Erythrocyte trans-fatty acids, type 2 diabetes and cardiovascular risk factors in middle-aged and older Chinese individuals

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.

Metabolic effects of milk fatty acids: A literature review

Milk and dairy products are known to have a significant role in human development and tissue maintenance due to their high nutritional value. With the higher incidence of obesity and metabolic diseases, nutrition and public health authorities have recommended the intake of fat-free or low-fat dairy due to the saturated fatty acid content of whole-fat products and their effect on serum cholesterol levels. However, recent studies have questioned the association between milk fat consumption and cardiometabolic risk. This literature review aims to compile the scientific evidence of the metabolic effects of milk fatty acids in clinical and basic research studies, as well as their relationship with metabolic disorders and gut microbiota composition. Research shows that various milk fatty acids exert effects on metabolic alterations (obesity, type 2 diabetes and cardiovascular diseases) by modifying glucose homeostasis, inflammation and lipid profile-related factors. Additionally, recent studies have associated the consumption of milk fatty acids with the production of metabolites and the promotion of healthy gut microbiota. From mainly observational studies, evidence suggests that milk and dairy fatty acids are not directly linked to cardiometabolic risk, but further controlled research is necessary to clarify such findings and to assess whether dietary recommendations to choose low-fat dairy foods are necessary for the population for the prevention of obesity and cardiometabolic disease.

Formation and application of edible oleogels prepared by dispersing soy fiber particles in oil phase

Oleogels containing less saturated and trans-fats were considered as an ideal option to replace the solid fats in foods. In this research, oleogel was fabricated by dispersing soy fiber particles (SFP) in soy oil, and further it was used in bread preparation. Effect of the particle size, particle content and the second fluid content on the formation of oleogels were evaluated, based on the appearance and rheological properties. Results showed that the suspension of SFP in soy oil (24%, w/w) could be transformed into gel-like state, upon the addition of the second fluid. The SFP based networks were dominated by the capillary force which was originated from the second fluid. The rheological properties and yield stress of the oleogels could be modulated by particle size and particle content of SFP in oil phase, as well as the second fluid content in the system. When the oleogels were applicated in bread preparation, a layered structure could be formed in the bread, indicating the possibility of replacing the solid fats in bakery products by our oleogels. Our results offered a feasibility approach for oil structuring with natural raw materials, and developed a new approach to replace the solid fats in foods.

Associations of erythrocyte polyunsaturated fatty acids with incidence of stroke and stroke types in adult Chinese: a prospective study of over 8000 individuals

PURPOSE

There is limited and inconsistent evidence about the relationships of erythrocyte polyunsaturated fatty acids (PUFAs) with stroke and stroke types, particularly in China where the stroke rates are high. We aimed to investigate the associations of different erythrocyte PUFAs with incidence of total stroke, ischemic stroke (IS), and intracerebral hemorrhage (ICH) in Chinese adults.

METHODS

In the prospective China Kadoorie Biobank, erythrocyte PUFAs were measured using gas chromatography in 10,563 participants who attended 2013-14 resurvey. After a mean follow-up of 3.8 years, 412 incident stroke cases (342 IS, 53 ICH) were recorded among 8,159 participants without prior vascular diseases or diabetes. Cox regression yielded adjusted hazard ratios (HRs) for stroke associated with 13 PUFAs.

RESULTS

Overall, the mean body mass index was 24.0 (3.4) kg/m² and the mean age was 58.1 (9.9) years. In multivariable analyses, 18:2n-6 was positively associated with ICH (HR = 2.33 [95% CIs 1.41, 3.82] for top versus bottom quintile, P_trend = 0.007), but inversely associated with IS (0.69 [0.53,0.90], P_trend = 0.027), while 20:3n-6 was positively associated with risk of IS (1.64 [1.32,2.04], P_trend < 0.001), but not with ICH. Inverted-U shape curve associations were observed of 20:5n-3 with IS (P_nonlinear = 0.002) and total stroke (P_nonlinear = 0.008), with a threshold at 0.70%. After further adjustment for conventional CVD risk factors and dietary factors, these associations remained similar.

CONCLUSION

Among relatively lean Chinese adults, erythrocyte PUFAs 18:2n-6, 20:3n-6 and 20:5n-3 showed different associations with risks of IS and ICH. These results would improve the understanding of stroke etiology.

Circulating Glycerolipids, Fatty Liver Index, and Incidence of Type 2 Diabetes: A Prospective Study Among Chinese

CONTEXT

Few lipidomic studies have specifically investigated the association of circulating glycerolipids and type 2 diabetes (T2D) risk, especially among Asian populations. It remains unknown whether or to what degree fatty liver could explain the associations between glycerolipids and T2D.

