Association of fish and n-3 fatty acid intake with the risk of type 2 diabetes: a meta-analysis of prospective studies

Associations of Total Fat and Fatty Acid Intake With the Risk of Type 2 Diabetes Mellitus Among Japanese Adults: Analysis Based on the JACC Study

BACKGROUND

We prospectively examined the associations of total fat and fatty acid intake with type 2 diabetes (T2D) among Japanese adults.

METHODS

This study was conducted using data from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC). A validated food frequency questionnaire evaluated the intake of total fat and fatty acids. Diabetes was assessed using self-reported data. Multivariable logistic regression analysis was performed to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of incident T2D across quintiles of total fat and fatty acid intake after adjusting for potential confounders.

RESULTS

A total of 19,088 non-diabetic participants (age range, 40-79 years) enrolled in the JACC between 1988 and 1990 were included in this study. During the 5-year study period, 494 the participants developed T2D. The OR of T2D for the highest versus lowest quintiles was 0.58 (95% CI, 0.37-0.90) for total fat, 0.78 (95% CI, 0.51-1.20) for saturated fatty acid (SFA), 0.55 (95% CI, 0.35-0.86) for monounsaturated fatty acids (MUFA), 0.61 (95% CI, 0.39-0.96) for polyunsaturated fatty acids (PUFA), 0.64 (95% CI, 0.42-0.99) for n-3 PUFA, and 0.70 (95% CI, 0.45-1.09) for n-6 PUFA. Total fat and fatty acid (except SFA and n-6 PUFA) intake were inversely associated with T2D in men. Total fat and fatty acid intake were not associated with T2D in women.

CONCLUSION

Higher intakes of total fats, MUFA, PUFA, and n-3 PUFA were inversely associated with T2D among Japanese men.

The protective role of oily fish intake against type 2 diabetes: insights from a genetic correlation and Mendelian randomization study

Background and aims

Previous research has underscored the association between oily fish intake and type 2 diabetes (T2DM), yet the causality remains elusive.

Methods

A bidirectional univariable Mendelian Randomization (MR) analysis was employed to evaluate the causal effects of oily fish and non-oily fish intake on T2DM. Replication analysis and meta-analysis were conducted to ensure robust results. Multivariable MR analysis was utilized to assess confounders, and further mediation MR analysis discerned mediating effects. Linkage Disequilibrium Score (LDSC) analysis was undertaken to compute genetic correlations. Inverse variance weighted (IVW) was the primary method, complemented by a series of sensitivity analyses.

Results

The LDSC analysis unveiled a significant genetic correlation between oily fish intake and T2DM (Genetic correlation: -0.102, p = 4.43 × 10-4). For each standard deviation (SD) increase in genetically predicted oily fish intake, the risk of T2DM was reduced by 38.6% (OR = 0.614, 95% CI 0.504 ~ 0.748, p = 1.24 × 10-6, False Discovery Rate (FDR) = 3.72 × 10-6). The meta-analysis across three data sources highlighted a persistent causal association (OR = 0.728, 95% CI 0.593 ~ 0.895, p = 0.003). No other causal effects were identified (all p > 0.5, FDR > 0.5). The main outcomes remained consistent in most sensitivity analyses. Both MVMR and mediation MR analyses emphasized the mediating roles of triglycerides (TG), body mass index (BMI), and 25-hydroxyvitamin D (25OHD) levels.

Conclusion

To encapsulate, there's an inverse association between oily fish intake and T2DM risk, suggesting potential benefits of oily fish intake in T2DM prevention.

Association between type 2 diabetes and different types of dietary fats: A case-control study

BACKGROUND

The effect of dietary fats on type 2 diabetes (T2D) is not clear. This study aimed to determine the association between T2D and dietary fatty acids among Iranian adults.

METHODS

This case-control study was performed on 4241 participants aged 35-70, including 1804 people with T2D and pre-diabetes as the case group and 2437 people without diabetes as the control group. Dietary intake was assessed using a food frequency questionnaire (FFQ).

RESULTS

The cases had higher age (48.36 ± 8.62 vs. 54.53 ± 7.75 y, P < 0.001), weight (73.7713.41 vs. 76.18 ± 13.49 kg, P = 0.001), body mass index (BMI) (28.02 ± 4.70 vs. 24 ± 4.74 kg/m2, P = 0.001), right systolic blood pressure (RSBP) (113.33 ± 16.7 vs. 121.61 ± 17.24 mmHg, P = 0.001), right diastolic blood pressure (RDBP) (71.41 ± 10.53 vs. 75.33 ± 9.92 mmHg, P = 0.001), fasting blood sugar (FBS) (96.87 ± 19.39 vs. 169.95 ± 69.28 mg/dl, P = 0.001), blood urine nitrogen (BUN) (13.65 ± 3.74 vs. 14.26 ± 4.03 mg/dl, P = 0.001), triglyceride (TG) (141.61 ± 99.37 vs. 175.96 ± 114.74 mg/dl, P = 0.001), alkaline phosphatase (ALP) (218.24 ± 66.35 vs. 246.97 ± 72.65 IU/L, P = 0.001), low-density lipoprotein cholesterol (LDL) (111.68 ± 33.02 vs. 101.97 ± 36.54 mg/dl, P = 0.001), serum glutamic-pyruvic transaminase (SGPT) (21.88 ± 15.15 vs. 23.55 ± 15.96 IU/L, P = 0.001), gamma-glutamyl transferase (GGT) (24.66 ± 20.42 vs. 30.72 ± 30.43 IU/L P = 0.001), and cholesterol (192.45 ± 39.1190 vs. 187.12 ± 46.19 mg/dl P = 0.001) compared to the control group. T2D was negatively associated with dietary intake of PUFAs (OR = 0.93, CI95%:0.84-1.03, P = 0.01) and positively associated with dietary cholesterol (OR: 1.01, CI95%:1.001-1.01, P = 0.02).

CONCLUSION

In summary, cholesterol was positively and PUFAs were negatively associated with diabetes. If the results of the present study on the effect of fat intake on diabetes are proven, future dietary recommendations for people at risk of diabetes may be corrected by providing diets rich in polyunsaturated fatty acids and low in cholesterol.

The Potential Cardiometabolic Effects of Long-Chain ω-3 Polyunsaturated Fatty Acids: Recent Updates and Controversies

Various health-related effects of long-chain (LC) ω-3 PUFAs, EPA, and DHA have been suggested. LC ω-3 PUFAs reduce TG concentrations and have anti-inflammatory, immunomodulatory, antiplatelet, and vascular protective effects. Controversially, they might help in restoring glucose homeostasis via the gut microbiota. However, previous studies have not shown the clear benefits of LC ω-3 PUFAs for CVDs. REDUCE-IT and STRENGTH-representative randomized controlled trials (RCTs) that examined whether LC ω-3 PUFAs would prevent major adverse cardiovascular (CV) events (MACE)-showed conflicting results with differences in the types, doses, or comparators of LC ω-3 PUFAs and study populations. Therefore, we performed a meta-analysis using major RCTs to address this inconsistency and assess the clinical and biological effects of LC ω-3 PUFAs. We included RCTs that involved ≥500 participants with ≥1 y follow-up. Of 17 studies involving 143,410 people, LC ω-3 PUFA supplementation showed beneficial effects on CV death (RR: 0.94; 95% CI: 0.88, 0.99; P = 0.029) and fatal or nonfatal MI (RR: 0.83; 95% CI: 0.72, 0.95; P = 0.010). RCTs on EPA alone showed better results for 3-point MACE, CV death, and fatal or nonfatal MI. However, the benefits were not found for fatal or nonfatal stroke, all-cause mortality, and hospitalization for heart failure. Of note, studies of both the EPA/DHA combination and EPA alone showed a significant increase in risk of new-onset atrial fibrillation. Thus, well-designed studies are needed to investigate the underlying mechanisms involved in the distinct effects of EPA compared with DHA on cardiometabolic diseases. This review discusses the potential benefits and safety of LC ω-3 PUFAs from a cardiometabolic perspective focusing on recent updates and controversies.

