Body iron stores and heme-iron intake in relation to risk of type 2 diabetes: a systematic review and meta-analysis

Associations Between Dietary Protein Sources, Plasma BCAA and Short-Chain Acylcarnitine Levels in Adults

Elevated plasma branched-chain amino acids (BCAA) and C3 and C5 acylcarnitines (AC) levels observed in individuals with insulin resistance (IR) might be influenced by dietary protein intakes. This study explores the associations between dietary protein sources, plasma BCAA levels and C3 and C5 ACs in normal weight (NW) or overweight (OW) individuals with or without metabolic syndrome (MS). Data from 199 men and women aged 18⁻55 years with complete metabolite profile were analyzed. Associations between metabolic parameters, protein sources, plasma BCAA and AC levels were tested. OW/MS+ consumed significantly more animal protein (p = 0.0388) and had higher plasma BCAA levels (p < 0.0001) than OW/MS- or NW/MS- individuals. Plasma BCAA levels were not associated with BCAA intakes in the whole cohort, while there was a trend for an association between plasma BCAA levels and red meat or with animal protein in OW/MS+. These associations were of weak magnitude. In NW/MS- individuals, the protein sources associated with BCAA levels varied greatly with adjustment for confounders. Plasma C3 and C5 ACs were associated with plasma BCAA levels in the whole cohort (p < 0.0001) and in subgroups based on OW and MS status. These results suggest a modest association of meat or animal protein intakes and an association of C3 and C5 ACs with plasma BCAA levels, obesity and MS.

High red and processed meat consumption is associated with non-alcoholic fatty liver disease and insulin resistance

BACKGROUND & AIMS

High red and processed meat consumption is related to type 2 diabetes. In addition, cooking meat at high temperatures for a long duration forms heterocyclic amines (HCAs), which are related to oxidative stress. However, the association between meat consumption and non-alcoholic fatty liver disease (NAFLD) is yet to be thoroughly tested. Therefore, we aimed to test the association of meat type and cooking method with NAFLD and insulin resistance (IR).

METHODS

This was a cross-sectional study in individuals who were 40-70 years old and underwent screening colonoscopy between 2013 and 2015 in a single center in Israel. NAFLD and IR were evaluated by ultrasonography and homeostasis model assessment. Meat type and cooking method were measured by a food frequency questionnaire (FFQ) and a detailed meat questionnaire. Unhealthy cooking methods were considered as frying and grilling to a level of well done and very well done. Dietary HCA intake was calculated.

RESULTS

A total of 789 individuals had a valid FFQ and 357 had a valid meat questionnaire. High consumption of total meat (portions/day above the median) (odds ratio [OR] 1.49; 95% CI 1.05-2.13; p = 0.028; OR 1.63; 1.12-2.37; p = 0.011), red and/or processed meat (OR1.47; 95% CI 1.04-2.09; p = 0.031; OR1.55; 1.07-2.23; p = 0.020) was independently associated with higher odds of NAFLD and IR, respectively, when adjusted for: body mass index, physical activity, smoking, alcohol, energy, saturated fat and cholesterol intake. High intake of meat cooked using unhealthy methods (OR1.92; 95% CI 1.12-3.30; p = 0.018) and HCAs (OR2.22; 95% CI 1.28-3.86; p = 0.005) were independently associated with higher odds of IR.

CONCLUSION

High consumption of red and/or processed meat is associated with both NAFLD and IR. High HCA intake is associated with IR. If confirmed in prospective studies, limiting the consumption of unhealthy meat types and improving preparation methods may be considered as part of NAFLD lifestyle treatment.

LAY SUMMARY

High red and processed meat consumption is related to several diseases. In addition, cooking meat at high temperatures for a long duration forms heterocyclic amines, which have harmful health effects. Non-alcoholic fatty liver disease is a significant public health burden and its formation is strongly related to insulin resistance. In this study, both were found to be more frequent in people who consume relatively high quantities of red and processed meat. In addition, a high intake of heterocyclic amines was associated with insulin resistance.

Elevated serum ferritin concentration is associated with incident type 2 diabetes mellitus in a Chinese population: A prospective cohort study

AIMS

We aimed to evaluate the association between serum ferritin levels and incident type 2 diabetes mellitus risk in a Chinese population.

METHODS

This cohort study assessed 2225 Chinese individuals aged 25-75 years. Diabetes mellitus was diagnosed using the 1999 World Health Organization definition with a median follow-up period of 20 months. Cox proportional hazard models were used to estimate adjusted hazard ratios and 95% confidence intervals (CI) for incident diabetes when serum ferritin concentrations increased by one standard deviation.

RESULTS

During the follow-up period, 112 cases (62 men and 50 women) of type 2 diabetes mellitus were identified. Baseline serum ferritin levels were higher in the diabetes than the non-diabetes group. After adjusting for age, body mass index, waist circumference, mean arterial pressure, fasting plasma glucose, fasting insulin, hemoglobin A1c, total cholesterol, high-density lipoprotein cholesterol, alanine transaminase and triglyceride levels, family history of diabetes mellitus, pork meat consumption, neutrophil/lymphocyte ratio, education, and annual household income, the hazard ratios for incident diabetes corresponding to one standard deviation increase in serum ferritin levels were 1.17 (95% CI 1.03, 1.34), 1.20 (95% CI 1.003, 1.43), and 1.03 (95% CI 0.82, 1.31) for the total population, men, and women, respectively.

CONCLUSIONS

High serum ferritin levels were associated with a higher risk of incident type 2 diabetes mellitus independent of traditional risk factors in the total population and men.

Iron: a Strong Element in the Pathogenesis of Chronic Hyperglycaemia After Acute Pancreatitis

Evidence shows an association between markers of iron metabolism and glucose metabolism in type 2 diabetes mellitus. Acute pancreatitis is the largest contributor to diabetes of the exocrine pancreas. However, the pathogenesis of new-onset pre-diabetes or diabetes after pancreatitis remains unclear. This study aimed to investigate associations between markers of iron metabolism and glucose metabolism following acute pancreatitis. Fasting blood samples were collected to analyse markers of glucose metabolism (haemoglobin A1c) and iron metabolism (hepcidin, ferritin, and soluble transferrin receptor). Participants were categorised into two groups: normoglycaemia after acute pancreatitis and chronic hyperglycaemia after acute pancreatitis. Binary logistic and linear regression analyses were conducted, and potential confounders were adjusted for in multivariable analyses. A total of 83 individuals following an episode of acute pancreatitis were included, of whom 19 developed chronic hyperglycaemia. Hepcidin was significantly increased in individuals with chronic hyperglycaemia after acute pancreatitis in two adjusted models (p = 0.045 and p = 0.048). Ferritin was significantly decreased in individuals with chronic hyperglycaemia after acute pancreatitis in three adjusted models (p = 0.016, p = 0.009, and p = 0.011). Soluble transferrin receptor was not significantly associated with chronic hyperglycaemia after acute pancreatitis. These findings suggest that iron metabolism is significantly altered in individuals with chronic hyperglycaemia after acute pancreatitis and may provide better insights into the pathogenesis of new-onset diabetes after pancreatitis.

The opportunity cost of animal based diets exceeds all food losses

With a third of all food production lost via leaky supply chains or spoilage, food loss is a key contributor to global food insecurity. Demand for resource-intensive animal-based food further limits food availability. In this paper, we show that plant-based replacements for each of the major animal categories in the United States (beef, pork, dairy, poultry, and eggs) can produce twofold to 20-fold more nutritionally similar food per unit cropland. Replacing all animal-based items with plant-based replacement diets can add enough food to feed 350 million additional people, more than the expected benefits of eliminating all supply chain food loss.

