Molecular effects of the consumption of margarine and butter varying in trans fat composition: a parallel human intervention study

Abstract

Background: Whereas the dietary intake of industrial trans fatty acids (iTFA) has been specifically associated with inflammation, cardiovascular disease, and type 2 diabetes, understanding the impact of dietary fats on human health remains challenging owing to their complex composition and individual effects of their lipid components on metabolism. The aim of this study is to profile the composition of blood, measured by the fatty acid (FAs) profile and untargeted metabolome of serum and the transcriptome of blood cells, in order to identify molecular signatures that discriminate dietary fat intakes.

Methods: In a parallel study, the molecular effects of consuming dairy fat containing ruminant TFA (rTFA) or margarine containing iTFA were investigated. Healthy volunteers (n = 42; 45-69 y) were randomly assigned to diets containing margarine without TFA as major source of fat (wTFA control group with 0.4 g TFA per 100 g margarine), margarine with iTFA (iTFA group with 4.1 g TFA per 100 g margarine), or butter with rTFA (rTFA group with 6.3 g TFA per 100 g butter) for 4 weeks. The amounts of test products were individually selected so that fat intake contributed to 30-33% of energy requirements and TFA in the rTFA and iTFA groups contributed to up to 2% of energy intake. Changes in fasting blood values of lipid profiles (GC with flame-ionization detection), metabolome profiles (LC-MS, GC-MS), and gene expression (microarray) were measured.

Results: Eighteen FAs, as well as 242 additional features measured by LC-MS (185) and GC-MS (54) showed significantly different responses to the diets (PFDR-adjusted < 0.05), mainly distinguishing butter from the margarine diets while gene expression was not differentially affected. The most abundant TFA in the butter, i.e. TFA containing (E)-octadec-11-enoic acid (C18:1 t11; trans vaccenic acid), and margarines, i.e. TFA containing (E)-octadec-9-enoic acid (C18:1 t9; elaidic acid) were reflected in the significantly different serum levels of TFAs measured after the dietary interventions.

Conclusions: The untargeted serum metabolome differentiates margarine from butter intake although the identification of the discriminating features remains a bottleneck. The targeted serum FA profile provides detailed information on specific molecules differentiating not only butter from margarine intake but also diets with different content of iTFAs in margarine.

Trial registration: ClinicalTrials.gov NCT00933322.

Keywords: Butter; Circulating lipids; Margarine; Metabolome; Trans fatty acids; Transcriptome.

Conflict of interest statement

The authors declare that they have no competing interests.

© 2022. The Author(s).

Figures

Fig. 1

Heatmap of 24 lipid parameters (18 lipids and 6 sum parameters) measured by high-resolution GC-FID that were selected from 85 features (66 single FAs and 19 sum parameters) by a Kruskal-Wallis test (Padjusted FDR < 0.05). The response of each subject (delta change between baseline and post-treatment) is denoted in columns with annotation for treatment groups, rTFA group (blue), margarine wTFA (green) and margarine with iTFA (red), study number and sex (m = male, f = female)

Fig. 2

Spearman correlation analysis in the whole study-population identified some positive (blue) and negative (red) significant associations between blood lipids showing a significant response to the interventions (n = 24) and clinical parameters (n = 14) after the 4 week treatments (delta change between baseline and post-treatment). Significance was considered where Padjusted FDR < 0.05. Non-significant correlations are left blank. The clustering method was Ward D2. The size of the coloured symbols and the coloured scale to the right indicate the rho correlation value. Clinical parameters highlighted in green

Fig. 3

Heatmap of 185 LC-MS features (rows) that were selected from 11′616 (normalised) LC-MS features by a Kruskal-Wallis test (Padjusted FDR < 0.05). The response of each subject (delta change between baseline and post-treatment) is denoted in columns with annotation for treatment groups, rTFA group (blue), margarine wTFA (green) and margarine with iTFA (red), study number and sex

Fig. 4

Boxplots of LC-MS metabolites that show a significant response (delta change between baseline and post-treatment) to the diets grouped by those that are either increased or decreased in the rTFA group. The identification levels of these metabolites were 1 for retinol and prostaglandin D3 and 3 for the two others. Different letters indicate significantly different values (paired Wilcoxon signed-rank Test, PFDR-adjusted < 0.05) paired. Plots show the IQR (box), the median dividing the IQR (—), with dashed line whiskers that extend to the last point included in the 1.5 x IQR range and outliers outside this range identified (o). One outlier in wTFA boxplot for 4-isopropylbenzoic acid was eliminated (baseline: 475.6, endpoint: 6464.7). This subject was however not removed from the robust statistical analysis

Fig. 5

Boxplots of identified GC-MS metabolites that show different responses (delta change between baseline and post-treatment) to the diets. Different letters indicate significantly different values (paired Wilcoxon signed-rank Test, PFDR-adjusted < 0.05) paired. Plots show the IQR (box), the median dividing the IQR (—), with dashed line whiskers that extend to the last point included in the 1.5 x IQR range and outliers outside this range identified (◊)