OBJECTIVE

We aimed to assess associations between plasma glycerolipids and incident T2D and to explore a potential role of liver fat accumulation in the associations.

METHODS

This was a prospective cohort study with 6 years of follow-up. The study population included 1781 Chinese participants aged 50 to 70 years. The main outcome measure was incident T2D.

RESULTS

At the 6-year resurvey, 463 participants had developed T2D. At the false discovery rate (FDR) of 5%, 43 of 104 glycerolipids were significantly associated with incident T2D risk after multivariate adjustment for conventional risk factors. After further controlling for glycated hemoglobin (HbA1c), 9 of the 43 glycerolipids remained significant, including 2 diacylglycerols (DAGs) (16:1/20:4, 18:2/20:5) and 7 triacylglycerols (TAGs) (46:1, 48:0, 48:1, 50:0, 50:1, 50:2, and 52:2), with relative risks (RRs) (95% CIs) ranging from 1.16 (1.05-1.27) to 1.23 (1.11-1.36) per SD increment of glycerolipids. However, additional adjustment for fatty liver index largely attenuated these findings (RR [95% CI] 0.88 [0.81 to 0.95] to 1.10 [1.01 to 1.21]). Mediation analyses suggested that the fatty liver index explained 12% to 28% of the glycerolipids-T2D associations (all P < 0.01).

CONCLUSION

Higher plasma levels of DAGs and TAGs were associated with increased incident T2D risk in this Chinese population, which might be partially explained by liver fat accumulation.

Fatty acids and cardiometabolic health: a review of studies in Chinese populations

Rapid nutrition transition from plant-based traditional diet to westernized diet has led to dramatically heightening burdens of cardiometabolic diseases in China in past decades. Recently, national surveys reported that poor dietary quality including low marine n-3 fatty acids and high intakes of red meat and processed meat was associated with considerably elevated cardiometabolic deaths. Previous studies mainly from Western population-based cohorts have indicated that not only fat quantity but also quality linked with different cardiometabolic outcomes. Compared with Western peoples, Asian peoples, including Chinese, are known to have different dietary patterns and lifestyle, as well as genetic heterogeneities, which may modify fatty acid metabolism and disease susceptibility in certain degree. To date, there were limited prospective studies investigating the relationships between fatty acids and cardiometabolic disease outcomes in Chinese, and most existing studies were cross-sectional nature and within one or two region(s). Notably, shifting dietary patterns could change not only amount, types, and ratio of fatty acids accounting for overall energy intake, but also their food sources and ratio to other macronutrients. Moreover, large geographic and urban-rural variations in prevalence of cardiometabolic diseases among Chinese may also reflect the effects of socioeconomic development and local diets on health status. Therefore, current review will summarize available literatures with more focus on the Chinese-based studies which may extend current knowledge about the roles of fatty acids in pathogenesis of cardiometabolic diseases for Asian populations and also provide useful information for trans-ethnic comparisons with other populations.

The association between consumption of monounsaturated fats from animal- v. plant-based foods and the risk of type 2 diabetes: a prospective nationwide cohort study

Although higher dietary intake of MUFA has been shown to improve glycaemic control and lipid profiles, whether MUFA consumption from different sources is linked to the development of type 2 diabetes (T2D) remains unclear. We aimed to prospectively assess the associations of plant-derived MUFA (P-MUFA) and animal-derived MUFA (A-MUFA) intakes with T2D risk in a nationwide oriental cohort. Overall, 15 022 Chinese adults, aged ≥20 years, from the China Health and Nutrition Survey (CHNS 1997–2011) were prospectively followed up for a median of 14 years. Consumption of MUFA from plant and animal sources was assessed using 3-d 24-h recalls in each survey, and the cumulative average of intake was calculated. Multivariable-adjusted Cox models were constructed to estimate the hazard ratios (HR) of T2D according to quartiles of MUFA intake. P-MUFA were mainly consumed from cooked vegetable oils, fried bread sticks and rice, while A-MUFA were mainly consumed from pork, lard and eggs. Intake of P-MUFA was associated with a higher risk of T2D (HRQ4 v. Q1 1·50 (95 % CI 1·18, 1·90); Ptrend = 0·0013), whereas A-MUFA showed no significant association (HRQ4 v. Q1 0·84 (95 % CI 0·59, 1·20); Ptrend = 0·30). When further considering the cooking method of food sources, consumption of P-MUFA from fried foods was positively associated with T2D risk (HRQ4 v. Q1 1·60 (95 % CI 1·26, 2·02); Ptrend = 0·0006), whereas non-fried P-MUFA were not associated. Intake of MUFA from fried plant-based foods may elevate T2D risk among the Chinese population.