Food loss is widely recognized as undermining food security and environmental sustainability. However, consumption of resource-intensive food items instead of more efficient, equally nutritious alternatives can also be considered as an effective food loss. Here we define and quantify these opportunity food losses as the food loss associated with consuming resource-intensive animal-based items instead of plant-based alternatives which are nutritionally comparable, e.g., in terms of protein content. We consider replacements that minimize cropland use for each of the main US animal-based food categories. We find that although the characteristic conventional retail-to-consumer food losses are ≈30% for plant and animal products, the opportunity food losses of beef, pork, dairy, poultry, and eggs are 96%, 90%, 75%, 50%, and 40%, respectively. This arises because plant-based replacement diets can produce 20-fold and twofold more nutritionally similar food per cropland than beef and eggs, the most and least resource-intensive animal categories, respectively. Although conventional and opportunity food losses are both targets for improvement, the high opportunity food losses highlight the large potential savings beyond conventionally defined food losses. Concurrently replacing all animal-based items in the US diet with plant-based alternatives will add enough food to feed, in full, 350 million additional people, well above the expected benefits of eliminating all supply chain food waste. These results highlight the importance of dietary shifts to improving food availability and security.

Influence of Haem, Non-Haem, and Total Iron Intake on Metabolic Syndrome and Its Components: A Population-Based Study

Studies suggest that haem, non-haem iron and total iron intake may be related to non-communicable diseases, especially metabolic syndrome. This study was undertaken to investigate the association of haem, non-haem iron and total iron intake with metabolic syndrome and its components. A cross-sectional population-based survey was performed in 2008, enrolling 591 adults and elderly adults living in São Paulo, Brazil. Dietary intake was measured by two 24 h dietary recalls. Metabolic syndrome was defined as the presence of at least three of the following: hypertension, hyperglycaemia, dyslipidaemia and central obesity. The association between different types of dietary iron and metabolic syndrome was evaluated using multiple logistic regression. After adjustment for potential confounders, a higher haem iron intake was positively associated with metabolic syndrome and with elevated triglyceride levels. A higher total iron intake was positively associated with hyperglycaemia. Non-haem iron intake was positively associated with hyperglycaemia in the fourth quintile. In conclusion, this study suggests that the different types of dietary iron are associated with metabolic syndrome, elevated triglyceride levels and hyperglycaemia. In addition, it emphasises the importance of investigating the roles of dietary iron in health outcomes, since its consumption may have different impacts on health.

Interaction of Dietary and Genetic Factors Influencing Body Iron Status and Risk of Type 2 Diabetes Within the EPIC-InterAct Study

OBJECTIVE

Meat intake has been consistently shown to be positively associated with incident type 2 diabetes. Part of that association may be mediated by body iron status, which is influenced by genetic factors. We aimed to test for interactions of genetic and dietary factors influencing body iron status in relation to the risk of incident type 2 diabetes.

RESEARCH DESIGN AND METHODS

The case-cohort comprised 9,347 case subjects and 12,301 subcohort participants from eight European countries. Single nucleotide polymorphisms (SNPs) were selected from genome-wide association studies on iron status biomarkers and candidate gene studies. A ferritin-related gene score was constructed. Multiplicative and additive interactions of heme iron and SNPs as well as the gene score were evaluated using Cox proportional hazards regression.

RESULTS

Higher heme iron intake (per 1 SD) was associated with higher ferritin levels (β = 0.113 [95% CI 0.082; 0.144]), but not with transferrin (-0.019 [-0.043; 0.006]) or transferrin saturation (0.016 [-0.006; 0.037]). Five SNPs located in four genes (rs1799945 [HFE H63D], rs1800562 [HFE C282Y], rs236918 [PCK7], rs744653 [SLC40A1], and rs855791 [TMPRSS6 V736A]) were associated with ferritin. We did not detect an interaction of heme iron and the gene score on the risk of diabetes in the overall study population (Padd = 0.16, Pmult = 0.21) but did detect a trend toward a negative interaction in men (Padd = 0.04, Pmult = 0.03).

CONCLUSIONS

We found no convincing evidence that the interplay of dietary and genetic factors related to body iron status associates with type 2 diabetes risk above the level expected from the sum or product of the two individual exposures.

Global aetiology and epidemiology of type 2 diabetes mellitus and its complications

Globally, the number of people with diabetes mellitus has quadrupled in the past three decades, and diabetes mellitus is the ninth major cause of death. About 1 in 11 adults worldwide now have diabetes mellitus, 90% of whom have type 2 diabetes mellitus (T2DM). Asia is a major area of the rapidly emerging T2DM global epidemic, with China and India the top two epicentres. Although genetic predisposition partly determines individual susceptibility to T2DM, an unhealthy diet and a sedentary lifestyle are important drivers of the current global epidemic; early developmental factors (such as intrauterine exposures) also have a role in susceptibility to T2DM later in life. Many cases of T2DM could be prevented with lifestyle changes, including maintaining a healthy body weight, consuming a healthy diet, staying physically active, not smoking and drinking alcohol in moderation. Most patients with T2DM have at least one complication, and cardiovascular complications are the leading cause of morbidity and mortality in these patients. This Review provides an updated view of the global epidemiology of T2DM, as well as dietary, lifestyle and other risk factors for T2DM and its complications.

Iron reduction response and demographic differences between diabetics and non-diabetics with cardiovascular disease entered into a controlled clinical trial

Filings of elemental iron separated magnetically from a homogenate of breakfast cereal implicated in the risk of cardiovascular disease and diabetes.

Dietary iron intake, iron status, and gestational diabetes

Pregnant women are particularly vulnerable to iron deficiency and related adverse pregnancy outcomes and, as such, are routinely recommended for iron supplementation. Emerging evidence from both animal and population-based studies, however, has raised potential concerns because significant associations have been observed between greater iron stores and disturbances in glucose metabolism, including increased risk of type 2 diabetes among nonpregnant individuals. Yet, the evidence is uncertain regarding the role of iron in the development of gestational diabetes mellitus (GDM), a common pregnancy complication which has short-term and long-term adverse health ramifications for both women and their children. In this review, we critically and systematically evaluate available data examining the risk of GDM associated with dietary iron, iron supplementation, and iron status as measured by blood concentrations of several indicators. We also discuss major methodologic concerns regarding the available epidemiologic studies on iron and GDM.

Increased Small Intestine Expression of Non-Heme Iron Transporters in Morbidly Obese Patients With Newly Diagnosed Type 2 Diabetes

SCOPE

To investigate intestinal markers of iron absorption in morbidly obese subjects according to glucose tolerance.

METHODS AND RESULTS

Gene expression of both non-heme (SLC40A1 (ferroportin), SLC11A2) and heme iron (SLC46A1 (HCP1), HMOX1) transporters is analyzed in 38 small intestine tissue samples [11 with normal glucose tolerance, 14 with glucose intolerance (GI), and 13 with newly diagnosed type 2 diabetes (T2D)]. SLC40A1 (r = 0.43, p = 0.008) and SLC11A2 (r = 0.35, p = 0.03) mRNA levels are positively correlated with ferritin-to-hepcidin ratio and with fasting glucose, being significantly increased in patients with T2D. Only ferroportin is negatively associated with serum hepcidin (r = -0.617, p < 0.0001). In multivariate regression analysis, fasting glucose contributes independently to intestinal SLC40A1 (p = 0.009) and SLC11A2 (p = 0.04) variance after controlling for age, sex, and BMI. When circulating hepcidin is incorporated into the model, fasting glucose contributes significantly and independently to intestinal SLC40A1 (p = 0.02), but not to SLC11A2 (p = 0.07) variance. SLC46A1 and HMOX1 are similar in all groups.

CONCLUSION

The expression of ferroportin and SLC11A2 is increased in the intestine of patients with T2D in association with iron stores and serum hepcidin levels. Increased intestinal iron absorption is a potential mechanism that could explain the increased body iron stores frequently observed in patients with T2D.

The Role of Iron in Type 1 Diabetes Etiology: A Systematic Review of New Evidence on a Long-Standing Mystery

BACKGROUND

The incidence of type 1 diabetes (T1D) is rising, which might be due to the influence of environmental factors. Biological and epidemiological evidence has shown that excess iron is associated with beta-cell damage and impaired insulin secretion.