The Effects of Omega 3 and Omega 6 Fatty Acids on Glucose Metabolism: An Updated Review

Massive changes have occurred in our diet. A growing consumption of vegetal oils rich in omega-6 (ω-6) and a depletion of omega-3 (ω-3) fatty acids (FAs) in our food has led to an imbalance between ω-3 and ω-6. In particular, eicosapentaenoic (EPA)/arachidonic acid (AA) ratio seems to be an indicator of this derangement, whose reduction is associated to the development of metabolic diseases, such as diabetes mellitus. Our aim was therefore to investigate the literature on the effects of ω-3 and ω-6 FAs on glucose metabolism. We discussed emerging evidence from pre-clinical studies and from clinical trials. Notably, conflicting results emerged. Source of ω-3, sample size, ethnicity, study duration and food cooking method may be responsible for the lack of univocal results. High EPA/AA ratio seems to be a promising indicator of better glycemic control and reduced inflammation. On the other hand, linoleic acid (LA) appears to be also associated to a minor incidence of type 2 diabetes mellitus, although it is still not clear if the outcome is related to a reduced production of AA or to its intrinsic effect. More data derived from multicenter, prospective randomized clinical trials are needed.

Egg Consumption in the Context of Plant-Based Diets and Diet Quality in Adults at Risk for Type 2 Diabetes: A Randomized Single Blind Cross-over Controlled Trial

Lifestyle changes that emphasis on plant-based diets (PBD) are typically recommended for those at risk for type 2 diabetes mellitus (T2DM) to mitigate their cardo-metabolic risk. We examined the impact of the inclusion of eggs compared with their exclusion from PBD on diet quality among adults at risk for T2DM.

This was a randomized, controlled, single-blind, crossover trial of 35 adults (mean age 60.7 years; 25 women, 10 men; 34 Caucasians, 1 African-American) at risk for T2DM (i.e., pre- diabetes or metabolic syndrome) assigned to one of two possible sequence permutations of two treatments (PBD with eggs and exclusively PBD), with a 4-week washout period. Participants received dietary counseling from a dietitian to exclude or to include 2 eggs daily in the context of PBD for a 6-week period. Diet quality was assessed using the Healthy Eating Index 2015 (HEI-2015) at baseline and 6 weeks.

Compared with the exclusion of eggs, the inclusion of eggs in the context of PBD improved the diet quality score for intake of total protein foods (1.0 ± 1.1 vs. -0.4 ± 1.0; p <.0001); seafood and plant proteins (0.2 ± 1.2 vs. -0.4 ± 1.1; p = 0.0338); and fatty acids (0.8 ± 2.5 vs. -0.7 ± 2.7; p = 0.0260). Overall diet quality score depreciated with the adoption of exclusively PBD without eggs (-3.1 ± 8.3; p = 0.0411), while it was unaffected with the adoption of a PBD with the inclusion of eggs (-0.6 ± 7.9; p = 0.6892).

Eggs could be used as an adjuvant to enhance the diet quality among those at risk for T2DM who adopt plant-based dietary patterns.

Sociodemographic, anthropometric, and lifestyle correlates of prediabetes and type 2 diabetes in europe: The Feel4Diabetes study

BACKGROUND AND AIMS

The current work aimed to identify the predominant correlates of prediabetes and T2DM among a variety of socio-demographic, anthropometric and lifestyle indices, in a large sample of adults from families at high risk for T2DM.

METHODS AND RESULTS

In this cross-sectional study, 2816 adults were recruited from low-socioeconomic areas in high-income countries (HICs) (Belgium-Finland), HICs under austerity measures (Greece-Spain), and low/middle-income countries (LMICs) (Bulgaria-Hungary). A positive association between the male sex (OR, 95% C.I.2.77 (1.69-4.54)) and prediabetes was revealed compared to females, while there was a negative association between younger age (<45 years) (OR, 95% C.I. 0.58 (0.37-0.92)), and low/medium levels of waist circumference (OR, 95% C.I. 0.44 (0.22-0.89)) with prediabetes compared to older age and high levels of waist circumference, respectively. Concerning T2DM, 0-0.5 cups/day of fruits and berries (OR, 95% C.I.2. 13 (1.16-3.91)) and 150-300 g fish/week (OR, 95% C.I. 2.55 (1.01-6.41)) have a positive association compared to higher consumptions, respectively. Conversely, <1 cup/week legumes (OR, 95% C.I. 0.55 (0.31-0.99) as well as 0-0.5 servings (OR, 95% C.I. 0.34 (0.12-0.95) and 0.5-1 servings (OR, 95% C.I. 0.37 (0.19-0.71) of full-fat dairy/day have a negative association compared to higher consumptions, respectively.

CONCLUSION

These findings indicate the need for diabetes prevention measures targeting young adults and especially men, above 45 years of age, with central obesity and poor dietary habits and prioritize vulnerable groups and populations living in LMICs.

NATIONAL CLINICAL TRIAL NUMBER

NCT02393872.

Dietary Patterns Derived from Reduced Rank Regression Are Associated with the 5-Year Occurrence of Metabolic Syndrome: Aichi Workers' Cohort Study

The aim of the present study was to derive dietary patterns to explain variation in a set of nutrient intakes or in the measurements of waist circumference (WC) and fasting blood glucose (FBG) using reduced rank regression (RRR) and to prospectively investigate these patterns in relation to the risk of developing metabolic syndrome (MetS) and its components during the follow-up. The study participants were comprised of 2944 government employees aged 30−59 years without MetS. RRR was applied with 38 food groups as predictors and with two sets of response variables. The first set included intake of putatively beneficial nutrients, and the first factor retained was named the Healthy Dietary Pattern (HDP). The second one included baseline WC and FBG, and the first factor was named the Unhealthy Dietary Pattern (UHDP). Multivariable Cox proportional hazard model was used to estimate hazard ratio and 95% confidence intervals with adjustments for age, sex, total energy consumption and other potential confounders. During the 5-year median follow-up, we ascertained 374 cases of MetS. The HDP score was inversely associated with the incidence of MetS (p-trend = 0.009) and hypertension (p-trend = 0.002) and marginally significantly associated with elevated triglyceride and decreased high-density lipoprotein cholesterol (p-trend = 0.08). The UHDP score was linearly positively associated with the incidence of MetS and all its components (all p-trend < 0.05). Both the HDP and UHDP predicted the development of MetS and its components.

Fish and human health: an umbrella review of observational studies

Fish represents one of the most important dietary sources of omega-3 polyunsaturated fatty acids, which are known to be associated with various health benefits. This study aimed to systematically review existing meta-analyses of observational studies exploring the association between fish intake and various health outcomes. A systematic search of electronic databases was conducted to retrieve a total of 63 studies. Evidence was deemed as possible for the association between higher fish intake and decreased risk of the acute coronary syndrome, liver cancer, and depression, and limited for other outcomes (including age-related macular degeneration, Alzheimer's disease, heart failure, all-cause and coronary heart disease mortality, total and ischaemic stroke) due to heterogeneity between results and potential otherwise inexplicable confounding factors. In conclusion, results from epidemiological studies support the mechanistic effects associated with omega-3 fatty acids from high fish consumption, but evidence needs to be further corroborated with more reliable results.

Dietary Protein Patterns during Pregnancy Are Associated with Risk of Gestational Diabetes Mellitus in Chinese Pregnant Women

Controversies around the association between dietary protein intake and gestational diabetes mellitus (GDM) persist. To the best of our knowledge, this association has not previously been reported from the perspective of dietary protein patterns. We aimed to investigate the relationship between dietary protein patterns and GDM risk in pregnant women, and 1014 pregnant women (20–28 weeks of gestation) were recruited in Guangzhou, China, during 2017–2018. Maternal dietary information was collected by a validated food frequency questionnaire, which covered the most common foods consumed in Guangzhou, China. GDM was identified by a 75g oral glucose tolerance test. A K-means cluster analysis was conducted to aggregate individuals into three groups, which were determined by the major sources of protein. Logistic regression was employed to explore the relationship between dietary protein patterns and the risk of GDM. Among the 1014 participants, 191 (18.84%) were diagnosed with GDM. In the total population, when comparing the highest quartile with the lowest, we found that total protein and animal protein intake increased the risk of GDM with the adjusted odds ratios (95%CI) being 6.27, 5.43 (1.71–23.03, 1.71–17.22), respectively. Pregnant women were further divided into three dietary protein patterns, namely, white meat, plant–dairy–eggs, and red meat protein patterns. Compared to women with the plant–dairy–eggs protein pattern, those with the red meat protein pattern (OR: 1.80; 95%CI: 1.06–3.07) or white meat protein pattern (OR: 1.83; 95%CI: 1.04–3.24) had an increased risk of GDM. Higher dietary intakes of total or animal protein during mid-pregnancy were related to an increased risk of GDM. Furthermore, we first found that, compared to women with the plant–dairy–eggs protein pattern, women with the red meat or white meat protein patterns had a higher risk of GDM.

