ARS | Publication request: Change in methodology for collection of drinking water intake in What We Eat In America/National Health and Nutrition Examination Survey: Implications for analysis

Submitted to: Public Health Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2012
Publication Date: February 20, 2012
Repository URL: http://dx.doi.org/10.1017/S1368980012000316
Citation: Sebastian, R.S., Enns, C.W., Goldman, J.D., Moshfegh, A.J. 2012. Change in methodology for collection of drinking water intake in What We Eat In America/National Health and Nutrition Examination Survey: Implications for analysis. Public Health Nutrition. 15(7):1190-1195. DOI: 10.1017/S1368980012000316.

Interpretive Summary: The method for collecting national drinking water data in the survey What We Eat In America, NHANES changed between 2003-2004 and 2005-2006. Prior to 2005, food frequency-type questions were used to obtain an overall estimate of how much water the survey respondent drank the previous day. Beginning in 2005, the same method that has been used for many years to collect data on other beverages and foods ' namely, the 24-hour recall ' has been used to collect information about the type and amount of water consumed each time the respondent drank water the previous day. The objective of this study was to provide updated estimates of drinking water intake for groups aged =1 year in the USA and to determine whether intakes collected in 2005-2006 using the 5-step USDA Automated Multiple-Pass Method (AMPM) for the 24 h recall differ from intakes collected in 2003-2004 via post-recall food-frequency type questions. Differences in estimates of drinking water, tap water, and plain bottled water between 2003-2004 and 2005-2006 were determined. Findings of some significant differences between 2003-2004 and 2005-2006 reinforce the fact that researchers must examine survey variables for comparability before combining or contrasting data from multiple WWEIA/NHANES release cycles. The updated estimates of drinking water intakes in this article will be beneficial to a wide audience, including scientists, policymakers, nutrition professionals, and the general public. Ultimately, findings of differences in estimates in water intake between survey cycles will be of benefit on a national basis, since researchers and policymakers use these data on for many purposes, including developing Dietary Reference Intakes for water, examining exposure to chemical contaminants and waterborne diseases, and estimating intake of nutrients naturally present in or purposely added to the water supply.

Technical Abstract: The objective of this study was to provide updated estimates of drinking water intake (total, tap, plain bottled) for groups aged =1 year in the USA and to determine whether intakes collected in 2005-2006 using the 5-step USDA Automated Multiple-Pass Method (AMPM) for the 24 h recall differ from intakes collected in 2003-2004 via post-recall food-frequency type questions. The addition of the collection of drinking water intake data to the AMPM recall was initiated in What We Eat In America (WWEIA), National Health and Nutrition Examination Survey (NHANES) 2005-2006. Before 2005-2006, plain water intake data were collected after the 24 h recall via food-frequency type questions which asked the respondent to estimate the total amounts of tap and bottled water consumed the previous day. This analysis is based on one day of recall data for individuals age 1+ years in WWEIA 2005-2006 (n=8,437) and 2003-2004 (n=8,249). T-tests were used to detect differences between the two time periods in (i) percentage of individuals reporting any plain water; (ii) mean intake of total plain water; (iii) percentage of individuals reporting specific water types (tap, bottled); and (iv) mean intake of each water type. The estimate for the percentage of individuals who reported total drinking water in 2005-2006 was significantly (P<0.001) smaller (76.9%) than that for 2003-2004 (87.1 %), attributable to a lower percentage reporting tap water (54.1% in 2005-2006 v. 67.0% in 2003-2004; P<0.001). Estimates of mean tap water intake differed between the survey cycles for men aged =71 years. Survey variables must be examined before combining or comparing data from multiple WWEIA/NHANES release cycles. For at least some age/gender groups, drinking water intake data from WWEIA/NHANES cycles prior to 2005–2006 should not be considered comparable to more recent data.