High consumptions of grain, fish, dairy products and combinations of these are associated with a low prevalence of metabolic syndrome

Adolescence as a sensitive period for neurotoxicity: Lifespan developmental effects of methylmercury

Neurotoxicity resulting from the environmental contaminant, methylmercury (MeHg), is a source of concern for many human populations that rely heavily on the consumption of fish and rice as stable ingredients in the diet. The developmental period of exposure is important both to the qualitative effects of MeHg and to the dose required to produce those effects. MeHg exposure during the sensitive prenatal period causes deleterious and long-lasting changes in neurodevelopment at particularly low doses. The effects include a wide host of cognitive and behavioral outcomes expressed in adulthood and sometimes not until aging. However, neurotoxic outcomes of methylmercury when exposure occurs during adolescence are only recently revealing impacts on human populations and animal models. This review examines the current body of work and showcases the sensitivity of adolescence, a period that straddles early development and adulthood, to methylmercury neurotoxicity and the implications such toxicity has in our understanding of methylmercury's effects in human populations and animal models.

Relationship between Egg Consumption and Metabolic Syndrome. A Meta-Analysis of Observational Studies

OBJECTIVES

Aims: To explore the association between egg consumption and metabolic syndrome (MetS) in the adult population.

METHODS

The PubMed, Web of Science and Embase electronic databases were searched up to December 2021 for observational studies on the association between egg consumption and MetS in the adult population. The pooled relative risk (RR) of MetS for the highest versus lowest category of egg consumption, and the standard mean difference (SMD) of egg consumption for MetS versus control subjects were calculated. Egg consumption was assessed by a food-frequency questionnaire (FFQ) and the 24-hour recall method. The criteria for MetS were National Cholesterol Education Program-Adult Treatment Panel III (NCEP ATP III), International Diabetes Federation (IDF), Joint Interim Statement (JIS) and American Heart Association (AHA).

RESULTS

A total of 19 articles with 20 observational studies (331667 participants) were included in this meta-analysis. The overall multivariable adjusted RR (18 studies included) demonstrated that higher egg consumption was associated with a lower probability of having MetS (RR=0.92, 95%CI: 0.88 to 0.96; P<0.001). Subgroup analysis confirmed these findings in cross-sectional studies (RR=0.91, 95% CI: 0.88 to 0.95; P<0.001), studies that used the NCEP ATP III criteria (RR=0.94, 95% CI: 0.89 to 0.99; P=0.02), Asia (RR=0.92, 95% CI: 0.86 to 0.99; P=0.02), studies with samples sizes >5000 (RR=0.92, 95% CI: 0.86 to 0.96; P<0.001), studies that adjusted body mass index (BMI) (RR=0.90, 95% CI: 0.86 to 0.95; P<0.001) and energy intake (RR=0.89, 95% CI: 0.83 to 0.94; P<0.001) and high-quality studies (RR=0.91, 95% CI: 0.88 to 0.95; P<0.001). Moreover, the overall combined SMD (5 studies included) showed that the level of egg consumption in subjects with MetS was also lower than that in control subjects. (SMD=-0.22, 95% CI: -0.25 to -0.20; P<0.001). Sensitivity analysis demonstrated that this finding only existed in studies with samples sizes >5000 (SMD=-0.21, 95% CI: -0.29 to -0.12; P<0.001) and high-quality studies (SMD=-0.23, 95% CI: -0.26 to -0.20; P<0.001).

CONCLUSION

Our results suggest that higher egg consumption is associated with a lower probability of having MetS in the adult population. However, due to the limited evidence, more global well-designed prospective cohort studies are still needed.

The association between meat consumption and the metabolic syndrome: a cross-sectional study and meta-analysis

The findings regarding the associations between red meat, fish and poultry consumption, and the metabolic syndrome (Mets) have been inconclusive, and evidence from Chinese populations is scarce. A cross-sectional study was performed to investigate the associations between red meat, fish and poultry consumption, and the prevalence of the Mets and its components among the residents of Suzhou Industrial Park, Suzhou, China. A total of 4424 participants were eligible for the analysis. A logistic regression model was used to estimate the OR and 95 % CI for the prevalence of the Mets and its components according to red meat, fish and poultry consumption. In addition, the data of our cross-sectional study were meta-analysed under a random effects model along with those of published observational studies to generate the summary relative risks (RR) of the associations between the highest v. lowest categories of red meat, fish and poultry consumption and the Mets and its components. In the cross-sectional study, the multivariable-adjusted OR for the highest v. lowest quartiles of consumption was 1·23 (95 % CI 1·02, 1·48) for red meat, 0·83 (95 % CI 0·72, 0·97) for fish and 0·93 (95 % CI 0·74, 1·18) for poultry. In the meta-analysis, the pooled RR for the highest v. lowest categories of consumption was 1·20 (95 % CI 1·06, 1·35) for red meat, 0·88 (95 % CI 0·81, 0·96) for fish and 0·97 (95 % CI 0·85, 1·10) for poultry. The findings of both cross-sectional studies and meta-analyses indicated that the association between fish consumption and the Mets may be partly driven by the inverse association of fish consumption with elevated TAG and reduced HDL-cholesterol and, to a lesser extent, fasting plasma glucose. No clear pattern of associations was observed between red meat or poultry consumption and the components of the Mets. The current findings add weight to the evidence that the Mets may be positively associated with red meat consumption, inversely associated with fish consumption and neutrally associated with poultry consumption.

Associations of Whole Grain and Refined Grain Consumption With Metabolic Syndrome. A Meta-Analysis of Observational Studies

Background: The associations of whole grain and refined grain consumption with metabolic syndrome (MetS) has been evaluated in several epidemiological studies with conflicting results. This meta-analysis was therefore employed to further investigate the above associations. Method: We searched the PubMed, Web of Science and Embase database until March 2021 (without restriction for inclusion time), for observational studies on the associations of whole grain and refined grain consumption with MetS. The pooled relative risk (RR) of MetS for the highest vs. lowest category of whole grain and refined grain consumption, as well as their corresponding 95% confidence interval (CI) were calculated. Results: A total of 14 observational studies, which involved seven cross-sectional and seven prospective cohort studies, were identified. Specifically, nine studies were related to whole grain consumption, and the overall multi-variable adjusted RR demonstrated that the whole grain consumption was inversely associated with MetS (RR = 0.80, 95%CI: 0.67-0.97; P = 0.021). With regard to refined grain consumption, 13 studies were included. The overall multi-variable adjusted RR indicated that refined grain consumption was positively associated with MetS (RR = 1.37, 95%CI: 1.02-1.84; P = 0.036). Conclusions: The existing evidence suggests that whole grain consumption is negatively associated with MetS, whereas refined grain consumption is positively associated with MetS. Our result might be helpful to better consider the diet effect on MetS. However, more well-designed prospective cohort studies are needed to elaborate the concerned issues further.

Fish Consumption: A Review of Its Effects on Metabolic and Hormonal Health

Dietary habits are a major determinant of the risk of chronic disease, particularly metabolic and endocrine disorders. Fish as a food group are a unique source of nutrients with metabolic and hormonal importance including omega-3 fatty acids, iodine, selenium, vitamin D, taurine and carnitine. Fish are also a source of high quality protein and have in general low caloric density. The impact of these nutrients on cardiovascular risk has been extensively reviewed, but the impact of fish on the broader field of endocrine and metabolic health is sometimes not sufficiently appreciated. This article aimed to summarize the impact the effect of regular fish consumption on conditions like the metabolic syndrome, obesity, diabetes, hypothyroidism, polycystic ovary syndrome and the menopausal transition, which are in and of themselves significant causes of morbidity and mortality worldwide. The review revealed that scientific evidence from food science, translational research, epidemiologic studies and interventional trials shows that regular fish consumption has a positive impact on thyroid homeostasis, facilitates maintenance of a healthy body weight, reduces the magnitude of age-associated increases in blood pressure, improves glucose homeostasis helping prevent diabetes and the metabolic syndrome, and has a positive impact on muscle mass preservation among the elderly. These effects are mediated by multiple mechanisms, only some of which have been identified. For most of these effects it holds true that the potential benefits are more substantial when baseline fish consumption is low.