The Prospective Associations of Lipid Metabolism-Related Dietary Patterns with the Risk of Diabetes in Chinese Adults

Background: This study aimed to identify lipid metabolism-related dietary patterns with reduced rank regression (RRR) among Chinese adults and examine their associations with incident diabetes. Methods: We derived lipid metabolism-related dietary patterns using an RRR with 21 food groups as predictors as well as total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, body mass index (BMI), and waist circumference from the responses of 17,318 participants from the second resurvey of the China Kadoorie Biobank (CKB). The dietary scores were calculated for the entire cohort. We followed up 479,207 participants for diabetes incidence from the baseline and used multivariable Cox regression models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). Results: Two lipid metabolism-related dietary patterns were extracted. The dietary pattern—characterized by high intakes of fish, poultry, and other staples as well as fresh fruit and vegetables—was correlated with a higher BMI, waist circumference, and LDL cholesterol. Participants in the highest quintile (Q5) had a 44% increased risk of diabetes incidence when compared with those in the lowest quintile (Q1) (HR = 1.44; 95% CI: 1.31–1.59). Conclusions: A dietary pattern characterized by high intakes of both animal and plant foods was related to obesity and dyslipidemia and could increase the risk of diabetes incidence.

Vascepa protects against high-fat diet-induced glucose intolerance, insulin resistance, and impaired β-cell function

Omega-3 fatty acid prescription drugs, Vascepa (≥96% eicosapentaenoic acid [EPA] ethyl ester) and Lovaza (46.5% EPA and 37.5% docosahexaenoic acid ethyl ester) are known therapeutic regimens to treat hypertriglyceridemia. However, their impact on glucose homeostasis, progression to type 2 diabetes, and pancreatic beta cell function are not well understood. In the present study, mice were treated with Vascepa or Lovaza for one week prior to six weeks of high-fat diet feeding. Vascepa but not Lovaza led to reduced insulin resistance, reduced fasting insulin and glucose, and improved glucose intolerance. Vascepa improved beta cell function, reduced liver triglycerides with enhanced expression of hepatic fatty acid oxidation genes, and altered microbiota composition. Vascepa has protective effects on diet-induced insulin resistance and glucose intolerance in mice.

Heterogeneity of Associations between Total and Types of Fish Intake and the Incidence of Type 2 Diabetes: Federated Meta-Analysis of 28 Prospective Studies Including 956,122 Participants

The association between fish consumption and new-onset type 2 diabetes is inconsistent and differs according to geographical location. We examined the association between the total and types of fish consumption and type 2 diabetes using individual participant data from 28 prospective cohort studies from the Americas (6), Europe (15), the Western Pacific (6), and the Eastern Mediterranean (1) comprising 956,122 participants and 48,084 cases of incident type 2 diabetes. Incidence rate ratios (IRRs) for associations of total fish, shellfish, fatty, lean, fried, freshwater, and saltwater fish intake and type 2 diabetes were derived for each study, adjusting for a consistent set of confounders and combined across studies using random-effects meta-analysis. We stratified all analyses by sex due to observed interaction (p = 0.002) on the association between fish and type 2 diabetes. In women, for each 100 g/week higher intake the IRRs (95% CIs) of type 2 diabetes were 1.02 (1.01-1.03, I2 = 61%) for total fish, 1.04 (1.01-1.07, I2 = 46%) for fatty fish, and 1.02 (1.00-1.04, I2 = 33%) for lean fish. In men, all associations were null. In women, we observed variation by geographical location: IRRs for total fish were 1.03 (1.02-1.04, I2 = 0%) in the Americas and null in other regions. In conclusion, we found evidence of a neutral association between total fish intake and type 2 diabetes in men, but there was a modest positive association among women with heterogeneity across studies, which was partly explained by geographical location and types of fish intake. Future research should investigate the role of cooking methods, accompanying foods and environmental pollutants, but meanwhile, existing dietary regional, national, or international guidelines should continue to guide fish consumption within overall healthy dietary patterns.

Intake of dietary fats and fatty acids and the incidence of type 2 diabetes: A systematic review and dose-response meta-analysis of prospective observational studies

BACKGROUND

The role of fat quantity and quality in type 2 diabetes (T2D) prevention is controversial. Thus, this systematic review and meta-analysis aimed to investigate the associations between intake of dietary fat and fatty acids and T2D, and to evaluate the certainty of evidence.

METHODS AND FINDINGS

We systematically searched PubMed and Web of Science through 28 October 2019 for prospective observational studies in adults on the associations between intake of dietary fat and fatty acids and T2D incidence. The systematic literature search and data extraction were conducted independently by 2 researchers. We conducted linear and nonlinear random effects dose-response meta-analyses, calculated summary relative risks (SRRs) with their corresponding 95% confidence intervals (95% CIs), and assessed the certainty of evidence. In total, 15,070 publications were identified in the literature search after the removal of duplicates. Out of the 180 articles screened in full text, 23 studies (19 cohorts) met our inclusion criteria, with 11 studies (6 cohorts) conducted in the US, 7 studies (7 cohorts) in Europe, 4 studies (5 cohorts) in Asia, and 1 study (1 cohort) in Australia. We mainly observed no or weak linear associations between dietary fats and fatty acids and T2D incidence. In nonlinear dose-response meta-analyses, the protective association for vegetable fat and T2D was steeper at lower levels up to 13 g/d (SRR [95% CI]: 0.81 [0.76; 0.88], pnonlinearity = 0.012, n = 5 studies) than at higher levels. Saturated fatty acids showed an apparent protective association above intakes around 17 g/d with T2D (SRR [95% CI]: 0.95 [0.90; 1.00], pnonlinearity = 0.028, n = 11). There was a nonsignificant association of a decrease in T2D incidence for polyunsaturated fatty acid intakes up to 5 g/d (SRR [95% CI]: 0.96 [0.91; 1.01], pnonlinearity = 0.023, n = 8), and for alpha-linolenic acid consumption up to 560 mg/d (SRR [95% CI]: 0.95 [0.90; 1.00], pnonlinearity = 0.014, n = 11), after which the curve rose slightly, remaining close to no association. The association for long-chain omega-3 fatty acids and T2D was approximately linear for intakes up to 270 mg/d (SRR [95% CI]: 1.10 [1.06; 1.15], pnonlinearity < 0.001, n = 16), with a flattening curve thereafter. Certainty of evidence was very low to moderate. Limitations of the study are the high unexplained inconsistency between studies, the measurement of intake of dietary fats and fatty acids via self-report on a food group level, which is likely to lead to measurement errors, and the possible influence of unmeasured confounders on the findings.

CONCLUSIONS

There was no association between total fat intake and the incidence of T2D. However, for specific fats and fatty acids, dose-response curves provided insights for significant associations with T2D. In particular, a high intake of vegetable fat was inversely associated with T2D incidence. Thus, a diet including vegetable fat rather than animal fat might be beneficial regarding T2D prevention.

Preventive Role of Diet Interventions and Dietary Factors in Type 2 Diabetes Mellitus: An Umbrella Review

BACKGROUND

Although the body of evidence indicates clear benefits of dietary modifications for prevention of type-2 diabetes mellitus (T2DM), it may be difficult for healthcare providers to recommend which diet interventions or dietary factors are appropriate for patients as there are too many modalities available. Accordingly, we performed an umbrella review to synthesize evidence on diet interventions and dietary factors in prevention of T2DM.

METHODS

Medline and Scopus databases were searched for relevant studies. Systematic reviews with meta-analyses of randomized-controlled trial or observational studies were eligible if they measured effects of diet interventions and/or dietary factors including dietary patterns, food groups, and nutrients on risk of T2DM. The effect of each diet intervention/factor was summarized qualitatively.

