An oily fish diet increases insulin sensitivity compared to a red meat diet in young iron-deficient women

Retracted article: The effects of fish oil omega-3 fatty acid supplementation on mental health parameters and metabolic status of patients with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial

We, the Editor and Publisher of the Journal of Psychosomatic Obstetrics & Gynecology have retracted the following article:Mehrdad Amini, Fereshteh Bahmani, Fatemeh Foroozanfard, Zahra Vahedpoor, Amir Ghaderi, Mohsen Taghizadeh, Hassan Karbassizadeh & Zatollah Asemi (2018), The effects of fish oil omega-3 fatty acid supplementation on mental health parameters and metabolic status of patients with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial. Journal of Psychosomatic Obstetrics & Gynecology, DOI: 10.1080/0167482X.2018.1508282.Following publication, significant concerns were raised by a third party 1 about the integrity of the data and the reported findings in the article.When approached for an explanation, the authors and their institution have been cooperative in providing some responses and documents. To verify the reported findings, the article and the documents provided by the authors were further evaluated by the journal editorial team, and also sent for review by an external statistical reviewer.Both the journal editorial team and the external statistical reviewer were unable to confirm the integrity of the trial design and the main outcome of the external review was that the article's results and conclusions are unreliable. Therefore, as the editorial team no longer have confidence in the reported conclusions the decision has been made to retract the article.The authors listed in the publication have been informed. The authors do not agree with the retraction.We have been informed in our decision-making by our editorial policies and the COPE guidelines.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted'.

Red meat consumption and risk factors for type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVES

Results from observational studies suggest an association of red meat intake with risk of type 2 diabetes mellitus (T2D). However, results from randomized controlled trials (RCTs) have not clearly supported a mechanistic link between red meat intake and T2D risk factors. Therefore, a systematic review and meta-analysis were conducted on RCTs evaluating the effects of diets containing red meat (beef, pork, lamb, etc.), compared to diets with lower or no red meat, on markers of glucose homeostasis in adults.

METHODS

A search of PubMed and CENTRAL yielded 21 relevant RCTs. Pooled estimates were expressed as standardized mean differences (SMDs) between the red meat intervention and the comparator intervention with less or no red meat.

RESULTS

Compared to diets with reduced or no red meat intake, there was no significant impact of red meat intake on insulin sensitivity (SMD: -0.11; 95% CI: -0.39, 0.16), insulin resistance (SMD: 0.11; 95% CI: -0.24, 0.45), fasting glucose (SMD: 0.13; 95% CI: -0.04, 0.29), fasting insulin (SMD: 0.08; 95% CI: -0.16, 0.32), glycated hemoglobin (HbA1c; SMD: 0.10; 95% CI: -0.37, 0.58), pancreatic beta-cell function (SMD: -0.13; 95% CI: -0.37, 0.10), or glucagon-like peptide-1 (GLP-1; SMD: 0.10; 95% CI: -0.37, 0.58). Red meat intake modestly reduced postprandial glucose (SMD: -0.44; 95% CI: -0.67, -0.22; P < 0.001) compared to meals with reduced or no red meat intake. The quality of evidence was low to moderate for all outcomes.

CONCLUSIONS

The results of this meta-analysis suggest red meat intake does not impact most glycemic and insulinemic risk factors for T2D. Further investigations are needed on other markers of glucose homeostasis to better understand whether a causal relationship exists between red meat intake and risk of T2D.

PROSPERO REGISTRATION

CRD42020176059.

Effects of Total Red Meat Intake on Glycemic Control and Inflammatory Biomarkers: A Meta-Analysis of Randomized Controlled Trials

Our objective was to conduct a systematic review and meta-analysis to assess the effects of total red meat (TRM) intake on glycemic control and inflammatory biomarkers using randomized controlled trials of individuals free from cardiometabolic disease. We hypothesized that higher TRM intake would negatively influence glycemic control and inflammation based on positive correlations between TRM and diabetes. We found 24 eligible articles (median duration, 8 weeks) from 1172 articles searched in PubMed, Cochrane, and CINAHL up to August 2019 that included 1) diet periods differing in TRM; 2) participants aged ≥19 years; 3) included either men or women who were not pregnant/lactating; 4) no diagnosed cardiometabolic disease; and 5) data on fasting glucose, insulin, HOMA-IR, glycated hemoglobin (HbA1c), C-reactive protein (CRP), or cytokines. We used 1) a repeated-measures ANOVA to assess pre to post diet period changes; 2) random-effects meta-analyses to compare pre to post changes between diet periods with ≥ vs. <0.5 servings (35g)/day of TRM; and 3) meta-regressions for dose-response relationships. We grouped diet periods to explore heterogeneity sources, including risk of bias, using the National Heart, Lung, and Blood Institute's Quality Assessment of Controlled Interventions Studies. Glucose, insulin, and HOMA-IR values decreased, while HbA1c and CRP values did not change during TRM or alternative diet periods. There was no difference in change values between diet periods with ≥ vs. <0.5 servings/day of TRM [weighted mean differences (95% CIs): glucose, 0.040 mmol/L (-0.049, 0.129); insulin, -0.710 pmol/L (-6.582, 5.162); HOMA-IR, 0.110 (-0.072, 0.293); CRP, 2.424 nmol/L (-1.460, 6.309)] and no dose response relationships (P > 0.2). Risk of bias (85% of studies were fair to good) did not influence results. Total red meat consumption, for up to 16 weeks, does not affect changes in biomarkers of glycemic control or inflammation for adults free of, but at risk for, cardiometabolic disease. This trial was registered at PROSPERO as 2018 CRD42018096031.

Food groups and intermediate disease markers: a systematic review and network meta-analysis of randomized trials

Background

In previous meta-analyses of prospective observational studies, we investigated the association between food groups and risk of chronic disease.

Objective

The aim of the present network meta-analysis (NMA) was to assess the effects of these food groups on intermediate-disease markers across randomized intervention trials.

Design

Literature searches were performed until January 2018. The following inclusion criteria were defined a priori: 1) randomized trial (≥4 wk duration) comparing ≥2 of the following food groups: refined grains, whole grains, nuts, legumes, fruits and vegetables, eggs, dairy, fish, red meat, and sugar-sweetened beverages (SSBs); 2) LDL cholesterol and triacylglycerol (TG) were defined as primary outcomes; total cholesterol, HDL cholesterol, fasting glucose, glycated hemoglobin, homeostasis model assessment insulin resistance, systolic and diastolic blood pressure, and C-reactive protein were defined as secondary outcomes. For each outcome, a random NMA was performed, and for the ranking, the surface under the cumulative ranking curves (SUCRA) was determined.

Results

A total of 66 randomized trials (86 reports) comparing 10 food groups and enrolling 3595 participants was identified. Nuts were ranked as the best food group at reducing LDL cholesterol (SUCRA: 93%), followed by legumes (85%) and whole grains (70%). For reducing TG, fish (97%) was ranked best, followed by nuts (78%) and red meat (72%). However, these findings are limited by the low quality of the evidence. When combining all 10 outcomes, the highest SUCRA values were found for nuts (66%), legumes (62%), and whole grains (62%), whereas SSBs performed worst (29%).

