of lithium excreted in 24-hour urine collections.	Measured from 24-hour urine collections in a subset of 150 study participants who used lithium labeled salt at the table and for home cooking in place of their usual salt	11 days

Collaborators and Investigators

• Sponsor: Mary Cogswell
• Collaborators: Stanford University; University of Minnesota; University of Birmingham
• Investigators: Principal Investigator: Lyn Steffen, PhD, MPH, RD, University of Minnesota

Publications and helpful links

General Publications

• Quader ZS, Zhao L, Harnack LJ, Gardner CD, Shikany JM, Steffen LM, Gillespie C, Moshfegh A, Cogswell ME. Self-Reported Measures of Discretionary Salt Use Accurately Estimated Sodium Intake Overall but not in Certain Subgroups of US Adults from 3 Geographic Regions in the Salt Sources Study. J Nutr. 2019 Sep 1;149(9):1623-1632. doi: 10.1093/jn/nxz110.
• Harnack LJ, Cogswell ME, Shikany JM, Gardner CD, Gillespie C, Loria CM, Zhou X, Yuan K, Steffen LM. Sources of Sodium in US Adults From 3 Geographic Regions. Circulation. 2017 May 9;135(19):1775-1783. doi: 10.1161/CIRCULATIONAHA.116.024446.

Helpful Links

• Study description, data collection forms and questionnaires included on the Office of Management and Budget website

Study record dates

Study Major Dates

• Study Start: January 1, 2014
• Primary Completion (Actual): December 1, 2014
• Study Completion (Actual): December 1, 2014

Study Registration Dates

• First Submitted: May 12, 2015
• First Submitted That Met QC Criteria: June 17, 2015
• First Posted (Estimate): June 18, 2015

Study Record Updates

• Last Update Posted (Estimate): January 28, 2016
• Last Update Submitted That Met QC Criteria: January 27, 2016
• Last Verified: January 1, 2016

More Information

Terms related to this study

• Other Study ID Numbers: 0920-0982

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Yes
• IPD Plan Description: When data cleaning is completed, data can be obtained through submission of a proposal to the proposal and publication committee through contacting one of the investigators