RESULTS

Sixty systematic reviews and meta-analyses were eligible. Results of the review suggest that healthy dietary patterns such as Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets, and high consumption of whole grains, low-fat dairy products, yogurt, olive oil, chocolate, fiber, magnesium, and flavonoid significantly reduced the risk of T2DM. In contrast, high glycemic index and glycemic load diets, high consumption of red and processed meat, and sugar or artificial sugar-sweetened beverages significantly increased risk of T2DM. Prescribing diet interventions with or without physical activity interventions significantly decreased risk of T2DM in both high-risk and general population.

CONCLUSION

High consumption of Mediterranean and DASH diet, and interventions that modified the quality of diet intake significantly reduced risk of T2DM especially in the high-risk population. These lifestyle modifications should be promoted in both individual and population levels to prevent and decrease burden from T2DM in the future.

DHA-enriched fish oil reduces insulin resistance in overweight and obese adults

Adipose tissue inflammation is major factor in the development of insulin resistance (IR). Long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are anti-inflammatory bioactive lipids, thus may protect against type 2 diabetes (T2D) development. Previous research has demonstrated a sex-dependent association between LCn-3PUFA and T2D, and evidence suggests LCn-3PUFA may improve IR in a sex-dependent manner. This double-blind, randomized, parallel-arm placebo-controlled study aimed to determine whether DHA-enriched fish oil (FO) supplementation improves IR. Sex-dependent effects were assessed by testing for an interaction between sex and treatment in the multiple regression models. Men and women with abdominal obesity (waist circumference: males, ≥102 cm; females, ≥88 cm) and without diabetes were recruited from the community. Participants (age: 50.9 ± 12.7 years, female: 63.7%, BMI: 32.4 ± 6.6 kg/m²) were randomly allocated to either 2 g FO (860 mg DHA + 120 mg EPA) (intervention, n = 38) or 2 g corn oil (CO) /day (control, n = 35) for 12 weeks in a double-blind randomised controlled trial. A fasting blood sample was collected at 0 and 12 weeks for assessment of IR, glucose and blood lipid profile. Sixty-eight participants completed the intervention. Compared with CO (n = 32), FO (n = 36) significantly reduced fasting insulin by -1.62 μIU/L (95%CI: -2.99, -0.26,) (p = 0.021) and HOMA-IR by -0.40 units (95%CI: -0.78, -0.02, p = 0.038). Higher insulin and HOMA-IR at baseline were associated with greater reductions in the FO group (p < 0.001). There was no interaction between sex and treatment for the change in insulin (p-interaction_{sex*treatment} = 0.816) or HOMA-IR (p-interaction_{sex*treatment} = 0.825). DHA-enriched FO reduces IR in adults with abdominal obesity, however, sex-dependent differences were not evident in this study.

Maternal fats and pregnancy complications: Implications for long-term health

Pregnancy imposes increased nutritional requirements for the well being of the mother and fetus. Maternal lipid metabolism is critical for fetal development and long-term health of the offspring as it plays a key role in energy storage, tissue growth and cell signaling. Maternal fat composition is considered as a modifiable risk for abnormal lipid metabolism and glucose tolerance during pregnancy. Data derived from observational studies demonstrate that higher intake of saturated fats during pregnancy is associated with pregnancy complications (preeclampsia, gestational diabetes mellitus and preterm delivery) and poor birth outcomes (intra uterine growth retardation and large for gestational age babies). On the other hand, prenatal long chain polyunsaturated fatty acids status is shown to improve birth outome. In this article, we discuss the role of maternal lipids during pregnancy on fetal growth and development and its consequences on the health of the offspring.

Effect of Cod Residual Protein Supplementation on Markers of Glucose Regulation in Lean Adults: A Randomized Double-Blind Study

Large quantities of protein-rich cod residuals, which are currently discarded, could be utilized for human consumption. Although fish fillet intake is related to beneficial health effects, little is known about the potential health effects of consuming cod residual protein powder. Fifty lean adults were randomized to consume capsules with 8.1 g/day of cod residual protein (Cod-RP) or placebo capsules (Control group) for eight weeks, in this randomized, double-blind study. The intervention was completed by 40 participants. Fasting glucose and insulin concentrations were unaffected by Cod-RP supplementation, whereas plasma concentrations of α-hydroxybutyrate, β-hydroxybutyrate and acetoacetate all were decreased compared with the Control group. Trimethylamine N-oxide concentration in plasma and urine were increased in the Cod-RP group compared with the Control group. To conclude, the reduction in these potential early markers of impaired glucose metabolism following Cod-RP supplementation may indicate beneficial glucoregulatory effects of cod residual proteins. Trimethylamine N-oxide appears to be an appropriate biomarker of cod residual protein intake in lean adults.

Are marine n-3 fatty acids protective towards insulin resistance? From cell to human

Marine n-3 fatty acids improve most of the biochemical alterations associated with insulin resistance (IR). Experimental models of dietary-induced IR in rodents have shown their ability (often at a very high dose) to prevent IR, but with sometimes a tissue specific effect. However, in a high sucrose diet-induced IR rat model, they are unable to reverse IR once installed; in other rodent models (dexamethasone, Zucker rats), they are inefficacious perhaps because of the severity of IR. The very low incidence of type-2 diabetes (T2D) in Inuits in the 1960s, which largely increased over the following decades in parallel to the replacement of their traditional marine food for a western diet strongly suggests a protective effect of marine n-3 towards the risk of T2D; this was confirmed by reversal of its incidence in intervention studies reintroducing their traditional food. In healthy subjects and insulin-resistant non-diabetic patients, most trials and meta-analyses conclude to an insulin-sensitising effect and to a very probable preventive or alleviating effect towards IR. Concerning the risk of T2D, concordant data allow us to conclude the protective effect of marine n-3 in Asians while suspicion exists of an aggravation of risk in Westerners, but with the possibility that it could be explained by a high heterogeneity of studies performed in this population. Some longitudinal cohorts in US/European people showed no association or a decreased risk. Further studies using more homogeneous doses, sources of n-3 and assessment of insulin sensitivity methods are required to better delineate their effects in Westerners.

The effects of omega-3 fatty acids on diabetic nephropathy: A meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the effects of omega-3 long-chain polyunsaturated fatty acids on proteinuria, estimated glomerular filtration rate (eGFR) and metabolic biomarkers among patients with diabetes.

STUDY DESIGN

Meta-analysis of randomized controlled clinical trials (RCTs).

SETTING & SUBJECTS

Patients with diabetes.

SELECTION CRITERIA FOR STUDIES

We conducted electronic searches in PubMed, Embase and Cochrane Central Register of Controlled Trials from January 1960 to April 2019 to identify RCTs, which examined the effects of omega-3 fatty acids on proteinuria, eGFR and metabolic biomarkers among diabetic patients.

RESULTS

Ten RCTs with 344 participants were included in our meta-analysis. Omega-3 fatty acids reduced the amount of proteinuria among type 2 diabetes mellitus (type 2 DM) and type 1 diabetes mellitus (type 1 DM). This association was only significant among type 2 DM (SMD = -0.29 (95% CI: -0.54, -0.03; p = 0.03). Only studies with duration of intervention of 24 weeks or longer demonstrated a significant lower proteinuria among omega-3 fatty acids compared to control group (SMD = -0.30 (95% CI: -0.58, -0.02; p = 0.04). There was a higher eGFR for both type 1 and type 2 DM groups among omega-3 fatty acids compared to control group, however, the effect was not statistically significant. Regarding serum total cholesterol, LDL-cholesterol and HbA1C, there was no significant difference comparing omega-3 fatty acids to control group. There was a non-significant systolic blood pressure reduction in the omega-3 fatty acids supplementation group compared to control.

CONCLUSION

Omega-3 fatty acids could help ameliorate proteinuria among type 2 DM who received omega-3 supplementation for at least 24 weeks without adverse effects on HbA1C, total serum cholesterol and LDL-cholesterol.

Omega-3, omega-6, and total dietary polyunsaturated fat for prevention and treatment of type 2 diabetes mellitus: systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To assess effects of increasing omega-3, omega-6, and total polyunsaturated fatty acids (PUFA) on diabetes diagnosis and glucose metabolism.

DESIGN

Systematic review and meta-analyses.

DATA SOURCES

Medline, Embase, Cochrane CENTRAL, WHO International Clinical Trials Registry Platform, Clinicaltrials.gov, and trials in relevant systematic reviews.

