Salt Sources Study
Condition: Dietary Sources of Sodium Intake
Study type: Observational

Summary: 
      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.
    

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.
    

Time perspective: Cross-Sectional
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.
      
Biospecimen description: 
      24 hour urine samples