Fatty acids as biomarkers of total dairy and dairy fat intakes: a systematic review and meta-analysis

Context

Dairy intake in humans is commonly assessed using questionnaires, but the data collected are often biased. As a result, there is increasing interest in biomarkers of dairy fat. To date, there has been no overview of the fatty acids suitable for use as biomarkers of dairy fat intake.

Objective

This systematic review and meta-analysis of observational studies was performed to identify circulating fatty acids as biomarkers of total dairy and dairy fat intakes in the general population.

Data Sources

MEDLINE, Embase, and Web of Knowledge databases were searched for eligible studies published until June 2017.

Study Selection

Articles were included when a correlation between circulating dairy fatty acids and intakes of total dairy and dairy fat was found, as measured by dietary assessment tools.

Data Extraction

Two authors extracted data independently and assessed the risk of bias. An adapted form of the Newcastle-Ottawa Scale was used for quality assessment.

Results

Data were pooled using the random-effects model. Meta-analysis revealed that the fatty acids in plasma/serum were significantly correlated with intakes of total dairy (C14:0 [r = 0.15; 95%CI, 0.11 - 0.18], C15:0 [r = 0.20; 95%CI, 0.13 - 0.27], and C17:0 [r = 0.10; 95%CI, 0.03 - 0.16] and dairy fat (C14:0 [r = 0.16; 95%CI, 0.10 - 0.22], C15:0 [r = 0.33; 95%CI, 0.27 - 0.39], C17:0 [r = 0.19; 95%CI, 0.14 - 0.25], and trans-C16:1n-7 [r = 0.21; 95%CI, 0.14 - 0.29).

Conclusions

C14:0, C15:0, C17:0, and trans-C16:1n-7 were identified as biomarkers of total dairy and dairy fat intakes in the general population. In light of the suboptimal measurement techniques used in some studies, correlations with trans-C18:1n-7 and conjugated linoleic acid require further investigation.

Fatty acid profiling of 75 Indian snack samples highlights overall low trans fatty acid content with high polyunsaturated fatty acid content in some samples

Diet-derived fatty acids have well-proven varying effects on human health. In particular, trans fatty acids (TFA) are associated with high risk of cardiovascular diseases whereas, polyunsaturated fatty acids (PUFA) are considered to be beneficial to the human health. In this study, we report fatty acid profiling of 75 food samples from India belonging to three broad categories, viz., perishable deep-fried, non-perishable deep-fried and bakery. Lipids were extracted from the snacks and fatty acids converted into methyl esters and analysed by gas chromatography. Thirty-seven detected fatty acids were classified into four categories: saturated (SFA), monounsaturated (MUFA), PUFA, and TFA, of which SFA represented the most abundant class in two-third of the samples. The highest average proportions of TFA and SFA of 3.26% and 56.1%, respectively, in total fatty acids were found in the bakery products; whereas, that of PUFA (38%) in the perishable deep-fried products. Principal Component Analysis depicted clustering of many samples according to the above-mentioned categories and helped predict the oil usage. Lower TFA content in all the samples and high proportion of PUFA in a quarter of the samples is suggestive of a better trend as compared to earlier studies.

Plant-sourced and animal-sourced monounsaturated fatty acid intakes in relation to mortality: a prospective nationwide cohort study

PURPOSE

Monounsaturated fatty acids (MUFAs) are typical components of various plant-sourced and animal-sourced foods. However, the associations of MUFA consumption from different sources with mortality remain unclear. This study aimed to investigate the relationships between MUFA intakes from plant and animal sources and mortality.

METHODS

A total of 14,305 participants from China Health and Nutrition Survey were prospectively followed up for 14 years. Dietary intake of MUFAs was assessed by 3-day 24-h dietary records in each round. Cox proportional hazards regression models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

A total of 1006 deaths occurred during 199,091 person-years of follow-up. Intake of total MUFAs was not associated with mortality (P-trend = 0.17). The plant-sourced MUFA intake was strongly associated with lower mortality [HR_Q4vsQ1 (95% CI) 0.72 (0.58-0.89); P-trend = 0.008], whereas animal-sourced MUFA intake showed no significant association. Likewise, oleic acid (OA) and palmitoleic acid (PA) intakes from plant sources were also inversely associated with mortality [HR_Q4vsQ1 (95% CI) 0.66 (0.52-0.84) for OA and 0.73 (0.59-0.91) for PA], while animal-sourced OA and PA were not related to mortality. Theoretically replacing saturated fatty acids (SFAs) (5% of total energy) with isocaloric plant-sourced MUFAs was associated with 15% (95% CI 5-25%) lower mortality. In addition, 18% (95% CI 10-26%) lower mortality was observed when theoretically replacing the sum of SFAs and animal-sourced MUFAs with isocaloric plant-sourced MUFAs.

CONCLUSIONS

Intakes of MUFAs, including OA and PA, from plant but not animal sources were associated with lower total mortality. These findings suggested the importance of consuming MUFAs from plant-based foods for overall health.

