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Adjusting Serum Biomarkers of Folate Status for Within‐person Variation
Author(s) -
Bailey Regan,
Carriquiry Alicia,
Gahche Jaime,
Dodd Kevin,
Joseph Maria,
Dwyer Johanna,
Yetley Elizabeth,
Sempos Chris,
Picciano Mary Frances
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.563.8
Subject(s) - national health and nutrition examination survey , medicine , population , biomarker , demography , nutrient , physiology , environmental health , biology , ecology , biochemistry , sociology
Controlling within‐person variability (WIV) is one strategy to minimize the error in short‐term measurements to make them reflective of usual (long term) estimates. Significant amount of WIV have been documented in nutrient intakes assessed by daily measures; however, less is known about the WIV in biomarkers of nutrient status. Using the estimates obtained from 2 days of biomarker data, we computed the WIV from National Health and Nutrition Examination Survey (NHANES) III for DRI age and gender groups. These WIV estimates were then applied to the corresponding age and gender groups in NHANES 2003–2006 to adjust the serum and red blood cell folate measures. Removing the WIV did not substantially change the measures of central tendency (mean and median), but did impact the estimates of the prevalence of the group below and above recommended cut‐points (RCP). For serum folate, < 1% of males and females had estimates below the RCP; the % above the RCP increased with age, with 42% of females and 35% of males 71+ y having high serum folate. About 5% of males and females had red blood cell folate below the recommended levels. Folate status has been related to neural tube defects, some types of cancer, and cognitive function. Thus, accurate estimates of the proportion of the US population above and below the RCP is critical to public health. Consideration of the WIV is necessary to adequately characterize the population status.