Kcnn2 blockade reverses learning deficits in a mouse model of fetal alcohol spectrum disorders

Learning disabilities are hallmarks of congenital conditions caused by prenatal exposure to harmful agents. Those include Fetal Alcohol Spectrum Disorders (FASD) with a wide range of cognitive deficiencies including impaired motor skill development. While these effects have been well characterized, the molecular effects that bring about these behavioral consequences remain to be determined. We have previously found that the acute molecular responses to alcohol in the embryonic brain are stochastic, varying among neural progenitor cells. However, the pathophysiological consequences stemming from these heterogeneous responses remain unknown. Here we show that acute responses to alcohol in progenitor cells alter gene expression in their descendant neurons. Among the altered genes, an increase of the calcium-activated potassium channel Kcnn2 in the motor cortex correlates with motor learning deficits in the mouse model of FASD. Pharmacologic blockade of Kcnn2 improves these learning deficits, suggesting Kcnn2 blockers as a novel intervention for learning disabilities in FASD.

A Combination of Metabolites Predicts Adherence to the Mediterranean Diet Pattern and Its Associations with Insulin Sensitivity and Lipid Homeostasis in the General Population: The Fenland Study, United Kingdom

BACKGROUND

Cardiometabolic benefits of the Mediterranean diet have been recognized, but underlying mechanisms are not fully understood.

OBJECTIVES

We aimed to investigate how the Mediterranean diet could influence circulating metabolites and how the metabolites could mediate the associations of the diet with cardiometabolic risk factors.

METHODS

Among 10,806 participants (58.9% women, mean age = 48.4 y) in the Fenland Study (2004-2015) in the United Kingdom, we assessed dietary consumption with FFQs and conducted a targeted metabolomics assay for 175 plasma metabolites (acylcarnitines, amines, sphingolipids, and phospholipids). We examined cross-sectional associations of the Mediterranean diet score (MDS) and its major components with each metabolite, modeling multivariable-adjusted linear regression. We used the regression estimates to summarize metabolites associated with the MDS into a metabolite score as a marker of the diet. Subsequently, we assessed how much metabolite subclasses and the metabolite score would mediate the associations of the MDS with circulating lipids, homeostasis model assessment of insulin resistance (HOMA-IR), and other metabolic factors by comparing regression estimates upon adjustment for the metabolites.

RESULTS

Sixty-six metabolites were significantly associated with the MDS (P ≤ 0.003, corrected for false discovery rate) (Spearman correlations, r: -0.28 to +0.28). The metabolite score was moderately correlated with the MDS (r = 0.43). Of MDS components, consumption of nuts, cereals, and meats contributed to variations in acylcarnitines; fruits, to amino acids and amines; and fish, to phospholipids. The metabolite score was estimated to explain 37.2% of the inverse association of the MDS with HOMA-IR (P for mediation < 0.05). The associations of the MDS with cardiometabolic factors were estimated to be mediated by acylcarnitines, sphingolipids, and phospholipids.

CONCLUSIONS

Multiple metabolites relate to the Mediterranean diet in a healthy general British population and highlight the potential to identify a set of biomarkers for an overall diet. The associations may involve pathways of phospholipid metabolism, carnitine metabolism, and development of insulin resistance and dyslipidemia.

Estimated Substitution of Tea or Coffee for Sugar-Sweetened Beverages Was Associated with Lower Type 2 Diabetes Incidence in Case-Cohort Analysis across 8 European Countries in the EPIC-InterAct Study

INTRODUCTION

Beverage consumption is a modifiable risk factor for type 2 diabetes (T2D), but there is insufficient evidence to inform the suitability of substituting 1 type of beverage for another.

OBJECTIVE

The aim of this study was to estimate the risk of T2D when consumption of sugar-sweetened beverages (SSBs) was replaced with consumption of fruit juice, milk, coffee, or tea.

METHODS

In the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct case-cohort study of 8 European countries (n = 27,662, with 12,333 cases of incident T2D, 1992-2007), beverage consumption was estimated at baseline by dietary questionnaires. Using Prentice-weighted Cox regression adjusting for other beverages and potential confounders, we estimated associations of substituting 1 type of beverage for another on incident T2D.

