Iron Intake and the Risk of Type 2 Diabetes in Women

Rajpathak, Swapnil; Ma, Jing; Manson, JoAnn E.; Willett, Walter C.; Hu, Frank B.

doi:10.2337/dc06-0119

Cited by 136 publications

(124 citation statements)

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“…Repeated exposure assessments are important in cohort studies to reduce misclassification due to dietary changes during follow-up. In a cohort study the RR of type 2 diabetes was 1.28 for high vs low haem-iron intake (as a proxy for meat intake) when using cumulative updated averages of intake, but with only the baseline questionnaire the RR was weaker and not significant (RR 1.08) [39]. Four of the twelve included studies used repeated exposure assessments.…”

Section: Discussionmentioning

confidence: 99%

“…Meat is an important source of total and saturated fat and could increase the risk of type 2 diabetes through overweight/obesity [41][42][43][44], the metabolic syndrome [45][46][47] and hyperinsulinaemia and hyperglycaemia [20, [48][49][50], although some studies found no association [51,52]. Another possible mechanism may be through the effects of haem-iron derived from meat [19,24,39,53]. Iron can promote oxidative stress by increasing the formation of hydroxyl radicals [54] which can cause damage to tissues, in particular the pancreatic beta cells [54].…”

Section: Discussionmentioning

confidence: 99%

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Meat consumption and the risk of type 2 diabetes: a systematic review and meta-analysis of cohort studies

2009

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Aims/hypothesis Diet is thought to play an important role in the aetiology of type 2 diabetes. Previous studies have found positive associations between meat consumption and the risk of type 2 diabetes, but the results have been inconsistent. We conducted a systematic review and meta-analysis of cohort studies of meat consumption and type 2 diabetes risk. Methods We searched several databases for cohort studies on meat consumption and type 2 diabetes risk, up to December 2008. Summary relative risks were estimated by use of a random-effects model. Results We identified 12 cohort studies. The estimated summary RR and 95% confidence interval of type 2 diabetes comparing high vs low intake was 1.17 (95% CI 0.92-1.48) for total meat, 1.21 (95% CI 1.07-1.38) for red meat and 1.41 (95% CI 1.25-1.60) for processed meat. There was heterogeneity amongst the studies of total, red and processed meat which, to some degree, was explained by the study characteristics. Conclusions/interpretation These results suggest that meat consumption increases the risk of type 2 diabetes. However, the possibility that residual confounding could explain this association cannot be excluded.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Meat consumption and the risk of type 2 diabetes: a systematic review and meta-analysis of cohort studies

2009

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“…In subjects without overt iron overload, higher serum ferritin levels are significantly associated with biochemical evidence of decreased insulin sensitivity (5,6). However, epidemiological studies of the association between dietary iron intake or biomarkers of tissue iron stores and the risk of diabetes in populations without overt iron overload have yielded mixed findings (5,6,(13)(14)(15)(16). The inconsistencies in these reports may be partly attributable to the presence of inflammation or other unmeasured confounders that alter the relationship between dietary iron intake, biochemical markers of tissue iron stores, and metabolic effects of iron.…”

Section: Figure 1-flow-mediated Dilation (Fmd In Low-frequency [Low Fmentioning

confidence: 98%

Insulin Sensitivity, Vascular Function, and Iron Stores in Voluntary Blood Donors