Conclusion

The present NMA provides evidence that increased intake of nuts, legumes, and whole grains is more effective at improving metabolic health than other food groups. For the credibility of diet-disease relations, high-quality randomized trials focusing on well-established intermediate-disease markers could play an important role. This systematic review was registered at PROSPERO (www.crd.york.ac.uk/PROSPERO) as CRD42018086753.

The Effects of Flaxseed Oil Omega-3 Fatty Acids Supplementation on Metabolic Status of Patients with Polycystic Ovary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial

Objective This study was conducted to evaluate the effects of flaxseed oil omega-3 fatty acids supplementation on metabolic status of patients with polycystic ovary syndrome (PCOS).

Methods This randomized double-blind, placebo-controlled trial was conducted on 60 women with PCOS according to the Rotterdam criteria aged 18–40 years old. Participants were randomly assigned into two groups to receive either 1,000 mg flaxseed oil omega-3 fatty acids (n=30) or placebo (n=30) twice a day for 12 weeks. Metabolic, endocrine, inflammatory factors were quantified at baseline and after the 12-week intervention.

Results After the 12-week intervention, compared to the placebo, flaxseed oil omega-3 supplementation significantly decreased insulin values (−2.6±7.7 vs.+1.3±3.9 µIU/mL, P=0.01), homeostasis model of assessment-estimated insulin resistance (−0.7±1.7 vs.+0.3±0.9, P=0.01), mF-G scores (−1.2±1.7 vs. -0.1±0.4, P=0.001), and increased quantitative insulin sensitivity check index (+0.01±0.02 vs. −0.01±0.02, P=0.01). In addition, supplementation with flaxseed oil omega-3 resulted in significant decreases in serum triglycerides (−5.1±20.9 vs.+9.7±26.1 mg/dL, P=0.01), VLDL-cholesterol (−1.0±4.2 vs.+1.9±5.2 mg/dL, P=0.01) and high-sensitivity C-reactive protein (hs-CRP) (−1.6±3.1 vs.+0.2±1.5 mg/L, P=0.004) compared to the placebo. We did not see any significant effect of flaxseed oil omega-3 supplementation on hormonal and other lipid profiles, and plasma nitric oxide levels.

Conclusions Overall, flaxseed oil omega-3 supplementation for 12 weeks in women with PCOS had beneficial effects on insulin metabolism, mF-G scores, serum triglycerides, VLDL-cholesterol and hs-CRP levels, but did not affect hormonal and other lipid profiles, and plasma nitric oxide levels.

Animal-Protein Intake Is Associated with Insulin Resistance in Adventist Health Study 2 (AHS-2) Calibration Substudy Participants: A Cross-Sectional Analysis

Background: High intakes of total and animal protein are associated with the risk of type 2 diabetes (T2D). The influence of protein type on insulin resistance, a key precursor of T2D, has not been extensively studied. Objective: The aim of this study was to determine the associations between dietary total, animal, and plant protein intakes as well as the animal-to-plant protein (AP) intake ratio with insulin resistance in middle-aged and older adults. Methods: This was a cross-sectional analysis in 548 participants (mean ± SD age: 66.2 ± 13.7 y) from the calibration substudy of the AHS-2 (Adventist Health Study 2) cohort. Participants consumed diets with a low AP intake ratio. Dietary intakes of total and particular types of protein were calculated from six 24-h dietary recalls. Participants completed a self-administered questionnaire on demographic, lifestyle, health, diet intake, and physical activity characteristics. Anthropometric variables including weight, height, and waist circumference were measured. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated by using fasting serum glucose and insulin. Multiple linear regression models were used to test the relations between total and specific protein intakes with insulin resistance. Results: The ranges of dietary intakes of animal and plant protein and the AP intake ratio were 0.4-87.4 and 14.0-79.2 g/d and 0.02-4.43, respectively. Dietary intakes per 10-g/d increments of total protein (β: 0.11; 95% CI: 0.02, 0.21) and animal protein (β: 0.11; 95% CI: 0.01, 0.20) and the AP intake ratio (β: 1.82; 95% CI: 0.80, 2.84) were positively related to HOMA-IR. Plant protein was not significantly related to insulin resistance. Conclusion: Total and animal protein intakes and the AP intake ratio were positively associated with HOMA-IR in adults with relatively a low intake of animal protein and a high consumption of plant protein.

Effect of omega-3 fatty acids supplementation on insulin resistance in women with polycystic ovary syndrome: Meta-analysis of randomized controlled trials

BACKGROUND

Several studies have shown that omega-3 polyunsaturated fatty acids (PUFA) may improve insulin resistance in various diseases. However, the possible effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on insulin resistance in PCOS still remains unclear. We evaluated the effect of omega-3 PUFA supplementation on insulin resistance in women with PCOS in a meta-analysis.

METHODS

Literature searches of MEDLINE, PubMed Central and EMBASE for publications in English were conducted up to December 2015. We included all randomized controlled trials (RCTs) that investigated effects of omega-3 fatty acids supplements on insulin resistance in women with PCOS. Results are summarized as mean differences (MD) with 95% confidence intervals (CI). Effect sizes of eligible studies were pooled using random-effects models (the DerSimonian-Laird estimator). We assessed the potential sources of heterogeneity using the standard χ2 test.

RESULTS

Of 1202 papers, three RCTs were eligible for inclusion which involved 72 cases and 73 controls. The dose range for omega3 supplement was 1.2g to 3.6g and the duration of follow-up was from 6 to 8 weeks. There was no significant effect of omega-3 fatty acids supplements compared to placebo on insulin resistance (MD: 6.18; CI; -3.347, 15.382; p=0.208) and HOMA -IR (MD: 0.276; 95% CI=-1.428, 1.981; p=0.751) in women with PCOS.

CONCLUSION

The results provide an evidence that supplementation with omega-3 fatty acids may not have a beneficial effect on improving insulin resistance in women with PCOS.

Consumption of red and processed meat and refined grains for 4weeks decreases insulin sensitivity in insulin-resistant adults: A randomized crossover study

BACKGROUND

Red and processed meat and refined grains are associated with an increased risk of type 2 diabetes. Interventions are limited. We hypothesized that a diet high in red and processed meat and refined grains (HMD) would decrease insulin sensitivity compared to a diet high in whole grains, nuts, dairy and legumes with no red meat (HWD).

METHODS

Forty-nine subjects without diabetes [15 men and 34 women, age, 35.6±15.7 years, body mass index (BMI), 27±5.9kg/m²] underwent two 4-week weight-stable dietary interventions in a randomized crossover design. The insulin sensitivity index (ISI) was calculated from the last 30min of a continuous low-dose insulin (25mU/kg·h) and glucose (4mg/kg·min) infusion test (LDIGIT _120-150min) at the end of each diet.