Linking of metabolomic biomarkers with cardiometabolic health in Chinese population

Due to rapid nutrition transitions, the prevalence of cardiometabolic diseases, such as metabolic syndrome, type 2 diabetes, and cardiovascular diseases, has been increasing at an alarming rate in the Chinese population. Moreover, Asians, including Chinese, have been hypothesized to have a higher susceptibility to cardiometabolic diseases than Caucasians. Early prediction and prevention are key to controlling this epidemic trend; to this end, the identification of novel biomarkers is critical to reflect environmental exposure, as well as to reveal endogenous metabolic and pathophysiologic mechanisms. The emerging "omics" technologies, especially metabolomics, offer a unique opportunity to provide novel signatures or fingerprints to understand the effects of genetic and non-genetic factors on cardiometabolic health. During the past two decades, metabolomic approaches have been increasingly used in various epidemiological studies, primarily in Western populations. Although the field is still in its early stages, some studies have tried to identify novel compounds or confirm their metabolites and associations with cardiometabolic diseases in Chinese populations, including amino acids, fatty acids, acylcarnitines and other metabolites. Despite major efforts to discover novel biomarkers for disease prediction or intervention, the limits in current study design, analytical platforms, and data processing approaches are challenges in metabolomic research worldwide. Therefore, future research with more advanced technologies, rigorous study designs, standardized detection and analytic approaches, and integrated data from multiomics approaches are essential to evaluate the feasibility of using metabolomics in clinical settings. Finally, the functional roles and underlying biological mechanisms of metabolomic biomarkers should be elucidated by future mechanistic research.

Circulating fatty acids as biomarkers of dairy fat intake: data from the lifelines biobank and cohort study

Background: C14:0, C15:0, C17:0 and trans-C16:1(n-7) are often used as biomarkers for dairy fat intake. Trans-C18:1(n-7) and CLA, two fatty acids which are also present in dairy, have hardly been explored. We investigated whether trans-C18:1(n-7) and CLA can enrich the existing biomarker portfolio. Methods: Data were obtained from Lifelines (n = 769). Dairy fat intake was determined by FFQ. Fatty acids were measured in fasting plasma triglycerides (TG), phospholipids (PL) and cholesterol esters (CE). Results: Median (25th-75th percentile) intakes of dairy and dairy fat were 322(209-447) and 12.3(8.4-17.4) g/d respectively. A pilot study showed that trans-C18:1(n-7) and CLA were only detectable in TG and PL. Of the established markers, TG C15:0 was most strongly associated with dairy fat intake (standardized β (std.β) = 0.286, R² = 0.111). Of the less established markers, TG trans-C18:1(n-7) was most strongly associated with dairy fat intake (Std.β = 0.292, R² = 0.115), followed by PL CLA (Std.β = 0.272, R² = 0.103) and PL trans-C18:1(n-7) (Std.β = 0.269, R² = 0.099). In TG, a combination of C15:0 and trans-C18:1(n-7) performed best (R² = 0.128). In PL, a combination of C14:0, C15:0, trans-C18:1(n-7) and CLA performed best (R² = 0.143). Conclusion: Trans-C18:1(n-7) and CLA can be used as biomarkers of dairy fat intake. Additionally, combining established with less established markers allowed even stronger predictions for dairy fat intake.

Saturated Fatty Acid Intake Is Associated with Total Mortality in a Nationwide Cohort Study

Background

Dietary intakes of total and specific types of saturated fatty acids (SFAs) in relation to total mortality remain largely unknown in China.

Objective

We assessed the associations of total and individual SFA intakes with total mortality in a Chinese nationwide population.

Methods

This prospective analysis included 7888 women and 6495 men, aged >20 y, from the China Health and Nutrition Survey (1989-2011). Cumulative mean of SFA intake was calculated based on 3 d of 24-h records in each round of the survey. Multivariable Cox proportional hazard models were used to estimate HR and 95% CI.

Results

There were 1011 deaths during a median of 14 y of follow-up. In isocaloric nutrient density models that replace total carbohydrates, intakes of total SFAs and even-chain SFAs were associated with higher total mortality in women but not in men. Compared with the lowest quartiles, the HRs (95% CIs) in the highest quartiles were 1.65 (1.03, 2.62) for total SFAs (P-trend = 0.042) and 1.83 (1.13, 2.94) for even-chain SFAs (P-trend = 0.016) in women. Intake of odd-chain SFAs was associated with lower total mortality both in men [HR (95% CI): 0.64 (0.47, 0.87); P-trend = 0.01] and in women [HR (95% CI): 0.59 (0.42, 0.84); P-trend = 0.0013]. Moreover, intake of medium-chain SFAs was linked with lower total mortality in men [HR (95% CI): 0.64 (0.44, 0.93); P-trend = 0.013]. However, isocalorically replacing 1% of energy from unsaturated fatty acids with even-chain SFAs was associated with higher total mortality in men [HRs (95% CIs): 1.08 (0.97, 1.20) and 1.39 (1.20, 1.60) for replacing PUFAs and MUFAs, respectively].