ELIGIBILITY CRITERIA

Randomised controlled trials of at least 24 weeks' duration assessing effects of increasing α-linolenic acid, long chain omega-3, omega-6, or total PUFA, which collected data on diabetes diagnoses, fasting glucose or insulin, glycated haemoglobin (HbA_1c), and/or homoeostatic model assessment for insulin resistance (HOMA-IR).

DATA SYNTHESIS

Statistical analysis included random effects meta-analyses using relative risk and mean difference, and sensitivity analyses. Funnel plots were examined and subgrouping assessed effects of intervention type, replacement, baseline risk of diabetes and use of antidiabetes drugs, trial duration, and dose. Risk of bias was assessed with the Cochrane tool and quality of evidence with GRADE.

RESULTS

83 randomised controlled trials (mainly assessing effects of supplementary long chain omega-3) were included; 10 were at low summary risk of bias. Long chain omega-3 had little or no effect on likelihood of diagnosis of diabetes (relative risk 1.00, 95% confidence interval 0.85 to 1.17; 58 643 participants, 3.7% developed diabetes) or measures of glucose metabolism (HbA_1c mean difference -0.02%, 95% confidence interval -0.07% to 0.04%; plasma glucose 0.04, 0.02 to 0.07, mmol/L; fasting insulin 1.02, -4.34 to 6.37, pmol/L; HOMA-IR 0.06, -0.21 to 0.33). A suggestion of negative outcomes was observed when dose of supplemental long chain omega-3 was above 4.4 g/d. Effects of α-linolenic acid, omega-6, and total PUFA on diagnosis of diabetes were unclear (as the evidence was of very low quality), but little or no effect on measures of glucose metabolism was seen, except that increasing α-linolenic acid may increase fasting insulin (by about 7%). No evidence was found that the omega-3/omega-6 ratio is important for diabetes or glucose metabolism.

CONCLUSIONS

This is the most extensive systematic review of trials to date to assess effects of polyunsaturated fats on newly diagnosed diabetes and glucose metabolism, including previously unpublished data following contact with authors. Evidence suggests that increasing omega-3, omega-6, or total PUFA has little or no effect on prevention and treatment of type 2 diabetes mellitus.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017064110.

The association between types of seafood intake and the risk of type 2 diabetes: a systematic review and meta-analysis of prospective cohort studies

Background: Seafood is the main source of long-chain n-3 polyunsaturated fatty acids (n-3PUFAs) with beneficial health effects; however, findings on the association between the consumption of different types of seafood and type 2 diabetes mellitus (T2DM) are conflicting. Our objective was to perform a systematic review and meta-analysis examining the relationship between different types of fish/seafood and the risk of T2DM in adult populations. Methods: A systematic search of PubMed/Medline, Scopus, and Web of Science (ISI) databases was performed for cohort studies, published in English, before 1 September 2017. Multivariate adjusted relative risk (RR) estimates with 95% confidence intervals (CIs) for each category of seafood were pooled to examine the association. Results: Comparing the highest vs. lowest fatty fish intake categories indicated that there was a significant inverse association between the consumption of fatty fish and onset of T2DM (RR:0.89; 95 % CI: 0.82, 0.98; I2: 0%, P=0.54). However, after performing sensitivity analysis, we found that eliminating one study resulted in a non-significant association (RR: 0.93; 95 % CI:0.80, 1.09). There were no significant associations between lean fish (RR: 1.03; 95% CI: 0.87,1.22, I2: 51.0%, P=0.08), seafood other than fish (RR: 0.95; 95% CI: 0.83, 1.10, I2: 71.2%,P=0.002), fish products (RR: 0.96; 95% CI: 0.82, 1.13, I2:0%, P=0.62), and fried fish (RR: 1.02;95% CI: 0.83, 1.26, I2:71.2%, P=0.06) and T2DM risk. Conclusion: The risk of T2DM was not associated with the intake of lean fish, seafood other than fish, and fish products. However, due to the low robustness of findings regarding protective roles of oily fish, more longitudinal studies are needed to clarify this association.

Dietary Fat and Risk for Type 2 Diabetes: a Review of Recent Research

Purpose of Review

It is estimated that over 400 million people worldwide are living with diabetes. Excess adiposity is the strongest risk factor for non-insulin-dependent diabetes, type 2. Lifestyle interventions have demonstrated that diet plays a critical role in preventing the onset of type 2 diabetes. Dietary fat is not only a source of energy and nutrients, but also bioactive fatty acids.

The purpose of this review was to examine data from recent prospective cohort studies and dietary interventions to determine if there are benefits to fat consumption on diabetes risk.

Recent Findings

The consumption of fish and marine n-3 fatty acids among Asian populations and regular-fat dairy foods and trans-palmitoleic acid (trans-16, n-7) among Western populations may be associated with reduced risk for type 2 diabetes.

Summary

Whereas some dietary fat may contribute to reduced diabetes risk, lifestyle recommendations to balance calories with physical activity are prudent at this time.

Role of diet in type 2 diabetes incidence: umbrella review of meta-analyses of prospective observational studies

OBJECTIVE

To summarise the evidence of associations between dietary factors and incidence of type 2 diabetes and to evaluate the strength and validity of these associations.

DESIGN

Umbrella review of systematic reviews with meta-analyses of prospective observational studies.

DATA SOURCES

PubMed, Web of Science, and Embase, searched up to August 2018.

ELIGIBILITY CRITERIA

Systematic reviews with meta-analyses reporting summary risk estimates for the associations between incidence of type 2 diabetes and dietary behaviours or diet quality indices, food groups, foods, beverages, alcoholic beverages, macronutrients, and micronutrients.

RESULTS

53 publications were included, with 153 adjusted summary hazard ratios on dietary behaviours or diet quality indices (n=12), food groups and foods (n=56), beverages (n=10), alcoholic beverages (n=12), macronutrients (n=32), and micronutrients (n=31), regarding incidence of type 2 diabetes. Methodological quality was high for 75% (n=115) of meta-analyses, moderate for 23% (n=35), and low for 2% (n=3). Quality of evidence was rated high for an inverse association for type 2 diabetes incidence with increased intake of whole grains (for an increment of 30 g/day, adjusted summary hazard ratio 0.87 (95% confidence interval 0.82 to 0.93)) and cereal fibre (for an increment of 10 g/day, 0.75 (0.65 to 0.86)), as well as for moderate intake of total alcohol (for an intake of 12-24 g/day v no consumption, 0.75 (0.67 to 0.83)). Quality of evidence was also high for the association for increased incidence of type 2 diabetes with higher intake of red meat (for an increment of 100 g/day, 1.17 (1.08 to 1.26)), processed meat (for an increment of 50 g/day, 1.37 (1.22 to 1.54)), bacon (per two slices/day, 2.07 (1.40 to 3.05)), and sugar sweetened beverages (for an increase of one serving/day, 1.26 (1.11 to 1.43)).

CONCLUSIONS

Overall, the association between dietary factors and type 2 diabetes has been extensively studied, but few of the associations were graded as high quality of evidence. Further factors are likely to be important in type 2 diabetes prevention; thus, more well conducted research, with more detailed assessment of diet, is needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018088106.

Fish Oil Derived Omega 3 Fatty Acids Suppress Adipose NLRP3 Inflammasome Signaling in Human Obesity

CONTEXT

The NRLP3 inflammasome is a multiprotein danger-sensing complex that serves as a critical link between obesity-related adipose inflammation and insulin resistance and has been shown in animal models to be inhibited by fish oil-derived long chain omega-3 polyunsaturated fatty acids (n-3 PUFA).

OBJECTIVE

We conducted a clinical trial and in vitro experiments to test our hypothesis that n-3 PUFA suppress NLRP3 inflammasome in human obesity through downregulation of inflammasome gene expression in adipocytes and macrophages.

DESIGN

Placebo-controlled clinical trial and in vitro coculture experiments with primary human adipocytes (from biopsy specimens) and human THP-1 monocyte-derived macrophages treated with eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) vs vehicle control.

SETTING

General community, research laboratory.

PATIENTS AND OTHER PARTICIPANTS

Obese (body mass index ≥ 30 kg/m2), nondiabetic males and females age 18 to 50. N = 25.

INTERVENTIONS

Clinical trial: Eight-week treatment with 4 g Lovaza (EPA and DHA) or placebo. Cells culture: EPA and/or DHA at 100 µg/mL or vehicle control in culture medium.