RESULTS

The population fell into two very discrete groups: those with a very low insulin response in the LDIGIT _120-150min on HMD (Group 1<56pmol/L, n=24), and those with relatively normal insulin responses (Group 2>56pmol/L, n=25). Group 2 had significantly higher insulin concentrations [(median and interquartile range) 153, 180 for HMD vs. 123, 149pmol/L for HWD; P=0.019] and glucose concentrations [(mean±standard deviation) 7.4±1.3 for HMD vs.6.7±1.2mmol/L for HWD; P=0.05], resulting in a significantly decreased ISI [(median and interquartile range) 21.1, 34.2 for HMD vs. 31.6, 39.4 for HWD; P=0.014] compared to HWD. Log ISI after HMD was significantly correlated with BMI (r=-0.5; P=0.009), fat mass (r=-0.55; P=0.004) and self-reported activity levels (r=-0.45; P=0.024).

CONCLUSIONS

A dietary pattern high in red and processed meat and refined grains decreased insulin sensitivity compared to a dietary pattern high in whole grains, nuts, dairy products and legumes only in relatively insulin-resistant adults.

Total red meat intake of ≥0.5 servings/d does not negatively influence cardiovascular disease risk factors: a systemically searched meta-analysis of randomized controlled trials

BACKGROUND

Observational associations between red meat intake and cardiovascular disease (CVD) are inconsistent. There are limited comprehensive analyses of randomized controlled trials (RCTs) that investigate the effects of red meat consumption on CVD risk factors.

OBJECTIVE

The purpose of this systematically searched meta-analysis was to assess the effects of consuming ≥0.5 or <0.5 servings of total red meat/d on CVD risk factors [blood total cholesterol (TC), LDL cholesterol, HDL cholesterol, triglycerides, ratio of TC to HDL cholesterol (TC:HDL), and systolic and diastolic blood pressures (SBP and DBP, respectively)]. We hypothesized that the consumption of ≥0.5 servings of total red meat/d would have a negative effect on these CVD risk factors.

DESIGN

Two researchers independently screened 945 studies from PubMed, Cochrane Library, and Scopus databases and extracted data from 24 qualified RCTs. Inclusion criteria were 1) RCT, 2) subjects aged ≥19 y, 3) consumption of ≥0.5 or <0.5 total red meat servings/d [35 g (1.25 ounces)], and 4) reporting ≥1 CVD risk factor. We performed an adjusted 2-factor nested ANOVA mixed-effects model procedure on the postintervention values of TC, LDL cholesterol, HDL cholesterol, TC:HDL cholesterol, triglycerides, SBP, and DBP; calculated overall effect sizes of change values; and used a repeated-measures ANOVA to assess pre- to postintervention changes.

RESULTS

Red meat intake did not affect lipid-lipoprotein profiles or blood pressure values postintervention (P > 0.05) or changes over time [weighted mean difference (95% CI): -0.01 mmol/L (-0.08, 0.06 mmol/L), 0.02 mmol/L (-0.05, 0.08 mmol/L), 0.03 mmol/L (-0.01, 0.07 mmol/L), and 0.04 mmol/L (-0.02, 0.10 mmol/L); -0.08 mm Hg (-0.26, 0.11 mm Hg); and -1.0 mm Hg (-2.4, 0.78 mm Hg) and 0.1 mm Hg (-1.2, 1.5 mm Hg) for TC, LDL cholesterol, HDL cholesterol, triglycerides, TC:HDL cholesterol, SBP, and DBP, respectively]. Among all subjects, TC, LDL cholesterol, HDL cholesterol, TC:HDL cholesterol, triglycerides, and DBP, but not SBP, decreased over time (P < 0.05).

CONCLUSIONS

The results from this systematically searched meta-analysis of RCTs support the idea that the consumption of ≥0.5 servings of total red meat/d does not influence blood lipids and lipoproteins or blood pressures.

Various Effects of Omega 3 and Omega 3 Plus Vitamin E Supplementations on Serum Glucose Level and Insulin Resistance in Patients with Coronary Artery Disease

BACKGROUND

Omega 3 and vitamin E are two critical nutrients which include beneficial effects in coronary artery disease (CAD). The aim of this study was to assess the effects of omega 3 alone supplementation or in combination with vitamin E on serum glucose and lipid levels and insulin resistance in CAD patients.

METHODS

Participants of this clinical trial included 60 male patients with CAD who selected from Tehran Heart Center in Tehran, Iran in 2014. They received 4 g/day omega 3 plus 400 IU/day vitamin E (OE), 4 g/day omega 3 with vitamin E placebo (OP), or omega 3 and vitamin E placebo (PP) for two months. Serum glucose, lipids and insulin were assessed and HOMA-IR was calculated before and after the trial and effects of these nutrients on the highlighted parameters were compared within the study groups.

RESULTS

Serum glucose level increased significantly in OP group (P=0.004), but not in OE group. OE and OP groups showed a significant decrease in fasting serum TG (P=0.020 and P=0.001, respectively). Serum insulin and HOMA-IR decreased significantly in OE group (P=0.044 and P=0.039, respectively) but did not change significantly in OP group.

CONCLUSION

Although, omega 3 supplementation may include adverse effects on serum glucose level, co-administration of omega 3 and vitamin E can beneficially decrease serum insulin and insulin resistance in CAD patients.

Do ω-3 PUFAs affect insulin resistance in a sex-specific manner? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Evidence has suggested that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) improve obesity-induced insulin resistance (IR); however, results from human intervention trials have been equivocal. Recently it has been reported that n-3 PUFA status is inversely associated with type 2 diabetes in women but not in men, suggesting a sex-dependent effect.

OBJECTIVE

We aimed to determine whether n-3 PUFA interventions affect IR in a sex-dependent manner.

DESIGN

Five databases were searched (Medline, EMBASE, CINAHL, Scopus, and Pre-Medline) for randomized controlled trials. Searches were limited to the English language and to studies with adults aged >18 y. When possible, studies were pooled for a meta-analysis. The principle summary measure was the standardized mean difference (SMD) between groups.

RESULTS

Thirty-one eligible trials were identified with a total of 1848 participants [men: 45.1%; weighted mean ± SD age: 52.5 ± 8.2 y; weighted body mass index (in kg/m²): 28.8 ± 3.0]. Seven studies were conducted in women, 4 studies were conducted in men, and the remaining studies pooled men and women together. Twenty-six trials were pooled for the meta-analysis (men: n = 2; women: n = 6). With all studies (n = 26) pooled, there was no effect of n-3 PUFA on IR at the group level (SMD: 0.089; 95% CI: -0.105, 0.283; P = 0.367). In trials of ≥6 wk, a significant improvement in IR was seen in women (SMD: -0.266; 95% CI: -0.524, -0.007; P = 0.045) but not in men (SMD: 0.619; 95% CI: -0.583, 1.820; P = 0.313).

CONCLUSIONS

With this analysis, we provide preliminary evidence of a sex-dependent response of IR to an n-3 PUFA intervention. Additional studies are needed to confirm sex-dependent associations and to elucidate the potential mechanisms that are involved. This trial was registered at www.crd.york.ac.uk/PROSPERO/ as CRD42015017940.