Conclusions

Total SFA and even-chain SFA intake was associated with higher total mortality in women, whereas intake of odd-chain SFAs was related to lower total mortality in both sexes. This analysis of cohort was registered at clinicaltrials.gov as NCT03281512.

Erythrocyte PUFAs, circulating acylcarnitines, and metabolic syndrome risk: a prospective study in Chinese

The effects of PUFAs on metabolic syndrome (MetS) remain to be characterized, particularly in Asians. We aimed to investigate the prospective associations of PUFAs with MetS and the role of acylcarnitines in these associations in Chinese individuals. Among 1,245 Chinese men and women aged 50-70 years who completed a 6 year follow-up, baseline erythrocyte FAs and plasma acylcarnitines were profiled using gas chromatography coupled with positive chemical ionization and liquid chromatography-tandem mass spectrometry, respectively. Total n-6 PUFAs and three 22-carbon n-6 PUFAs were significantly associated with lower MetS risk comparing extreme quartiles: relative risks (RRs) (95% CIs) were 0.75 (0.57, 0.97) for total n-6 PUFAs, 0.69 (0.56, 0.85) for 22:2n-6, 0.76 (0.59, 0.99) for 22:4n-6, and 0.74 (0.58, 0.94) for 22:5n-6, while 18:3n-3 and 18:3n-6 were positively associated with MetS risk. In a network analysis, a module mostly consisting of long-chain n-6 PUFAs and very-long-chain saturated FAs was inversely associated with incident MetS (RR per SD: 0.84; 95% CI: 0.76, 0.92), and this module was more strongly associated with lower MetS risk when a short- to medium-chain acylcarnitine (C5-C10) module score was lower (P _interaction = 0.03). Our data suggested inverse associations of total n-6 and certain long-chain n-6 PUFAs with cardiometabolic disorders, and this association might be modified by certain acy-l-carnitines.

Biomarker of food intake for assessing the consumption of dairy and egg products

Dairy and egg products constitute an important part of Western diets as they represent an excellent source of high-quality proteins, vitamins, minerals and fats. Dairy and egg products are highly diverse and their associations with a range of nutritional and health outcomes are therefore heterogeneous. Such associations are also often weak or debated due to the difficulty in establishing correct assessments of dietary intake. Therefore, in order to better characterize associations between the consumption of these foods and health outcomes, it is important to identify reliable biomarkers of their intake. Biomarkers of food intake (BFIs) provide an accurate measure of intake, which is independent of the memory and sincerity of the subjects as well as of their knowledge about the consumed foods. We have, therefore, conducted a systematic search of the scientific literature to evaluate the current status of potential BFIs for dairy products and BFIs for egg products commonly consumed in Europe. Strikingly, only a limited number of compounds have been reported as markers for the intake of these products and none of them have been sufficiently validated. A series of challenges hinders the identification and validation of BFI for dairy and egg products, in particular, the heterogeneous composition of these foods and the lack of specificity of the markers identified so far. Further studies are, therefore, necessary to validate these compounds and to discover new candidate BFIs. Untargeted metabolomic strategies may allow the identification of novel biomarkers, which, when taken separately or in combination, could be used to assess the intake of dairy and egg products.

