Fiber and Magnesium Intake and Incidence of Type 2 Diabetes

1. Fiber and Magnesium Intake and Incidenceof Type 2 Diabetes 指導老師：彭惠鈺 營養師 實習學生：林佳萱 報告日期：2012/12/25

2. The benefits of increased fiber intake result principally from the greater consumption of soluble forms due to effects on gastric emptying, macronutrient absorption, and reduced postprandial glucose responses. Although prospective studies have observed reduced diabetes risk with high cereal fiber and whole grain consumption, these findings have not been confirmed by all studies, and beneficial effects of fruit and vegetable fiber remain unclear so far. Several studies have indicated an inverse association between the incidence of diabetes mellitus and magnesium and dietary fiber intake. Introduction

3. Magnesium (Mg) is the second most abundant cation in the intracellular compartments of the human body. In an animal study, Mg supplements prevented a deterioration of insulin resistance or glucose intolerance and delayed the development of spontaneous DM. Mg is abundant in fiber-rich foods. Dietary fiber is also believed to be inversely associated with DM risk. Previous studies have found inverse associations between calcium and magnesium intakes and the risk of T2D . Intake of dairy foods, good sources of both calcium and magnesium, have also been associated with lower risk of T2D, although the effect was only found for low-fat dairy products . Introduction

4. Lower intake of magnesium and dietary fiberincreases the incidence of type 2 diabetes in Taiwanese Fiber and Magnesium Intake and Incidenceof Type 2 DiabetesA Prospective Study and Meta-analysis Dietary calcium and magnesium intakes and the risk of type 2 diabetes: the Shanghai Women’s Health Study Outline

5. Lower intake of magnesium and dietary fiberincreases the incidence of type 2 diabetesin Taiwanese Journal of the Formosan Medical Association. (2012) xx, 1-9

6. Studying how dietary magnesium and fiber intake levels affect diabetes incidence separately or in combination, in a prospective study in Taiwan. Aim

7. Methods Study participants were from the CardioVascular Disease risk FACtor Two-township Study (CVDFACTS) cycle 2.(A total of 1604 healthy subjects aged 30 years and over.) Used a validated food frequency questionnaire (FFQ) to assess dietary intake in the previous year. Ascertainment of diabetes incidence: when either one of the following conditions occurred: a fasting plasma glucose concentration over 126 mg/dL [7.0 mmol/L]. Clinical and questionnaire. Cox proportional hazard model was used to study the association between diabetes incidence and dietary magnesium and fiber intake level.

8. Results

11. However, we do not advocate“the higher the better” concept with regard to Mg and fiberintake due to their potentially adverse effects at excesslevels.(the FFQ in this study was not designed specifically for Mg intake and the validity and reliability of Mg intake were not examined in the previous validation study. Misclassification of Mg intake may underestimate the association between Mg intake and the risk of DM. ) Discussion

12. Fiber and Magnesium Intake and Incidenceof Type 2 DiabetesA Prospective Study and Meta-analysis Arch Intern Med 2007;167:956-65

13. The aims of this study were to evaluate the association between total, cereal, fruit, and vegetable fiber, as well as soluble and insoluble fiber and magnesium intake, and risk of type 2 diabetes in a large prospective cohort study of men and women and to summarize the existing evidence from prospective studies by meta-analysis. Aim

14. Methods Prospective Study cohort study of 9,702 men and 15,365 women (aged 35 to 65 years who were observed for incident diabetes from 1994 to 2005) Dietary intake of fiber and magnesium were measured with a validated food-frequency questionnaire. The relative risk (RR) by means of Cox proportional hazards analysis. Prospective cohort studies of fiber and magnesium intake and risk of type 2 diabetes.(May 2006)

15. Methods Meta-analysis Identified 9 cohort studies of fiber and 8 studies of magnesium intake and calculated summary RRs by means of a randomeffects model.

16. Results

18. Cereal fiber Fruit fiber

19. Vegetable fiber Magnesium

20. Food-frequency questionnaires work well in ranking individuals with regard to their intake, but they are not suitable tools for quantifying dietary intake in absolute terms.(It is possible that participants in our study changed their dietary intake after the baseline measurement. The lack of repeated measurement of diet may have led to an underestimation of association.) Discussion

21. Dietary calcium and magnesium intakes and the risk of type 2 diabetes:the Shanghai Women’s Health Study Am J Clin Nutr 2009;89:1059-67

22. Examined associations between calcium and magnesium intakes and the risk of T2D in a Chinese population. Aim

23. Methods A population-based, prospective study(64,191 women who were free of T2D or other chronic diseases at study recruitment and were living in urban Shanghai, China.) Dietary intake, physical activity, and anthropometric measurements were assessed through in-person interviews. A Cox regression model.( evaluate the association of the exposures under study with the risk of T2D)

24. Results

27. Misclassification of dietary information is unavoidable, but it would most likely be nondifferential and thus would attenuate the true associations.(although we did adjust for confounders, we cannot exclude the possibility of residual confounding.) We lacked information on use of calcium and magnesium supplements and the fat content of milk, although in this population most participants have access to only whole milk.(a diet low in whole-grain foods and high in high-fat dairy resembles a Western dietary pattern that has been associated with higher risk of T2D. Thus, it is difficult to assess the effect of calcium and magnesium on the risk of T2D without confounding from this overall unfavorable dietary pattern typical of Western populations.) Discussion

28. The study suggested that adequate fiber or Mg maybe beneficial for DM prevention and management in theTaiwanese population. (Weng et al.,2012) Dietary fiber,such as TDF, fruit and vegetable fibers were also protectiveagainst DM in our study. (Weng et al.,2012) Higher cereal fiber and magnesium intakes may decrease diabetes risk. (Schulze et al.,2007) Whole-grain foods are therefore important in diabetes prevention. (Schulze et al.,2007) Calcium and magnesium play a protective role in the development of T2D. (Villegas et al.,2009) 總論

29. Intake

30. Intake 30

31. Schulze MB, Schulz M, Heidemann C, Schienkiewitz A, Hoffmann K, Boeing H. Fiber and magnesium intake and incidence of type 2 diabetes: A prospective study and metaanalysis.Arch Intern Med 2007;167:956-65. Villegas R, Gao YT, Dai Q, Yang G, Cai H, Li H, et al. Dietary calcium and magnesium intakes and the risk of type 2 diabetes: the shanghai women’s health study. Am J Clin Nutr 2009;89:1059-67. Weng LC, Lee NJ, Yeh WT, Ho LT, Pan WH. Lower intake of magnesium and dietary fiber increases the incidence of type 2 diabetes in Taiwanese. Journal of the Formosan Medical Association 2012; xx:1-9. References

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