Effects of sardine-enriched diet on metabolic control, inflammation and gut microbiota in drug-naïve patients with type 2 diabetes: a pilot randomized trial

BACKGROUND

Nutrition therapy is the cornerstone of treating diabetes mellitus. The inclusion of fish (particularly oily fish) at least two times per week is recommended by current international dietary guidelines for type 2 diabetes. In contrast to a large number of human studies examining the effects of oily fish on different cardiovascular risk factors, little research on this topic is available in patients with type 2 diabetes. The aims of this pilot study were to investigate the effects of a sardine-enriched diet on metabolic control, adiponectin, inflammatory markers, erythrocyte membrane fatty acid (EMFA) composition, and gut microbiota in drug-naïve patients with type 2 diabetes.

METHODS

35 drug-naïve patients with type 2 diabetes were randomized to follow either a type 2 diabetes standard diet (control group: CG), or a standard diet enriched with 100 g of sardines 5 days a week (sardine group: SG) for 6 months. Anthropometric, dietary information, fasting glycated hemoglobin, glucose, insulin, adiponectin, inflammatory markers, EMFA and specific bacterial strains were determined before and after intervention.

RESULTS

There were no significant differences in glycemic control between groups at the end of the study. Both groups decreased plasma insulin (SG: -35.3%, P = 0.01, CG: -22.6%, P = 0.02) and homeostasis model of assessment--insulin resistance (HOMA-IR) (SG: -39.2%, P = 0.007, CG: -21.8%, P = 0.04) at 6-months from baseline. However only SG increased adiponectin in plasma compared to baseline level (+40.7%, P = 0.04). The omega-3 index increased 2.6% in the SG compared to 0.6% in the CG (P = 0.001). Both dietary interventions decreased phylum Firmicutes (SG and CG: P = 0.04) and increased E. coli concentrations (SG: P = 0.01, CG: P = 0.03) at the end of the study from baseline, whereas SG decreased Firmicutes/Bacteroidetes ratio (P = 0.04) and increased Bacteroides-Prevotella (P = 0.004) compared to baseline.

CONCLUSIONS

Although enriching diet with 100 g of sardines 5 days a week during 6 months to a type 2 diabetes standard diet seems to have neutral effects on glycemic control in drug-naïve patients with type 2 diabetes, this nutritional intervention could have beneficial effects on cardiovascular risk. Furthermore, both dietary interventions decreased HOMA-IR and altered gut microbiota composition of drug-naïve patients with type 2 diabetes.

TRIAL REGISTRATION

Trial number and name of the registry: NCT02294526, ClinicalTrials.gov.

Acute effect of red meat and dairy on glucose and insulin: a randomized crossover study

BACKGROUND

In contrast with some epidemiologic evidence, our previous research showed that a 4-wk diet that was high in low-fat dairy reduced insulin sensitivity compared with the effect of a diet that was high in red meat.

OBJECTIVE

We investigated whether a dairy meal would produce a greater insulin response than a carbohydrate-matched red meat meal would, which might account for the change in insulin sensitivity.

DESIGN

One meal contained lean red meat, bread, and orange juice, and the other meal contained skim milk, low-fat yogurt, cheese, and bread. Meals were isoenergetic, equal in macronutrient profile, and consumed 1 wk apart. Glucose, insulin, and triglycerides were measured before and 30, 60, 90, 120, 150, and 180 min after meal consumption. Differences between meals were tested with the use of a repeated-measures ANOVA and paired sample t tests.

RESULTS

Nineteen men and 24 women [mean ± SD age: 50.8 ± 16.0 y; body mass index (in kg/m(2)): 30.0 ± 3.5] completed the study. Twenty-two participants had normal glucose tolerance, and 21 participants had impaired fasting glucose or impaired glucose tolerance. The red meat meal resulted in a higher glucose response at 30 min after consumption (P < 0.001); however, the glucose total AUC was not different between meals (P = NS). The mean ± SEM incremental AUC (iAUC) for glucose was significantly higher after the dairy meal than after the red meat meal (2.23 ± 0.49 compared with 0.88 ± 0.57 mmol/L · 3 h, respectively; P = 0.004). The insulin total AUC and iAUC were not different between meals (iAUC: 159.65 ± 20.0 mU/L · 3 h for red meat compared with 167.49 ± 24.1 mU/L · 3 h for dairy; P = NS).

CONCLUSIONS

Lean red meat and low-fat dairy produced a similar glycemic response. The higher glucose response 30 min after consumption of the red meat meal was likely attributable to differences in the glycemic load between orange juice and milk and yogurt. An insulinotropic effect of dairy was not observed. This trial was registered at www.anzctr.org.au as ACTRN12615000164594.

Herring and Beef Meals Lead to Differences in Plasma 2-Aminoadipic Acid, β-Alanine, 4-Hydroxyproline, Cetoleic Acid, and Docosahexaenoic Acid Concentrations in Overweight Men

BACKGROUND

Dietary guidelines generally recommend increasing fish intake and reducing red meat intake for better long-term health. Few studies have compared the metabolic differences between eating meat and fish.

OBJECTIVE

The objective of this study was to determine whether there are differences in the postprandial plasma metabolic response to meals containing baked beef, baked herring, and pickled herring.

METHODS

Seventeen overweight men (BMI 25-30 kg/m(2), 41-67 y of age) were included in a randomized crossover intervention study. Subjects ate baked herring-, pickled herring-, and baked beef-based meals in a randomized order and postprandial blood plasma samples were taken over 7 h. Plasma metabolomics were measured with the use of gas chromatography-mass spectrometry and areas under the curve for detected metabolites were compared between meals.

RESULTS

The plasma postprandial response of 2-aminoadipic acid, a suggested marker of diabetes risk, was 1.6 times higher after the beef meal than after the baked herring meal (P < 0.001). Plasma β-alanine and 4-hydroxyproline both were markedly greater after beef intake than after herring intake (16 and 3.4 times the response of baked herring, respectively; P < 0.001). Herring intake led to a greater plasma postprandial response from docosahexaenoic acid (DHA) and cetoleic acid compared with beef (17.6 and 150 times greater, respectively; P < 0.001), whereas hippuric acid and benzoic acid were elevated after pickled herring compared with baked herring (5.4 and 43 times higher; P < 0.001).

CONCLUSIONS

These results in overweight men confirm that DHA and cetoleic acid reflect herring intake, whereas β-alanine and 4-hydroxyproline are potential biomarkers for beef intake. The greater postprandial rise in 2-aminoadipic acid after the beef meal, coupled to its proposed role in stimulating insulin secretion, may have importance in the context of red meat intake and increased diabetes risk. This trial was registered at clinicaltrials.gov as NCT02381613.

Effect of consuming novel foods consisting high oleic canola oil, barley β-glucan, and DHA on cardiovascular disease risk in humans: the CONFIDENCE (Canola Oil and Fibre with DHA Enhanced) study - protocol for a randomized controlled trial

Background

Metabolic syndrome (MetS) has been identified as a major contributor to the development of cardiovascular disease (CVD). Current recommendations for dietary management of people with MetS involve quantitative and qualitative modifications of food intake, such as high consumption of vegetables, fruits, and whole grain foods. The results from our previous human trials revealed the potential of the dietary components high-oleic acid canola oil (HOCO)-docosahexaenoic acid (DHA) and high molecular weight barley β-glucan individually in managing CVD risk factors. Foods with a combination of HOCO-DHA and barley β-glucan have never been tested for their effects on CVD risk. The objective is to determine the effects of consuming novel foods HOCO-DHA, and barley β-glucan on managing CVD risk factors in people with MetS.