Lipid profile changes in erythrocyte membranes of women with diagnosed GDM

Gestational diabetes mellitus (GDM) is a glucose intolerance that begins or is first recognized during pregnancy. It is currently a growing health problem worldwide affecting from 1% to 14% of all pregnant women depending on racial and ethnic group as well as the diagnostic and screening criteria. Our preliminary study aimed at investigating the erythrocyte membrane fatty acid profiles of pregnant women, in particular with diagnosed with gestational diabetes mellitus (GDM), and with normal glucose tolerant (NGT) pregnant women as a control group. The study group comprised 43 pregnant women, 32 of whom were diagnosed with GDM according to the WHO criteria, and 11 with normal glucose tolerance. The erythrocyte membrane phospholipids were obtained according to the Folch extraction procedure. Fatty acids (FA) were analyzed by gas chromatography (GC) as the corresponding fatty acid methyl esters (FAME). A cluster of 14 fatty acids identified contained >98% of the recognized peaks in the GC analysis. The analysis of fatty acids from erythrocytes revealed important differences between GDM and NGT women in the third trimester, and the results were correlated with biochemical data. Among the 14 measured FA representing the membrane lipidomic profile, the levels of three saturated FA (myristic, palmitic, stearic acids) tended to decrease in GDM patients, with the percentage content of stearic acid significantly changed. The relative content of monounsaturated fatty acids (MUFA) tended to increase, in particular the oleic acid and vaccenic acid contents were significantly increased in erythrocyte membranes of the GDM group in comparison with the NGT group. The GDM group demonstrated higher sapienic acid levels (+29%) but this change was not statistically significant. This study revealed association between an impaired cis-vaccenic acid concentration in erythrocytes membrane and GDM development. No significant changes of polyunsaturated fatty acids (PUFA) were observed in GDM and NGT erythrocytes. We postulate, basing on the differences between the GDM and NGT lipidomic profiles, that stearic and cis-vaccenic acids can be considered as dual biomarkers of specific SFA-MUFA conversion pathway, involving the coupling of delta-9 desaturase and elongase enzymes. Our results indicate that the SFA-MUFA families may be involved in the pathophysiology of metabolic diseases such as GDM, but the further studies are needed to confirm our hypothesis. In conclusion, the erythrocyte membranes of GDM women undergo remodeling resulting in abnormal fatty acid profiles, which are reflection of the long-term status of organism and can have great impact on both the mother and her offspring.

Association between plasma trans-fatty acid concentrations and diabetes in a nationally representative sample of US adults

BACKGROUND

A diet high in trans-fatty acids (TFA) induces insulin resistance in rodent models and primates. However, previous epidemiological studies on the association between TFAs, based primarily on self-reported intake from the diet, and diabetes in humans have yielded conflicting results. Herein we examined the associations of objectively measured plasma TFA concentrations with diabetes in a large population-based study among US adults.

METHODS

We included 3801 participants aged ≥20 years from the National Health and Nutrition Examination Survey 1999-2000 and 2009-10. Four major TFAs, namely palmitelaidic acid (C16:1 n-7t), elaidic acid (C18:1 n-9t), vaccenic acid (C18:1 n-7t), and linolelaidic acid (C18:2 n-6t, 9t), were measured in fasting plasma using gas chromatography-mass spectrometry. Diabetes was defined by self-reported physician diagnosis, plasma fasting glucose ≥126 mg/dL, or HbA1c ≥6.5%.

RESULTS

After adjustment for other major risk factors, the odds ratios (95% confidence intervals) of diabetes comparing the highest with lowest quintile of plasma TFAs was 2.19 (1.27-3.79) for total TFAs (P_trend  = 0.01), 2.34 (1.48-3.72) for elaidic acid (P_trend  = 0.0004), 1.33 (0.82-2.15) for linolelaidic acid (P_trend  = 0.18), 1.58 (0.97-2.58) for palmitelaidic acid (P_trend  = 0.02), and 1.64 (0.95-2.84) for vaccenic acid (P_trend  = 0.08). In addition, total TFAs, elaidic acid, palmitelaidic acid, and vaccenic acid were significantly associated with fasting glucose, fasting insulin, the insulin resistance index, and HbA1c.

CONCLUSIONS

In a nationally representative population, plasma TFAs, in particular elaidic acid, were positively associated with diabetes and biomarkers of glucose metabolism.

Alterations of polyunsaturated fatty acid metabolism in ovarian tissues of polycystic ovary syndrome rats

The metabolism of polyunsaturated fatty acids (PUFAs) remains poorly characterized in ovarian tissues of patients with polycystic ovary syndrome (PCOS). This study aimed to explore alterations in the levels of PUFAs and their metabolites in serum and ovarian tissues in a PCOS rat model treated with a high‐fat diet and andronate. Levels of PUFAs and their metabolites were measured using gas/liquid chromatography‐mass spectrometry after the establishment of a PCOS rat model. Only 3 kinds of PUFAs [linoleic acid, arachidonic acid (AA) and docosahexaenoic acid] were detected in both the circulation and ovarian tissues of the rats, and their concentrations were lower in ovarian tissues than in serum. Moreover, significant differences in the ovarian levels of AA were observed between control, high‐fat diet‐fed and PCOS rats. The levels of prostaglandins, AA metabolites via the cyclooxygenase (COX) pathway, in ovarian tissues of the PCOS group were significantly increased compared to those in the controls. Further studies on the mechanism underlying this phenomenon showed a correlation between decreased expression of phosphorylated cytosolic phospholipase A2 (p‐cPLA2) and increased mRNA and protein expression of COX2, potentially leading to a deeper understanding of altered AA and prostaglandin levels in ovarian tissues of PCOS rats.

