Plasma Industrial and Ruminant Trans Fatty Acids and Incident Type 2 Diabetes in the EPIC-Potsdam Cohort

Effects of beef fat enriched with trans vaccenic acid and cis9, trans11-CLA on glucose homoeostasis and hepatic lipid accumulation in high-fat diet-induced obese mice

Trans vaccenic acid (TVA, trans11-18 : 1) and cis9, trans11-CLA (also known as rumenic acid; RA) have received widespread attention as potentially beneficial trans-FA due to their putative health benefits, including anti-diabetic properties. The objective of this study was to determine the effects of beef fat naturally enriched with TVA and RA on parameters related to glucose homoeostasis and associated metabolic markers in diet-induced obese (DIO) mice. Thirty-six male C57BL/6J mice (8 weeks old) were fed for 19 weeks with either a control low-fat diet (CLF), a control high-fat diet (CHF), or a TVA+RA-enriched high-fat diet (EHF). Compared with CLF, feeding either CHF or EHF resulted in adverse metabolic outcomes associated with high-fat diets, including adiposity, impaired glucose control and hepatic steatosis. However, the EHF diet induced a significantly higher liver weight TAG content and elevated plasma alanine transaminase levels compared with the CHF diet. Collectively, the findings from this study suggest that EHF does not improve glucose tolerance and worsens liver steatosis in DIO mice. However, the adverse effects of EHF on the liver could be in part related to the presence of other trans-FA in the enriched beef fat.

Integration of hepatic lipidomics and transcriptomics reveals the effect of butter-derived ruminant trans fatty acids on lipid metabolism in C57BL/6J mice

Dysregulation of lipid metabolism results in metabolism-related diseases. Our previous research indicated that 1.3% E and 4% E ruminant trans fatty acids (R-TFA) caused dyslipidemia and promoted atherosclerotic plaques in ApoE-/- mice, presenting detrimental effects. However, the effect of R-TFA on the lipid metabolism of normal mice remains unclear. Therefore, our current research aims to explore the effects of butter-derived R-TFAs on the lipid metabolism of C57BL/6J mice through the integration of lipidomics and transcriptomics. As a result, we found that 1.3% E butter-derived R-TFA promoted dyslipidemia and impaired hepatic function in C57BL/6J mice fed a high-fat diet, which was associated with an increase in DG (18:1/22:5), TG (18:1/18:2/22:4) and FA (24:5) as determined through lipidomics analysis, but had a less significant effect on C57BL/6J mice fed a low-fat diet. Through a combination analysis and verification of gene expression, we found that the arachidonic acid pathway might be involved in the disruption of lipid metabolism by butter-derived R-TFA. In addition, butter-derived R-TFA up-regulated the expression of unigene thromboxane-A synthase 1 (Tbxas1), arachidonate lipoxygenase 3 (Aloxe3), acyl-coenzyme A thioesterase 2 (Acot2), epoxide hydrolase 2 (Ephx2) and carbonyl reductase 3 (Cbr3) in C57BL/6J mice fed a high-fat diet. Herein, our research provides a new perspective for exploring the effects of butter-derived R-TFA on lipid metabolism and speculates on the possible mechanism of lipid metabolism disorder induced by butter-derived R-TFA in C57BL/6J mice fed a high-fat diet.

Differences in DNA methylation of HAMP in blood cells predicts the development of type 2 diabetes

OBJECTIVES

Better disease management can be achieved with earlier detection through robust, sensitive, and easily accessible biomarkers. The aim of the current study was to identify novel epigenetic biomarkers determining the risk of type 2 diabetes (T2D).

METHODS

Livers of 10-week-old female New Zealand Obese (NZO) mice, slightly differing in their degree of hyperglycemia and liver fat content and thereby in their diabetes susceptibility were used for expression and methylation profiling. We screened for differences in hepatic expression and DNA methylation in diabetes-prone and -resistant mice, and verified a candidate (HAMP) in human livers and blood cells. Hamp expression was manipulated in primary hepatocytes and insulin-stimulated pAKT was detected. Luciferase reporter assays were conducted in a murine liver cell line to test the impact of DNA methylation on promoter activity.

