Plasma concentrations of trans fatty acids in persons with type 2 diabetes between September 2002 and April 2004

Body Fat Depletion: the Yin Paradigm for Treating Type 2 Diabetes

PURPOSE OF REVIEW

To highlight that body fat depletion (the Yin paradigm) with glucose-lowering treatments (the Yang paradigm) are associated with metabolic benefits for patients with type 2 diabetes mellitus (T2DM).

RECENT FINDINGS

The sodium-glucose cotransporter-2 inhibitor-mediated sodium/glucose deprivation can directly improve glycemic control and kidney outcome in patients with T2DM. The glucose deprivation might also promote systemic fatty acid β-oxidation to deplete ectopic/visceral fat and thereby contribute to the prevention of cardiovascular diseases. As with metabolic surgery, bioengineered incretin-based medications with potent anorexigenic and insulinotropic efficacy can significantly reduce blood glucose as well as body weight (especially in the ectopic/visceral fat depots). The latter effects could be a key contributor to their cardiovascular-renal protective effects. In addition to a healthy diet, the newer glucose-lowering medications, with body fat reduction effects, should be prioritized when treating patients with T2DM, especially for those with established cardiovascular/renal risks or diseases.

Epigenetic modifications in pancreas development, diabetes, and therapeutics

A recent International Diabetes Federation report suggests that more than 463 million people between 20 and 79 years have diabetes. Of the 20 million women affected by hyperglycemia during pregnancy, 84% have gestational diabetes. In addition, more than 1.1 million children or adolescents are affected by type 1 diabetes. Factors contributing to the increase in diabetes prevalence are complex and include contributions from genetic, environmental, and epigenetic factors. However, molecular regulatory mechanisms influencing the progression of an individual towards increased susceptibility to metabolic diseases such as diabetes are not fully understood. Recent studies suggest that the pathogenesis of diabetes involves epigenetic changes, resulting in a persistently dysregulated metabolic phenotype. This review summarizes the role of epigenetic mechanisms, mainly DNA methylation and histone modifications, in the development of the pancreas, their contribution to the development of diabetes, and the potential employment of epigenetic modulators in diabetes treatment.

A 24-year prospective study of dietary α-linolenic acid and lethal prostate cancer

Several meta-analyses have attempted to determine the relationships between intake of α-linolenic acid (ALA) and prostate cancer, but results were inconclusive. 47,885 men aged 40-75 years without prior cancer in the Health Professionals Follow-Up Study were prospectively followed from 1986 to 2010. Intake of ALA was determined from validated food frequency questionnaires every 4 years. We used multivariate Cox proportional hazards models to estimate hazard ratios (HR) with 95% confidence intervals (CIs) for lethal prostate cancer (distant metastasis or prostate cancer death). 386 lethal prostate cancers were diagnosed in the pre-PSA era (before February, 1994) and 403 cancers in the PSA era. Intake of ALA was associated with increased risk of lethal prostate cancer in the pre-PSA era (comparing top to bottom quintile of intake, multivariate-adjusted HR = 1.78; 95% CI = 1.22-2.06; p_trend  = 0.003), but not in the PSA era (HR = 0.81; 95% CI = 0.56-1.17; p_trend  = 0.53), and the difference in associations was statistically significant (p for interaction = 0.02). Mayonnaise, a primary food source of ALA intake in our cohort, was likewise only significantly associated with lethal prostate cancer in the pre-PSA era. Among many other fatty acids that are correlated with ALA due to shared food sources, none was associated with lethal prostate cancer in the pre-PSA era. In conclusion, higher intake of ALA was associated with an increased risk of lethal prostate cancer in the pre-PSA era, but not in the PSA era. Potential reasons for the differential associations warrant further investigation.