RESULTS

Mean ± SD of estimated consumption of SSB was 55 ± 105 g/d. Means ± SDs for the other beverages were as follows: fruit juice, 59 ± 101 g/d; milk, 209 ± 203 g/d; coffee, 381 ± 372 g/d; and tea, 152 ± 282 g/d. Substituting coffee for SSBs by 250 g/d was associated with a 21% lower incidence of T2D (95% CI: 12%, 29%). The rate difference was -12.0 (95% CI: -20.0, -5.0) per 10,000 person-years among adults consuming SSBs ≥250 g/d (absolute rate = 48.3/10,000). Substituting tea for SSBs was estimated to lower T2D incidence by 22% (95% CI: 15%, 28%) or -11.0 (95% CI: -20.0, -2.6) per 10,000 person-years, whereas substituting fruit juice or milk was estimated not to alter T2D risk significantly.

CONCLUSIONS

These findings indicate a potential benefit of substituting coffee or tea for SSBs for the primary prevention of T2D and may help formulate public health recommendations on beverage consumption in different populations.

Validity and reliability of an online self-report 24-h dietary recall method (Intake24): a doubly labelled water study and repeated-measures analysis

Online self-reported 24-h dietary recall systems promise increased feasibility of dietary assessment. Comparison against interviewer-led recalls established their convergent validity; however, reliability and criterion-validity information is lacking. The validity of energy intakes (EI) reported using Intake24, an online 24-h recall system, was assessed against concurrent measurement of total energy expenditure (TEE) using doubly labelled water in ninety-eight UK adults (40-65 years). Accuracy and precision of EI were assessed using correlation and Bland-Altman analysis. Test-retest reliability of energy and nutrient intakes was assessed using data from three further UK studies where participants (11-88 years) completed Intake24 at least four times; reliability was assessed using intra-class correlations (ICC). Compared with TEE, participants under-reported EI by 25 % (95 % limits of agreement -73 % to +68 %) in the first recall, 22 % (-61 % to +41 %) for average of first two, and 25 % (-60 % to +28 %) for first three recalls. Correlations between EI and TEE were 0·31 (first), 0·47 (first two) and 0·39 (first three recalls), respectively. ICC for a single recall was 0·35 for EI and ranged from 0·31 for Fe to 0·43 for non-milk extrinsic sugars (NMES). Considering pairs of recalls (first two v. third and fourth recalls), ICC was 0·52 for EI and ranged from 0·37 for fat to 0·63 for NMES. EI reported with Intake24 was moderately correlated with objectively measured TEE and underestimated on average to the same extent as seen with interviewer-led 24-h recalls and estimated weight food diaries. Online 24-h recall systems may offer low-cost, low-burden alternatives for collecting dietary information.

Association of alcohol consumption with prevalence of fatty liver after adjustment for dietary patterns: Cross-sectional analysis of Japanese middle-aged adults

Background & aims

Moderate alcohol intake is associated with reduced prevalence or incidence of fatty liver. However, whether or not the association is independent of dietary patterns remains unclear. We aimed to evaluate the cross-sectional association of alcohol intake with fatty liver after accounting for dietary patterns and obesity.

Methods

We assessed 4579 adults aged 30–79 years who participated in routine clinical examinations in St. Luke's International Hospital, Japan (January to March, 2015). We assessed their habitual diet using diet-history questionnaire, estimated alcohol intake, and derived dietary pattern variables using factor analysis. Fatty liver was ascertained using ultrasonography. Linear and U-shaped associations of alcohol intake with fatty liver were evaluated using Poisson regression, and a post hoc analysis was conducted after detecting potential outliers for alcohol intake and excluding them using sex-specific statistics (median plus 2 × interquartile range).

Results

Fatty liver was ascertained in 1120 participants (24.5%). Whereas no significant association of alcohol intake with fatty liver was observed when potential outliers of alcohol intake were included (p = 0.25), a significant U-shaped association was observed after excluding the outliers with and without adjustment for dietary patterns (p = 0.003 and 0.02, respectively). The lowest prevalence was estimated when alcohol consumption was approximately 7% of energy, with a prevalence ratio of 0.72 (95% confidence interval = 0.59–0.86) compared to non-drinkers. The association became imprecise and attenuated toward the null after further adjustment for body mass index (p = 0.06).

Conclusions

Alcohol intake showed a U-shaped association with fatty liver prevalence. This association was independent of underlying dietary patterns, while it was sensitive to excessive alcohol intake and obesity status, providing clinical implications for the prevention of fatty liver.