Dairy Consumption and Risk of Metabolic Syndrome: Results from Korean Population and Meta-Analysis

Dairy consumption has been associated with decreased risk of metabolic syndrome (MetS) in previous studies, but the association may be different according to each type of dairy products and its subgroups. Thus, we conducted an updated meta-analysis of observational studies to examine the association between various dairy products and risk of MetS. The PubMed and Web of Science databases were searched for eligible studies published up to February 2021. In addition, we included unpublished results from Korea National Health and Nutrition Examination Survey, 2013-2018, including 23,319 Korean adults and the elderly. A total of 35 studies (12 cohort studies and 25 cross-sectional studies) with 398,877 subjects were included in the meta-analysis. The pooled relative risks (RR) of MetS for the highest versus lowest categories of dairy consumption was 0.80 [95% confidence interval (CI): 0.72-0.88]. For the type of dairy products, there were also significant inverse associations with milk (RR: 0.83; 95% CI: 0.78-0.89) and yogurt consumption (RR: 0.89; 95% CI: 0.83-0.95). For cheese consumption, however, no significant association was found (RR: 0.98; 95% CI: 0.86-1.11). Our findings suggest that milk and yogurt consumption is inversely associated with the risk of MetS, but not cheese consumption.

Dietary Habits and their Association with Metabolic Syndrome in a sample of Iranian adults: A population-based study

BACKGROUND

Central obesity, insulin resistance, dyslipidemia, and hypertension are the core components of metabolic syndrome (MetS) which is coincident with unhealthy dietary habits in the Middle-Eastern countries. The aim of this study was to explore the association between dietary habits and MetS of the adult population living in Yazd Greater Area, Iran.

METHODS

This is a cross-sectional study that uses the data of a population-based cohort study on Iranian adults, known as Yazd Health Study (YaHS). The relationship between dietary habits and metabolic syndrome among adults (n = 2,896) was analyzed using multiple logistic regression method.

RESULTS

The prevalence of MetS among the participants was 32.2%. Outcomes from logistic regression examination show that breakfast consumption has a significant inverse effect on the occurrence of MetS after adjustment for age, education level, physical activity statue, history of chronic diseases, and smoking (odds ratio (OR) = 0.38, 95% confidence interval (CI) = 0.14, 0.97). This effect remains significant even after adjustment for body mass index (BMI) and reveals that odds of having MetS is 69% lower in breakfast consumers in contrast to nonconsumers (OR = 0.31, 95% CI = 0.11, 0.87). However, no significant relationship was observed between other dietary habits including consumption of sweetened drinks, sugar cubes, and fast foods and MetS after adjustment for all potential confounders.

CONCLUSIONS

This study revealed that eating breakfast has an inverse relationship with metabolic syndrome. To find out stronger evidence in relation to dietary habits and MetS, more researches especially population-based cohort studies are needed to be conducted.

A systematic review and meta-analysis of the association between fish consumption and risk of metabolic syndrome

AIMS

Results regarding the association between fish intake and risk of metabolic syndrome (MetS) are ambiguous. Therefore, this study aims to evaluate whether there is an association between fish consumption and risk of MetS.

DATA SYNTHESIS

A comprehensive literature search was conducted of PubMed, Embase, ScienceDirect and Google Scholar up to August 2019. A random-effects model was used to pool the risk of MetS in the highest category of fish consumption compared with the lowest one. Subgroup analysis was conducted based on country of region, gender, dietary tool, MetS definition, energy adjustment and sample size. A dose-response of analysis of fish intake and risk of MetS was also conducted. Twelve studies with a total of 16 effect sizes (10 cross-sectional and six cohort) were included. An inverse association was observed between fish intake and risk of MetS in cohort (OR = 0.80, 95% CI: 0.66, 0.96; P = 0.017, I² = 62.9%) but not cross-sectional studies (OR = 0.80, 95% CI: 0.70, 1.02; P = 0.085, I² = 50.1%). Subgroup analysis suggested that the results were influenced by all the included variables but sample size. A significant non-linear association was observed between fish intake levels and risk of MetS (P-value for non-linearity = 0.010).

CONCLUSION

An inverse association existed between fish intake and risk of MetS when combining data from prospective cohort studies. Further studies are needed to confirm such an effect.

The association between milk consumption and the metabolic syndrome: a cross-sectional study of the residents of Suzhou, China and a meta-analysis

The association between milk consumption and the metabolic syndrome remains inconclusive, and data from Chinese populations are scarce. We conducted a cross-sectional study to investigate the association between milk consumption and the metabolic syndrome and its components among the residents of Suzhou Industrial Park, Suzhou, China. A total of 5149 participants were included in the final analysis. A logistic regression model was applied to estimate the OR and 95 % CI for the prevalence of the metabolic syndrome and its components according to milk consumption. In addition, the results of our study were further meta-analysed with other published observational studies to quantify the association between the highest v. lowest categories of milk consumption and the metabolic syndrome and its components. There was no significant difference in the odds of having the metabolic syndrome between milk consumers and non-milk consumers (OR 0·86, 95 % CI 0·73, 1·01). However, milk consumers had lower odds of having elevated waist circumference (OR 0·78, 95 % CI 0·67, 0·92), elevated TAG (OR 0·83, 95 % CI 0·70, 0·99) and elevated blood pressure (OR 0·85, 95 % CI 0·73, 0·99). When the results were pooled together with other published studies, higher milk consumption was inversely associated with the risk of the metabolic syndrome (relative risk 0·80, 95 % CI 0·72, 0·88) and its components (except elevated fasting blood glucose); however, these results should be treated with caution as high heterogeneity was observed. In summary, the currently available evidence from observational studies suggests that higher milk consumption may be inversely associated with the metabolic syndrome.

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.

Laxative effects of triple fermented barley extracts (FBe) on loperamide (LP)-induced constipation in rats

BACKGROUND

Constipation, a common health problem, causes discomfort and affects the quality of life. This study intended to evaluate the potential laxative effect of triple fermented barley (Hordeum vulgare L.) extract (FBe), produced by saccharification, Saccharomyces cerevisiae, and Weissella cibaria, on loperamide (LP)-induced constipation in Sprague-Dawley (SD) rats, a well-established animal model of spastic constipation.

METHODS

Spastic constipation was induced via oral treatment with LP (3 mg/kg) for 6 days 1 h before the administration of each test compound. Similarly, FBe (100, 200 and 300 mg/kg) was orally administered to rats once a day for 6 days. The changes in number, weight, and water content of fecal, motility ratio, colonic mucosa histology, and fecal mucous contents were recorded. The laxative properties of FBe were compared with those of a cathartic stimulant, sodium picosulfate. A total of 48 (8 rats in 6 groups) healthy male rats were selected and following 10 days of acclimatization. Fecal pellets were collected one day before administration of the first dose and starting from immediately after the fourth administration for a duration of 24 h. Charcoal transfer was conducted after the sixth and final administration of the test compounds.

RESULTS

In the present study, oral administration of 100-300 mg/kg of FBe exhibited promising laxative properties including intestinal charcoal transit ratio, thicknesses and mucous producing goblet cells of colonic mucosa with decreases of fecal pellet numbers and mean diameters remained in the lumen of colon, mediated by increases in gastrointestinal motility.

CONCLUSION

Therefore, FBe might act as a promising laxative agent and functional food ingredient to cure spastic constipation, with less toxicity observed at a dose of 100 mg/kg.

The effect of high compared with low dairy consumption on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults: a randomized crossover trial

BACKGROUND

Dairy products contain many nutritious components that may benefit metabolic health. There are indications that glucose metabolism and insulin sensitivity, which are generally disturbed in overweight and obese individuals, may improve by increased dairy intake. This may also affect one's metabolic flexibility.

OBJECTIVE

The aim of this study was to investigate the effects of high compared with low dairy intake on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults (aged 45-65 y).

METHODS

In this randomized intervention study, subjects consumed a high- and a low-dairy diet [HDD (5-6 dairy portions) and LDD (≤1 dairy portion), respectively] for 6 wk in a crossover design, with a washout period of 4 wk. Dairy portions were 200 g semi-skimmed yoghurt, 30 g reduced-fat (30+) cheese, and 250 mL semiskimmed milk and buttermilk. After 6 wk, a 75-g oral-glucose-tolerance test (13C-labeled) and a subsequent fasting challenge were performed. Metabolic flexibility was studied by determining the respiratory quotient (RQ) using indirect calorimetry. Fasting and postprandial plasma concentrations of glucose and insulin were analyzed. The dual isotope technique enabled calculation of glucose kinetics.