MAIN OUTCOME MEASURES

Adipose tissue or adipocyte/macrophage mRNA expression of IL-1β and IL-18 and circulating IL-18 levels.

RESULTS

Treatment of obese human subjects with fish oil supplements reduced expression of adipose inflammatory genes including inflammasome-associated IL-18 and IL-1β and circulating IL-18 levels. Both EPA and DHA reduced inflammasome gene expression in obese human adipose and human adipocyte and macrophages.

CONCLUSIONS

N-3 PUFA reduce NLRP3 inflammasome in human adipose through downregulation of gene expression in adipocytes and monocytes/macrophages and has potential as nutritional therapeutic agent in prevention of obesity-related inflammation.

Dietary fat and risk of type 2 diabetes

PURPOSE OF REVIEW

Nutrition recommendations emphasize that not only dietary fat quantity but also fat quality plays a role in the prevention of type 2 diabetes (T2D). The aim of this review is to summarize the evidence for dietary fat and risk of T2D, to highlight recent findings and point out future research directions.

RECENT FINDINGS

Total fat intake was not associated with risk of T2D, whereas the findings on fatty acids (FAs) and risk of T2D were controversial. Recent findings suggested that FAs from the same classes (e.g. omega-6 FAs) but different sources might be differently associated with the risk of T2D, with indication for an association with lower risk of T2D for plant-based and higher risk/no association for animal-based FAs. In addition, differences between populations from different geographic areas might exist, but no interaction effects for fat intake and genetic predisposition were observed regarding T2D risk. The simultaneous investigation of different fats and dietary patterns can provide important and meaningful insights into these associations.

SUMMARY

The evidence for the association between dietary fat intake and risk of T2D is not conclusive yet. To strengthen the evidence, the complexity of the different associations of dietary fats should be considered in well conducted future studies.

Diabetes escalates knee osteoarthritis in rats: Evidence of adaptive mechanism

Clinical reports on the coexistence of diabetes mellitus (DM) and osteoarthritis (OA) dated back to the 1960 s. Therefore, the study investigated the effects of induced DM and/or knee osteoarthritis (KOA) on known biomarkers in male Wistar rats. Twenty rats of five animals per group were induced with DM and/or knee OA using streptozotocin plus nicotinamide and sodium monoiodoacetate. Afterwards, they were left untreated for four weeks.The results showed that pro-inflammatory and pro-oxidative events were most significantly expressed in D + OA group and least in OA group. In contrast to the other experimental groups, there was a decreased bone formation in DM group.Unexpectedly, there were significant increases in bone and cartilage degradation markers in diabetic group, relative to D + OA group. In conclusion, diabetic-osteoarthritic state is characterised by more altered biochemical profile, relative to what is probable in either disease condition. Nevertheless, this situation remains subject to the influence of endogenous homeostatic mechanisms.

Red meat, diseases, and healthy alternatives: A critical review

Meat is an important food for human nutrition, by especially providing high-quality protein and also some essential micronutrients, in front iron, zinc, and vitamin B₁₂. However, a high intake of red and processed meat is associated with an increased risk for diseases, especially type 2 diabetes and colorectal cancer, as several epidemiological studies and meta-analyses have shown. This review summarizes meta-analyses of publications studying the association between red and processed meat intake and type 2 diabetes, cardiovascular diseases, colorectal and other cancers, and all-cause mortality. Various potential mechanisms involved in the increased disease risk are discussed. Furthermore, the beneficial effects of healthy alternatives for meat, like fish, nuts, vegetables and fruits, pulses and legumes, whole grains, and dairy products are reviewed by including selected papers and recent meta-analyses.

Gene-Diet Interactions in Type 2 Diabetes: The Chicken and Egg Debate

Consistent evidence from both experimental and human studies indicates that Type 2 diabetes mellitus (T2DM) is a complex disease resulting from the interaction of genetic, epigenetic, environmental, and lifestyle factors. Nutrients and dietary patterns are important environmental factors to consider in the prevention, development and treatment of this disease. Nutritional genomics focuses on the interaction between bioactive food components and the genome and includes studies of nutrigenetics, nutrigenomics and epigenetic modifications caused by nutrients. There is evidence supporting the existence of nutrient-gene and T2DM interactions coming from animal studies and family-based intervention studies. Moreover, many case-control, cohort, cross-sectional cohort studies and clinical trials have identified relationships between individual genetic load, diet and T2DM. Some of these studies were on a large scale. In addition, studies with animal models and human observational studies, in different countries over periods of time, support a causative relationship between adverse nutritional conditions during in utero development, persistent epigenetic changes and T2DM. This review provides comprehensive information on the current state of nutrient-gene interactions and their role in T2DM pathogenesis, the relationship between individual genetic load and diet, and the importance of epigenetic factors in influencing gene expression and defining the individual risk of T2DM.

Higher Maternal Dietary Protein Intake Is Associated with a Higher Risk of Gestational Diabetes Mellitus in a Multiethnic Asian Cohort

Background: Dietary protein may affect glucose metabolism through several mechanisms, but results from studies on dietary protein intake and risk of gestational diabetes mellitus (GDM) have been inconsistent.Objective: We examined the cross-sectional associations of dietary protein intake from different food sources during pregnancy with the risk of GDM in a multiethnic Asian population.Methods: We included 980 participants with singleton pregnancies from the Growing Up in Singapore Toward healthy Outcomes (GUSTO) cohort. Protein intake was ascertained from 24-h dietary recall and 3-d food diaries at 26-28 wk gestation. GDM was defined as fasting glucose ≥7.0 mmol/L and/or 2-h postload glucose ≥7.8 mmol/L at 26-28 wk gestation. We evaluated the association of dietary protein intake with GDM risk by substituting carbohydrate with protein in an isocaloric model with the use of multivariable logistic regression analysis.Results: The prevalence of GDM was 17.9% among our participants. After adjustment for potential confounders, a higher total dietary protein intake was associated with a higher risk of GDM; the OR comparing the highest with the lowest quartile of intake was 2.15 (95% CI: 1.27, 3.62; P-trend = 0.016). Higher intake levels of both animal protein (OR: 2.87; 95% CI: 1.58, 5.20; P-trend = 0.001) and vegetable protein (OR: 1.78; 95% CI: 0.99, 3.20; P-trend = 0.009) were associated with a higher risk of GDM. Among the animal protein sources, higher intake levels of seafood protein (OR: 2.17; 95% CI: 1.26, 3.72; P-trend = 0.023) and dairy protein (OR: 1.87; 95% CI: 1.11, 3.15; P-trend = 0.017) were significantly associated with a higher GDM risk.Conclusion: Higher intake levels of both animal and vegetable protein were associated with a higher risk of GDM in Asian women. This trial was registered at clinicaltrials.gov as NCT01174875.

Association between omega-3 fatty acids consumption and the risk of type 2 diabetes: A meta-analysis of cohort studies

Aims/Introduction

Epidemiological evidence for the effect of omega‐3 fatty acids on the risk of type 2 diabetes is controversial. A meta‐analysis based on prospective cohorts was carried out to evaluate this issue.

Materials and Methods

Pooled diabetic risk was calculated using a fixed or random effects model. The dose–response relationship was assessed by meta‐regression analysis.

Results

The study showed that consumption of single omega‐3 was associated with an increased risk of type 2 diabetes (relative risk [RR] = 1.45, P < 0.001); whereas the RR for mixed omega‐3 was statistically insignificant. The dose–response curve presented an inverted U‐shape of diabetes risk corresponding to the dose of omega‐3 consumption. Subanalysis showed that omega‐3 was inversely associated with type 2 diabetes risk in Asians (RR = 0.82, P < 0.001); whereas the risk was increased in Westerners (RR = 1.30, P < 0.001). Studies with follow‐up duration ≥16 years and baseline age ≥54 years showed a positive association between type 2 diabetes risk and omega‐3 intake.

Conclusions

The present findings suggest that dosage and composition of omega‐3, ethnicity, trial duration, and age could influence the effect of omega‐3 on type 2 diabetes progression.