Quality of dietary fat and genetic risk of type 2 diabetes: individual participant data meta-analysis

OBJECTIVE

To investigate whether the genetic burden of type 2 diabetes modifies the association between the quality of dietary fat and the incidence of type 2 diabetes.

DESIGN

Individual participant data meta-analysis.

DATA SOURCES

Eligible prospective cohort studies were systematically sourced from studies published between January 1970 and February 2017 through electronic searches in major medical databases (Medline, Embase, and Scopus) and discussion with investigators.

REVIEW METHODS

Data from cohort studies or multicohort consortia with available genome-wide genetic data and information about the quality of dietary fat and the incidence of type 2 diabetes in participants of European descent was sought. Prospective cohorts that had accrued five or more years of follow-up were included. The type 2 diabetes genetic risk profile was characterized by a 68-variant polygenic risk score weighted by published effect sizes. Diet was recorded by using validated cohort-specific dietary assessment tools. Outcome measures were summary adjusted hazard ratios of incident type 2 diabetes for polygenic risk score, isocaloric replacement of carbohydrate (refined starch and sugars) with types of fat, and the interaction of types of fat with polygenic risk score.

RESULTS

Of 102 305 participants from 15 prospective cohort studies, 20 015 type 2 diabetes cases were documented after a median follow-up of 12 years (interquartile range 9.4-14.2). The hazard ratio of type 2 diabetes per increment of 10 risk alleles in the polygenic risk score was 1.64 (95% confidence interval 1.54 to 1.75, I²=7.1%, τ²=0.003). The increase of polyunsaturated fat and total omega 6 polyunsaturated fat intake in place of carbohydrate was associated with a lower risk of type 2 diabetes, with hazard ratios of 0.90 (0.82 to 0.98, I²=18.0%, τ²=0.006; per 5% of energy) and 0.99 (0.97 to 1.00, I²=58.8%, τ²=0.001; per increment of 1 g/d), respectively. Increasing monounsaturated fat in place of carbohydrate was associated with a higher risk of type 2 diabetes (hazard ratio 1.10, 95% confidence interval 1.01 to 1.19, I²=25.9%, τ²=0.006; per 5% of energy). Evidence of small study effects was detected for the overall association of polyunsaturated fat with the risk of type 2 diabetes, but not for the omega 6 polyunsaturated fat and monounsaturated fat associations. Significant interactions between dietary fat and polygenic risk score on the risk of type 2 diabetes (P>0.05 for interaction) were not observed.

CONCLUSIONS

These data indicate that genetic burden and the quality of dietary fat are each associated with the incidence of type 2 diabetes. The findings do not support tailoring recommendations on the quality of dietary fat to individual type 2 diabetes genetic risk profiles for the primary prevention of type 2 diabetes, and suggest that dietary fat is associated with the risk of type 2 diabetes across the spectrum of type 2 diabetes genetic risk.

Changes in plasma phospholipid fatty acid profiles over 13 years and correlates of change: European Prospective Investigation into Cancer and Nutrition-Norfolk Study

BACKGROUND

Little is known about changes in blood fatty acid compositions over time and the correlates of any changes in a general population.

OBJECTIVE

The aim of this study was to estimate changes in 27 individual plasma phospholipid fatty acids and fatty acid groups over time, and to identify potential correlates of these changes.

METHODS

Plasma phospholipid fatty acids were profiled at 3 time-points (1993-1997, 1998-2000, 2004-2011) among 722 participants in the European Prospective Investigation into Cancer and Nutrition-Norfolk Study, UK. Linear regression models were used to estimate both 1) mean changes over time in 27 individual fatty acids and 8 prespecified fatty acid groups and 2) associations of changes in dietary and lifestyle factors with changes in the 8 fatty acid groups, mutually adjusted for dietary/lifestyle factors and other confounders. The prespecified fatty acid groups were odd-chain saturated fatty acids (SFAs), even-chain SFAs, very-long-chain SFAs, marine n-3 polyunsaturated fatty acids (PUFAs), plant n-3 PUFA, n-6 PUFAs, monounsaturated fatty acids (MUFAs), and trans-fatty acids (TFAs).