RESULTS

The study was completed by 45 overweight men and postmenopausal women [age 58.9 ± 4.3 y, BMI 27.9 ± 1.9 kg/m2 (mean ± SD)]. Fasting RQ and ΔRQ, reflecting metabolic flexibility, did not differ after both diets. Fasting glucose concentrations were similar, whereas fasting insulin concentrations were lower after the LDD (LDD: 8.1 ± 2.8 mU/L; HDD: 8.9 ± 3.3 mU/L; P = 0.024). This resulted in a higher HOMA-IR after the HDD (P = 0.027). Postprandial glucose and insulin responses as well as glucose kinetics were similar after both diets.

CONCLUSIONS

The amount of dairy intake during a 6-wk period had a neutral effect on metabolic flexibility or postprandial glucose metabolism in middle-aged overweight subjects. More trials are needed to study the effects of specific dairy types and to differentiate between metabolic subgroups. This trial was registered at trialregister.nl as NTR4899.

The Association between Fish Consumption and Risk of Metabolic Syndrome in Adults: Tehran Lipid and Glucose Study

Objective: Although fish consumption may play a role in prevention of the risk of metabolic syndrome (MetS), results of studies available on this topic are controversial. In this study, we have examined the association of fish consumption and 3.6-year incidence of MetS in Tehranian adults.

METHODS

We conducted a population based cohort study of 3382 adult subjects, aged 19-55 years, from the Tehran Lipid and Glucose Study (TLGS). Fish consumption data were collected using a valid and reliable food-frequency questionnaire. The consumption of fish, in the form of canned and non-canned fish was designated for all subjects, and was classified into three categories (< 30, 30-45, and > 45 g/week). Odds ratio (OR) for the occurrence of MetS according to categories of fish consumption was assessed by multivariable logistic regression.

RESULTS

The mean age of participants (35% male) at baseline was 35 years. Mean fish consumption was 11.3 g/d and incidence of MetS was 13.1%. In the fully adjusted model, subjects, who consumed > 45 g/week of fish had lower incidence of MetS, compared to those who consumed < 30 g/week (OR = 0.73; CI: 0.56-0.95). However, there were no associations between consumption of non-canned fish (OR = 0.86; 95% CI: 0.67-1.10) and canned fish (OR = 0.91; 95% CI: 0.64-1.29) and the incidence of MetS.

CONCLUSION

Our findings suggest that high consumption of fish can reduce the incidence of MetS among adults.

Effects of food items and related nutrients on metabolic syndrome using Bayesian multilevel modelling using the Tehran Lipid and Glucose Study (TLGS): a cohort study

OBJECTIVES

Diet and nutrition might play an important role in the aetiology of metabolic syndrome (MetS). Most studies that examine the effects of food intake on MetS have used conventional statistical analyses which usually investigate only a limited number of food items and are subject to sparse data bias. This study was undertaken with the goal of investigating the concurrent effect of numerous food items and related nutrients on the incidence of MetS using Bayesian multilevel modelling which can control for sparse data bias.

DESIGN

Prospective cohort study.

SETTING

This prospective study was a subcohort of the Tehran Lipid and Glucose Study. We analysed dietary intake as well as pertinent covariates for cohort members in the fourth (2008-2011) and fifth (2011-2014) follow-up examinations. We fitted Bayesian multilevel model and compared the results with two logistic regression models: (1) full model which included all variables and (2) reduced model through backward selection of dietary variables.

PARTICIPANTS

3616 healthy Iranian adults, aged ≥20 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Incident cases of MetS.

RESULTS

Bayesian multilevel approach produced results that were more precise and biologically plausible compared with conventional logistic regression models. The OR and 95% confidence limits for the effects of the four foods comparing the Bayesian multilevel with the full conventional model were as follows: (1) noodle soup (1.20 (0.67 to 2.14) vs 1.91 (0.65 to 5.64)), (2) beans (0.96 (0.5 to 1.85) vs 0.55 (0.03 to 11.41)), (3) turnip (1.23 (0.68 to 2.23) vs 2.48 (0.82 to 7.52)) and (4) eggplant (1.01 (0.51 to 2.00) vs 1 09 396 (0.152×10-6 to 768×1012)). For most food items, the Bayesian multilevel analysis gave narrower confidence limits than both logistic regression models, and hence provided the highest precision.

CONCLUSIONS

This study demonstrates that conventional regression methods do not perform well and might even be biased when assessing highly correlated exposures such as food items in dietary epidemiological studies. Despite the complexity of the Bayesian multilevel models and their inherent assumptions, this approach performs superior to conventional statistical models in studies that examine multiple nutritional exposures that are highly correlated.

Nutrients in Fish and Possible Associations with Cardiovascular Disease Risk Factors in Metabolic Syndrome

Non-communicable diseases (NSDs) are responsible for two-thirds of all deaths globally, whereas cardiovascular disease (CVD) alone counts for nearly half of them. To reduce the impact of CVD, targeting modifiable risk factors comprised in metabolic syndrome (e.g., waist circumference, lipid profile, blood pressure, and blood glucose) is of great importance. Beneficial effects of fish consumption on CVD has been revealed over the past decades, and some studies suggest that fish consumption may have a protective role in preventing metabolic syndrome. Fish contains a variety of nutrients that may contribute to health benefits. This review examines current recommendations for fish intake as a source of various nutrients (proteins, n-3 fatty acids, vitamin D, iodine, selenium, and taurine), and their effects on metabolic syndrome and the CVD risk factors. Fatty fish is recommended due to its high levels of n-3 fatty acids, however lean fish also contains nutrients that may be beneficial in the prevention of CVD.

Dairy food consumption is associated with a lower risk of the metabolic syndrome and its components: a systematic review and meta-analysis

A systematic review and a meta-analysis of observational studies were performed to assess the dose–response relationship between specific types of dairy foods and the risk of the metabolic syndrome (MetS) and its components. Studies of dairy foods and the risk of the MetS and its components published up to June 2016 were searched using PubMed, EMBASE and a reference search. Random-effects models were used to estimate the pooled relative risks (RR) with 95 % CI. Finally, ten cross-sectional studies, two nested case–control studies and twenty-nine cohort studies were included for the analysis. In a dose–response analysis of cohort studies and cross-sectional studies, the pooled RR of the MetS for a one-serving/d increment of total dairy food (nine studies) and milk (six studies) consumption (200 g/d) were 0·91 (95 % CI 0·85, 0·96) and 0·87 (95 % CI 0·79, 0·95), respectively. The pooled RR of the MetS for yogurt (three studies) consumption (100 g/d) was 0·82 (95 % CI 0·73, 0·91). Total dairy food consumption was associated with lower risk of MetS components, such as hyperglycaemia, elevated blood pressure, hypertriacylglycerolaemia and low HDL- cholesterol. A one-serving/d increment of milk was related to a 12 % lower risk of abdominal obesity, and a one-serving/d increment of yogurt was associated with a 16 % lower risk of hyperglycaemia. These associations were not significantly different by study design, study location or adjustment factors. This meta-analysis showed that specific types of dairy food consumption such as milk and yogurt as well as total dairy food consumption were inversely related to risk of the MetS and its components.

Meat Consumption and Risk of Metabolic Syndrome: Results from the Korean Population and a Meta-Analysis of Observational Studies

Many studies have reported harmful effects of red meat or processed meat on chronic diseases including cancer and diabetes, but epidemiological evidence for metabolic syndrome is limited and remains controversial. Therefore, we performed a meta-analysis of observational studies to assess the association between various meat consumption and risk of metabolic syndrome. The PubMed and ISI Web of Science databases were searched through June 2017, and further included unpublished results from Korea National Health and Nutrition Examination Survey 2012–2015, including 8387 Korean adults. Sixteen studies were suitable for meta-analysis, which included 19,579 cases among 76,111 participants. We used a random-effects model to calculate the pooled relative risks (RR) and 95% confidence intervals (CI). The pooled RR for metabolic syndrome of the highest versus lowest category of meat intake was 1.14 (95% CI: 1.05, 1.23) for total meat, 1.33 (95% CI: 1.01, 1.74) for red meat, 1.35 (95% CI: 1.18, 1.54) for processed meat, and 0.86 (95% CI: 0.76, 0.97) for white meat. All of these associations did not differ significantly by study design and adjustment factors. Our findings indicated that total, red, and processed meat intake is positively associated with metabolic syndrome, and white meat intake is inversely associated with metabolic syndrome.