Methods/Design

We are conducting a randomized, single-blind crossover trial with four treatment phases of 28 days each separated by a 4-week washout interval. Participants (n=35) will be provided with weight-maintaining, healthy balanced diet recommendations according to their energy requirements during the intervention periods. Participants will receive muffins and cookies as treatment foods in a random order and will consume at least one meal per day at the research center under supervision. The four treatments include muffins and cookies consisting of (1) all-purpose flour and HOCO-DHA (50 g/day); (2) barley flour (4.36 g/day of β-glucan) and a blend of sunflower oil, safflower oil, and butter as control oil (50 g/day); (3) barley flour (4.36 g/day of β-glucan) and HOCO-DHA (50 g/day; dosage of DHA would be 3 g/day); and (4) all-purpose flour and control oil (50 g/day). At the beginning and end of each phase, we will evaluate anthropometrics; systolic and diastolic blood pressure; blood lipid profile; low-density lipoprotein subfractions and particle size; 10-year Framingham CVD risk score; inflammatory status; and plasma and red blood cell fatty acid profiles, fecal microbiome, and body composition by dual-energy X-ray absorptiometry.

Conclusion

Cholesterol synthesis will also be studied, using a stable isotope approach. The proposed study will lead to innovation of novel food products, which may result in improvement in the overall cardiovascular health of humans.

Trial registration

Clinical trials.gov identifier: NCT02091583. Date of registration: 12 March 2014.

A review of the effect of omega-3 polyunsaturated fatty acids on blood triacylglycerol levels in normolipidemic and borderline hyperlipidemic individuals

Circulating levels of triacylglycerol (TG) is a recognized risk factor for developing cardiovascular disease, a leading cause of death worldwide. The Institute of Medicine and the American Heart Association both recommend the consumption of n-3 polyunsaturated fatty acids (PUFA), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), to reduce serum TG in hyperlipidemic individuals. Additionally, a number of systematic reviews have shown that individuals with any degree of dyslipidemia, elevated serum TG and/or cholesterol, may benefit from a 20-30 % reduction in serum TG after consuming n-3 PUFA derived from marine sources. Given that individuals with serum lipid levels ranging from healthy to borderline dyslipidemic constitute a large portion of the population, the focus of this review was to assess the potential for n-3 PUFA consumption to reduce serum TG in such individuals. A total of 1341 studies were retrieved and 38 clinical intervention studies, assessing 2270 individuals, were identified for inclusion in the current review. In summary, a 9-26 % reduction in circulating TG was demonstrated in studies where ≥ 4 g/day of n-3 PUFA were consumed from either marine or EPA/DHA-enriched food sources, while a 4-51 % reduction was found in studies where 1–5 g/day of EPA and/or DHA was consumed through supplements. Overall, this review summarizes the current evidence with regards to the beneficial effect of n-3 PUFA on circulating TG levels in normolipidemic to borderline hyperlipidemic, otherwise healthy, individuals. Thus demonstrating that n-3 PUFA may play an important role in the maintenance of cardiovascular health and disease prevention.

Red meat, dairy, and insulin sensitivity: a randomized crossover intervention study

BACKGROUND

Epidemiologic studies have linked high consumption of red and processed meat with risk of developing type 2 diabetes, whereas high dairy consumption has been associated with decreased risk, but interventions have been limited.

OBJECTIVE

We compared the effects on insulin sensitivity of consuming a diet high in lean red meat with minimal dairy, a diet high in primarily low-fat dairy (from milk, yogurt, or custard) with no red meat, and a control diet that contained neither red meat nor dairy.

DESIGN

A randomized crossover study was undertaken with 47 overweight and obese men and women divided into 2 groups as follows: those with normal glucose tolerance and those with impaired fasting glucose or impaired glucose tolerance. Participants followed the 3 weight-stable dietary interventions for 4 wk with glucose, insulin, and C-peptide measured by using oral-glucose-tolerance tests at the end of each diet.

RESULTS

Fasting insulin was significantly higher after the dairy diet than after the red meat diet (P < 0.01) with no change in fasting glucose resulting in a decrease in insulin sensitivity after the high-dairy diet (P < 0.05) as assessed by homeostasis model assessment of insulin resistance (HOMA-IR). A significant interaction between diet and sex was observed such that, in women alone, HOMA-IR was significantly lower after the red meat diet than after the dairy diet (1.33 ± 0.8 compared with 1.71 ± 0.8, respectively; P < 0.01). Insulin sensitivity calculated by using the Matsuda method was 14.7% lower in women after the dairy diet than after the red meat diet (P < 0.01) with no difference between diets in men. C-peptide was not different between diets.

CONCLUSION

In contrast to some epidemiologic findings, these results suggest that high consumption of dairy reduces insulin sensitivity compared with a diet high in lean red meat in overweight and obese subjects, some of whom had glucose intolerance. This trial was registered at the Australian New Zealand Clinical Trials Registry as ACTRN12613000441718.

Effects of supplementation with omega-3 on insulin sensitivity and non-esterified free fatty acid (NEFA) in type 2 diabetic patients

OBJECTIVE

The aim of this study was to determine the role of omega-3 supplementation on NEFA concentration, insulin sensitivity and resistance, and glucose and lipid metabolism in type 2 diabetic patients.

SUBJECTS AND METHODS

Forty-four type 2 diabetic patients were randomly recruited into two groups. Group A received 4 g/day omega-3 soft gels, and group B received a placebo for 10 wks. Blood samples were collected after 12-h fast. Physical activity records, three-day food records, and anthropometric measurements were obtained from all participants at the beginning and end of the study.

RESULTS

Omega-3 supplementation caused a significant reduction in NEFA in the intervention group compared with the placebo group (P = 0.009). Additionally, the administration of omega-3 resulted in significantly greater changes (Diff) for the intervention group in various parameters, such as insulin and Quicki indices compared with the placebo group (P < 0.05).

CONCLUSIONS

Omega-3 fatty acid supplementation in type 2 diabetic patients improved insulin sensitivity, probably due to the decrease in NEFA concentrations.

Total n-3 fatty acid and SFA intakes in relation to insulin resistance in a Canadian First Nation at risk for the development of type 2 diabetes

OBJECTIVE

The present study sought to investigate the associations of total n-3 fatty acid and SFA intakes with insulin resistance in a Canadian First Nation sample at risk for type 2 diabetes.

DESIGN

Fasting values for glucose and insulin were used to estimate insulin resistance by homeostasis model assessment (HOMA-IR). Intakes of n-3 fatty acids and SFA were computed from dietary food and drink data obtained using 3 d food records. Associations between HOMA-IR and dietary n-3 and SFA consumption were tested using linear regression models accounting for age, sex, community, education, physical activity, waist circumference, fibre, protein and carbohydrate intakes, and HDL-cholesterol and TAG concentrations.

SETTING

Rural Okanagan region of British Columbia, Canada.