RESULTS

Adjusted for confounders, fatty acid concentrations decreased for odd-chain SFAs (annual percentage difference in mol percentage: -0.63%), even-chain SFAs (-0.05%), n-6 PUFAs (-0.25%), and TFAs (-7.84%). In contrast, concentrations increased for marine n-3 PUFAs (1.28%) and MUFAs (0.45%), but there were no changes in very-long-chain SFAs or plant n-3 PUFA. Changes in fatty acid levels were associated with consumption of different food groups. For example, a mean 100 g/d increase in fatty fish intake was associated with a 19.3% greater annual increase in marine n-3 PUFAs.

CONCLUSIONS

Even-chain SFAs and TFAs declined and marine n-3 PUFAs increased over time. These changes were partially explained by changes in dietary habits, and could potentially help interpret associations of baseline fatty acid composition with future disease risk.

Traditional Diet Influences Erythrocyte Fatty Acids Differentially Across Genetic Variants of Fatty Acid Metabolism: The Greenlandic Inuit Health in Transition Cohort (FS11-02-19)

Objectives

Traditional foods of the Greenlandic Inuit are mainly fish and marine mammals. Hence, the high fat content and unique dietary fatty acid (FA) profile may affect circulating FA profiles. Moreover, it is shown that the rs80356779 variant of the carnitine palmitoyl-transferase 1A (CPT1A) gene, involved in FA transportation, underwent positive selection in Inuit ancestors. The variant is associated with circulating FA profiles in Inuit, and selection may be a result of diet adaptation. While the variant may modify the dietary effect on FA metabolism, the gene-diet interaction has not been tested. Therefore, we aimed to assess if an interaction exists between the CPT1A variant and intake of traditional diet on erythrocyte membrane levels of very-long-chain n-3 PUFAs and the FAs previously found to be associated with the variant in Greenlandic Inuit.

Methods

We included 3005 individuals (mean age = 45 years) living in Greenland, who were genotyped and had erythrocyte membranes measured for the content of 40 FA. Food intake was estimated from a 68-item semi-quantitative food-frequency questionnaire. Consumption of 25 food items typical of the traditional diet was expressed as percentage of total energy intake. Linear mixed models were fitted, regressing a normalized FA variable on genotype, the Inuit diet variable, and their cross-product term, adjusting for population structure, relatedness, age, and sex. P-values were corrected by genomic control. Subsequent QQ-plots based on genome wide markers showed no indication of confounding.

Results

Sixty % of participants were homozygous for the derived CPT1A allele; 33% were heterozygous. Median % (interquartile range) of energy from traditional diet was 17% (8.8–30.5%). Of the 10 FAs that CPT1A had a main effect on (P < 10−5), significant diet × gene interactions (P < 0.001) were found for 20:1n-9, where the derived allele attenuated the positive association between diet and the FA, and for 20:3n-6, where the derived allele amplified the negative association between diet and the FA. Nominal effects (P < 0.05) were seen for 18:2n-6, 20:0, 24:0, and 22:5n-3.

Conclusions

Our results suggest the association between traditional diet and erythrocyte FA composition is affected by CPT1A genotype. Further analyses are needed to explore which specific foods drive the interaction.

Funding Sources

Lundbeck Foundation.

The State of Diet Quality Globally: A Systematic Assessment of Worldwide Dietary Patterns Using the Global Dietary Database (P10-045-19)

Objectives

Healthy diet patterns are a global priority to reduce undernutrition and chronic disease. Prior work suggests that healthy and unhealthy diet patterns are distributed and changing independently across the world. Our objective was to characterize current healthy and unhealthy diet patterns by age, sex, education, residence and country using the 2015 Global Dietary Database (GDD).

Methods

The GDD 2015 evaluates dietary intake based on 1137 surveys-years of systematically identified national and subnational individual-level diet surveys worldwide from 185 countries (97.5% of the global population). Dietary intake estimates and their uncertainty were generated for 15 dietary factors using a Bayesian hierarchical model including the individual-level data, country-level food availability data, and other covariates. Two types of diet patterns were assessed: one reflecting greater intake of 11 healthy dietary items; and the other, lower intake of 4 unhealthy dietary items. Mean intake of each dietary factor was divided into quintiles. Quintiles were assigned an ordinal score and scores were summed to generate each pattern, scaled from 0–100. Higher scores correspond to healthier diets for each age-sex-country-year-education-residence stratum.