Analyzing metabolomics data for association with genotypes using two-component Gaussian mixture distributions

Standard approaches to evaluate the impact of single nucleotide polymorphisms (SNP) on quantitative phenotypes use linear models. However, these normal-based approaches may not optimally model phenotypes which are better represented by Gaussian mixture distributions (e.g., some metabolomics data). We develop a likelihood ratio test on the mixing proportions of two-component Gaussian mixture distributions and consider more restrictive models to increase power in light of a priori biological knowledge. Data were simulated to validate the improved power of the likelihood ratio test and the restricted likelihood ratio test over a linear model and a log transformed linear model. Then, using real data from the Framingham Heart Study, we analyzed 20,315 SNPs on chromosome 11, demonstrating that the proposed likelihood ratio test identifies SNPs well known to participate in the desaturation of certain fatty acids. Our study both validates the approach of increasing power by using the likelihood ratio test that leverages Gaussian mixture models, and creates a model with improved sensitivity and interpretability.

Plasma trans-fatty acids levels and mortality: a cohort study based on 1999-2000 National Health and Nutrition Examination Survey (NHANES)

Background

Trans-fatty acids (TFAs) occur in small amounts in nature but became widely produced by the food industry. The hazardous effects of different TFA subtypes to human health are controversial. We aimed to evaluate the association of plasma TFAs levels (elaidic acid, vaccenic acid, palmitelaidic acid, and linoelaidic acid) with mortality.

Methods

Utilizing 1999–2000 Nutrition Examination Survey (NHANES) and linked mortality data, we performed a cohort study with 1456 participants and used Cox proportional hazards models and penalized smoothing spline plots to elucidate the relationships between TFAs and all-cause, cardiovascular diseases (CVD) and cancer mortality.

Results

During 16,034 person-years of follow-up, a total of 221 deaths occurred. In the multivariate model, including mutual adjustment for the 4 TFA subtypes, elaidic acid associated with higher all-cause mortality (hazard ratio (HR) = 2.00, 95% confidence interval (CI) = 1.18 to 3.40, fourth quartiles versus second quartiles) and CVD mortality (HR = 1.64, 95% CI = 1.07 to 2.50, per 10 units increase). Higher palmitelaidic acid levels were associated with increased cancer mortality (HR = 2.91, 95% CI = 1.09 to 7.81, fourth quartiles versus second quartiles). A J-shaped pattern was observed in the regression curve of elaidic acid and all-cause mortality, as well palmitelaidic acid and cancer mortality.

Conclusions

Plasma elaidic acid levels are associated with higher risk of all-cause and CVD mortality, and palmitelaidic acid levels are associated with higher cancer mortality in later life. Further studies are needed to investigate current inconsistent results in this field and the possible underlying mechanisms.

Electronic supplementary material

The online version of this article (10.1186/s12944-017-0567-6) contains supplementary material, which is available to authorized users.

Margarines and Fast-Food French Fries: Low Content of trans Fatty Acids

The lipid fraction of margarines and fast food French fries, two types of foods traditionally high in trans fatty acids (TFA), is assessed. TFA data reported worldwide during the last 20 years have been gathered and show that some countries still report high TFA amounts in these products. The content of TFA was analysed in margarines (two store and four premium brands) and French-fries from fast-food restaurants (five chains). All samples were collected in Pamplona (Navarra, Spain). The margarines showed mean values of 0.68% and 0.43% (g TFA/100 g fat) for the store and premium brands, respectively. The French fries’ values ranged from 0.49% to 0.89%. All samples were lower than the 2% set by some European countries as the maximum legal content of TFA in fats, and contained less than 0.5 g/serving, so they could also be considered “trans free products”. This work confirmed that the presence of TFA is not significant in the two analysed products and contributes updated food composition tables, key tools for epidemiological and nutrition studies.