et al. 2007

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OBJECTIVE -Reduced iron stores after blood donation are associated with improved vascular function and decreased cardiovascular risk. We sought to determine whether irondependent changes in glucose metabolism may contribute to improved vascular function in blood donors.RESEARCH DESIGN AND METHODS -We conducted a prospective cross-sectional study in 21 high-frequency blood donors (more than eight donations in the last 2 years) and 21 low-frequency blood donors (one to two donations in the last 2 years) aged 50 -75 years. Serum markers of iron stores, whole-body insulin sensitivity index (WBISI) during oral glucose tolerance testing, and flow-mediated dilation in the brachial artery were determined in all subjects.RESULTS -Serum ferritin was decreased (median values 23 vs. 36 ng/ml, P Ͻ 0.05) and flow-mediated dilation in the brachial artery was increased (median values 5.9 vs. 5.3%, P Ͻ 0.05) in high-frequency donors compared with low-frequency donors, respectively, but WBISI (median values 4.8 vs. 4.7) and related measures of glucose tolerance did not differ between groups. Flow-mediated dilation significantly decreased at 1 h after oral glucose loading in both groups, but the decrease in flow-mediated dilation at 1 h did not differ between high-and low-frequency donors.CONCLUSIONS -High-frequency blood donation reduced serum ferritin and increased flow-mediated dilation compared with low-frequency donation but did not improve insulin sensitivity or protect the vascular endothelium from the adverse effects of acute hyperglycemia after oral glucose loading. These findings suggest that the mechanisms linking blood donation to improved vascular function are not likely related to changes in glucose metabolism. Diabetes Care 30:2685-2689, 2007I ron is a prooxidant cofactor that has been proposed to be associated with increased risk of cardiovascular events in humans (1,2). Chronic reduction in iron stores in response to frequent blood donation is associated with improved vascular function in the brachial artery and biochemical evidence of decreased oxidative stress (3). In a randomized trial of patients with peripheral vascular disease, reduction of iron stores with serial phlebotomy decreased mortality compared with conventional therapy in the subjects in the youngest age quartile (aged 43-61 years) (4).A potential mechanistic link between iron stores, vascular function, and cardiovascular risk may be related to irondependent effects on glucose metabolism (5,6). Diabetes is a well-recognized modifiable cardiovascular risk factor associated with increased serum ferritin levels and evidence of vascular endothelial dysfunction (7,8). Iron overload is associated with decreased insulin production, increased insulin resistance, and increased risk of diabetes (5,6). We hypothesized that improved vascular function associated with reduction in iron stores after blood donation might be partly attributable to improved insulin sensitivity. To test this hypothesis, we assessed insulin sensitivity during an oral glucose tolerance...

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“…Diet plays an important role in both diseases (2,3) . While Fe deficiency may lead to anaemia (3) , findings from many countries show that high Fe intake, especially haem Fe intake (4) , and high body Fe stores increase the risk of diabetes (5)(6)(7) . Possible mechanisms for Fe increasing the risk of diabetes may include oxidative stress, inflammation, free fatty acid oxidation, insulin extraction and secretion (6) .…”

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confidence: 99%

Iron intake and body iron stores, anaemia and risk of hyperglycaemia among Chinese adults: the prospective Jiangsu Nutrition Study (JIN)

Shi

Zhou

Bao

et al. 2009

Public Health Nutr.

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Objective: Fe supplementation has been used to prevent anaemia in China; however, high Fe intake and body Fe stores may increase diabetes risk. The present study aimed to prospectively examine the association between Fe intake/ stores and hyperglycaemia, and to assess the joint effects on anaemia. Design: We followed 1056 healthy adults aged 20 years and older from 2002 to 2007. Body Fe stores were measured. Dietary data were collected using a 3 d food record and FFQ. Hyperglycaemia was defined as fasting plasma glucose .5?6 mmol/l. Results: Of the participants, 28?8 % were anaemic at baseline. During the 5 years of follow-up, we documented 125 incident cases of hyperglycaemia, among them twenty-three were diabetic. Haem Fe intake was positively associated with the risk of hyperglycaemia in men and women: the OR (95 % CI) across increasing quartiles of haem Fe intake was 1?00 (referent), 1?49 (0?74, 3?01), 2?16 (1?06, 4?42) and 3?48 (1?71, 7?11), respectively (P for trend ,0?001). Comparing the fourth quartile of serum ferritin with the others, the age-and gender-adjusted OR (95 % CI) was 1?54 (1?01, 2?34), P for trend 5 0?043. The association between total Fe intake and the risk of hyperglycaemia was significant in men (P for trend 5 0?002). Anaemia added additional risk of hyperglycaemia on haem Fe intake. Comparing extreme quartiles of haem Fe intake, the OR (95 % CI) was 5?67 (1?43, 22?49) and 3?44 (1?51, 7?85) for hyperglycaemia among anaemic and non-anaemic participants (P for trend 5 0?008 and 0?010, respectively). Conclusions: The present cohort study suggests that high haem Fe intake, anaemia and high ferritin are associated with an increased risk of hyperglycaemia in Chinese men and women. There was a joint effect between anaemia and haem Fe intake on the risk of hyperglycaemia.

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Iron Intake and the Risk of Type 2 Diabetes in Women

Cited by 136 publications

References 59 publications

Meat consumption and the risk of type 2 diabetes: a systematic review and meta-analysis of cohort studies

Meat consumption and the risk of type 2 diabetes: a systematic review and meta-analysis of cohort studies

Insulin Sensitivity, Vascular Function, and Iron Stores in Voluntary Blood Donors

Iron intake and body iron stores, anaemia and risk of hyperglycaemia among Chinese adults: the prospective Jiangsu Nutrition Study (JIN)

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