Results

In 2015, the global mean score was 48 [95% UI: 39–58] for the healthy diet pattern (Fig 1) and 51 [32–69] for the unhealthy diet pattern (Fig 2). Healthy vs unhealthy diet pattern scores across the 41,040 global strata annually were not strongly interrelated (r < -0.4). Western (54 [45–63]) and Latin American (63 [53–72]) regions had highest scores for the healthy diet pattern but lowest for the unhealthy diet pattern (37 [19, 54]; 27 [13, 42], respectively). Asia (57 [40–76]) and Sub-Saharan Africa (57 [34–76]) had the highest unhealthy diet pattern scores but lowest healthy diet pattern scores (42 [33, 52]; 41 [30, 53], respectively). Healthy diet pattern scores were generally higher in urban areas and among more educated strata, while unhealthy diet pattern scores were higher in rural areas and in less educated strata.

Conclusions

These novel data provide quantitative estimates of the specific heterogeneity in diet patterns across the world, providing the best estimates to date to inform policies and priorities for reducing the health and economic burdens of poor diet quality.

Funding Sources

Gates Foundation.

Supporting Tables, Images and/or Graphs

Preventable Cancer Burden Associated With Poor Diet in the United States

BACKGROUND

Diet is an important risk factor for cancer that is amenable to intervention. Estimating the cancer burden associated with diet informs evidence-based priorities for nutrition policies to reduce cancer burden in the United States.

METHODS

Using a comparative risk assessment model that incorporated nationally representative data on dietary intake, national cancer incidence, and estimated associations of diet with cancer risk from meta-analyses of prospective cohort studies, we estimated the annual number and proportion of new cancer cases attributable to suboptimal intakes of seven dietary factors among US adults ages 20 years or older, and by population subgroups.

RESULTS

An estimated 80 110 (95% uncertainty interval [UI] = 76 316 to 83 657) new cancer cases were attributable to suboptimal diet, accounting for 5.2% (95% UI = 5.0% to 5.5%) of all new cancer cases in 2015. Of these, 67 488 (95% UI = 63 583 to 70 978) and 4.4% (95% UI = 4.2% to 4.6%) were attributable to direct associations and 12 589 (95% UI = 12 156 to 13 038) and 0.82% (95% UI = 0.79% to 0.85%) to obesity-mediated associations. By cancer type, colorectal cancer had the highest number and proportion of diet-related cases (n = 52 225, 38.3%). By diet, low consumption of whole grains (n = 27 763, 1.8%) and dairy products (n = 17 692, 1.2%) and high intake of processed meats (n = 14 524, 1.0%) contributed to the highest burden. Men, middle-aged (45-64 years) and racial/ethnic minorities (non-Hispanic blacks, Hispanics, and others) had the highest proportion of diet-associated cancer burden than other age, sex, and race/ethnicity groups.

CONCLUSIONS

More than 80 000 new cancer cases are estimated to be associated with suboptimal diet among US adults in 2015, with middle-aged men and racial/ethnic minorities experiencing the largest proportion of diet-associated cancer burden in the United States.

Trans Fatty Acid Biomarkers and Incident Type 2 Diabetes: Pooled Analysis from 10 Prospective Cohort Studies in the Fatty Acids and Outcome Research Consortium (FORCE) (OR33-02-19)

Objectives

To assess prospective association between circulating biomarkers of individual trans fatty acids (TFAs) and incident type 2 diabetes (T2D) in diverse populations.

Methods

A harmonized analysis of individual level data was conducted for TFA biomarkers and incident T2D by pooling ten prospective cohort or nested-case-control studies from five countries (Australia, Germany, Iceland, UK, and USA). Fatty acids (FAs) were measured in plasma phospholipid, red blood cell membrane phospholipid, or total plasma collected between 1990–2008 from 22,711 participants aged ≥18 years without prevalent diabetes. Evaluated TFAs included trans-16:1n-9, sum of trans-18:1 isomers (trans-18:1n6 to trans-18:1n12), sum of trans-18:2 isomers (cis/trans-18:2, trans/cis-18:2, trans/trans-18:2), and individual trans-18:2 isomers. The multivariable-adjusted relative risk or odds ratio was estimated in each cohort by lipid compartments using a pre-specified protocol for definitions of exposures, covariates, and outcomes for statistical analysis. Association estimates were pooled using fixed-effects inverse-variance weighted meta-analysis.