SUBJECTS

On-reserve First Nation individuals (Interior Salishan) aged 18 years and over, recruited for community-based diabetes screening and determined to be normoglycaemic (n 126).

RESULTS

HOMA-IR was negatively associated with dietary n-3 fatty acid intake (β = -0·22; 95 % CI -0·39, -0·04; P = 0·016) and positively associated with dietary SFA intake (β = 0·34; 95 % CI 0·15, 0·53; P = 0·0 0 1).

CONCLUSIONS

Intake of dietary n-3 fatty acids may be protective against whereas SFA intake may promote insulin resistance in this high-risk Canadian First Nation sample. Reduced dietary SFA intake and greater n-3 fatty acid intake may assist the prevention of glycaemic disease among First Nations peoples. More rigorous, controlled trials are required to test whether dietary supplementation with n-3 fatty acids in natural or supplement-based form might reduce diabetes risk in high-risk aboriginal groups.

Omega-3 fatty acids improve glucose metabolism without effects on obesity values and serum visfatin levels in women with polycystic ovary syndrome

OBJECTIVE

Polycystic ovary syndrome (PCOS) is the most common female endocrine disorder. Affected women present a higher risk of type 2 diabetes. The objectives of this study were to investigate the effects of omega-3 fatty acids on obesity status, insulin resistance, and serum levels of visfatin in PCOS patients.

METHODS

This double-blind, randomized, controlled clinical trial was conducted on 61 women who were diagnosed with PCOS, had a body mass index (BMI) between 25 and 40 kg/m(2), and were from 20-35 years old. Thirty of the subjects had taken four 1-g omega-3 fatty acids capsules per day, providing 1200 mg n-3 long chain polyunsaturated fatty acids (n-3 LC PUFA), and 31 were given a placebo over 8 weeks. Fasting blood samples, anthropometric measurements, and dietary intake data were collected at the baseline and at the end of the trial. Data were analyzed by independent t test, paired t test, Pearson correlation test, and analysis of covariance.

RESULTS

Omega-3 fatty acids had no significant effects on weight, BMI, waist circumference, and waist to hip ratio at the end of the study. Omega-3 fatty acids significantly decreased glucose (by 11.4%, p < 0.001), insulin (by 8.4%, p < 0.05), and homeostatic model assessment for insulin resistance (by 21.8%, p < 0.001) compared with placebo. Changes in serum visfatin levels were not significant in either of the groups.

CONCLUSION

Omega-3 fatty acids improved insulin sensitivity in PCOS patients. This beneficial effect was not associated with alteration in anthropometric measurements and serum visfatin levels.

Fish consumption, insulin sensitivity and beta-cell function in the Insulin Resistance Atherosclerosis Study (IRAS)

BACKGROUND AND AIMS

Previous research on the association between fish consumption and incident type 2 diabetes has been inconclusive. In addition, few studies have investigated how fish consumption may be related to the metabolic abnormalities underlying diabetes. Therefore, we examined the association of fish consumption with measures of insulin sensitivity and beta-cell function in a multi-ethnic population.

METHODS AND RESULTS

We examined the cross-sectional association between fish consumption and measures of insulin sensitivity and secretion in 951 non-diabetic participants in the Insulin Resistance Atherosclerosis Study (IRAS). Fish consumption, categorized as <2 vs. ≥2 portions/week, was measured using a validated food frequency questionnaire. Insulin sensitivity (S(I)) and acute insulin response (AIR) were determined from frequently sampled intravenous glucose tolerance tests. Higher fish consumption was independently associated with lower S(I)-adjusted AIR (β = -0.13 [-0.25, -0.016], p = 0.03, comparing ≥2 vs. <2 portions/week). Fish consumption was positively associated with intact and split proinsulin/C-peptide ratios, however, these associations were confounded by ethnicity (multivariable-adjusted β = 0.073 [-0.014, 0.16] for intact proinsulin/C-peptide ratio, β = 0.031 [-0.065, 0.13] for split proinsulin/C-peptide ratio). We also observed a significant positive association between fish consumption and fasting blood glucose (multivariable-adjusted β = 2.27 [0.68, 3.86], p = 0.005). We found no association between fish consumption and S(I) (multivariable-adjusted β = -0.015 [-0.083, 0.053]) or fasting insulin (multivariable-adjusted β = 0.016 [-0.066, 0.10]).

CONCLUSIONS

Fish consumption was not associated with measures of insulin sensitivity in the multi-ethnic IRAS cohort. However, higher fish consumption may be associated with pancreatic beta-cell dysfunction.

Immunometabolic role of long-chain omega-3 fatty acids in obesity-induced inflammation

Inflammation links obesity with the development of insulin resistance. Macrophages and phagocytic immune cells communicate with metabolic tissues to direct an inflammatory response caused by overnutrition and expanding adipose tissue. Marine-derived omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), modulate inflammatory signalling events, providing various anti-inflammatory and cardioprotective benefits. Moreover, EPA and DHA may improve insulin sensitivity by generating proresolving lipid mediators and promoting alternatively activated macrophages. This review will assess the role of EPA and DHA in ameliorating obesity-induced inflammation, evaluating clinical evidence and mechanisms of action. The pathophysiology of insulin resistance resulting from obesity-induced inflammation will be discussed, highlighting the relationship between metabolism and immunity, and in particular, how EPA and DHA work with both systems to modulate immunometabolic complications and chronic disease.

A new dietary strategy for long-term treatment of the metabolic syndrome is compared with the American Heart Association (AHA) guidelines: the MEtabolic Syndrome REduction in NAvarra (RESMENA) project

The long-term effects of dietary strategies designed to combat the metabolic syndrome (MetS) remain unknown. The present study evaluated the effectiveness of a new dietary strategy based on macronutrient distribution, antioxidant capacity and meal frequency (MEtabolic Syndrome REduction in NAvarra (RESMENA) diet) for the treatment of the MetS when compared with the American Heart Association guidelines, used as Control. Subjects with the MetS (fifty-two men and forty-one women, age 49 (se 1) years, BMI 36·11 (se 0·5) kg/m²) were randomly assigned to one of two dietary groups. After a 2-month nutritional-learning intervention period, during which a nutritional assessment was made for the participants every 15 d, a 4-month self-control period began. No significant differences were found between the groups concerning anthropometry, but only the RESMENA group exhibited a significant decrease in body weight ( - 1·7%; P= 0·018), BMI ( - 1·7%; P= 0·019), waist circumference ( - 1·8%; P= 0·021), waist:hip ratio ( - 1·4%; P= 0·035) and android fat mass ( - 6·9%; P= 0·008). The RESMENA group exhibited a significant decrease in alanine aminotransferase and aspartate aminotransferase (AST) concentrations ( - 26·8%; P= 0·008 and - 14·0%; P= 0·018, respectively), while the Control group exhibited a significant increase in glucose (7·9%; P= 0·011), AST (11·3%; P= 0·045) and uric acid (9·0%; P< 0·001) concentrations. LDL-cholesterol (LDL-C) concentrations were increased (Control group: 34·4%; P< 0·001 and RESMENA group: 33·8%; P< 0·001), but interestingly so were the LDL-C:apoB ratio (Control group: 28·7%; P< 0·001, RESMENA group: 17·1%; P= 0·009) and HDL-cholesterol concentrations (Control group: 21·1%; P< 0·001, RESMENA group: 8·7; P= 0·001). Fibre was the dietary component that most contributed to the improvement of anthropometry, while body-weight loss explained changes in some biochemical markers. In conclusion, the RESMENA diet is a good long-term dietary treatment for the MetS.

