this study involved analyses of cross-sectional data from US children aged 2 to 18 years and aduats aged > 19 years participating in the 2001-2002, 2003-2004, 2005-2006, 2007-2008, and 2009-2010 NHANES. the data from these five cycles were merged to in crease sample size. the study population was limited to participants with complete, reliable 24hour dietary recall data. pregnant or lactating females were excluded. details of NHANES study design, implementation, datasets, analytic considerations, and other documentation are available online. as described therein,following administration of a series of questionnaires in a detailed in-home interview, participants visit a mobile examination center where in-person health examinations and a dietary interview, commonly referred to as the what we eat in america component of the NHANES was conducted. all participants or proxies provided written informed consent and the research ethics review board at the national center for health statistics approved the survey protocol