Trans fatty acids (TFA) are considered risk factors for cardiovascular disease (CVD), while the details of distribution and metabolism of the individual isomers are not clear. Here we investigated the accumulation and catabolic rate of TFA positional isomers of octadecenoic acid (18:1) in mice. ICR mice were fed deuterium- and [1-
13C] stable isotope-labeled
trans-9-18:1 (9
t-18:1*),
trans-10-18:1 (10
t-18:1*), or
trans-11-18:1 (11
t-18:1*) for 2 or 4 weeks, or a TFA mixture (9
t-18:1*, 10
t-18:1*, and 11
t-18:1*) for 3 weeks. Analysis of whole-body tissues by gas chromatography-chemical ionization mass spectrometry revealed the highest 9
t-18:1* levels in the heart. Significant differences in the accumulation of the respective
trans-18:1 were observed in the heart and erythrocytes, where 9
t- > 11
t- > 10
t-18:1*, but no significant difference was observed in the liver or white adipose tissue (WAT). Mice fed on 11
t-18:1 demonstrated accumulation of endogenously synthesized conjugated linoleic acid in the liver, WAT, and heart, but any other metabolites were not found in other groups. Furthermore, we analyzed catabolic rates of single-dose-administered
trans-18:1* isomers into [
13C]-labeled CO
2 using isotope-ratio mass spectrometry, and the 10
t-18:1*catabolic rate was significantly higher than those of 9
t- and 11
t-18:1*. We found that the accumulation and catabolism of
trans-18:1 positional isomers varied in these mice. Differential accumulation in tissues suggests that individual TFA positional isomers may play different roles in human health.
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