Dietary intake of α-linolenic acid and risk of age-related macular degeneration

Background: The relation between α-linolenic acid (ALA), a plant-derived omega-3 (n-3) fatty acid, and age-related macular degeneration (AMD) is unclear. European researchers reported that ≤40% of ALA can be present as trans forms.Objective: We aimed to evaluate the associations between intake of ALA and intermediate and advanced AMD.Design: Seventy-five thousand eight hundred eighty-nine women from the Nurses' Health Study and 38,961 men from Health Professionals Follow-Up Study were followed up from 1984 to 2012 and from 1986 to 2010, respectively. We assessed dietary intake by a validated food-frequency questionnaire at baseline and every 4 y thereafter. One thousand five hundred eighty-nine incident intermediate and 1356 advanced AMD cases (primarily neovascular AMD) were confirmed by medical record review.Results: The multivariable-adjusted HR for intermediate AMD comparing ALA intake at the top quintile to the bottom quintile was 1.28 (95% CI: 1.05, 1.56; P-trend = 0.01) in the analyses combining 2 cohorts. The HR in each cohort was in the positive direction but reached statistical significance only in the women. However, the positive association was apparent only in the pre-2002 era in each cohort and not afterward (P-time interaction = 0.003). ALA intake was not associated with advanced AMD in either time period. Using gas-liquid chromatography, we identified both cis ALA (mean ± SD: 0.13% ± 0.04%) and trans ALA isomers (0.05% ± 0.01%) in 395 erythrocyte samples collected in 1989-1990. In stepwise regression models, mayonnaise was the leading predictor of erythrocyte concentrations of cis ALA and one isomer of trans ALA. We also found trans ALA in mayonnaise samples.Conclusions: A high intake of ALA was associated with an increased risk of intermediate AMD before 2002 but not afterward. The period before 2002 coincides with the same time period when trans ALA was found in food and participants' blood; this finding deserves further study.

Evaluation of the Impact of Ruminant Trans Fatty Acids on Human Health: Important Aspects to Consider

The definition and evaluation of trans fatty acids (TFA) with regard to foodstuffs and health hazard are not consistent. Based on the current situation, the term should be restricted only to TFA with isolated double bonds in trans-configuration. Conjugated linoleic acids (CLA) should be separately assessed. Ideally, the origin of the consumed fat should be declared, i.e., ruminant TFA (R-TFA) and industrial TFA (non-ruminant; I-TFA). In ruminant fat, more than 50% of R-TFA consists of vaccenic acid (C18:1 t11). In addition, natural CLA, i.e., c9,t11 CLA is also present. Both are elevated in products from organic farming. In contrast to elaidic acid (t9) and t10, which occur mainly in partially hydrogenated industrial fat, t11 is partially metabolized into c9,t11 CLA via Δ9-desaturation. This is the major metabolic criterion used to differentiate between t11 and other trans C18:1. t11 indicates health beneficial effects in several studies. Moreover, CLA in milk fat is associated with the prevention of allergy and asthma. An analysis of the few studies relating to R-TFA alone makes clear that no convincing adverse physiological effect can be attributed to R-TFA. Only extremely high R-TFA intakes cause negative change in blood lipids. In conclusion, in most European countries, the intake of R-TFA is assessed as being low to moderate. Restriction of R-TFA would unjustifiably represent a disadvantage for organic farming of milk.

Changes in mean intake of fatty acids and intake of saturated and trans fats from potatoes: NHANES 2005-2006, 2007-2008, and 2009-2010

Studies have shown that higher than usual intakes of trans fatty acids (TFAs) have adverse effects on blood lipids. Because of this, in 2006 the US FDA mandated labeling of TFAs on food packages. The food and restaurant industries, including the potato industry, reformulated their foods to reduce or eliminate partially hydrogenated vegetable oils and TFAs. Before mandatory labeling, grain-based desserts, yeast breads, and French-fried potatoes (FFPs) were the top sources of TFAs in the food supply; by 2007, potato food manufacturers and quick-service restaurants had reduced or eliminated TFAs without increasing saturated fatty acids (SFAs). FFPs are no longer a source of TFAs in the food supply. This study examined energy and fatty acid intake among children aged 6-11 y, adolescents aged 12-18 y, and adults aged ≥19 y across 3 time periods by using data from the NHANES 2005-2006, 2007-2008, and 2009-2010. On average, intakes of total energy, total fat, SFAs, and monounsaturated fatty acids (MUFAs) decreased significantly between 2005-2006 and 2009-2010 among children and adolescents; however, the intake of polyunsaturated fatty acids (PUFAs) did not change. Among adults, intakes of total fat, SFAs, and MUFAs decreased; however, total energy and PUFA intake did not change. On the day of the 2009-2010 survey, ∼13% of children and 10% of adolescents reported consuming fried FFPs, whereas <7% of adults reported consumption of fried FFPs. Intakes of SFAs and TFAs from fried FFPs decreased significantly between 2005-2006 and 2009-2010 among children, adolescents, and adults. This study confirms that intake of TFAs from FFPs is trivial.

