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Published on: September 18, 2018
Comparison of Methods to Assess Discretionary Salt Intake among Nonpregnant Women of Reproductive Age in Punjab,
Yvonne E Goh1, Mari S Manger1,2, Mona Duggal3
1Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, University of California, San Francisco, San Francisco, CA, United States.
Background:
Accurate and precise estimates of discretionary salt intake are critical for the design of salt fortification programs and salt reduction interventions.
Objectives:
This study aimed to compare 4 methods of estimating discretionary salt intake among nonpregnant females of reproductive age in Punjab, India.
Methods:
One-day, observer-recorded, weighed food records (WFRs), household salt disappearance (HHSD) data, duplicate diet composites, and samples of household salt and milk were collected from 100 females and repeated in a subset of 40 to adjust for intraperson variation and estimate usual discretionary salt intake. Diet composites were also replicated from 40 randomly selected WFR but prepared without the addition of discretionary salt. The duplicate diet composites' sodium and iodine contents were analyzed using inductively coupled plasma (ICP)-optical emission spectrometry and ICP-mass spectrometry, respectively. The iodine content of household salt samples was analyzed using the ion-selective electrode method. The association and agreement between the WFR method, the selected reference method, and the HHSD, replicate diet (RD), and iodine methods (IMs) were explored using correlation and Bland-Altman analyses.
Results:
Mean ± standard deviation (SD) discretionary salt intakes according to the WFR, HHSD, RD, and IM methods were 4.7 ± 1.8 g/d, 5.7 ± 2.6 g/d, 4.1 ± 2.1 g/d, and 7.8 ± 5.3 g/d, respectively. The RD method showed the strongest correlation (ρ = 0.76; P < 0.001) and the smallest mean difference ± SD (-0.68 ± 1.25 g/d), with limits of agreement from -3.18 to 1.82 g/d, compared with the WFR method. However, the HHSD method was also moderately correlated (ρ = 0.48; P < 0.001) and showed good agreement [0.98 ± 2.12 (-3.27, 5.23) g/d] with the WFR despite lower precision.
Conclusions:
Although intensive to implement, the WFR and RD methods produce precise estimates of discretionary salt intake. Repeated measurements may improve the precision of the HHSD method for large population-based surveys.
