Effect of industrially produced trans fat on markers of systemic inflammation: evidence from a randomized trial in women

Abstract

Consumption of industrially produced trans fatty acids (IP-TFA) has been positively associated with systemic markers of low-grade inflammation and endothelial dysfunction in cross-sectional studies, but results from intervention studies are inconclusive. Therefore, we conducted a 16 week double-blind parallel intervention study with the objective to examine the effect of IP-TFA intake on biomarkers of inflammation, oxidative stress, and endothelial dysfunction. Fifty-two healthy overweight postmenopausal women (49 completers) were randomly assigned to receive either partially hydrogenated soybean oil (15.7 g/day IP-TFA) or control oil without IP-TFA. After 16 weeks, IP-TFA intake increased baseline-adjusted serum tumor necrosis factor (TNF) α by 12% [95% confidence interval (CI): 5-20; P = 0.002] more in the IP-TFA group compared with controls. Plasma soluble TNF receptors 1 and 2 were also increased by IP-TFA [155 pg/ml (CI: 63-247); P < 0.001 and 480 pg/ml (CI: 72-887); P = 0.02, respectively]. Serum C-reactive protein, interleukin (IL) 6 and adiponectin and subcutaneous abdominal adipose tissue mRNA expression of IL6, IL8, TNFα, and adiponectin as well as ceramide content were not affected by IP-TFA, nor was urinary 8-iso-prostaglandin-F(2α). In conclusion, this dietary trial indicates that the mechanisms linking dietary IP-TFA to cardiovascular disease may involve activation of the TNFα system.

Trial registration: ClinicalTrials.gov NCT00655902.

Figures

Fig. 1.

Systemic concentrations of markers of inflammation and endothelial dysfunction before and after 8 and 16 weeks (wk) of supplementation with 15.7 g/d industrially produced trans fatty acids (IP-TFA; dark gray bars; n = 24) or a control oil (CTR; white bars; n = 25), and in lean references (light gray bars; n = 19). A: Tumor necrosis factor (TNF) α assessed by ELISA and soluble tumor necrosis factor receptors 1 and 2 (sTNF-R1 and sTNF-R2) assessed by bead immunoassay. B: C-reactive protein (CRP; n = 23, 22, and 18 in the IP-TFA and CTR group and lean references, respectively, due to exclusion of CRP values >10 mg/l), interleukin 6 (IL6) and adiponectin assessed by ELISA. C: Soluble E-selectin (sE-selectin), soluble intercellular adhesion molecule 1 (sICAM-1), and soluble vascular adhesion molecule 1 (sVCAM-1) assessed by bead immunoassay. Bars represent means [95% confidence intervals (CI)] for TNF-R1 and TNF-R2 and geometric means (CI) for all other variables. P-values are for effect of diet, by baseline-adjusted ANCOVA for variables measured at wks 0 and 16, and by baseline-adjusted repeated measures ANCOVA for variables measured at wks 0, 8, and 16. There were no time-by-diet interactions and no effect of time in analyses omitting the interaction term. *Significantly different from overweight intervention subjects (diet groups combined); P < 0.05 by 2-tailed t-tests or Kruskal-Wallis’ χ2 test.

Fig. 2.

Subcutaneous abdominal adipose tissue mRNA expression before and after 16 weeks (wk) of supplementation with 15.7 g/d industrially produced trans fatty acids (IP-TFA; dark gray bars; n = 24; n = 23 for IL8) or a control oil (CTR; white bars; n = 25), and in lean references (light gray bars; n = 17). mRNA expressions are expressed relative to β-actin and bars represent geometric means (95% confidence intervals). There were no differences between diet groups at wk 16 by ANCOVA with baseline value as a covariate (P > 0.20). * Significantly different from overweight intervention subjects (diet groups combined); P < 0.001 by Kruskal-Wallis’ χ2 test. IL, interleukin 6; TNF, tumor necrosis factor.