AIM

In this review, our aim was to assess the association between iron and the risk of T1D.

METHODS

A systematic literature search was performed in PubMed and EMBASE in July 2016. Studies investigating the effect of iron status/intake on the risk of developing T1D later were included, and study quality was evaluated. The results have been summarized in narrative form.

RESULTS

From a total of 931 studies screened, we included 4 observational studies evaluating iron intake from drinking water or food during early life and the risk of T1D. The quality of the studies was moderate to high assessed via the nine-star Newcastle Ottawa Scale. One out of the four studies included in this review found estimates of dietary iron intake to be associated with risk of T1D development, whereas three studies found no such relationship for estimates of iron in drinking water.

CONCLUSIONS

The limited number of studies included found dietary iron, but not iron in drinking water, to be associated with risk of T1D. Further studies are needed to clarify the association between iron and risk of T1D, especially studies including measurements of body iron status.

Interplay between innate immunity and iron metabolism after acute pancreatitis

Emerging evidence shows that chronic low-grade inflammation and changes in markers of innate immunity are implicated in a range of metabolic abnormalities following an episode of acute pancreatitis. Also, deranged iron metabolism has been linked to type 2 diabetes mellitus, gestational diabetes, and new-onset diabetes after pancreatitis - the conditions characterized by high haemoglobin glycation index (HGI). This study aimed to investigate the associations between markers of innate immunity and iron metabolism in individuals after acute pancreatitis. Fasting blood samples were collected to analyse lipopolysaccharide binding protein (LBP), interleukin (IL)-6, tumor necrosis factor-α, hepcidin, ferritin, soluble transferrin receptor, HbA1c, and glucose. Participants were categorized into two groups: low HGI and high HGI. Linear regression analyses were conducted, and potential confounders (age, sex, ethnicity, body mass index, diabetes mellitus status, smoking status, aetiology of pancreatitis, duration, recurrence, and severity of pancreatitis) were adjusted for in 5 statistical models. A total of 93 patients following an episode of acute pancreatitis were included, of who 40 (43%) had high HGI. In the overall cohort, LBP was significantly associated with hepcidin and ferritin, and IL-6 was significantly associated with hepcidin, consistently in all the models. Further, LBP contributed to 7.7% and 9.5% of variance in hepcidin and ferritin levels, respectively, whereas IL-6 contributed to 5.3% of hepcidin variance. Upon subgroup analysis, the observed LBP associations were maintained in the high HGI subgroup only and the IL-6 association in the low HGI subgroup only. No consistently significant associations were found between any of the other markers. The interplay between LBP, IL-6, hepcidin, and ferritin characterizes metabolic derangements after acute pancreatitis and may play a role in the pathogenesis of new-onset diabetes after pancreatitis.

Increased adipose tissue heme levels and exportation are associated with altered systemic glucose metabolism

Iron status is known to be associated with the physiology of adipose tissue (AT). We aimed to investigate AT heme and expression of heme exporter (FLVCR1) in association with obesity and type 2 diabetes (T2D). Substantial amounts of FLVCR1 mRNA and protein levels were detected in AT, being significantly increased in subjects with T2D, and positively correlated with fasting glucose, fasting triglycerides and with circulating markers of iron stores (serum ferritin, blood hemoglobin and hematocrit). In both visceral (VAT) and subcutaneous AT (SAT), increased heme levels were found in subjects with T2D. Reinforcing these associations, FLVCR1 mRNA levels were positively linked to fasting glucose in an independent cohort. Longitudianlly, the percent change of FLVCR1 positively correlated with the percent change in fasting glucose (r = 0.52, p = 0.03) after bariatric surgery-induced weight loss. High-fat diet-induced weight gain in rats did not result in significant changes in AT Flvcr1 mRNA but, remarkably, the expression of this gene positively correlated with fasting glucose and negatively with insulin sensitivity (QUICKI). Altogether, these findings showed a direct association between FLVCR1 mRNA levels and hyperglycemia, suggesting that increased adipose tissue heme exportation might disrupt, or is the consequence of, impaired systemic glucose metabolism during the progression to T2D.

The Mediterranean dietary pattern as the diet of choice for non-alcoholic fatty liver disease: Evidence and plausible mechanisms

Non-alcoholic fatty liver disease (NAFLD) has become a major global health burden, leading to increased risk for cirrhosis, hepatocellular carcinoma, type-2 diabetes and cardiovascular disease. Lifestyle intervention aiming at weight reduction is the most established treatment. However, changing the dietary composition even without weight loss can also reduce steatosis and improve metabolic alterations as insulin resistance and lipid profile. The Mediterranean diet (MD) pattern has been proposed as appropriate for this goal, and was recommended as the diet of choice for the treatment of NAFLD by the EASL-EASD-EASO Clinical Practice Guidelines. The MD has an established superiority in long term weight reduction over low fat diet, but it improves metabolic status and steatosis even without it. However, the effect on liver inflammation and fibrosis was tested only in few observational studies with positive results. Furthermore, considering the strong association between NAFLD and diabetes and CVD, the MD has a highly established advantage in prevention of these diseases, demonstrated in randomized clinical trials. The individual components of the MD such as olive oil, fish, nuts, whole grains, fruits, and vegetables, have been shown to beneficially effect or negatively correlate with NAFLD, while consumption of components that characterize a Western dietary pattern as soft drinks, fructose, meat and saturated fatty acids have been shown to have detrimental association with NAFLD. In this review we will cover the epidemiological evidence and the plausible molecular mechanisms by which the MD as a whole and each of its components can be of benefit in NAFLD.

A Contemporary Review of the Relationship between Red Meat Consumption and Cardiovascular Risk

Cardiovascular diseases burden is increasing due to aging populations and represents one of the major health issues worldwide. Dietary habits have been extensively studied in the cardiovascular field despite the difficulty in the quantification of the assumption of each single food and the observation that several foods affect cardiovascular risk with opposite effects. Moreover, some older findings have been reverted by more recent studies. Red meat has been widely studied in this context, and it has been suggested to increase cardiovascular risk primarily by causing dyslipidemia. Our aim is to review the relationship between red meat assumption and cardiovascular risk and to present novel findings regarding their link.

Mortality from different causes associated with meat, heme iron, nitrates, and nitrites in the NIH-AARP Diet and Health Study: population based cohort study

Objective To determine the association of different types of meat intake and meat associated compounds with overall and cause specific mortality.Design Population based cohort study.Setting Baseline dietary data of the NIH-AARP Diet and Health Study (prospective cohort of the general population from six states and two metropolitan areas in the US) and 16 year follow-up data until 31 December 2011.Participants 536 969 AARP members aged 50-71 at baseline.Exposures Intake of total meat, processed and unprocessed red meat (beef, lamb, and pork) and white meat (poultry and fish), heme iron, and nitrate/nitrite from processed meat based on dietary questionnaire. Adjusted Cox proportional hazards regression models were used with the lowest fifth of calorie adjusted intakes as reference categories.Main outcome measure Mortality from any cause during follow-up.Results An increased risk of all cause mortality (hazard ratio for highest versus lowest fifth 1.26, 95% confidence interval 1.23 to 1.29) and death due to nine different causes associated with red meat intake was observed. Both processed and unprocessed red meat intakes were associated with all cause and cause specific mortality. Heme iron and processed meat nitrate/nitrite were independently associated with increased risk of all cause and cause specific mortality. Mediation models estimated that the increased mortality associated with processed red meat was influenced by nitrate intake (37.0-72.0%) and to a lesser degree by heme iron (20.9-24.1%). When the total meat intake was constant, the highest fifth of white meat intake was associated with a 25% reduction in risk of all cause mortality compared with the lowest intake level. Almost all causes of death showed an inverse association with white meat intake.Conclusions The results show increased risks of all cause mortality and death due to nine different causes associated with both processed and unprocessed red meat, accounted for, in part, by heme iron and nitrate/nitrite from processed meat. They also show reduced risks associated with substituting white meat, particularly unprocessed white meat.