Results

During an average maximum of 14 years of follow-up, 2244 cases of incident T2D were identified. Median levels of TFAs across cohorts were 0.05–0.18% total FAs for trans-16:1n-9, 0.09–2.05% for total trans-18:1, 0.10–0.73% for total trans-18:2, and 0.01–0.36% for individual trans-18:2 isomers. In overall pooled analysis, TFAs evaluated per inter-quintile range were not significantly associated with risk of T2D (Figure 1). Findings were consistent when TFAs were assessed categorically in study specific-quintiles, and when associations were pooled within lipid compartment (i.e., phospholipids vs. total plasma).

Conclusions

Overall, biomarker levels of TFAs were not significantly associated with risk of incident T2D in this international pooling project. Findings may be due to mixed TFA sources (industrial vs. ruminant), a general decline in TFA exposure during this period, or no effect of circulating TFA on diabetes. Associations of TFA biomarkers with T2D at higher exposures should be investigated.

Funding Sources

See Table 1.

Supporting Tables, Images and/or Graphs

Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality

BACKGROUND

Global dietary recommendations for and cardiovascular effects of linoleic acid, the major dietary omega-6 fatty acid, and its major metabolite, arachidonic acid, remain controversial. To address this uncertainty and inform international recommendations, we evaluated how in vivo circulating and tissue levels of linoleic acid (LA) and arachidonic acid (AA) relate to incident cardiovascular disease (CVD) across multiple international studies.

METHODS

We performed harmonized, de novo, individual-level analyses in a global consortium of 30 prospective observational studies from 13 countries. Multivariable-adjusted associations of circulating and adipose tissue LA and AA biomarkers with incident total CVD and subtypes (coronary heart disease, ischemic stroke, cardiovascular mortality) were investigated according to a prespecified analytic plan. Levels of LA and AA, measured as the percentage of total fatty acids, were evaluated linearly according to their interquintile range (ie, the range between the midpoint of the first and fifth quintiles), and categorically by quintiles. Study-specific results were pooled using inverse-variance-weighted meta-analysis. Heterogeneity was explored by age, sex, race, diabetes mellitus, statin use, aspirin use, omega-3 levels, and fatty acid desaturase 1 genotype (when available).

RESULTS

In 30 prospective studies with medians of follow-up ranging 2.5 to 31.9 years, 15 198 incident cardiovascular events occurred among 68 659 participants. Higher levels of LA were significantly associated with lower risks of total CVD, cardiovascular mortality, and ischemic stroke, with hazard ratios per interquintile range of 0.93 (95% CI, 0.88-0.99), 0.78 (0.70-0.85), and 0.88 (0.79-0.98), respectively, and nonsignificantly with lower coronary heart disease risk (0.94; 0.88-1.00). Relationships were similar for LA evaluated across quintiles. AA levels were not associated with higher risk of cardiovascular outcomes; in a comparison of extreme quintiles, higher levels were associated with lower risk of total CVD (0.92; 0.86-0.99). No consistent heterogeneity by population subgroups was identified in the observed relationships.

CONCLUSIONS

In pooled global analyses, higher in vivo circulating and tissue levels of LA and possibly AA were associated with lower risk of major cardiovascular events. These results support a favorable role for LA in CVD prevention.

Dairy Product Intake and Risk of Type 2 Diabetes in EPIC-InterAct: A Mendelian Randomization Study

OBJECTIVE

To estimate the causal association between intake of dairy products and incident type 2 diabetes.

RESEARCH DESIGN AND METHODS

The analysis included 21,820 European individuals (9,686 diabetes cases) of the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct case-cohort study. Participants were genotyped, and rs4988235 (LCT-12910C>T), a single nucleotide polymorphism (SNP) for lactase persistence (LP) that enables digestion of dairy sugar, i.e., lactose, was imputed. Baseline dietary intakes were assessed with diet questionnaires. We investigated the associations between imputed SNP dosage for rs4988235 and intake of dairy products and other foods through linear regression. Mendelian randomization (MR) estimates for the milk-diabetes relationship were obtained through a two-stage least squares regression.

RESULTS

Each additional LP allele was associated with a higher intake of milk (β 17.1 g/day, 95% CI 10.6-23.6) and milk beverages (β 2.8 g/day, 95% CI 1.0-4.5) but not with intake of other dairy products. Other dietary intakes associated with rs4988235 included fruits (β -7.0 g/day, 95% CI -12.4 to -1.7 per additional LP allele), nonalcoholic beverages (β -18.0 g/day, 95% CI -34.4 to -1.6), and wine (β -4.8 g/day, 95% CI -9.1 to -0.6). In instrumental variable analysis, LP-associated milk intake was not associated with diabetes (hazard ratioper 15 g/day 0.99, 95% CI 0.93-1.05).