Effect of dietary habits on the risk of metabolic syndrome: Yazd Healthy Heart Project

Objective

Metabolic syndrome (MetS) refers to a group of risk factors that increase the risk of cardiovascular mortality and morbidity. Dietary habits are among the most important risk factors for MetS. The current study aimed at assessing the effect of dietary habits on the risk of MetS in a 10-year follow-up study in central Iran.

Design

Cohort study.

Setting

Yazd, Iran.

Subjects

Participants aged 20–74 years without any history of MetS, who were originally recruited for Yazd Healthy Heart Project (YHHP) during 2005–2006, were revisited during 2015–2016. At phase I of YHHP, demographic data, anthropometric measurements, five components of MetS, biochemical tests and dietary habits were evaluated; and the same data were collected in phase II.

Results

A total of 1092 participants were eligible to be included in the present study. After follow-up, the 10-year cumulative incidence of MetS was 56·1 %. After adjustment for potential confounders, increased risk of MetS (hazard ratio; 95 % CI) was found in those who did not try to control their body weight (1·57; 1·06, 2·35), did not usually eat salad (1·91; 1·22, 3·00) and added salt to their food (1·57, 1·06, 2·33). These associations were stronger in men than in the total population after subgroup analysis, but were not present in women.

Conclusions

Dietary habits affect the risk of MetS in the Iranian population. Lifestyle interventions are needed to improve dietary habits to reduce the risk of MetS. Future studies are highly recommended to confirm our results in other populations.

Lifestyle recommendations for the prevention and management of metabolic syndrome: an international panel recommendation

The importance of metabolic syndrome (MetS) lies in its associated risk of cardiovascular disease and type 2 diabetes, as well as other harmful conditions such as nonalcoholic fatty liver disease. In this report, the available scientific evidence on the associations between lifestyle changes and MetS and its components is reviewed to derive recommendations for MetS prevention and management. Weight loss through an energy-restricted diet together with increased energy expenditure through physical activity contribute to the prevention and treatment of MetS. A Mediterranean-type diet, with or without energy restriction, is an effective treatment component. This dietary pattern should be built upon an increased intake of unsaturated fat, primarily from olive oil, and emphasize the consumption of legumes, cereals (whole grains), fruits, vegetables, nuts, fish, and low-fat dairy products, as well as moderate consumption of alcohol. Other dietary patterns (Dietary Approaches to Stop Hypertension, new Nordic, and vegetarian diets) have also been proposed as alternatives for preventing MetS. Quitting smoking and reducing intake of sugar-sweetened beverages and meat and meat products are mandatory. Nevertheless, there are inconsistencies and gaps in the evidence, and additional research is needed to define the most appropriate therapies for MetS. In conclusion, a healthy lifestyle is critical to prevent or delay the onset of MetS in susceptible individuals and to prevent cardiovascular disease and type 2 diabetes in those with existing MetS. The recommendations provided in this article should help patients and clinicians understand and implement the most effective approaches for lifestyle change to prevent MetS and improve cardiometabolic health.

Associations between fish intake and the metabolic syndrome and its components among middle-aged men and women: the Hordaland Health Study

In epidemiologic studies, the relationship between fish consumption and the metabolic syndrome (MetS) have been inconclusive and sex differences reported. The aim was to investigate associations between fish intake and the MetS in a cross-sectional study of men and women. Fish intake, waist circumference, triglycerides (TG), HDL-C, glucose and blood pressure were assessed among 2874 men and women (46–49 y) in the Hordaland Health Study (1997–1999). Fatty fish intake was inversely associated with TG in men only; mean difference in TG between highest and lowest quartile of fatty fish intake was –0.33 mmol/L (95% CI: –0.51, –0.15). Lean fish intake was inversely associated with TG in women only; mean difference in TG between highest and lowest quartile of lean fish intake was –0.23 mmol/L (95% CI: –0.34, –0.11). Fatty fish intake was positively associated with serum HDL-C in both men and women. Total fish intake was inversely associated with MetS; adjusted OR 0.75 (95% CI 0.57, 0.97). Higher fish intake was associated with lower odds of having MetS possibly driven by associations of higher fish intake with lower TG and higher HDL-C. The findings of differential associations by sex needs to be confirmed and possible biologic mechanisms explored.

n-3 Polyunsaturated Fatty Acids and Metabolic Syndrome Risk: A Meta-Analysis

The associations between n-3 polyunsaturated fatty acids (PUFAs) and metabolic syndrome (MetS) risk have demonstrated inconsistent results. The present study aimed to investigate whether higher circulating n-3 PUFAs and dietary n-3 PUFAs intake have a protective effect on MetS risk. A systematic literature search in the PubMed, Scopus, and Chinese National Knowledge Infrastructure (CNKI) databases was conducted up to March 2017. Odd ratios (ORs) from case-control and cross-sectional studies were combined using a random-effects model for the highest versus lowest category. The differences of n-3 PUFAs between healthy subjects and patients with MetS were calculated as weighted mean difference (WMD) by using a random-effects model. Seven case-control and 20 cross-sectional studies were included. A higher plasma/serum n-3 PUFAs was associated with a lower MetS risk (Pooled OR = 0.63, 95% CI: 0.49, 0.81). The plasma/serum n-3 PUFAs in controls was significantly higher than cases (WMD: 0.24; 95% CI: 0.04, 0.43), especially docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). However, no significant association was found between dietary intake of n-3 PUFAs or fish and MetS risk. The present study provides substantial evidence of a higher circulating n-3 PUFAs associated with a lower MetS risk. The circulating n-3 PUFAs can be regarded as biomarkers indicating MetS risk, especially DPA and DHA.

Lean Fish Consumption Is Associated with Beneficial Changes in the Metabolic Syndrome Components: A 13-Year Follow-Up Study from the Norwegian Tromsø Study

BACKGROUND

Fish consumption may have beneficial effects on metabolic syndrome (MetS); however, limited information of such associations exists. This study investigated possible associations between fish consumption and changes in MetS components during a 13-year follow-up period.

METHODS

The sample included participants (26-69 years) from the Tromsø Study 4 (1994-1995, n = 23,907) and Tromsø Study 6 (2007-2008, n = 12,981). Data were collected using questionnaires including food frequency questions, non-fasting blood samples, and physical examinations. MetS was defined using the Joint Interim Societies (JIS) definition, in which one point was given for each MetS criteria fulfilled (metabolic score). Longitudinal analyses were performed using Linear mixed models.

RESULTS

For both genders, lean fish consumption once a week or more was significantly associated with decreased future metabolic score, decreased triglycerides, and increased high-density lipoprotein (HDL)-cholesterol, whereas decreased waist circumference and blood pressure was identified only for men (age adjusted models). Fatty fish consumption was significantly associated with increased waist circumference for both genders and increased HDL-cholesterol levels in men. Conclusion: The results suggest that fatty and lean fish consumption may influence MetS differently and that lean fish consumption in particular seems to be associated with beneficial changes in the MetS components.

Dairy food products: good or bad for cardiometabolic disease?

Prevalence of type 2 diabetes mellitus (T2DM) is rapidly increasingly and is a key risk for CVD development, now recognised as the leading cause of death globally. Dietary strategies to reduce CVD development include reduction of saturated fat intake. Milk and dairy products are the largest contributors to dietary saturated fats in the UK and reduced consumption is often recommended as a strategy for risk reduction. However, overall evidence from prospective cohort studies does not confirm a detrimental association between dairy product consumption and CVD risk. The present review critically evaluates the current evidence on the association between milk and dairy products and risk of CVD, T2DM and the metabolic syndrome (collectively, cardiometabolic disease). The effects of total and individual dairy foods on cardiometabolic risk factors and new information on the effects of the food matrix on reducing fat digestion are also reviewed. It is concluded that a policy to lower SFA intake by reducing dairy food consumption to reduce cardiometabolic disease risk is likely to have limited or possibly negative effects. There remain many uncertainties, including differential effects of different dairy products and those of differing fat content. Focused and suitably designed and powered studies are needed to provide clearer evidence not only of the mechanisms involved, but how they may be beneficially influenced during milk production and processing.