Plasma trans-fatty acid concentrations continue to be associated with metabolic syndrome among US adults after reductions in trans-fatty acid intake

No study examined and compared the association between intake of trans-fatty acids (TFAs) and risk of metabolic syndrome before and after significant reduction of TFA intakes in the US population. We hypothesized that the relationship might remain significant after substantial reduction of TFA intakes in the population. We used data on 1442 and 2233 adults aged ≥20 years from the National Health and Nutrition Examination Survey 1999-2000 and 2009-2010, respectively. Multivariable logistic regression analysis was used to assess the association between plasma TFA concentrations and metabolic syndrome, including each of its 5 components. The median plasma TFA concentrations were reduced from 79.8 μmol/L in 1999-2000 to 36.9 μmol/L in 2009-2010. The fully adjusted prevalence ratios comparing the highest vs the lowest quintile of plasma TFA concentrations in 1999-2000 were 3.43 (95% confidence interval, 2.39-4.92) for metabolic syndrome, 1.72 (1.38-2.14) for large waistline, 8.25 (6.34-10.74) for high triglycerides, 1.96 (1.46-2.62) for low high-density lipoprotein cholesterol, 1.14 (0.85-1.55) for high blood pressure, and 1.48 (1.19-1.85) for high fasting glucose, respectively. The corresponding prevalence ratios in 2009-2010 were 2.93 (2.41-3.54), 1.62 (1.39-1.89), 14.93 (9.28-24.02), 3.09 (2.18-4.37), 1.27 (1.11-1.46), and 1.24 (1.06-1.46), respectively. The pattern of association between TFAs and metabolic syndrome and its components did not differ by cycles. The observed associations were consistent across the subgroups examined. Despite a 54% decline in plasma TFA concentrations from 1999-2000 to 2009-2010, it was positively associated with risk of metabolic syndrome and its individual components except for blood pressure in 1999-2000. Our findings support Food and Drug Administration initiatives to remove TFAs from the industrially-produced foods.

Discovery of Novel Lipid Profiles in PCOS: Do Insulin and Androgen Oppositely Regulate Bioactive Lipid Production?

CONTEXT

Polycystic ovary syndrome (PCOS) is a complex syndrome showing clinical features of an endocrine/metabolic disorder, including hyperinsulinemia and hyperandrogenism. Polyunsaturated fatty acids (PUFAs) and their derivatives, both tightly linked to PCOS and obesity, play important roles in inflammation and reproduction.

OBJECTIVE

This study aimed to investigate serum lipid profiles in newly diagnosed patients with PCOS using lipidomics and correlate these features with the hyperinsulinemia and hyperandrogenism associated with PCOS and obesity.

DESIGN AND SETTING

Thirty-two newly diagnosed women with PCOS and 34 controls were divided into obese and lean subgroups. A PCOS rat model was used to validate results of the human studies.

MAIN OUTCOME MEASURES

Serum lipid profiles, including phospholipids, free fatty acids (FFAs), and bioactive lipids, were analyzed using gas chromatography-mass spectrometry (MS) and liquid chromatography-MS.

RESULTS

Elevation in phosphatidylcholine and a concomitant decrease in lysophospholipid were found in obese patients with PCOS vs lean controls. Obese patients with PCOS had decreased PUFA levels and increased levels of long-chain saturated fatty acids vs lean controls. Serum bioactive lipids downstream of arachidonic acid were increased in obese controls, but reduced in both obese and lean patients with PCOS vs their respective controls.

CONCLUSIONS

Patients with PCOS showed abnormal levels of phosphatidylcholine, FFAs, and PUFA metabolites. Circulating insulin and androgens may have opposing effects on lipid profiles in patients with PCOS, particularly on the bioactive lipid metabolites derived from PUFAs. These clinical observations warrant further studies of the molecular mechanisms and clinical implications of PCOS and obesity.

Trans-11 vaccenic acid improves insulin secretion in models of type 2 diabetes in vivo and in vitro

SCOPE

Trans-11 vaccenic acid (VA) is a fatty acid produced by ruminants entering the human food supply through meat and dairy products, which appears not to have the health risks associated with industrially produced trans-fatty acids. In this study, we investigated the effect of VA on insulin secretion in vivo in rats and in vitro in human and rat islets after diabetogenic insult.

METHODS AND RESULTS

Hyperglycemic clamp showed that VA dietary supplementation for 8 weeks significantly increased glucose turnover in rats with type 2 diabetes (T2D), accompanied by an elevated plasma C-peptide concentration, indicating improved insulin secretion. The β-cell area and proliferation rate were higher in T2D+VA than T2D group. Isolated islets from T2D+VA rats had higher glucose-stimulated insulin secretion (GSIS) than T2D group. In vitro, VA treatment for 24 and 48 h significantly enhanced GSIS in rat and human islets after diabetogenic challenges. The mRNA expression of G-protein-coupled receptor 40 (GPR40) and regenerating islet-derived 1α (REG-1α) were consistently increased by VA in both rat and human islets.