RESULTS

In livers of NZO mice, the overlap of methylome and transcriptome analyses revealed a potential transcriptional dysregulation of 12 hepatokines. The strongest effect with a 52% decreased expression in livers of diabetes-prone mice was detected for the Hamp gene, mediated by elevated DNA methylation of two CpG sites located in the promoter. Hamp encodes the iron-regulatory hormone hepcidin, which had a lower abundance in the livers of mice prone to developing diabetes. Suppression of Hamp reduces the levels of pAKT in insulin-treated hepatocytes. In liver biopsies of obese insulin-resistant women, HAMP expression was significantly downregulated along with increased DNA methylation of a homologous CpG site. In blood cells of incident T2D cases from the prospective EPIC-Potsdam cohort, higher DNA methylation of two CpG sites was related to increased risk of incident diabetes.

CONCLUSIONS

We identified epigenetic changes in the HAMP gene which may be used as an early marker preceding T2D.

Circulating trans fatty acids are associated with prostate cancer in Ghanaian and American men

The association between fatty acids and prostate cancer remains poorly explored in African-descent populations. Here, we analyze 24 circulating fatty acids in 2934 men, including 1431 prostate cancer cases and 1503 population controls from Ghana and the United States, using CLIA-certified mass spectrometry-based assays. We investigate their associations with population groups (Ghanaian, African American, European American men), lifestyle factors, the fatty acid desaturase (FADS) genetic locus, and prostate cancer. Blood levels of circulating fatty acids vary significantly between the three population groups, particularly trans, omega-3 and omega-6 fatty acids. FADS1/2 germline genetic variants and lifestyle factors explain some of the variation in fatty acid levels, with the FADS1/2 locus showing population-specific associations, suggesting differences in their control by germline genetic factors. All trans fatty acids, namely elaidic, palmitelaidic, and linoelaidic acids, associated with an increase in the odds of developing prostate cancer, independent of ancestry, geographic location, or potential confounders.

Fatty Acid Profile and Genetic Variants of Proteins Involved in Fatty Acid Metabolism Could Be Considered as Disease Predictor

Circulating fatty acids (FA) have an endogenous or exogenous origin and are metabolized under the effect of many enzymes. They play crucial roles in many mechanisms: cell signaling, modulation of gene expression, etc., which leads to the hypothesis that their perturbation could be the cause of disease development. FA in erythrocytes and plasma rather than dietary FA could be used as a biomarker for many diseases. Cardiovascular disease was associated with elevated trans FA and decreased DHA and EPA. Increased arachidonic acid and decreased Docosahexaenoic Acids (DHA) were associated with Alzheimer's disease. Low Arachidonic acid and DHA are associated with neonatal morbidities and mortality. Decreased saturated fatty acids (SFA), increased monounsaturated FA (MUFA) and polyunsaturated FA (PUFA) (C18:2 n-6 and C20:3 n-6) are associated with cancer. Additionally, genetic polymorphisms in genes coding for enzymes implicated in FA metabolism are associated with disease development. FA desaturase (FADS1 and FADS2) polymorphisms are associated with Alzheimer's disease, Acute Coronary Syndrome, Autism spectrum disorder and obesity. Polymorphisms in FA elongase (ELOVL2) are associated with Alzheimer's disease, Autism spectrum disorder and obesity. FA-binding protein polymorphism is associated with dyslipidemia, type 2 diabetes, metabolic syndrome, obesity, hypertension, non-alcoholic fatty liver disease, peripheral atherosclerosis combined with type 2 diabetes and polycystic ovary syndrome. Acetyl-coenzyme A carboxylase polymorphisms are associated with diabetes, obesity and diabetic nephropathy. FA profile and genetic variants of proteins implicated in FA metabolism could be considered as disease biomarkers and may help with the prevention and management of diseases.

Different Types of Industry-Produced and Ruminant Trans Fatty Acid Intake and Risk of Type 2 Diabetes: Findings From the NutriNet-Santé Prospective Cohort

OBJECTIVE

The deleterious effects of trans fatty acids (TFAs) on cardiovascular health are well established; however, their impact on type 2 diabetes remains poorly understood. In particular, little is known about the impact of specific TFA types on type 2 diabetes etiology. We aimed to explore the associations between different types of TFAs (total, ruminant, industry produced [iTFAs], and corresponding specific isomers) and risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 105,551 participants age >18 years from the French NutriNet-Santé cohort (2009-2021) were included (mean baseline age 42.7 years; SD 14.6 years); 79.2% were women. Dietary intake data, including usual TFA intake, were collected using repeated 24-h dietary records (n = 5.7; SD 3.1). Associations between sex-specific quartile of dietary TFAs and diabetes risk were assessed using multivariable Cox models.