Application of seaweeds to develop new food products with enhanced shelf-life, quality and health-related beneficial properties

Edible seaweeds are a good source of antioxidants, dietary fibers, essential amino acids, vitamins, phytochemicals, polyunsaturated fatty acids, and minerals. Many studies have evaluated the gelling, thickening and therapeutic properties of seaweeds when they are used individually. This review gives an overview on the nutritional, textural, sensorial, and health-related properties of food products enriched with seaweeds and seaweed extracts. The effect of seaweed incorporation on properties of meat, fish, bakery, and other food products were highlighted in depth. Moreover, the positive effects of foods enriched with seaweeds and seaweed extracts on different lifestyle diseases such as obesity, dyslipidemia, hypertension, and diabetes were also discussed. The results of the studies demonstrated that the addition of seaweeds, in powder or extract form, can improve the nutritional and textural properties of food products. Additionally, low-fat products with less calories and less saturated fatty acids can be prepared using seaweeds. Moreover, the addition of seaweeds also affected the health properties of food products. The results of these studies demonstrated that the health value, shelf-life and overall quality of foods can be improved through the addition of either seaweeds or seaweed extracts.

Emerging Evidence for the Importance of Dietary Protein Source on Glucoregulatory Markers and Type 2 Diabetes: Different Effects of Dairy, Meat, Fish, Egg, and Plant Protein Foods

Observational studies provide evidence that a higher intake of protein from plant-based foods and certain animal-based foods is associated with a lower risk for type 2 diabetes. However, there are few distinguishable differences between the glucoregulatory qualities of the proteins in plant-based foods, and it is likely their numerous non-protein components (e.g., fibers and phytochemicals) that drive the relationship with type 2 diabetes risk reduction. Conversely, the glucoregulatory qualities of the proteins in animal-based foods are extremely divergent, with a higher intake of certain animal-based protein foods showing negative effects, and others showing neutral or positive effects on type 2 diabetes risk. Among the various types of animal-based protein foods, a higher intake of dairy products (such as milk, yogurt, cheese and whey protein) consistently shows a beneficial relationship with glucose regulation and/or type 2 diabetes risk reduction. Intervention studies provide evidence that dairy proteins have more potent effects on insulin and incretin secretion compared to other commonly consumed animal proteins. In addition to their protein components, such as insulinogenic amino acids and bioactive peptides, dairy products also contain a food matrix rich in calcium, magnesium, potassium, trans-palmitoleic fatty acids, and low-glycemic index sugars-all of which have been shown to have beneficial effects on aspects of glucose control, insulin secretion, insulin sensitivity and/or type 2 diabetes risk. Furthermore, fermentation and fortification of dairy products with probiotics and vitamin D may improve a dairy product's glucoregulatory effects.

Sex-dependent association between erythrocyte n-3 PUFA and type 2 diabetes in older overweight people

The association between n-3 PUFA intake and type 2 diabetes (T2D) is unclear, and studies relating objective biomarkers of n-3 PUFA consumption to diabetic status remain limited. The aim of this study was to determine whether erythrocyte n-3 PUFA levels (n-3 index; n-3I) are associated with T2D in a cohort of older adults (n 608). To achieve this, the n-3I (erythrocyte %EPA+%DHA) was determined by GC and associated with fasting blood glucose; HbA1c; and plasma insulin. Insulin resistance (IR) was assessed using the homeostatic model assessment of insulin resistance (HOMA--IR). OR for T2D were calculated for each quartile of n-3I. In all, eighty-two type 2 diabetic (46·3 % female; 76·7 (sd 5·9) years) and 466 non-diabetic (57·9 % female; 77·8 (sd 7·1) years) individuals were included in the analysis. In overweight/obese (BMI≥27 kg/m2), the prevalence of T2D decreased across ascending n-3I quartiles: 1·0 (reference), 0·82 (95 % CI 0·31, 2·18), 0·56 (95 % CI 0·21, 1·52) and 0·22 (95 % CI 0·06, 0·82) (P trend=0·015). A similar but non-significant trend was seen in overweight men. After adjusting for BMI, no associations were found between n-3I and fasting blood glucose, HbA1c, insulin or HOMA-IR. In conclusion, higher erythrocyte n-3 PUFA status may be protective against the development of T2D in overweight women. Further research is warranted to determine whether dietary interventions that improve n-3 PUFA status can improve measures of IR, and to further elucidate sex-dependent differences.

Red Blood Cell Fatty Acids and Incident Diabetes Mellitus in the Women's Health Initiative Memory Study

Context

The relations between dietary and/or circulating levels of fatty acids and the development of type 2 diabetes is unclear. Protective associations with the marine omega-3 fatty acids and linoleic acid, and with a marker of fatty acid desaturase activity delta-5 desaturase (D5D ratio) have been reported, as have adverse relations with saturated fatty acids and D6D ratio.

Objective

To determine the associations between red blood cell (RBC) fatty acid distributions and incident type 2 diabetes.

Design

Prospective observational cohort study nested in the Women’s Health Initiative Memory Study.

Setting

General population.

Subjects

Postmenopausal women.

Main Outcome Measures

Self-reported incident type 2 diabetes.

Results

There were 703 new cases of type 2 diabetes over 11 years of follow up among 6379 postmenopausal women. In the fully adjusted models, baseline RBC D5D ratio was inversely associated with incident type 2 diabetes [Hazard Ratio (HR) 0.88, 95% confidence interval (CI) 0.81–0.95) per 1 SD increase. Similarly, baseline RBC D6D ratio and palmitic acid were directly associated with incident type 2 diabetes (HR 1.14, 95% CI 1.04–1.25; and HR 1.24, 95% CI 1.14–1.35, respectively). None of these relations were materially altered by excluding incident cases in the first two years of follow-up. There were no significant relations with eicosapentaenoic, docosahexaenoic or linoleic acids.

Conclusions

Whether altered fatty acid desaturase activities or palmitic acid levels are causally related to the development of type 2 diabetes cannot be determined from this study, but our findings suggest that proportions of certain fatty acids in RBC membranes are associated with risk for type 2 diabetes.

Interaction of low dose of fish oil and glucocorticoids on insulin sensitivity and lipolysis in healthy humans: A randomized controlled study

SCOPE

This study examined the interaction of fish oil (FO) with dexamethasone on glucose and lipid metabolisms in healthy subjects.

METHODS AND RESULTS

The study included two consecutive parts. Part A (randomized) in 16 subjects studied the effects of dexamethasone (2 days, 2 mg/day) versus placebo (lactose), part B (two parallel subgroups of eight) studied the interaction of FO (3 wk, 840 mg/day of EPA + DHA) with dexamethasone. Insulin sensitivity of lipolysis (d5-glycerol infusion + microdialysis), endogenous glucose production, and muscle glucose uptake were assessed by a three-step hot insulin clamp and substrate oxidation by indirect calorimetry. Dexamethasone induced liver and peripheral insulin resistance, an increase in fat oxidation, and a decrease in suppression of plasma nonesterified fatty acids (NEFAs). FO amplified the effects of dexamethasone by increasing liver and muscle insulin resistance, by reducing suppression of plasma NEFAs and fat oxidation and by increasing adipose tissue (AT) lipolysis.

CONCLUSION

FO, given at a moderate dose in healthy subjects prior to a very short-term (2 days) low dose of a synthetic glucocorticoid, worsened its deleterious effects on insulin sensitivity. The enhancing effect of FO on fat oxidation and AT lipolysis might be a protective effect toward an increase in fat mass.

Dietary and Policy Priorities for Cardiovascular Disease, Diabetes, and Obesity: A Comprehensive Review

Suboptimal nutrition is a leading cause of poor health. Nutrition and policy science have advanced rapidly, creating confusion yet also providing powerful opportunities to reduce the adverse health and economic impacts of poor diets. This review considers the history, new evidence, controversies, and corresponding lessons for modern dietary and policy priorities for cardiovascular diseases, obesity, and diabetes mellitus. Major identified themes include the importance of evaluating the full diversity of diet-related risk pathways, not only blood lipids or obesity; focusing on foods and overall diet patterns, rather than single isolated nutrients; recognizing the complex influences of different foods on long-term weight regulation, rather than simply counting calories; and characterizing and implementing evidence-based strategies, including policy approaches, for lifestyle change. Evidence-informed dietary priorities include increased fruits, nonstarchy vegetables, nuts, legumes, fish, vegetable oils, yogurt, and minimally processed whole grains; and fewer red meats, processed (eg, sodium-preserved) meats, and foods rich in refined grains, starch, added sugars, salt, and trans fat. More investigation is needed on the cardiometabolic effects of phenolics, dairy fat, probiotics, fermentation, coffee, tea, cocoa, eggs, specific vegetable and tropical oils, vitamin D, individual fatty acids, and diet-microbiome interactions. Little evidence to date supports the cardiometabolic relevance of other popular priorities: eg, local, organic, grass-fed, farmed/wild, or non-genetically modified. Evidence-based personalized nutrition appears to depend more on nongenetic characteristics (eg, physical activity, abdominal adiposity, gender, socioeconomic status, culture) than genetic factors. Food choices must be strongly supported by clinical behavior change efforts, health systems reforms, novel technologies, and robust policy strategies targeting economic incentives, schools and workplaces, neighborhood environments, and the food system. Scientific advances provide crucial new insights on optimal targets and best practices to reduce the burdens of diet-related cardiometabolic diseases.