Dietary intake and peripheral arterial disease incidence in middle-aged adults: the Atherosclerosis Risk in Communities (ARIC) Study

Background: Peripheral arterial disease (PAD) is a costly source of morbidity and mortality among older persons in the United States. Dietary intake plays a role in the development of atherosclerotic cardiovascular disease; however, few studies have examined the relation of food intake or dietary patterns with PAD.Objective: We examined the relation between habitual dietary intake at midlife and incident PAD over ∼20 y of follow-up.Design: Among 14,082 participants enrolled in the ARIC (Atherosclerosis Risk in Communities) Study initially free of PAD, dietary intake was assessed at baseline in 1987-1989 by using a modified Harvard food-frequency questionnaire. Food groups were created, and principal components analysis was used to develop "healthy" and "Western" dietary patterns; both were categorized into quintiles or quartiles. Incident PAD was determined by an ankle-brachial index <0.9 assessed at 2 subsequent examinations and hospital discharge codes through 2012. Multivariate-adjusted Cox proportional hazards regression was used.Results: During a mean follow-up of 19.9 y, 1569 participants developed incident PAD. In models adjusted for demographic characteristics, behaviors, and food groups, the HRs (95% CIs) for incident PAD increased across quintiles of meat consumption [quintile 1: reference, quintile 2: 1.38 (1.16, 1.65), quintile 3: 1.38 (1.16, 1.65), quintile 4: 1.45 (1.20, 1.74), quintile 5: 1.66 (1.36, 2.03); P-trend <0.001]. Compared with those who drank no alcohol, those who had 1-6 drinks/wk had a lower risk of incident PAD [0.78 (0.68, 0.89)]. For coffee, ≥4 cups/d compared with none was inversely associated with incident PAD [quintile 5 compared with quintile 1: 0.84 (0.75, 1.00); P-trend = 0.014]. There was no association between other food groups or patterns and incident PAD.Conclusions: In this prospective cohort study, greater meat consumption was associated with a higher risk, and moderate alcohol consumption was associated with a lower risk of incident PAD. Whether these associations are causal remains to be seen. This trial was registered at clinicaltrials.gov as NCT00005131.

Diabetes mellitus caused by secondary hemochromatosis after multiple blood transfusions in 2 patients with severe aplastic anemia

Hemochromatosis is an inherited or secondary disorder caused by excessive iron storage leading to multiple organ damage. We describe 2 patients with diabetes mellitus caused by hemochromatosis secondary to multiple blood transfusions due to severe aplastic anemia. Subject 1, who was diagnosed with severe aplastic anemia at 15 years of age, received multiple red blood cell transfusions before he underwent autologous peripheral blood stem cell transplantation (PBSCT) at 22 years of age. At 21 years of age, hyperglycemia was detected with increased hemoglobin A1c and serum ferritin levels, 9.7% and 12,910 ng/mL (normal range, 20-320 ng/mL), respectively. The 24-hour urine C-peptide level was normal with negative antiglutamic acid decarboxylase antibody. Subsequently, metformin and an iron-chelating agent were administered. However, an intensive insulin regimen was necessary 2 years after the onset of diabetes. Subject 2, who was diagnosed with severe aplastic anemia at 2 years of age, received multiple blood transfusions until she underwent haploidentical PBSCT at 13 years of age. At 11 years of age, she developed diabetes mellitus with a high serum ferritin level (12,559.8 ng/mL). She is currently 18 years old and has been treated with an intensive insulin regimen and estrogen/progesterone replacement therapy because of hypogonadotropic hypogonadism. It is presumed that the loss of insulin secretory capacity and insulin resistance played a role in the pathogenesis of diabetes mellitus due to hemochromatosis in these cases.

Associations between dietary intakes of iron, copper and zinc with risk of type 2 diabetes mellitus: A large population-based prospective cohort study

BACKGROUND & AIMS

Abnormal homeostasis of iron, copper and zinc has been included in the pathogenesis of type 2 diabetes mellitus (T2DM). However, the evidence of associations between dietary intakes of these elements and T2DM is limited. We thought to examine the association between dietary intakes of iron, copper and zinc with risk of T2DM in Japanese population.

METHODS

A prospective study encompassing 16,160 healthy Japanese men and women aged 40-65 years in whom the associations between dietary intakes of iron, copper and zinc, determined by a validated self-administered food frequency questionnaire, with risk of 5-year cumulative incidence of validated physician-diagnosed T2DM, were evaluated by logistic regression model.

RESULTS

We ascertained 396 self-reported new cases of diabetes within 5-year period. Dietary intakes of iron (total and nonheme but not heme iron) and copper were positively associated with risk of T2DM; the multivariable OR in the highest versus lowest quartiles of intakes were 1.32 (1.04, 1.70; P-trend = 0.03) and 1.55 (1.13, 2.02; P-trend = 0.003), respectively. These associations were more evident in the high risk group; older, overweight, smokers and those with family history of diabetes. The dietary intake of zinc was inversely associated with risk of T2DM; the multivariable OR was 0.64 (0.54, 1.00; P-trend = 0.003), and such association was evident among younger subjects (age 40-55 years) only.

CONCLUSIONS

Dietary intakes of iron and copper were associated with a higher risk, while dietary intake of zinc was associated with a reduced risk of T2DM in Japanese population.

A longitudinal study of iron status during pregnancy and the risk of gestational diabetes: findings from a prospective, multiracial cohort

AIMS/HYPOTHESIS

The aim of this study was to prospectively and longitudinally investigate maternal iron status during early to mid-pregnancy, and subsequent risk of gestational diabetes mellitus (GDM), using a comprehensive panel of conventional and novel iron biomarkers.

METHODS

A case-control study of 107 women with GDM and 214 controls (matched on age, race/ethnicity and gestational week during blood collection) was conducted within the the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies-Singleton Cohort (2009-2013), a prospective and multiracial pregnancy cohort. Plasma hepcidin, ferritin and soluble transferrin receptor (sTfR) were measured and sTfR:ferritin ratio was derived, twice before GDM diagnosis (gestational weeks 10-14 and 15-26) and at weeks 23-31 and 33-39. GDM diagnosis was ascertained from medical records. Adjusted ORs (aORs) for GDM were estimated using conditional logistic regression analysis, adjusting for demographics, prepregnancy BMI and other major risk factors.

RESULTS

Hepcidin concentrations during weeks 15-26 were 16% higher among women with GDM vs controls (median 6.4 vs 5.5 ng/ml; p = 0.02 ), and were positively associated with GDM risk; the aOR (95% CI) for highest vs lowest quartile was 2.61 (1.07, 6.36). Ferritin levels were also positively associated with GDM risk; the aOR (95% CI) for highest vs lowest quartile was 2.43 (1.12, 5.28) at weeks 10-14 and 3.95 (1.38, 11.30) at weeks 15-26. The sTfR:ferritin ratio was inversely related to GDM risk; the aOR (95% CI) for highest vs lowest quartile was 0.33 (0.14, 0.80) at weeks 10-14 and 0.15 (0.05, 0.48) at weeks 15-26.

CONCLUSIONS/INTERPRETATION

Our findings suggest that elevated iron stores may be involved in the development of GDM from as early as the first trimester. This raises potential concerns for the recommendation of routine iron supplementation among iron-replete pregnant women.