Whole-grain intake and total, cardiovascular, and cancer mortality: a systematic review and meta-analysis of prospective studies

BACKGROUND

The potential role of whole grain in preventing various mortality outcomes has been inconsistently reported in a wealth of prospective observational studies.

OBJECTIVE

We evaluated the relations between whole-grain intake and risks of dying from any cause, cardiovascular disease (CVD), and cancer through a meta-analytic approach.

DESIGN

Relevant studies were identified by searching PubMed and EMBASE databases and bibliographies of retrieved full publications. Summary RRs with 95% CIs were calculated with a random-effects model.

RESULTS

Thirteen studies on total mortality (104,061 deaths), 12 on CVD mortality (26,352 deaths), and 8 on cancer mortality (34,797 deaths) were included. Three studies reported whole-grain intake, and the remaining studies reported whole-grain product intake. In the dose-response analysis in which the intake of whole-grain products was converted to the amount of whole grain, the summary RRs for an increment in whole-grain intake of 50 g/d were 0.78 (95% CI: 0.67, 0.91) for total mortality, 0.70 (95% CI: 0.61, 0.79) for CVD mortality, and 0.82 (95% CI: 0.69, 0.96) for cancer mortality. A similar reduction was observed for the mortality from ischemic heart disease (RR: 0.68; 95% CI: 0.55, 0.84) but not from stroke (RR: 0.93; 95% CI: 0.54, 1.62). There was evidence of nonlinear associations of whole-grain intake with total (P-nonlinearity < 0.001) and CVD mortality (P-nonlinearity <0.001), but not with cancer mortality (P-nonlinearity = 0.12), with the curves for the associations appearing slightly steeper at lower ranges (<35 g/d) of the intake than at higher ranges.

CONCLUSIONS

Our findings suggest significant inverse relations between whole-grain intake and mortality due to any cause, CVD, or cancer. The findings support the recommendation of increasing whole-grain intake to improve public health.

Intake of fish and long-chain omega-3 polyunsaturated fatty acids and incidence of metabolic syndrome among American young adults: a 25-year follow-up study

PURPOSE

Studies suggest that long-chain ω-3 polyunsaturated fatty acid (LCω3PUFA) intake and its primary food source-fish-may have beneficial effects on the individual components of metabolic syndrome (MetS). We examined the longitudinal association between fish or LCω3PUFA intake and MetS incidence.

METHODS

We prospectively followed 4356 American young adults, free from MetS and diabetes at baseline, for incident MetS and its components in relation to fish and LCω3PUFA intake. MetS was defined by the National Cholesterol Education Program/Adult Treatment Panel III criteria. Cox proportional hazards model was used for analyses, controlling for socio-demographic, behavioral, and dietary factors.

RESULTS

During the 25-year follow-up, a total of 1069 incident cases of MetS were identified. LCω3PUFA intake was inversely associated with the incidence of MetS in a dose-response manner. The multivariable adjusted hazards ratio (HR) [95 % confidence interval (CI)] of incident MetS was 0.54 (95 % CI 0.44, 0.67; P for linear trend < 0.01) as compared the highest to the lowest quintile of LCω3PUFA intake. A threshold inverse association was found between non-fried fish consumption and the incidence of MetS. The multivariable adjusted HRs (95 % CIs) from the lowest to the highest quintile were 1.00, 0.70 (0.51, 0.95), 0.68 (0.52, 0.91), 0.67 (0.53, 0.86), and 0.71 (0.56, 0.89) (P for linear trend = 0.49). The observed inverse associations were independent of the status of baseline individual components of MetS.

CONCLUSIONS

Our findings suggest that intakes of LCω3PUFAs and non-fried fish in young adulthood are inversely associated with the incidence of MetS later in life.

Lean fish consumption is associated with lower risk of metabolic syndrome: a Norwegian cross sectional study

Background

Fish consumption may have a role in reducing the prevalence of metabolic syndrome (MetS). The aim of this study was to identify associations between fish consumption and MetS and its components, especially regarding differences concerning consumption of fatty and lean fish.

Methods

This cross sectional study uses data from the Tromsø 6 survey (2007–08), where a sample of 12 981 adults, aged 30–87 years (47 % men) from the Norwegian general population was included. Fish consumption was assessed using food frequency questionnaires (FFQ). Blood sample assessments, anthropometric and blood pressure measurements were carried out according to standard protocols. MetS was defined using the Joint Interim Societies (JIS) definition. All tests were two-sided. Analyses were performed using IBM SPSS Statistics 22 (Pearson’s correlation, Chi-Square tests, analysis of variance (ANOVA), linear and logistic regression models).

Results

Mean age was 57.5, and the prevalence of MetS was 22.6 %. Fish consumption once a week or more was associated with lower risk of having MetS among men (OR 0.85, CI 95 % 0.74 to 0.98, P = 0.03). In the adjusted models, lean fish consumption was associated with a decreased risk of having MetS, whereas fatty fish consumption was not associated with a decreased risk of having MetS. Both an increased fatty and lean fish consumption (0–1 times per month, 2–3 times per month, 1–3 times per week, 4–6 times per week, 1–2 times per day) were associated with decreased serum triglyceride (TG), and increased high-density lipoprotein cholesterol (HDL-C).

Conclusions

Fish consumption may be associated with a lower risk of having MetS and consumption of lean fish seems to be driving the association. Further investigation is warranted to establish associations between fish consumption and MetS.

Dairy consumption and risk of metabolic syndrome: a meta-analysis

AIMS

To conduct a systematic review and meta-analysis of epidemiological studies in order to assess quantitatively the effect of dairy consumption on risk of metabolic syndrome.

METHODS

We searched for eligible studies published up to March 2015 through the PubMed and Embase databases and reviewed the references of relevant articles. Random-effects models were used to calculate the pooled relative risks with 95% CIs after adjusting for several confounders.

RESULTS

We identified nine prospective cohort studies including a total of 35 379 subjects and 7322 incident cases of metabolic syndrome, and 12 cross-sectional studies including 37 706 subjects. In the meta-analysis of prospective cohort studies, the pooled relative risk of incidence of metabolic syndrome for the highest vs. the lowest category of dairy consumption was 0.85 (95% CI 0.73-0.98), and for a 1-serving/day increment of dairy consumption, the pooled relative risk was 0.88 (95% CI 0.82-0.95). In the meta-analysis of cross-sectional studies, the pooled relative risk of prevalence of metabolic syndrome for the highest vs. the lowest category of dairy consumption was 0.73 (95% CI 0.63-0.86). The association was not significantly different by geographical region, follow-up time and adjustment factors.

CONCLUSION

Our findings indicate that dairy consumption is inversely associated with the incidence and prevalence of metabolic syndrome. Further well-designed cohort studies and randomized controlled trials are warranted to provide definitive evidence.

Food groups associated with a reduced risk of 15-year all-cause death

BACKGROUND/OBJECTIVES

Long-term observational cohorts provide the opportunity to investigate the potential impact of dietary patterns on death. We aimed to investigate all-cause death according to the consumption of selected food groups, and then to identify those independently associated with reduced mortality.

SUBJECTS/METHODS

Population survey of middle-aged men randomly selected in the period 1995-1997 from the general population of three French areas and followed over a median of 14.8 years. Dietary data were collected through a 3-day food record. Cox modeling was used to assess the risk of death according to selected foods groups after extensive adjustment for confounders, including a diet quality index.

RESULTS

The study population comprised 960 men (mean age 55.5 ±6.2 years). After a median follow-up of 14.8 (interquartile range 14.3-15.2) years, 150 (15.6%) subjects had died. Food groups that remained independently predictive of a lower risk of death after extensive adjustment were an above-median consumption of milk (adjusted relative risk: 0.61, 95% confidence interval (CI): 0.43-0.86, P-value=0.005), fruits and vegetables (0.68, 0.46-0.98, P-value=0.041) and a moderate consumption of yogurts and cottage cheese (0.50, 95% CI: 0.31-0.81, P-value=0.005), other cheeses (0.62, 0.39-0.97, P-value=0.036) and bread (0.57, 0.37-0.89, P-value=0.014). Besides, there was a nonsignificant trend for a higher risk of death associated with highest sodium intakes.