CONCLUSIONS

rs4988235 was associated with milk intake but not with intake of other dairy products. This MR study does not suggest that milk intake is associated with diabetes, which is consistent with previous observational and genetic associations. LP may be associated with intake of other foods as well, but owing to the modest associations, we consider it unlikely that this caused the observed null result.

Association of Plasma Vitamin D Metabolites With Incident Type 2 Diabetes: EPIC-InterAct Case-Cohort Study

BACKGROUND

Existing evidence for the prospective association of vitamin D status with type 2 diabetes (T2D) is focused almost exclusively on circulating total 25-hydroxyvitamin D [25(OH)D] without distinction between its subtypes: nonepimeric and epimeric 25(OH)D3 stereoisomers, and 25(OH)D2, the minor component of 25(OH)D. We aimed to investigate the prospective associations of circulating levels of the sum and each of these three metabolites with incident T2D.

METHODS

This analysis in the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct case-cohort study for T2D included 9671 incident T2D cases and 13,562 subcohort members. Plasma vitamin D metabolites were quantified by liquid chromatography-mass spectrometry. We used a multivariable Prentice-weighted Cox regression to estimate hazard ratios (HRs) of T2D for each metabolite. Analyses were performed separately within country, and estimates were combined across countries using random-effects meta-analysis.

RESULTS

The mean concentrations (SD) of total 25(OH)D, nonepimeric 25(OH)D3, epimeric 25(OH)D3, and 25(OH)D2 were 41.1 (17.2), 40.7 (17.3), 2.13 (1.31), and 8.16 (6.52) nmol/L, respectively. Plasma total 25(OH)D and nonepimeric 25(OH)D3 were inversely associated with incident T2D [multivariable-adjusted HR per 1 SD = 0.81 (95% CI, 0.77, 0.86) for both variables], whereas epimeric 25(OH)D3 was positively associated [per 1 SD HR = 1.16 (1.09, 1.25)]. There was no statistically significant association with T2D for 25(OH)D2 [per 1 SD HR = 0.94 (0.76, 1.18)].

CONCLUSIONS

Plasma nonepimeric 25(OH)D3 was inversely associated with incident T2D, consistent with it being the major metabolite contributing to total 25(OH)D. The positive association of the epimeric form of 25(OH)D3 with incident T2D provides novel information to assess the biological relevance of vitamin D epimerization and vitamin D subtypes in diabetes etiology.

Associations of circulating very-long-chain saturated fatty acids and incident type 2 diabetes: a pooled analysis of prospective cohort studies

BACKGROUND

Saturated fatty acids (SFAs) of different chain lengths have unique metabolic and biological effects, and a small number of recent studies suggest that higher circulating concentrations of the very-long-chain SFAs (VLSFAs) arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0) are associated with a lower risk of diabetes. Confirmation of these findings in a large and diverse population is needed.

OBJECTIVE

We investigated the associations of circulating VLSFAs 20:0, 22:0, and 24:0 with incident type 2 diabetes in prospective studies.

METHODS

Twelve studies that are part of the Fatty Acids and Outcomes Research Consortium participated in the analysis. Using Cox or logistic regression within studies and an inverse-variance-weighted meta-analysis across studies, we examined the associations of VLSFAs 20:0, 22:0, and 24:0 with incident diabetes among 51,431 participants.

RESULTS

There were 14,276 cases of incident diabetes across participating studies. Higher circulating concentrations of 20:0, 22:0, and 24:0 were each associated with a lower risk of incident diabetes. Pooling across cohorts, the RR (95% CI) for incident diabetes comparing the 90th percentile to the 10th percentile was 0.78 (0.70, 0.87) for 20:0, 0.84 (0.77, 0.91) for 22:0, and 0.75 (0.69, 0.83) for 24:0 after adjustment for demographic, lifestyle, adiposity, and other health factors. Results were fully attenuated in exploratory models that adjusted for circulating 16:0 and triglycerides.

CONCLUSIONS

Results from this pooled analysis indicate that higher concentrations of circulating VLSFAs 20:0, 22:0, and 24:0 are each associated with a lower risk of diabetes.