Potential health hazards of eating red meat

Red meat (beef, veal, pork, lamb and mutton) consumption contributes several important nutrients to the diet, for example essential amino acids, vitamins (including B12) and minerals (including iron and zinc). Processed red meat (ham, sausages, bacon, frankfurters, salami, etc.) undergoes treatment (curing, smoking, salting or the use of chemical preservatives and additives) to improve its shelf life and/or taste. During recent decades, consumption of red meat has been increasing globally, especially in developing countries. At the same time, there has been growing evidence that high consumption of red meat, especially of processed meat, may be associated with an increased risk of several major chronic diseases. Here, a comprehensive summary is provided of the accumulated evidence based on prospective cohort studies regarding the potential adverse health effects of red meat consumption on major chronic diseases, such as diabetes, coronary heart disease, heart failure, stroke and cancer at several sites, and mortality. Risk estimates from pooled analyses and meta-analyses are presented together with recently published findings. Based on at least six cohorts, summary results for the consumption of unprocessed red meat of 100 g day^-1 varied from nonsignificant to statistically significantly increased risk (11% for stroke and for breast cancer, 15% for cardiovascular mortality, 17% for colorectal and 19% for advanced prostate cancer); for the consumption of 50 g day^-1 processed meat, the risks were statistically significantly increased for most of the studied diseases (4% for total prostate cancer, 8% for cancer mortality, 9% for breast, 18% for colorectal and 19% for pancreatic cancer, 13% for stroke, 22% for total and 24% for cardiovascular mortality and 32% for diabetes). Potential biological mechanisms underlying the observed risks and the environmental impact of red meat production are also discussed. The evidence-based integrated message is that it is plausible to conclude that high consumption of red meat, and especially processed meat, is associated with an increased risk of several major chronic diseases and preterm mortality. Production of red meat involves an environmental burden. Therefore, some European countries have already integrated these two issues, human health and the 'health of the planet', into new dietary guidelines and recommended limiting consumption of red meat.

Liver-Specific Overexpression of Gamma-Glutamyltransferase Ameliorates Insulin Sensitivity of Male C57BL/6 Mice

In the current study, we developed a liver-specific GGT-overexpressing mice model by rapid injection pLIVE-GGT vector through tail vein and investigated the effects of GGT elevation on glucose metabolism and insulin sensitivity. The serum GGT activity was significantly increased after 7 days of pLIVE-GGT1 vector delivery and lasted for about 3 weeks. GGT overexpression reduced the levels of GSSG and GSH in the liver and serum and had no effects on total antioxidative capacity in the liver, kidney, and skeletal muscle except for the pancreas. Increased GGT activity had no effect on the glucose tolerance but could facilitate blood glucose lowering after intraperitoneal insulin administration. The results of Western blotting showed that increased GGT activity enhanced insulin-induced AKT phosphorylation at Ser473. Furthermore, GGT inhibitor could attenuate the changes of insulin-induced blood glucose uptake and AKT phosphorylation in the liver. In summary, the present study developed a liver-specific GGT-overexpressing mice model and found that GGT elevation in short term had no effects on glucose metabolism but could increase insulin sensitivity through enhancing the activity of insulin signaling pathway.

Red Meat and Health

Despite its nutritional benefits, there is an increasing body of evidence to suggest that regular consumption of red meat may negatively impact health and disease risk, including the risk of most common chronic diseases. This chapter reviews the current evidence linking red and processed meat intakes with chronic disease, obesity and mortality risks and discusses possible mechanisms to explain these associations. Research on the health benefits of diets low in red meat, including vegetarian, vegan, Mediterranean and other plant-based diets, is also reviewed.

Effect of Iron Chelation Therapy on Glucose Metabolism in Non-Transfusion-Dependent Thalassaemia

AIMS

To compare insulin sensitivity, β-cell function and iron status biomarkers in non-transfusion-dependent thalassaemia (NTDT) with iron excess during pre- and post-iron chelation.

METHODS

Subjects with NTDT, aged older than 10 years, with serum ferritin >300 ng/ml, were included. Iron chelation with deferasirox (10 mg/kg/day) was prescribed daily for 6 months.

RESULTS

Ten patients with a median age of 17.4 years were enrolled. The comparison between pre- and post-chelation demonstrated significantly lower iron load: median serum ferritin (551.4 vs. 486.2 ng/ml, p = 0.047), median TIBC (211.5 vs. 233.5 µg/dl, p = 0.009) and median non-transferrin binding iron (5.5 vs. 1.4 µM, p = 0.005). All patients had a normal oral glucose tolerance test (OGTT) both pre- and post-chelation. However, fasting plasma glucose was significantly reduced after iron chelation (85.0 vs.79.5 mg/dl, p = 0.047). MRI revealed no significant changes of iron accumulation in the heart and liver after chelation, but there was a significantly lower iron load in the pancreas, assessed by higher T2* at post-chelation compared with pre-chelation (41.9 vs. 36.7 ms, p = 0.047). No adverse events were detected.

CONCLUSIONS

A trend towards improving insulin sensitivity and β-cell function as well as a reduced pancreatic iron load was observed following 6 months of iron chelation (TCTR20160523003).

Soluble transferrin receptor levels are positively associated with insulin resistance but not with the metabolic syndrome or its individual components

The metabolic syndrome (MetS) is known to be associated with elevated serum ferritin levels. The possible association with other Fe markers has been less well studied. We aimed to investigate the cross-sectional association of soluble transferrin receptor (sTfR) and ferritin levels with the MetS components, insulin resistance and glycosylated Hb (HbA1C). The sample consisted of 725 adults, aged 19-93 years (284 men, 151 premenopausal and 290 postmenopausal women), from the Croatian island of Vis. Serum sTfR and ferritin levels were measured by immunoturbidimetry and electrochemiluminescence assays, respectively. The MetS was defined using modified international consensus criteria. Logistic and linear regression analyses were conducted to investigate the associations adjusting for age, fibrinogen, smoking status, alcohol consumption and BMI. Prevalence of the MetS was 48·7 %. Standardised values of ferritin were positively associated with all of the MetS components (except high blood pressure and waist circumference) in men (P0·05). sTfR levels could be spuriously elevated in subjects with insulin resistance and without association with the MetS or its components. We conclude that different markers of Fe metabolism are not consistently associated with cardiometabolic risk.

Meat Consumption and Risk of Developing Type 2 Diabetes in the SUN Project: A Highly Educated Middle-Class Population

BACKGROUND

Meat consumption has been consistently associated with the risk of diabetes in different populations. The aim of our study was to investigate the incidence of type 2 diabetes according to baseline total meat consumption in a longitudinal assessment of a middle-aged Mediterranean population.

METHODS

We followed 18,527 participants (mean age: 38 years, 61% women) in the SUN Project, an open-enrolment cohort of a highly educated population of middle-class Spanish graduate students. All participants were initially free of diabetes. Diet was assessed at baseline using a semi-quantitative food frequency questionnaire of 136-items previously validated. Incident diabetes was defined according to the American Diabetes Association's criteria.

RESULTS

We identified 146 incident cases of diabetes after a maximum of 14 years of follow-up period (mean: 8.7 years). In the fully adjusted model, the consumption of ≥3 servings/day of all types of meat was significantly associated with a higher risk of diabetes (HR: 1.85; 95% CI: 1.03-3.31; p for trend = 0.031) in comparison with the reference category (<2 servings/day). When we separated processed from non-processed meat, we observed a non-significant higher risk associated with greater consumption of processed meat and a non-significant lower risk associated with non-processed meat consumption (p for trend = 0.123 and 0.487, respectively). No significant difference was found between the two types of meat (p = 0.594).

CONCLUSIONS

Our results suggest that meat consumption, especially processed meat, was associated with a higher risk of developing diabetes in our young Mediterranean cohort.

The Effects of Dietary Iron and Capsaicin on Hemoglobin, Blood Glucose, Insulin Tolerance, Cholesterol, and Triglycerides, in Healthy and Diabetic Wistar Rats

Objective

Our aim was to assess the effects of dietary iron, and the compound capsaicin, on hemoglobin as well as metabolic indicators including blood glucose, cholesterol, triglycerides, insulin, and glucose tolerance.