Effects of supplementation with n-3 polyunsaturated fatty acids on cognitive performance and cardiometabolic risk markers in healthy 51 to 72 years old subjects: a randomized controlled cross-over study

Background

Higher plasma n-3 polyunsaturated fatty acids (PUFA) have been associated with a lower risk of age related cognitive decline, and to beneficially affect cardiometabolic risk factors. A relation exists between metabolic disorders such as diabetes type 2 and cognitive decline. Results regarding the potential effects of n-3 PUFA on risk factors in healthy subjects are divergent, and studies regarding the possible relation between cardiometabolic parameters and cognitive performance are scarce. The objective was to evaluate the effects of five weeks intake of long chain n-3 PUFA on cognitive performance in healthy individuals, and to exploit the possible relation between outcomes in cognitive tests to cardiometabolic risk parameters.

Methods

Fish oil n-3 PUFA (3g daily) were consumed during 5weeks separated by a 5 week washout period in a cross-over placebo controlled study, including 40 healthy middle aged to elderly subjects. Cognitive performance was determined by tests measuring working memory (WM) and selective attention.

Results

Supplementation with n-3 PUFA resulted in better performance in the WM-test compared with placebo (p < 0.05). In contrast to placebo, n-3 PUFA lowered plasma triacylglycerides (P < 0.05) and systolic blood pressure (p < 0.0001). Systolic blood pressure (p < 0.05), f-glucose (p = 0.05), and s-TNF-α (p = 0.05), were inversely related to the performance in cognitive tests.

Conclusions

Intake of n-3 PUFA improved cognitive performance in healthy subjects after five weeks compared with placebo. In addition, inverse relations were obtained between cardiometabolic risk factors and cognitive performance, indicating a potential of dietary prevention strategies to delay onset of metabolic disorders and associated cognitive decline.

Relationship between vitamin D deficiency, bone remodelling and iron status in iron-deficient young women consuming an iron-fortified food

BACKGROUND

Iron and vitamin D deficiencies are two of the most widespread nutritional disorders in the world. Our aim was to know whether the consumption of an iron-fortified fruit juice modifies bone remodelling and the possible influence of baseline vitamin D status on the recovery of iron status in a group of iron-deficient women.

METHODS

Iron biomarkers, 25-hydroxyvitamin D levels and dietary intake were measured in 123 iron-deficient menstruating women. A subgroup (n = 41) participated in a randomised double-blind placebo-controlled study of 16-weeks during winter. They consumed a placebo fruit juice (P) or iron-fortified fruit juice (F). Dietary intake, 25-hydroxyvitamin D, parathormone (PTH), bone alkaline phosphatase (ALP), aminoterminal telopeptide of collagen I (NTX) and iron biomarkers were determined.

RESULTS

Ninety-two per cent of the iron-deficient women were vitamin D deficient or insufficient. Transferrin saturation and 25-hydroxyvitamin D were positively correlated. Iron status improved in F, 25-hydroxyvitamin D decreased in F and P, and PTH, ALP and NTX levels were within the normal range and did not vary. Women with 25-hydroxyvitamin D ≥ 50 nmol/L compared with 25-hydroxyvitamin D < 50 nmol/L showed a higher increase in transferrin saturation (a marker of iron supply to tissues) during iron recovery.

CONCLUSION

The prevalence of vitamin D deficiency or insufficiency is very high in iron-deficient women. The recovery of iron status by consuming an iron-fortified food does not affect 25-hydroxyvitamin D levels; however, the increase in iron supply to tissues is lower if the women also present vitamin D deficiency. Although bone health does not seem to be affected in this group of women, correction of iron and vitamin D deficiencies should be promoted in young women to improve present and future health.

Fatty acids as biocompounds: their role in human metabolism, health and disease: a review. part 2: fatty acid physiological roles and applications in human health and disease

BACKGROUND

This is the second of two review parts aiming at describing the major physiological roles of fatty acids, as well as their applications in specific conditions related to human health.

RESULTS

The review included the current literature published in Pubmed up to March 2011. In humans, fatty acids are a principle energy substrate and structural components of cell membranes (phospholipids) and second messengers. Fatty acids are also ligands of nuclear receptors affecting gene expression. Longer-chain (LC) polyunsaturated fatty acids (PUFA), including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid are precursors of lipid mediators such as eicosanoids (prostaglandins, leukotrienes, thromboxanes), resolvins and neuroprotectins. Lipid mediators produced by EPA and DHA (LC n-3 PUFA; mainly found in oily fish) are considered as inflammation-resolving, and thus, fish oil has been characterised as antiinflammatory. Recommendations for EPA plus DHA intake from oily fish vary between 250-450 mg/day. Dietary reference values for fat vary between nutrition bodies, but mainly agree on a low total and saturated fat intake. The existing literature supports the protective effects of LC n-3 PUFA (as opposed to n-6 PUFA and saturated fat) in maternal and offspring health, cardiovascular health, insulin sensitivity, the metabolic syndrome, cancer, critically ill patients, and immune system disorders.

CONCLUSION

Fatty acids are involved in multiple pathways and play a major role in health. Further investigation and a nutrigenomics approach to the effects of these biocompounds on health and disease development are imperative and highlight the importance of environmental modifications on disease outcome.

Dietary sources of omega 3 fatty acids: public health risks and benefits

Omega 3 fatty acids can be obtained from several sources, and should be added to the daily diet to enjoy a good health and to prevent many diseases. Worldwide, general population use omega-3 fatty acid supplements and enriched foods to get and maintain adequate amounts of these fatty acids. The aim of this paper was to review main scientific evidence regarding the public health risks and benefits of the dietary sources of omega-3 fatty acids. A systematic literature search was performed, and one hundred and forty-five articles were included in the results for their methodological quality. The literature described benefits and risks of algal, fish oil, plant, enriched dairy products, animal-derived food, krill oil, and seal oil omega-3 fatty acids.

Dietary inclusion of salmon, herring and pompano as oily fish reduces CVD risk markers in dyslipidaemic middle-aged and elderly Chinese women

Dietary intervention studies to assess the cardioprotective effects of oily fish are scarce in China. The present study aimed to examine the effects of the oily fish, Norwegian salmon, herring and local farmed pompano (Trachinotus ovatus) on CVD risk markers when included in the Chinese diet. In this 8-week, parallel-arm, randomised intervention study, 126 Chinese women with hypertriacylglycerolaemia, aged 35-70 years, were assigned to four groups to consume an experimental lunch containing 80 g fillets of either one of three oily fish or a mix of commonly eaten meats (pork/chicken/beef/lean fish) for 5 d/week. The results showed that inclusion of the three oily fish significantly increased the intake of n-3 long-chain PUFA (LC-PUFA) while decreasing the dietary n-6:n-3 PUFA ratio. Compared to the control group, significant increases of DHA, EPA+DHA and total n-3 PUFA in plasma choline phosphoglyceride were observed in the three oily fish groups. Plasma TAG levels were significantly reduced only in the salmon and herring groups. When compared to the baseline level, the three oily fish diets significantly decreased serum concentrations of TAG, apoB, apoCII and apoCIII, but only the salmon and herring diets significantly lowered TNF-α and raised adiponectin levels in serum. The salmon diet additionally decreased the serum concentration of IL-6. To conclude, dietary inclusion of salmon, herring and pompano as oily fish can effectively increase serum n-3 LC-PUFA content and are associated with favourable biochemical changes in dyslipidaemic middle-aged and elderly Chinese women, and these beneficial effects are mainly associated with n-3 LC-PUFA contents.

