Abstract
OBJECTIVES: Trans-fatty acids (TFA) are geometric isomers of naturally occurring cis-fatty acids, formed industrially through partial hydrogenation of vegetable oils or naturally in ruminant animals. TFA intake has been associated with risk factors for cardiovascular disease; therefore, reduced TFA consumption is a major public health objective. Food intake studies have provided estimates for TFA levels in the U.S. and we previously assessed TFA blood concentrations in fasting U.S. adults in the National Health and Nutrition Examination Survey (NHANES), finding an average 54% decrease in TFA between 1999-2000 and 2009-2010. The aim of this study was to determine nationally representative estimates for plasma TFA concentrations in children in the U.S. population. METHODS: We used the CDC isotope dilution-gas chromatography-negative chemical ionization-mass spectrometry (ID-GC-NCI-MS) method to quantitate four major TFA, palmitelaidic acid, elaidic acid, trans-vaccenic acid, and linoelaidic acid, in a nationally representative group of children in the U.S. population using NHANES samples. TFA were derivatized with pentafluorobenzyl-bromide and analyzed by GC-MS in selected ion monitoring mode using NCI with methane reagent gas. Separation was carried out on a Select FAME 200 m column with hydrogen carrier gas. The TFA limits of detection ranged from 0.02 μM to 0.43 μM. The intraday and inter-day % coefficients of variation ranged from 1-11% CV and 6-15% CV respectively. The mean accuracy for all four TFA was 102% (95% CI: 98%-107%). RESULTS: The TFA were measured in 916 participants (age: 6-19 years) from NHANES 1999-2000 and 1718 participants (age: 3-19 years) from NHANES 2009-2010, and were detected in all samples. Geometric means for the sum of the 4 TFAs were 80.7 μmol/l (95% CI: 74.6-87.3 μmol/L) and 30.6 μmol/l (95% CI: 29.0-32.3 μmol/L) in the NHANES 1999-2000 and 2009-2010, respectively. Overall TFA concentrations were 62% lower in NHANES 2009-2010 compared to 1999-2000. CONCLUSIONS: TFA levels in children in the U.S. population are notably lower in NHANES 2009-2010 compared to NHANES 1999-2000 suggesting an overall reduction of TFA levels in children. FUNDING SOURCES: N/A.