Associations between intake of fish and n-3 long-chain polyunsaturated fatty acids and plasma metabolites related to the kynurenine pathway in patients with coronary artery disease

PURPOSE

Enhanced tryptophan degradation via the kynurenine pathway has been related to several pathological conditions. However, little is known about the effect of diet on individual metabolites of this pathway. We investigated cross-sectional associations between reported intake of fish and omega-3 (n-3) long-chain PUFA (LC-PUFA) and plasma metabolites related to the kynurenine pathway.

METHODS

Participants were 2324 individuals with coronary artery disease from the Western Norway B Vitamin Intervention Trial. Fish and n-3 LC-PUFA intakes were assessed using a food frequency questionnaire. Plasma concentrations of tryptophan, kynurenine, kynurenic acid, anthranilic acid, 3-hydroxykynurenine, xanthurenic acid, 3-hydroxyanthranilic acid, neopterin, and kynurenine-to-tryptophan ratio (KTR) were analyzed. Associations were investigated using partial Spearman's rank correlations and multiple linear regressions.

RESULTS

Median age at inclusion was 62 years (80 % males), and 84 % had stable angina pectoris. Intake of fatty fish and n-3 LC-PUFA was inversely associated with plasma 3-hydroxykynurenine. Consumption of total fish, lean fish, and n-3 LC-PUFA was inversely associated with plasma neopterin. Intake of total fish, fatty fish, and n-3 LC-PUFA was inversely associated with KTR. All these correlations were weak (ρ between -0.12 and -0.06, P < 0.01). In 306 patients with diabetes, lean fish intake was positively associated with plasma 3-hydroxyanthranilic acid (ρ = 0.22, P < 0.001, P for interaction = 0.01), and total fish intake was inversely associated with KTR (ρ = -0.17, P < 0.01, P for interaction = 0.02).

CONCLUSION

Fish intake was not an important determinant of individual metabolites in the kynurenine pathway. However, some correlations were stronger in patients with diabetes. The inverse associations of fish or n-3 LC-PUFA with neopterin and KTR may suggest a slightly lower IFN-γ-mediated immune activation with a higher intake.

Effects of Omega-3 Fatty Acid Supplementation on Glucose Control and Lipid Levels in Type 2 Diabetes: A Meta-Analysis

Background

Many studies assessed the impact of marine omega-3 fatty acids on glycemic homeostasis and lipid profiles in patients with type 2 diabetes (T2DM), but reported controversial results. Our goal was to systematically evaluate the effects of omega-3 on glucose control and lipid levels.

Methods

Medline, Pubmed, Cochrane Library, Embase, the National Research Register, and SIGLE were searched to identify eligible randomized clinical trials (RCTs). Extracted data from RCTs were analyzed using STATA 11.0 statistical software with fixed or random effects model. Effect sizes were presented as weighted mean differences (WMD) with 95% confidence intervals (95% CI). Heterogeneity was assessed using the Chi-square test with significance level set at p < 0.1.

Results

20 RCT trials were included into this meta-analysis. Among patients with omega-3 supplementation, triglyceride (TG) levels were significantly decreased by 0.24 mmol/L. No marked change in total cholesterol (TC), HbA1c, fasting plasma glucose, postprandial plasma glucose, BMI or body weight was observed. High ratio of EPA/DHA contributed to a greater decreasing tendency in plasma insulin, HbAc1, TC, TG, and BMI measures, although no statistical significance was identified (except TG). FPG levels were increased by 0.42 mmol/L in Asians. No evidence of publication bias was observed in this meta-analysis.

Conclusions

The ratio of EPA/DHA and early intervention with omega 3 fatty acids may affect their effects on glucose control and lipid levels, which may serve as a dietary reference for clinicians or nutritionists who manage diabetic patients.

Do we need 'new' omega-3 polyunsaturated fatty acids formulations?

The therapeutic value of omega-3 polyunsaturated fatty acids (PUFAs), mainly (but not only) found in fish oils, eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), has been extensively studied in a wide variety of disease conditions, predominantly in cardiovascular disease. However, the significant difference in efficacy observed in various conditions with different dosages seems to be at least partly related to the large discrepancy in quality of the product and to the bioavailability of the omega-3 PUFA. The research of new sources (e.g., from arctic Krill oil) and pharmaceutical forms of omega-3 PUFA (e.g., omega-3 carboxylic acids) is needed in order to detect the one with the best bioavailability and efficacy, and with a parallel reduction in the production costs. There is also the need to understand if long-term PUFA supplementation could increase the efficacy of the already-available evidence-based therapies for cardiovascular disease prevention and for the management of the diseases where the use of PUFA could have a possible improving effect.

Serum carbon and nitrogen stable isotopes as potential biomarkers of dietary intake and their relation with incident type 2 diabetes: the EPIC-Norfolk study

BACKGROUND

Stable-isotope ratios of carbon (¹³C/¹²C, expressed as δ¹³C) and nitrogen (¹⁵N/¹⁴N, or δ¹⁵N) have been proposed as potential nutritional biomarkers to distinguish between meat, fish, and plant-based foods.

OBJECTIVE

The objective was to investigate dietary correlates of δ¹³C and δ¹⁵N and examine the association of these biomarkers with incident type 2 diabetes in a prospective study.

DESIGN

Serum δ¹³C and δ¹⁵N (‰) were measured by using isotope ratio mass spectrometry in a case-cohort study (n = 476 diabetes cases; n = 718 subcohort) nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population-based cohort. We examined dietary (food-frequency questionnaire) correlates of δ¹³C and δ¹⁵N in the subcohort. HRs and 95% CIs were estimated by using Prentice-weighted Cox regression.

RESULTS

Mean (±SD) δ¹³C and δ¹⁵N were -22.8 ± 0.4‰ and 10.2 ± 0.4‰, respectively, and δ¹³C (r = 0.22) and δ¹⁵N (r = 0.20) were positively correlated (P < 0.001) with fish protein intake. Animal protein was not correlated with δ¹³C but was significantly correlated with δ¹⁵N (dairy protein: r = 0.11; meat protein: r = 0.09; terrestrial animal protein: r = 0.12, P ≤ 0.013). δ¹³C was inversely associated with diabetes in adjusted analyses (HR per tertile: 0.74; 95% CI: 0.65, 0.83; P-trend < 0.001], whereas δ¹⁵N was positively associated (HR: 1.23; 95% CI: 1.09, 1.38; P-trend = 0.001).

CONCLUSIONS

The isotope ratios δ¹³C and δ¹⁵N may both serve as potential biomarkers of fish protein intake, whereas only δ¹⁵N may reflect broader animal-source protein intake in a European population. The inverse association of δ¹³C but a positive association of δ¹⁵N with incident diabetes should be interpreted in the light of knowledge of dietary intake and may assist in identifying dietary components that are associated with health risks and benefits.

The EPIC-InterAct Study: A Study of the Interplay between Genetic and Lifestyle Behavioral Factors on the Risk of Type 2 Diabetes in European Populations

The rising prevalence of type 2 diabetes around the world and the global pattern of variation in risk between countries have been widely attributed to an interplay between rising rates of obesity and poor lifestyles, and genetic or developmental susceptibility to disease. Although this general hypothesis has been in existence for more than 50 years, the precise mechanisms that may explain it have remained uncertain. Advances in technology and the application of new methods in large scale population studies have made it possible to study these mechanisms. The InterAct project, funded by the European Commission, is a large case-cohort study which has verified 12,403 incident cases of type 2 diabetes, facilitating the study of genetic and lifestyle factors on the risk of type 2 diabetes among European populations.