Trends in fatty acid intake of adults in the Minneapolis-St Paul, MN Metropolitan Area, 1980-1982 through 2007-2009

Background

Intake of dietary fatty acids has been linked to cardiovascular disease risk. However, data available to evaluate trends in fatty acid intake in the US population are limited, particularly with regard to trans fatty acids, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA).

Methods and Results

The present analysis examined trends in fatty acid intake from 1980–1982 through 2007–2009 and compared levels of intake to those recommended in the 2010 Dietary Guidelines for Americans and by the American Heart Association. Twenty‐four‐hour dietary recalls were collected from 12 526 participants enrolled in the Minnesota Heart Survey, a series of 6 independent cross‐sectional surveys designed to monitor cardiovascular risk factors in noninstitutionalized adults residing in the Minneapolis‐St Paul, MN metropolitan area. Mean intake estimates were generated for each survey, and a generalized linear mixed model was used to test the null hypothesis of no difference in the age‐adjusted, sex‐specific means across survey years. Downward trends were observed for total, saturated, and trans fat as a percent of total energy in both men and women. However, mean intakes were still above recommended levels for both trans and saturated fatty acids. Mean intakes of DHA and EPA were also below recommended levels.

Conclusions

Despite promising trends, mean intakes of trans and saturated fatty acids do not meet current recommendations. Additional public health strategies are needed to promote recommended intakes of dietary fats.

trans Fatty acids in the Canadian food supply: an updated analysis

BACKGROUND

Dietary trans fatty acids (TFAs) increase the risk of heart disease. In 2007, Canada set voluntary TFA limits for industrial TFAs added to food and encouraged substitution of TFAs with unsaturated fats during reformulation. No longitudinal follow-up assessment of TFA amounts in foods has occurred in Canada since termination of a government-led Trans Fat Monitoring Program (TFMP).

OBJECTIVE

The objective was to conduct an updated assessment and longitudinally evaluate TFA amounts in the food supply and to determine whether saturated fats have replaced TFAs in reformulation.

DESIGN

This was a cross-sectional study that used 3 databases: TFMP (Health Canada, 2005-2009; n = 921), the University of Toronto Food Label Information Program (2010-2011; n = 5544), and the Restaurant Database (2010; n = 4272). Outcomes were TFAs as a percentage of fat, proportion of foods meeting TFA limits, and saturated fat amounts in foods with high or low TFAs.

RESULTS

The proportion of foods meeting TFA limits improved from 75% in 2005-2009 to 97% in 2010-2011, particularly in the following packaged foods: croissants (25% to 100%), pies (36% to 98%), cakes (43% to 90%), and garlic spreads (33% to 100%). Most restaurant categories assessed by the TFMP had 100% of foods meeting TFA limits. Some categories had a large proportion that exceeded TFA limits: dairy-free cheeses (100%), frosting (72.0%), lard and shortening (66.7%), coffee whiteners (66.7%), and restaurant-prepared biscuits and scones (47.4%). Saturated fat amounts were significantly higher (P < 0.05) among some foods with the lowest TFAs, such as cookies, brownies and squares, cakes with pudding/mousse, dessert toppings, and lard and shortening.

CONCLUSIONS

There has been an impressive improvement in TFA amounts in the Canadian food supply since the termination of the TFMP. However, action by the food industry is required to reduce TFAs in foods that exceed the recommended TFA limits and to minimize the use of saturated fats in replacing TFAs during reformulation.