CONCLUSIONS

Consumption of food groups that largely match recommendations is associated with a reduced risk of all-cause death in men. A diet providing moderate amounts of diverse food groups appears associated with the highest life expectancy.

Total and Full-Fat, but Not Low-Fat, Dairy Product Intakes are Inversely Associated with Metabolic Syndrome in Adults

BACKGROUND

Growing evidence suggests that dairy products may have beneficial cardiometabolic effects. The current guidelines, however, limit the intake of full-fat dairy products.

OBJECTIVE

We investigated the association of dairy consumption, types of dairy products, and dairy fat content with metabolic syndrome (MetSyn).

METHODS

We analyzed baseline data of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a multicenter cohort study of 15,105 adults aged 35-74 y. We excluded participants with known diabetes, cardiovascular diseases, or other chronic diseases, and those who had extreme values of energy intake, leaving 9835 for analysis. Dairy consumption was assessed by a food-frequency questionnaire. We computed servings per day for total and subgroups of dairy intake. We computed a metabolic risk score (MetScore) as the mean z score of waist circumference, systolic blood pressure, HDL cholesterol (negative z score), fasting triglycerides, and fasting glucose. We performed multivariable linear regression to test the association of servings per day of dairy products with MetScore.

RESULTS

In analyses that adjusted for demographics, menopausal status, family history of diabetes, dietary intake, nondietary lifestyle factors, and body mass index, we observed a graded inverse association for MetScore with total dairy (-0.044 ± 0.01, P = 0.009 for each additional dairy servings per day) and full-fat dairy (-0.126 ± 0.03, P < 0.001) but not with low-fat dairy intake. Associations were no longer present after additional adjustments for dairy-derived saturated fatty acids.

CONCLUSIONS

Total and especially full-fat dairy food intakes are inversely and independently associated with metabolic syndrome in middle-aged and older adults, associations that seem to be mediated by dairy saturated fatty acids. Dietary recommendations to avoid full-fat dairy intake are not supported by our findings.

Associations between fish consumption and metabolic syndrome. A large cross-sectional study from the Norwegian Tromsø Study: Tromsø 4

BACKGROUND

Fish consumption may prevent or improve metabolic health. The aim of this study was to identify associations between fish consumption, both fatty and lean, and metabolic syndrome and its components.

METHODS

Associations between fish consumption and metabolic syndrome and its components were studied in a large sample from a Norwegian population (N = 23,907), using cross-sectional data from the Tromsø 4 survey (1994-1995). Metabolic syndrome was defined using the JIS definition, and dietary data was collected using food frequency questionnaires (FFQ). Blood samples were taken for biochemical assessments, and anthropometric and blood pressure measurements were carried out according to standard protocols.

RESULTS

In this sample from an adult population (aged 26-70 years, mean age 44 years, SD 11.69, 48 % men), a higher fish consumption (≥1/week) was associated with a healthier lipid profile with increased HDL-C and decreased TG. Participants aged 60-70 years consuming fish once a week or more had significantly lower risk of having MetS, compared to those consuming fish less than once a week (OR 0.64, CI 0.45-0.91). When investigating fatty and lean fish separately, only lean fish consumption was associated with a reduced the risk of having MetS. Participants aged 60-70 years consuming lean fish once a week or more, had lower risk of having MetS compared to those consuming lean fish less than once a week (OR 0.65, CI 0.48-0.87). No association was found for consumption of fatty fish, or for lean fish in the age groups <45 or 45-59 years.

CONCLUSIONS

These results indicates that fatty and lean fish consumption influences MetS risk differently, possibly also related to age. However, further investigation is needed to establish how various fish consumption may influence MetS and its components, particularly when stratified by fatty and lean fish.

Consumption of Yogurt, Low-Fat Milk, and Other Low-Fat Dairy Products Is Associated with Lower Risk of Metabolic Syndrome Incidence in an Elderly Mediterranean Population

BACKGROUND

The association between consumption of dairy products and the risk of developing metabolic syndrome (MetS) is unclear.

OBJECTIVE

The purpose of this study was to evaluate the associations between consumption of dairy products (total and different subtypes) and incident MetS in a Mediterranean population at high cardiovascular disease risk.

METHODS

We prospectively analyzed 1868 men and women (55-80 y old) without MetS at baseline, recruited from different PREDIMED (Prevención con Dieta Mediterránea) centers between October 2003 and June 2009 and followed up until December 2010. MetS was defined according to updated, harmonized criteria. At baseline and yearly thereafter, we determined anthropometric variables, dietary habits by a 137-item validated food-frequency questionnaire, and blood biochemistry. Multivariable-adjusted HRs of MetS or its components were estimated for each of the 2 upper tertiles (vs. the lowest one) of mean consumption of dairy products during the follow-up.

RESULTS

During a median follow-up of 3.2 y, we documented 930 incident MetS cases. In the multivariable-adjusted model, HRs (95% CIs) of MetS for the comparison of extreme tertiles of dairy product consumption were 0.72 (0.61, 0.86) for low-fat dairy, 0.73 (0.62, 0.86) for low-fat yogurt, 0.78 (0.66, 0.92) for whole-fat yogurt, and 0.80 (0.67, 0.95) for low-fat milk. The respective HR for cheese was 1.31 (1.10, 1.56).

CONCLUSIONS

Higher consumption of low-fat dairy products, yogurt (total, low-fat, and whole-fat yogurt) and low-fat milk was associated with a reduced risk of MetS in individuals at high cardiovascular disease risk from a Mediterranean population. Conversely, higher consumption of cheese was related to a higher risk of MetS. This trial was registered at controlled-trials.com as ISRCTN35739639.

Dairy products consumption and metabolic syndrome in adults: systematic review and meta-analysis of observational studies

The association of dairy products consumption with risk of metabolic syndrome (MetS) has been inconsistently reported in observational studies. A systematic review and meta-analysis of published observational studies was conducted to quantitatively evaluate this association. Relevant studies were identified by searching PubMed and EMBASE databases and by carefully checking the bibliographies of retrieved full reports and related reviews. Eligible studies were observational studies that investigated the association between dairy products consumption and risk of MetS in adults, with risk estimates available. Random-effects model was assigned to calculate the summary risk estimates. The final analysis included 15 cross-sectional studies, one case-control study and seven prospective cohort studies. Higher dairy consumption significantly reduced MetS by 17% in the cross-sectional/case-control studies (odds ratio = 0.83, 95% confidence interval [CI], 0.73-0.94), and by 14% (relative risk [RR] = 0.86, 95% CI, 0.79-0.92) in cohort studies. The inverse dairy-MetS association was consistent in subgroup and sensitivity analyses. The dose-response analysis of the cohort studies conferred a significant 6% (RR = 0.94, 95% CI, 0.90-0.98) reduction in the risk of MetS for each increment in dairy consumption of one serving/d. No significant publication bias was observed. Our findings suggest an inverse dose-response relationship between dairy consumption and risk of MetS.

Dietary Fat Intake and the Risk of Metabolic Syndrome in Korean Adults

Background

The effect of dietary fat intake on the risk of cardiovascular disease remains unclear. We investigated the association between dietary fat and specific types of fat intake and the risk of metabolic syndrome.

Methods

The study population included 1,662 healthy adults who were 50.2 years of age and had no known hypertension, diabetes, hyperlipidemia, or metabolic syndrome at the initial visit. Dietary intake was obtained from a 1-day food record. During 20.7 months of follow-up, we documented 147 cases of metabolic syndrome confirmed by self-report, anthropometric data, and blood test results. The intakes of total fat, vegetable fat, animal fat, saturated fatty acid (SFA), polyunsaturated fatty acid (PUFA), monounsaturated fatty acid (MUFA), and cholesterol level divided by quintile. Multivariate analyses included age, sex, body mass index, smoking status, alcohol intake, physical activity, total calorie, and protein intake.

Results

Vegetable fat intake was inversely associated with metabolic syndrome risk (odds ratio for the highest vs. the lowest quintile, 0.33; 95% confidence interval, 0.14 to 0.76). Total fat, animal fat, SFA, PUFA, MUFA, and cholesterol intakes showed no association with metabolic syndrome. Vegetable fat intake was inversely associated with the risk of hypertriglyceridemia among the components of metabolic syndrome.

Conclusion

These data support an inverse association between vegetable fat and the risk of metabolic syndrome.