CONCLUSION

These results indicate that VA may improve insulin secretion and growth of islets in T2D, at least partly by altering GPR40 and REG-1α mRNA expression.

Metabolically healthy and unhealthy obese--the 2013 Stock Conference report

Obesity is closely associated with cardiovascular diseases and type 2 diabetes, but some obese individuals, despite having excessive body fat, exhibit metabolic health that is comparable with that of lean individuals. The 'healthy obese' phenotype was described in the 1980s, but major advancements in its characterization were only made in the past five years. During this time, several new mechanisms that may be involved in health preservation in obesity were proposed through the use of transgenic animal models, use of sophisticated imaging techniques and in vivo measurements of insulin sensitivity. However, the main obstacle in advancing our understanding of the metabolically healthy obese phenotype and its related long-term health risks is the lack of a standardized definition. Here, we summarize the proceedings of the 13th Stock Conference of the International Association of the Study of Obesity. We describe the current research and highlight the unanswered questions and gaps in the field. Better understanding of metabolic health in obesity will assist in therapeutic decision-making and help identify therapeutic targets to improve metabolic health in obesity.

Mass spectrometry-based metabolomic profiling identifies alterations in salivary redox status and fatty acid metabolism in response to inflammation and oxidative stress in periodontal disease

Periodontal diseases represent the most common chronic inflammatory diseases in humans and a major cause of tooth loss. Combining mass spectrometry-based ionomics and targeted lipidomics on fatty acid metabolites, we identified significant alterations in redox status and fatty acid metabolism in saliva in response to chronic inflammation and oxidative stress in periodontal disease in a cohort of nonsmoker subjects with chronic periodontitis. For the first time, ionomic profiling of around 30 ions in saliva revealed significantly decreased levels of redox-active metal ions including Mn, Cu, and Zn in the periodontal group, which is consistent with decreased levels of superoxide dismutases in saliva and serum. A targeted lipidomic approach was employed to monitor the major metabolites of arachidonic acid and linoleic acid in saliva. We observed increased levels of cyclooxygenase products including PGE2, PGD2, and PGF2α and TXB2, but decreased level of PGI2 in the periodontal group. A unique pattern of the lipoxygenase products of arachidonic acid and linoleic acid was observed with increased level of 5-HETE but decreased levels of 13-HODE and 9-HODE. Levels of salivary F2-isoprostanes, free radical lipid peroxidation products, and a gold standard for oxidative stress in vivo were also significantly elevated. Taking these data together, our study using multiple powerful omics techniques demonstrates that local redox alteration contributes significantly to periodontitis through the modulation of fatty acid metabolism in response to inflammation and oxidative stress. This study highlights the importance of redox status in periodontitis and provides a rationale for preventing periodontal disease by dietary interventions aiming to restore redox balance.

Dairy consumption, type 2 diabetes, and changes in cardiometabolic traits: a prospective cohort study of middle-aged and older Chinese in Beijing and Shanghai

OBJECTIVE To prospectively investigate associations of dairy consumption with risk of type 2 diabetes and changes of cardiometabolic traits. RESEARCH DESIGN AND METHODS In 2005, 2,091 middle-aged and older Chinese men and women were recruited and followed for 6 years. Baseline dairy consumption was assessed by a 74-item food frequency questionnaire. Erythrocyte fatty acids were analyzed by gas chromatography coupled with flame ion detector. Cardiometabolic traits were measured at both baseline and follow-up visits. RESULTS Only 1,202 (57.5%) participants reported any dairy consumption, with a median intake of 0.89 (interquartile range 0.19-1.03) serving/day. Compared with nonconsumers, the relative risks (RRs) of type 2 diabetes among those having 0.5-1 serving/day and >1 serving/day were 0.70 (95% CI 0.55-0.88) and 0.65 (0.49-0.85), respectively, after multivariate adjustment (Ptrend < 0.001), which were attenuated by further adjusting for changes in glucose during follow-up (Ptrend = 0.07). Total dairy consumption was associated with favorable changes in glucose, waist circumference, BMI, diastolic blood pressure (all Ptrend < 0.05), and systolic blood pressure (Ptrend = 0.05) after multivariate adjustment, including baseline values of dependent variables. Erythrocyte trans-18:1 isomers were significantly correlated with total dairy consumption (rs = 0.37, Ptrend < 0.001), and these dairy food biomarkers were associated with a lower risk of type 2 diabetes. The RR of type 2 diabetes comparing extreme quartiles of trans-18:1 isomers was 0.82 (0.65-1.04, Ptrend = 0.02), which was attenuated after adjustment for dairy consumption (Ptrend = 0.15). CONCLUSIONS Dairy consumption was associated with a significantly lower risk of type 2 diabetes and favorable changes of cardiometabolic traits in Chinese.