Materials and Methods

Our animal model was the Wistar rat, fed a chow diet, with or without experimentally induced diabetes. Diabetic males were fed control, low, or high-iron diets, the latter, with or without capsaicin. Healthy rats were fed identical diets, but without the capsaicin supplement. We then measured the parameters listed above, using the Student t-test and ANOVA, to compare groups.

Results

Healthy rats fed a low-iron diet exhibited significantly reduced total cholesterol and triglyceride levels, compared with rats fed a control diet. Significantly reduced blood lipid was also provoked by low dietary iron in diabetic rats, compared with those fed a control diet. Insulin, and glucose tolerance was only improved in healthy rats fed the low-iron diet. Significant increases in total cholesterol were found in diabetic rats fed a high-iron diet, compared with healthy rats fed the same diet, although no statistical differences were found for triglycerides. Hemoglobin levels, which were not statistically different in diabetic versus healthy rats fed the high-iron diet, fell when capsaicin was added. Capsaicin also provoked a fall in the level of cholesterol and triglycerides in diabetic animals, versus diabetics fed with the high iron diet alone. In conclusion, low levels of dietary iron reduced levels of serum triglycerides, hemoglobin, and cholesterol, and significantly improved insulin, and glucose tolerance in healthy rats. In contrast, a high-iron diet increased cholesterol significantly, with no significant changes to triglyceride concentrations. The addition of capsaicin to the high-iron diet (for diabetic rats) further reduced levels of hemoglobin, cholesterol, and triglycerides. These results suggest that capsaicin, may be suitable for the treatment of elevated hemoglobin, in patients.

The role of nerve inflammation and exogenous iron load in experimental peripheral diabetic neuropathy (PDN)

BACKGROUND

Iron is an essential but potentially toxic metal in mammals. Here we investigated a pathogenic role of exogenous iron in peripheral diabetic neuropathy (PDN) in an animal model for type 1 diabetes.

METHODS

Diabetes was induced by a single injection of streptozotocin (STZ) in 4-month-old Sprague-Dawley rats. STZ-diabetic rats and non-diabetic rats were fed with high, standard, or low iron diet. After three months of feeding, animals were tested.

RESULTS

STZ-rats on standard iron diet showed overt diabetes, slowed motor nerve conduction, marked degeneration of distal intraepidermal nerve fibers, mild intraneural infiltration with macrophages and T-cells in the sciatic nerve, and increased iron levels in serum and dorsal root ganglion (DRG) neurons. While motor fibers were afflicted in all STZ-groups, only a low iron-diet led also to reduced sensory conduction velocities in the sciatic nerve. In addition, only STZ-rats on a low iron diet showed damaged mitochondria in numerous DRG neurons, a more profound intraepidermal nerve fiber degeneration indicating small fiber neuropathy, and even more inflammatory cells in sciatic nerves than seen in any other experimental group.

CONCLUSIONS

These results indicate that dietary iron-deficiency rather than iron overload, and mild inflammation may both promote neuropathy in STZ-induced experimental PDN.

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

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

Tipping the balance: Haemoglobinopathies and the risk of diabetes

AIM: To establish a link between the risk of diabetes with haemoglobinopathies by examining available evidence of the effects of iron and blood glucose homeostasis from molecular to epidemiological perspectives.

METHODS: A systematic literature search was performed using electronic literature databases using various search terms. The International Diabetes Federation World Atlas was used to generate a list of populations with high rates of diabetes. PubMed, Scopus and Google Scholar were used to identify which of these populations also had a reported prevalence of haemoglobin abnormalities.

RESULTS: Abnormalities in iron homeostasis leads to increases in reactive oxygen species in the blood. This promotes oxidative stress which contributes to peripheral resistance to insulin in two ways: (1) reduced insulin/insulin receptor interaction; and (2) β-cell dysfunction. Hepcidin is crucial in terms of maintaining appropriate amounts of iron in the body and is in turn affected by haemoglobinopathies. Hepcidin also has other metabolic effects in places such as the liver but so far the extent of these is not well understood. It does however directly control the levels of serum ferritin. High serum ferritin is found in obese patients and those with diabetes and a meta-analysis of the various studies shows that high serum ferritin does indeed increase diabetes risk.

CONCLUSION: From an epidemiological standpoint, it is plausible that the well-documented protective effects of haemoglobinopathies with regard to malaria may have also offered other evolutionary advantages. By contributing to peripheral insulin resistance, haemoglobinopathies may have helped to sculpt the so-called “thrifty genotype”, which hypothetically is advantageous in times of famine. The prevalence data however is not extensive enough to provide concrete associations between diabetes and haemoglobinopathies - more precise studies are required.

Association of Serum Ferritin Level with Risk of Incident Abnormal Glucose Metabolism in Southwestern China: a Prospective Cohort Study

This prospective cohort study aimed to analyze the association between serum ferritin levels and the risk of abnormal glucose metabolism (AGM) in Southwestern Chinese population. The 383 subjects who are aged ≥20 years and free of AGM at baseline between in 2007 and in 2008 were included in Southwestern China, and their baseline serum ferritin levels were measured. Among these subjects, 140 subjects were developed into AGM during the follow-up (2008-2012). In logistic regression models, the relative risk in the top versus that in the lowest quartile of serum ferritin levels was 2.86 (p = 0.013) in females and 3.50 (p = 0.029) in males after adjusting the age, gender, family history of diabetes, current smoking, and alcohol; however, serum ferritin levels were not significantly associated with incident of AGM after controlling for metabolic factors (waist circumference, systolic pressure (SBP), triglyceride (TG), and homeostasis model assessment formula insulin resistance (HOMA-IR)). Elevated serum ferritin levels are associated with AGM but not an independent risk factor.

Red Meat and Health

Despite its nutritional benefits, there is an increasing body of evidence to suggest that regular consumption of red meat may negatively impact health and disease risk, including the risk of most common chronic diseases. This chapter reviews the current evidence linking red and processed meat intakes with chronic disease, obesity and mortality risks and discusses possible mechanisms to explain these associations. Research on the health benefits of diets low in red meat, including vegetarian, vegan, Mediterranean and other plant-based diets, is also reviewed.

Circulating hepcidin in type 2 diabetes: A multivariate analysis and double blind evaluation of metformin effects

SCOPE

Very few studies have evaluated serum hepcidin in patients with type 2 diabetes and they have reported conflicting results. In addition, the effect of antidiabetic drugs on circulating hepcidin has not been explored so far. The aims of the study were to evaluate hepcidin concentrations and hepcidin/ferritin ratio in type 2 diabetes subjects and healthy non-diabetic controls and to evaluate the effect of metformin on hepcidin concentrations.

METHODS AND RESULTS

Study 1: Cross-sectional multivariate study of 239 non-diabetic individuals and 65 people with type 2 diabetes. The multivariate analysis included covariates of chronic inflammation, BMI, pharmacological treatment, menopausal status and insulin resistance. Study 2: Randomized, double-blinded, placebo-controlled 4-month trial metformin compared to placebo among 36 type 2 diabetic patients. In both groups diet was controlled by maintaining a hypocaloric intake across the trial. Hepcidin levels were significantly lower in patients with type 2 diabetes than in non-diabetic individuals either in crude or adjusted regression models (P<0.05). Hepcidin decreased in both arms of the trial (Placebo, p = 0.004; metformin, p = 0.022).

CONCLUSION

Circulating hepcidin was significantly and independently lower in type 2 diabetes. Metformin treatment is not associated with reductions in hepcidin but hypocaloric diet could be involved.