Increased Dietary Intake of Saturated Fatty Acid Heptadecanoic Acid (C17:0) Associated with Decreasing Ferritin and Alleviated Metabolic Syndrome in Dolphins

Similar to humans, bottlenose dolphins (Tursiops truncatus) can develop metabolic syndrome and associated high ferritin. While fish and fish-based fatty acids may protect against metabolic syndrome in humans, findings have been inconsistent. To assess potential protective factors against metabolic syndrome related to fish diets, fatty acids were compared between two dolphin populations with higher (n = 30, Group A) and lower (n = 19, Group B) mean insulin (11 ± 12 and 2 ± 5 μIU/ml, respectively; P < 0.0001) and their dietary fish. In addition to higher insulin, triglycerides, and ferritin, Group A had lower percent serum heptadecanoic acid (C17:0) compared to Group B (0.3 ± 0.1 and 1.3 ± 0.4%, respectively; P < 0.0001). Using multivariate stepwise regression, higher percent serum C17:0, a saturated fat found in dairy fat, rye, and some fish, was an independent predictor of lower insulin in dolphins. Capelin, a common dietary fish for Group A, had no detectable C17:0, while pinfish and mullet, common in Group B's diet, had C17:0 (41 and 67 mg/100g, respectively). When a modified diet adding 25% pinfish and/or mullet was fed to six Group A dolphins over 24 weeks (increasing the average daily dietary C17:0 intake from 400 to 1700 mg), C17:0 serum levels increased, high ferritin decreased, and blood-based metabolic syndrome indices normalized toward reference levels. These effects were not found in four reference dolphins. Further, higher total serum C17:0 was an independent and linear predictor of lower ferritin in dolphins in Group B dolphins. Among off the shelf dairy products tested, butter had the highest C17:0 (423mg/100g); nonfat dairy products had no detectable C17:0. We hypothesize that humans' movement away from diets with potentially beneficial saturated fatty acid C17:0, including whole fat dairy products, could be a contributor to widespread low C17:0 levels, higher ferritin, and metabolic syndrome.

The Association of Dairy Intake With Metabolic Syndrome and Its Components in Adolescents: Tehran Lipid and Glucose Study

BACKGROUND

Epidemiological studies have shown that consumption of dairy product plays an important role in prevention and treatment of Metabolic Syndrome (MetS).

OBJECTIVES

The objective of this study was to examine the association of dairy intake with MetS and its components in Tehranian adolescents.

PATIENTS AND METHODS

In this cross-sectional study, 785 adolescent aged 10 to 19 years, participated from the fourth phase of the Tehran Lipid and Glucose Study. Usual dietary intake was assessed using a valid semi quantitative food frequency questionnaire. Total dairy, low fat and high fat dairy, milk, yoghurt and cheese were evaluated. Assessment of anthropometric, biochemical and blood pressure was performed and MetS was defined according to the de Ferranti criteria.

RESULTS

The mean age of subjects was 14.8 ± 2.9 years. The prevalence of MetS was 22.2% (girls: 19.5% and boys: 25.2%). The most prevalent risk factor for MetS in boys was high waist circumference (53.4%) and among girls was low HDL-C (53.1%). Energy density and intake of protein, total fat, saturated fat, cholesterol, calcium and phosphor were higher in the highest quartile of dairy consumption than the lowest quartile. After adjustments for confounders, odds ratios with 95% confidence interval for MetS in the highest quartile of total dairy, low fat dairy, high fat dairy, milk, yoghurt and cheese compared with lowest quartile were respectively 0.97 (0.57 - 1.66), 1.44 (0.83 - 2.49), 0.97 (0.56 - 1.67), 0.70 (0.42 - 1.18), 1.62 (0.99 - 2.64) and 0.72 (0.44 - 1.18).

CONCLUSIONS

Results of this study did not support the hypothesis that dairy products consumption protects against MetS and its components.

Fish consumption, long-chain omega-3 polyunsaturated fatty acid intake and risk of metabolic syndrome: a meta-analysis

Fish and long-chain ω-3 polyunsaturated fatty acid (LCω3PUFA) intake in relation to the risk of cardiovascular diseases have been well studied. However, studies that directly link fish consumption or LCω3PUFA intake to the risk of metabolic syndrome (MetS) are sparse and the results are inconsistent. We reviewed literature through December 2014 and used random-effects or fixed-effects models, as appropriate, to pool the associations of fish or LCω3PUFA intake with the risk of MetS. Nine independent cross-sectional samples (seven cross-sectional studies) and three independent prospective cohorts (two prospective cohort studies) were identified as eligible for this meta-analysis. By pooling data from the prospective cohorts (7860 participants and 1671 incident cases), a significant inverse association between fish consumption and incidence of MetS was found. The pooled RR (95% CI) was 0.71 (0.58, 0.87), comparing the highest to the lowest category of fish consumption, and 0.94 (0.90, 0.98) for one serving/week increment. Consistent results were found for LCω3PUFA intake. Non-significant inverse association of fish or LCω3PUFA intake with risk of MetS was found when pooling the cross-sectional studies. By quantitatively summarizing the literature, a modest inverse association between fish or LCω3PUFA intake and risk of MetS cannot be excluded.

Sugar-sweetened product consumption alters glucose homeostasis compared with dairy product consumption in men and women at risk of type 2 diabetes mellitus

BACKGROUND

Dietary patterns characterized by high intakes of fruits and vegetables, whole grains, low-fat dairy products, and low glycemic load have been associated with lower type 2 diabetes mellitus (T2DM) risk. In contrast, dietary patterns that include high intakes of refined grains, processed meats, and high amounts of added sugars have been associated with increased T2DM risk.

OBJECTIVE

This randomized, 2-period crossover trial compared the effects of dairy and sugar-sweetened product (SSP) consumption on insulin sensitivity and pancreatic β-cell function in men and women at risk of the development of T2DM who habitually consume sugar-sweetened beverages.

METHODS

In a randomized, controlled crossover trial, participants consumed dairy products (474 mL/d 2% milk and 170 g/d low-fat yogurt) and SSPs (710 mL/d nondiet soda and 108 g/d nondairy pudding), each for 6 wk, with a 2-wk washout between treatments. A liquid meal tolerance test (LMTT) was administered at baseline and the end of each period.

RESULTS

Participants were 50% female with a mean age and body mass index of 53.8 y and 32.2 kg/m(2), respectively. Changes from baseline were significantly different between dairy product and SSP conditions for median homeostasis model assessment 2-insulin sensitivity (HOMA2-%S) (1.3 vs. -21.3%, respectively, P = 0.009; baseline = 118%), mean LMTT disposition index (-0.03 vs. -0.36, respectively, P = 0.011; baseline = 2.59), mean HDL cholesterol (0.8 vs. -4.2%, respectively, P = 0.015; baseline = 44.3 mg/dL), and mean serum 25-hydroxyvitamin D [25(OH)D] (11.7 vs. -3.3, respectively, P = 0.022; baseline = 24.5 μg/L). Changes from baseline in LMTT Matsuda insulin sensitivity index (-0.10 vs. -0.49, respectively; baseline = 4.16) and mean HOMA2-β-cell function (-2.0 vs. 5.3%, respectively; baseline = 72.6%) did not differ significantly between treatments.

CONCLUSION

These results suggest that SSP consumption is associated with less favorable values for HOMA2-%S, LMTT disposition index, HDL cholesterol, and serum 25(OH)D in men and women at risk of T2DM vs. baseline values and values during dairy product consumption. This trial was registered at clinicaltrials.gov as NCT01936935.

Frequency of fish intake and diabetes among adult Indians

OBJECTIVES

Recent studies have shown that the choice of foods plays a role in diabetes prevention. However, little empirical evidence on this association exists in developing countries. We aimed to examine the association between frequency of fish intake and self-reported diabetes status among adult men and women in India.

METHODS

Analysis of cross-sectional data from participants in India's third National Family Health Survey conducted during 2005-2006 was performed. Associations between fish intake, determined by frequency of consumption (daily, weekly, occasionally, and never), and self-reported diabetes were estimated using multivariable-adjusted models in 99,574 women, 56,742 men, and 39,257 couples aged 20-49 years after adjusting for frequency of consumption of other food items, body mass index (BMI) status, tobacco smoking, alcohol drinking, watching television, age, education, living standard of the household, and place of residence.