Four variants in transferrin and HFE genes as potential markers of iron deficiency anaemia risk: an association study in menstruating women

BACKGROUND

Iron deficiency anaemia is a worldwide health problem in which environmental, physiologic and genetic factors play important roles. The associations between iron status biomarkers and single nucleotide polymorphisms (SNPs) known to be related to iron metabolism were studied in menstruating women.

METHODS

A group of 270 Caucasian menstruating women, a population group at risk of iron deficiency anaemia, participated in the study. Haematological and biochemical parameters were analysed and 10 selected SNPs were genotyped by minisequencing assay. The associations between genetic and biochemical data were analysed by Bayesian Model Averaging (BMA) test and decision trees. Dietary intake of a representative subgroup of these volunteers (n = 141) was assessed, and the relationship between nutrients and iron biomarkers was also determined by linear regression.

RESULTS

Four variants, two in the transferrin gene (rs3811647, rs1799852) and two in the HFE gene (C282Y, H63D), explain 35% of the genetic variation or heritability of serum transferrin in menstruating women. The minor allele of rs3811647 was associated with higher serum transferrin levels and lower transferrin saturation, while the minor alleles of rs1799852 and the C282Y and H63D mutations of HFE were associated with lower serum transferrin levels. No association between nutrient intake and iron biomarkers was found.

CONCLUSIONS

In contrast to dietary intake, these four SNPs are strongly associated with serum transferrin. Carriers of the minor allele of rs3811647 present a reduction in iron transport to tissues, which might indicate higher iron deficiency anaemia risk, although the simultaneous presence of the minor allele of rs1799852 and HFE mutations appear to have compensatory effects. Therefore, it is suggested that these genetic variants might potentially be used as markers of iron deficiency anaemia risk.

Omega-3 fatty acids and metabolic syndrome: effects and emerging mechanisms of action

Epidemiological, human, animal, and cell culture studies show that n-3 fatty acids, especially α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), reduce the risk factors of cardiovascular diseases. EPA and DHA, rather than ALA, have been the focus of research on the n-3 fatty acids, probably due to the relatively inefficient conversion of ALA to EPA and DHA in rodents and humans. This review will assess our current understanding of the effects and potential mechanisms of actions of individual n-3 fatty acids on multiple risk factors of metabolic syndrome. Evidence for pharmacological responses and the mechanism of action of each of the n-3 fatty acid trio will be discussed for the major risk factors of metabolic syndrome, especially adiposity, dyslipidemia, insulin resistance and diabetes, hypertension, oxidative stress, and inflammation. Metabolism of n-3 and n-6 fatty acids as well as the interactions of n-3 fatty acids with nutrients, gene expression, and disease states will be addressed to provide a rationale for the use of n-3 fatty acids to reduce the risk factors of metabolic syndrome.

Efficacy of a microencapsulated iron pyrophosphate-fortified fruit juice: a randomised, double-blind, placebo-controlled study in Spanish iron-deficient women

Fe-deficiency anaemia is a worldwide health problem. We studied the influence of consuming an Fe-fortified fruit juice on Fe status in menstruating women. A randomised, double-blind, placebo-controlled study of 16 weeks of duration was performed. Subjects were randomised into two groups: the P group (n 58) or the F group (n 64), and consumed, as a supplement to their usual diet, 500 ml/d of a placebo fruit juice or an Fe-fortified fruit juice, respectively. The Fe-fortified fruit juice, containing microencapsulated iron pyrophosphate, provided 18 mg Fe/d (100 % of the RDA). At baseline and monthly, dietary intake, body weight and Fe parameters were determined: total erythrocytes, haematocrit, mean corpuscular volume (MCV), red blood cell distribution width (RDW), Hb, serum Fe, serum ferritin, serum transferrin, transferrin saturation, soluble transferrin receptor (sTfR) and zinc protoporphyrin (ZnPP). The fruit juice consumption involved increased intake of carbohydrates and vitamin C, and increased BMI within normal limits. Ferritin was higher in the F group after week 4 (P < 0·05) and became 80 % higher than in the P group after week 16 (P < 0·001), and transferrin decreased in the F group compared with the P group after week 4 (P < 0·001). RDW was higher at weeks 4 and 8 in the F group compared with the P group (P < 0·05). Transferrin saturation increased after week 8, and haematocrit, MCV and Hb increased after week 12, in the F group compared with the P group. Serum Fe did not change. sTfR and ZnPP decreased in the F group at week 16 (P < 0·05). Iron pyrophosphate-fortified fruit juice improves Fe status and may be used to prevent Fe-deficiency anaemia.

Inclusion of Atlantic salmon in the Chinese diet reduces cardiovascular disease risk markers in dyslipidemic adult men

Although the beneficial effects of n-3 fatty acids on several physiologic functions have been widely reported, information about the effects of oily fish in the Asian diet on cardiovascular disease (CVD) risk is diminutive. We hypothesize that daily inclusion of oily fish for 8 weeks in the Chinese diet will elevate serum eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels and reduce CVD risk markers in dyslipidemic adult men, comparable with the effects generally observed by inclusion of oily fish in the Western diet. In this 8-week randomized, parallel-arm, food-based intervention study, lunches were prepared with 500 g pork/chicken/beef, typically consumed fish (hairtail and freshwater carp), or oily fish (salmon). Male subjects aged between 35 and 70 years with hyperlipidemia were randomly assigned to eat lunches with pork/chicken/beef (n = 30 subjects at 8 weeks), freshwater fish (n = 30), or oily fish (n = 32). Circulating markers were measured at baseline and at 8 weeks. In the oily fish diet, dietary EPA and DHA levels were significantly increased as compared with other diets; and the n-6:n-3 polyunsaturated fatty acid ratio was decreased (P < .05). Thus, the oily fish diet significantly elevated serum EPA and DHA concentrations (P < .01) and lowered serum n-6:n-3 ratio at 8 weeks (P < .05). Furthermore, oily fish intake significantly reduced serum levels of triglycerides (P < .05) and interleukin-6 (P < .01) and increased levels of high-density lipoprotein cholesterol (P < .01). In conclusion, daily inclusion of oily fish as part of the Chinese diet for 8 weeks is sufficient to significantly increase the serum content of long-chain n-3 polyunsaturated fatty acids and reduce levels of CVD risk markers in dyslipidemic adult men.