A review of potential metabolic etiologies of the observed association between red meat consumption and development of type 2 diabetes mellitus

Epidemiological studies suggest that red and processed meat consumption is related to an increased risk of type 2 diabetes. However, it is not clearly understood which components of red and processed meat contribute to this increased risk. This review examines potential mechanisms addressing the role of saturated fatty acid, sodium, advanced glycation end products (AGEs), nitrates/nitrites, heme iron, trimethylamine N-oxide (TMAO), branched amino acids (BCAAs) and endocrine disruptor chemicals (EDCs) in the development of type 2 diabetes based on data from published clinical trials and animal models. TMAO which is derived from dietary carnitine and choline by the action of bacterial enzymes followed by oxidation in the liver may be a strong candidate molecule mediating the risk of type 2 diabetes. BCAAs may induce insulin resistance via the mammalian target of rapamycin complex 1 (mTORC1) and ribosomal protein S6 kinase β 1 (S6k1)-associated pathways. The increased risk associated with processed meat compared with red meat suggests that there are interactions between the saturated fat, salt, and nitrates in processed meat and iron, AGEs and TMAO. Intervention studies are required to clarify potential mechanisms and explore interactions among components, in order to make firm recommendations on red and processed meat consumption.

Poorly controlled type 2 diabetes is accompanied by significant morphological and ultrastructural changes in both erythrocytes and in thrombin-generated fibrin: implications for diagnostics

We have noted in previous work, in a variety of inflammatory diseases, where iron dysregulation occurs, a strong tendency for erythrocytes to lose their normal discoid shape and to adopt a skewed morphology (as judged by their axial ratios in the light microscope and by their ultrastructure in the SEM). Similarly, the polymerization of fibrinogen, as induced in vitro by added thrombin, leads not to the common ‘spaghetti-like’ structures but to dense matted deposits. Type 2 diabetes is a known inflammatory disease. In the present work, we found that the axial ratio of the erythrocytes of poorly controlled (as suggested by increased HbA1c levels) type 2 diabetics was significantly increased, and that their fibrin morphologies were again highly aberrant. As judged by scanning electron microscopy and in the atomic force microscope, these could be reversed, to some degree, by the addition of the iron chelators deferoxamine (DFO) or deferasirox (DFX). As well as their demonstrated diagnostic significance, these morphological indicators may have prognostic value.

Pleiotropic actions of iron balance in diabetes mellitus

As an essential element, iron plays a central role in many physiological processes, including redox balance, inflammation, energy metabolism, and environment sensing. Perturbations in iron homeostasis are associated with several conditions, including hyperglycemia and diabetes, both of which have been studied in patients and animal models. To clarify the pleiotropic role of iron homeostasis in diabetes development, the early studies on diseases with iron-overload, studies on clinical iron depletion therapies, associations between iron-related genetic polymorphisms and diabetes, and etiological mechanisms underlying iron perturbations-impaired insulin secretion and insulin sensitivity were carefully reviewed and discussed. Hereditary hemochromatosis, transfusion-dependent thalassemia, and excess heme iron intake can increase the risk of developing diabetes. Genetically modified mice and mice fed a high-iron diet present with discrepant phenotypes due to differences in tissue iron distribution. Moreover, several genetic polymorphisms related to iron homeostasis have been associated with the risk of developing diabetes. Tightly controlled iron metabolism is essential for insulin secretion and insulin sensitivity, and iron overload in pancreatic islets alters reactive oxygen species (ROS) generation, as well as hypoxia-inducible factor-1α (HIF-1α) stability and adenosine triphosphate (ATP) synthesis, thereby impairing the function and viability of β-cells. Decreased levels of adiponectin, macrophage-mediated inflammation, and ROS-mediated liver kinase B1 (LKB1)/adenosine monophosphate-activated protein kinase (AMPK) activation can contribute to iron overload-induced insulin resistance, whereas iron deficiency could also participate in obesity-related inflammation, hypoxia, and insulin resistance. Because iron homeostasis is closely correlated with many metabolic processes, future studies are needed in order to elucidate the finely tuned network among iron homeostasis, carbohydrate and lipid metabolism, inflammation, and hypoxia.

Serum ferritin is an important inflammatory disease marker, as it is mainly a leakage product from damaged cells

"Serum ferritin" presents a paradox, as the iron storage protein ferritin is not synthesised in serum yet is to be found there. Serum ferritin is also a well known inflammatory marker, but it is unclear whether serum ferritin reflects or causes inflammation, or whether it is involved in an inflammatory cycle. We argue here that serum ferritin arises from damaged cells, and is thus a marker of cellular damage. The protein in serum ferritin is considered benign, but it has lost (i.e. dumped) most of its normal complement of iron which when unliganded is highly toxic. The facts that serum ferritin levels can correlate with both disease and with body iron stores are thus expected on simple chemical kinetic grounds. Serum ferritin levels also correlate with other phenotypic readouts such as erythrocyte morphology. Overall, this systems approach serves to explain a number of apparent paradoxes of serum ferritin, including (i) why it correlates with biomarkers of cell damage, (ii) why it correlates with biomarkers of hydroxyl radical formation (and oxidative stress) and (iii) therefore why it correlates with the presence and/or severity of numerous diseases. This leads to suggestions for how one might exploit the corollaries of the recognition that serum ferritin levels mainly represent a consequence of cell stress and damage.

Association of iron indices and type 2 diabetes: a meta-analysis of observational studies

The literature on the role of body iron status in the development of type 2 diabetes (T2D) in humans is inconsistent. We aimed to assess the association between iron indices and T2D by a meta-analysis of previously published studies. A systematic literature search was conducted in PubMed and EMBASE. Observational studies on the association of ferritin (when controlled for age and sex), transferrin saturation, soluble transferrin receptor and transferrin with T2D were included. Pooled association estimates were calculated using a random effects model. Forty-six eligible studies were identified. The pooled multivariable adjusted relative risks of T2D in the highest versus lowest quartile of ferritin levels were significantly elevated in both cross-sectional as well as prospective studies and after restriction to inflammation-adjusted studies [overall: 1.67 (95% CI 1.41-1.99)]. The mean difference indicated 43.54 ng/mL (95% CI 28.14-58.94) higher ferritin levels in type 2 diabetic individuals. The relative risk for a transferrin saturation ≥ 50% was 1.59 (95% CI 1.28-1.97), the mean difference was -1.92% [95% CI -2.99-(-0.85)]. Study-specific results of soluble transferrin receptor and transferrin levels were extremely heterogeneous. Ferritin and clinically elevated transferrin saturation were strongly associated with an increased risk of T2D, overall and in prospective studies. Ferritin was also significantly associated after multivariable adjustment including inflammation. Thus, the current evidence hints at a causal effect; however, publication bias and unmeasured confounding cannot be excluded.

Body iron stores in middle-aged North Indian patients with type 2 diabetes and obesity

Introduction:

Evidence from various epidemiological and clinical studies suggests that iron overload is proinflammatory and proatherosclerotic. Excess body iron has been positively associated with insulin resistance, type 2 diabetes and obesity.

Aim of the Study:

To study the relationship of body iron stores with type 2 diabetes and obesity in middle aged North Indian population.

Materials and Methods:

The participant population consisted of four groups of randomly selected participants (between 40 and 65 years of age and postmenopausal women); Group A: Normal individuals (controls), Group B: Obese nondiabetic individuals, Group C: Lean diabetic patients, Group D: Obese diabetic patients. Blood was examined for hematological, biochemical estimations, C-reactive protein, and serum ferritin (SF).

Observation and Results:

A total of 197 participants were enrolled. The mean SF levels (ng/ml) among males were: Group A (n = 18) 148.56 ± 119.90; Group B (n = 25) 129.11 ± 94.77; Group C (n = 27) 127.96 ± 109.65 and Group D (n = 22) 148.36 ± 104.94. The mean SF levels (ng/ml) among females were: Group A (n = 23) 67.44 ± 37.59; Group B (n = 25) 59.62 ± 43.56; Group C (n = 24) 77.97 ± 91.46 and Group D (n = 33) 66.46 ± 86.05. No statistical difference was found among the groups in both the sexes.

Conclusions:

Our observation is in sharp contrast to the earlier studies published from the West stressing that iron stores are increased in obesity and diabetes. We conclude that SF may not be a strong risk factor in the pathogenesis of obesity and diabetes in middle aged North Indians.