RESULTS

After adjustment for other dietary, lifestyle, and socioeconomic and demographic characteristics, odds of diabetes were 2 times higher (odds ratio [OR]: 2.02; 95% confidence interval [CI], 1.59-2.57; p < 0.0001) among those who reported consuming fish daily compared to those who never consumed fish. Weekly fish intake was also associated with a higher odds of having diabetes (OR: 1.55; 95% CI, 1.25-1.93; p < 0.0001). The adjusted effect of daily fish intake on diabetes was greater among men (OR: 2.46; 95% CI, 1.66-3.65) than among women (OR: 1.72; 95% CI, 1.26-2.33). In cross-spousal sensitivity analysis, the odds of a husband having diabetes was also associated with wife's daily/weekly consumption of fish (OR: 1.36; 95% CI, 0.92-2.01) and the odds of a wife having diabetes was also associated with husband's daily/weekly consumption of fish (OR: 1.21; 95% CI, 0.87-1.68).

CONCLUSIONS

In a large nationally representative sample of adult men and women in India, daily or weekly fish intake was positively associated with the presence of diabetes. However, this is an observational finding and uncontrolled confounding cannot be excluded as an explanation for the association. More epidemiological research with better measures of food intake and clinical measures of diabetes is needed in a developing country setting to validate the findings.

Fish consumption and its possible preventive role on the development and prevalence of metabolic syndrome - a systematic review

Metabolic syndrome (MetS) has a huge impact on public health, and today lifestyle interventions remain the primary mode for MetS therapy. It is therefore important to elucidate the possible preventive effects of diet and foods, and their MetS-related health implications. To examine how fish consumption affects the development and prevalence of MetS, we systematically reviewed cross-sectional, prospective cohort, and intervention studies conducted among adults (humans) and, reporting consumption of fish or seafood as being related to MetS (prevalence or incidence), where MetS was defined via an established definition. The literature search in PubMed identified 502 citations, and after screening, 49 full-text articles were retrieved and assessed for eligibility. After excluding duplicates and those not meeting the inclusion criteria, seven studies from Croatia, Finland, France, Iceland, Iran, Korea, and US were included. Four studies (one follow-up and three cross-sectional) found associations between fish consumption and MetS (three among men, and one among women), suggesting that fish consumption may prevent or improve metabolic health and have a protective role in MetS prevention. This protective role might be related to gender, and men may benefit more from the consumption of fish. However, lack of controlling for potential confounders may also inflict the results. Additional research is required to further explore fish consumption and its potential role in improving or reversing MetS and its components.

High dairy fat intake related to less central obesity: a male cohort study with 12 years' follow-up

OBJECTIVE

To study associations between dairy fat intake and development of central obesity.

DESIGN

A prospective population-based cohort study with two surveys 12 years apart.

SETTING

Nine municipalities selected from different parts of Sweden representing the rural areas in the country.

SUBJECTS

1782 men (farmers and non-farmers) aged 40-60 years at baseline participated in a baseline survey (participation rate 76%) and 1589 men participated at the follow-up. 116 men with central obesity at baseline were excluded from the analyses.

MAIN OUTCOME MEASURES

Central obesity at follow-up defined as waist hip ratio ≥ 1.

RESULTS

197 men (15%) developed central obesity during follow-up. A low intake of dairy fat at baseline (no butter and low fat milk and seldom/never whipping cream) was associated with a higher risk of developing central obesity (OR 1.53, 95% CI 1.05-2.24) and a high intake of dairy fat (butter as spread and high fat milk and whipping cream) was associated with a lower risk of central obesity (OR 0.52, 95% CI 0.33-0.83) as compared with medium intake (all other combinations of spread, milk, and cream) after adjustment for intake of fruit and vegetables, smoking, alcohol consumption, physical activity, age, education, and profession. The associations between dairy fat intake and central obesity were consistent across body mass index categories at baseline.

CONCLUSION

A high intake of dairy fat was associated with a lower risk of central obesity and a low dairy fat intake was associated with a higher risk of central obesity.

Consumption of low-fat dairy foods for 6 months improves insulin resistance without adversely affecting lipids or bodyweight in healthy adults: a randomized free-living cross-over study

Background

Given the highly debated role of dairy food consumption in modulating biomarkers of metabolic syndrome, this study was conducted to examine the influence of long-term (6 month) dairy consumption on metabolic parameters in healthy volunteers under free-living conditions without energy restriction.

Methods

Twenty-three healthy subjects completed a randomized, crossover trial of 12 months. Participants consumed their habitual diets and were randomly assigned to one of two treatment groups: a high dairy supplemented group instructed to consume 4 servings of dairy per day (HD); or a low dairy supplemented group limited to no more than 2 servings of dairy per day (LD). Baseline, midpoint, and endpoint metabolic responses were examined.

Results

Endpoint measurements of body weight and composition, energy expenditure, blood pressure, blood glucose, and blood lipid and lipoprotein responses did not differ (p > 0.05) between the LD and HD groups. HD consumption improved (p < 0.05) plasma insulin (-9%) and insulin resistance (-11%, p = 0.03) as estimated by HOMA-IR compared with the LD group.

Conclusions

Study results suggest that high dairy consumption (4 servings/d) may improve insulin resistance without negatively impacting bodyweight or lipid status under free-living conditions.

Trial registration

Trial registration: NCT01761955

Comparison of the fatty acid composition of the serum phospholipids of controls, prediabetics and adults with type 2 diabetes

OBJECTIVE

Although abnormalities in the fatty acid composition of serum and red cell membrane phospholipids of patients with type 2 diabetes are well-documented, lacking are studies of this issue in prediabetic individuals.

MATERIALS/METHODS

For this cross-sectional study, we recruited 180 subjects (30-80 years), 56 of whom were normal with regard to glucose control (HbA1c, <5.7%), 61 who had prediabetes (HbA1c, 5.7%-6.4%) and 59 who had type 2 diabetes (HbA1c, >6.5%). Serum phospholipids were isolated and analyzed for fatty acids.

RESULTS

Most importantly, the fatty acid compositions of the controls and prediabetic subjects were not different for 19 fatty acids. However, the fatty acid profile of the phospholipids of the patients with diabetes differed from the other two groups; the 14 to 18-carbon saturated fatty acids were decreased by 12%-26% whereas the unsaturated fatty acids 16:1n-7, 18:1n-9, 18:2n-6, 20:3n-6 and 20:4n-6 were increased by 45%-64%. Of note, the docosahexaenoic acid (DHA) status of individuals in all three study groups was remarkably low compared with international values, as indicated by DHA proportions in the 1.62%-2.07% range, and there were no differences between groups. The mean melting point of the phospholipid fatty acids of the diabetic patients (32.2°C) was significantly lower (p < 0.001) than that of the prediabetic subjects (38.1°C) and the controls (39.9°C) which were not different from each other.

CONCLUSION

These observations indicate that the fatty acid changes associated with type 2 diabetes follow the onset of the disease as opposed to being a causative factor of poor glucose control and insulin insensitivity.

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

Results from observational studies on the association of fish and n-3 fatty acid consumption with type 2 diabetes mellitus (T2DM) risk are conflicting. Hence, a meta-analysis was performed to investigate this association from cohort studies. A comprehensive search was then conducted to identify cohort studies on the association of fish and/or n-3 fatty acid intake with T2DM risk. In the highest v. lowest categorical analyses, the fixed or random-effect model was selected based on the homogeneity test among studies. Linear and non-linear dose-response relationships were also assessed by univariate and bivariate random-effect meta-regression with restricted maximum likelihood estimation. In the highest v. lowest categorical analyses, the pooled relative risk (RR) of T2DM for intake of fish and n-3 fatty acid was 1·146 (95 % CI 0·975, 1·346) and 1·076 (95 % CI 0·955, 1·213), respectively. In the linear dose-response relationship, the pooled RR for an increment of one time (about 105 g)/week of fish intake (four times/month) and of 0·1 g/d of n-3 fatty acid intake was 1·042 (95 % CI 1·026, 1·058) and 1·057 (95 % CI 1·042, 1·073), respectively. The significant non-linear dose-response associations of fish and n-3 fatty acid intake with T2DM risk were not observed. The present evidence from observational studies suggests that the intake of both fish and n-3 fatty acids might be weakly positively associated with the T2DM risk. Further studies are needed to confirm these results.