RESULTS

Total TFA intake was associated with higher type 2 diabetes risk (hazard ratio [HR]quartile 4 vs. 1 1.38; 95% CI 1.11-1.73; Ptrend < 0.001; n = 969 incident cases). This association, specifically observed for iTFAs (HR 1.45; 95% CI 1.15-1.83; Ptrend < 0.001), was mainly driven by elaidic acid (HR 1.37; 95% CI 1.09-1.72; Ptrend < 0.001) and linolelaidic acid (HR 1.29; 95% CI 1.04-1.58; Ptrend = 0.07). In contrast, ruminant TFAs were not significantly associated with risk of type 2 diabetes.

CONCLUSIONS

In this large prospective cohort, higher intakes of total and iTFAs were associated with increased type 2 diabetes risk. These findings support the World Health Organization's recommendation to eliminate iTFAs from the food supply worldwide. Consumers should be advised to limit the consumption of food products containing partially hydrogenated oils (main vector of iTFAs). This may contribute to lowering the substantial global burden of type 2 diabetes.

Dietary and Plasma Phospholipid Profiles in Vegans and Omnivores-Results from the RBVD Study

Over the last few years, the vegan diet has become increasingly popular in Germany. It has been proposed that this diet is generally lower in fat, but less is known about the impact on fatty acid (FA) profiles. Therefore, the cross-sectional “Risks and Benefits of a Vegan Diet” (RBVD) study (n = 72) was used to investigate dietary FA intake as well as plasma phospholipid FA in vegans (n = 36) compared to omnivores (n = 36). Vegans had a significantly lower dietary intake of total fat (median 86 g/day, IQR 64−111) in comparison to omnivores (median 104 g/day, IQR 88−143, p = 0.004). Further, vegans had a lower intake of saturated fatty acids (SFA) (p < 0.0001) and monounsaturated fatty acids (MUFA) (p = 0.001) compared to omnivores. Vegans had a higher intake in total polyunsaturated fatty acids (PUFA), omega-3 and omega-6 PUFA compared to omnivores, but without statistical significance after Bonferroni correction. According to plasma phospholipid profiles, relatively lower proportions of SFA (p < 0.0001), total trans fatty acids (TFA) (p = 0.0004) and omega-3-FA (p < 0.0001), but higher proportions of omega-6-FA (p < 0.0001) were observed in vegans. With the exception of omega-3 PUFA, a vegan diet is associated with a more favorable dietary fat intake and more favorable plasma FA profiles and therefore may reduce cardiovascular risk.

Different Metabolism and Toxicity of TRANS Fatty Acids, Elaidate and Vaccenate Compared to Cis-Oleate in HepG2 Cells

Trans fatty acids (TFAs) are not synthesized in the human body but are generally ingested in substantial amounts. The widespread view that TFAs, particularly those of industrial origin, are unhealthy and contribute to obesity, cardiovascular diseases and diabetes is based mostly on in vivo studies, and the underlying molecular mechanisms remain to be elucidated. Here, we used a hepatoma model of palmitate-induced lipotoxicity to compare the metabolism and effects of the representative industrial and ruminant TFAs, elaidate and vaccenate, respectively, with those of cis-oleate. Cellular FAs, triacylglycerols, diacylglycerols and ceramides were quantitated using chromatography, markers of stress and apoptosis were assessed at mRNA and protein levels, ultrastructural changes were examined by electron microscopy and viability was evaluated by MTT assay. While TFAs were just slightly more damaging than oleate when applied alone, they were remarkably less protective against palmitate toxicity in cotreatments. These differences correlated with their diverse incorporation into the accumulating diacylglycerols and ceramides. Our results provide in vitro evidence for the unfavorable metabolic features and potent stress-inducing character of TFAs in comparison with oleate. These findings strengthen the reasoning against dietary trans fat intake, and they can also help us better understand the molecular mechanisms of lipotoxicity.