Association between total, processed, red and white meat consumption and all-cause, CVD and IHD mortality: a meta-analysis of cohort studies

An association between processed and red meat consumption and total mortality has been reported by epidemiological studies; however, there are many controversial reports regarding the association between meat consumption and CVD and IHD mortality. The present meta-analysis was carried out to summarise the evidence from prospective cohort studies on the association between consumption of meat (total, red, white and processed) and all-cause, CVD and IHD mortality. Cohort studies were identified by searching the PubMed and ISI Web of Knowledge databases. Risk estimates for the highest v. the lowest consumption category and dose-response meta-analysis were calculated using a random-effects model. Heterogeneity among the studies was also evaluated. A total of thirteen cohort studies were identified (1 674 272 individuals). Subjects in the highest category of processed meat consumption had 22 and 18 % higher risk of mortality from any cause and CVD, respectively. Red meat consumption was found to be associated with a 16 % higher risk of CVD mortality, while no association was found for total and white meat consumption. In the dose-response meta-analysis, an increase of 50 g/d in processed meat intake was found to be positively associated with all-cause and CVD mortality, while an increase of 100 g/d in red meat intake was found to be positively associated with CVD mortality. No significant associations were observed between consumption of any type of meat and IHD mortality. The results of the present meta-analysis indicate that processed meat consumption could increase the risk of mortality from any cause and CVD, while red meat consumption is positively but weakly associated with CVD mortality. These results should be interpreted with caution due to the high heterogeneity observed in most of the analyses as well as the possibility of residual confounding.

Prevention and management of type 2 diabetes: dietary components and nutritional strategies

In the past couple of decades, evidence from prospective observational studies and clinical trials has converged to support the importance of individual nutrients, foods, and dietary patterns in the prevention and management of type 2 diabetes. The quality of dietary fats and carbohydrates consumed is more crucial than is the quantity of these macronutrients. Diets rich in wholegrains, fruits, vegetables, legumes, and nuts; moderate in alcohol consumption; and lower in refined grains, red or processed meats, and sugar-sweetened beverages have been shown to reduce the risk of diabetes and improve glycaemic control and blood lipids in patients with diabetes. With an emphasis on overall diet quality, several dietary patterns such as Mediterranean, low glycaemic index, moderately low carbohydrate, and vegetarian diets can be tailored to personal and cultural food preferences and appropriate calorie needs for weight control and diabetes prevention and management. Although much progress has been made in development and implementation of evidence-based nutrition recommendations in developed countries, concerted worldwide efforts and policies are warranted to alleviate regional disparities.

Effects of iron overload on chronic metabolic diseases

Iron can affect the clinical course of several chronic metabolic diseases such as type 2 diabetes, obesity, non-alcoholic fatty liver disease, and atherosclerosis. Iron overload can affect major tissues involved in glucose and lipid metabolism (pancreatic β cells, liver, muscle, and adipose tissue) and organs affected by chronic diabetic complications. Because iron is a potent pro-oxidant, fine-tuned control mechanisms have evolved to regulate entry, recycling, and loss of body iron. These mechanisms include the interplay of iron with transferrin, ferritin, insulin, and hepcidin, as well as with adipokines and proinflammatory molecules. An imbalance of these homoeostatic mechanisms results in systemic and parenchymal siderosis that contributes to organ damage (such as β-cell dysfunction, fibrosis in liver diseases, and atherosclerotic plaque growth and instability). Conversely, iron depletion can exert beneficial effects in patients with iron overload and even in healthy frequent blood donors. Regular assessment of iron balance should be recommended for patients with chronic metabolic diseases, and further research is needed to produce guidelines for the identification of patients who would benefit from iron depletion.

Effects of Dietary Supplementation with Agaricus sylvaticus Schaeffer on Glycemia and Cholesterol after Streptozotocin-Induced Diabetes in Rats

This study evaluated the effect of the Agaricus sylvaticus (sun mushroom) on biochemical tests of the plasma and on the morphology of the pancreas in an experimental model of type I diabetes mellitus (DM1) induced by streptozotocin. One gram of dry A. sylvaticus was homogenized and mixed with the chow. Male Wistar rats were allocated as follows: normoglycemic control that received commercial chow; normoglycemic control group that received chow with A. sylvaticus; diabetic group that received commercial chow; and diabetic group that received chow with A. sylvaticus. Weight, food, and water consumption were measured every two days. Blood glucose levels were measured twice a week. After 30 days, the animals were euthanized and blood was collected for the analysis of cholesterol, HDL, triglycerides, blood sugar, glutamic-pyruvic transaminase (GPT), alkaline phosphatase, iron, transferrin, and urea. The pancreas was processed for microscopic analysis. A. sylvaticus modulated the levels of cholesterol, HDL, triglycerides, blood sugar, GPT, alkaline phosphatase, iron, transferrin, and urea to levels similar to those found in the controls and led to compensatory hyperplasia of the islets of Langerhans. A. sylvaticus is potentially beneficial in the control of type 1 diabetes, and it may also prevent pancreas damage.

Ferritin levels and risk of metabolic syndrome: meta-analysis of observational studies

Background

Elevated ferritin levels have been associated with single cardiovascular risk factors but the relationship to the presence of metabolic syndrome is inconclusive.

The aim of this systematic review and meta-analysis of published observational studies was to estimate the association between serum ferritin levels and metabolic syndrome in adults.

Methods

The Pubmed, SCOPUS and the Cochrane Library databases were searched for epidemiological studies that assessed the association between ferritin levels and metabolic syndrome and were published before September 2013. There were no language restrictions. Two investigators independently selected eligible studies. Measures of association were pooled by using an inverse-variance weighted random-effects model. The heterogeneity among studies was examined using the I² index. Publication bias was evaluated using the funnel plot.

Results

Twelve cross-sectional, one case–control and two prospective studies met our inclusion criteria including data from a total of 56,053 participants. The pooled odds ratio (OR) for the metabolic syndrome comparing the highest and lowest category of ferritin levels was 1.73 (95% CI: 1.54, 1.95; I² = 75,4%). Subgroup analyses indicate that pooled OR was 1.92 (95% CI: 1.61, 2.30; I² = 78%) for studies adjusting for C-reactive protein (CRP), and 1.52 (95% CI:1. 36, 1.69; I² = 41%) for studies that did not adjust for CRP (P = 0.044). This finding was remarkably robust in the sensitivity analysis. We did not find publication bias.

Conclusions

The meta-analysis suggests that increased ferritin levels are independently and positively associated with the presence of the metabolic syndrome with an odds ratio higher than 1.73.

Epidemiological associations between iron and cardiovascular disease and diabetes

Disruptions in iron homeostasis are linked to a broad spectrum of chronic conditions including cardiovascular, malignant, metabolic, and neurodegenerative disease. Evidence supporting this contention derives from a variety of analytical approaches, ranging from molecular to population-based studies. This review focuses on key epidemiological studies that assess the relationship between body iron status and chronic diseases, with particular emphasis on atherosclerosis ,metabolic syndrome and diabetes. Multiple surrogates have been used to measure body iron status, including serum ferritin, transferrin saturation, serum iron, and dietary iron intake. The lack of a uniform and standardized means of assessing body iron status has limited the precision of epidemiological associations. Intervention studies using depletion of iron to alter risk have been conducted. Genetic and molecular techniques have helped to explicate the biochemistry of iron metabolism at the molecular level. Plausible explanations for how iron contributes to the pathogenesis of these chronic diseases are beginning to be elucidated. Most evidence supports the hypothesis that excess iron contributes to chronic disease by fostering excess production of free radicals. Overall, epidemiological studies, reinforced by basic science experiments, provide a strong line of evidence supporting the association between iron and elevated risk of cardiovascular disease and diabetes. In this narrative review we attempt to condense the information from existing literature on this topic.