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Increased magnesium intake may lower type 2 diabetes risk

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October 5, 2017

A low-carbohydrate, high-quality diet rich in magnesium may help reduce the risk for type 2 diabetes, according to findings published in Diabetes Care.

Adela Hruby, PhD, MPH, of the nutritional epidemiology program at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University and the department of nutrition at Harvard T.H. Chan School of Public Health, and colleagues evaluated data from the Nurses’ Health Study (NHS; 1984-2012; n = 69,176), NHS2 (1991-2013; n = 91,471) and the Health Professionals’ Follow-Up Study (1986-2012; n = 42,096) to determine the association between magnesium intake and carbohydrate quality on the risk for type 2 diabetes.

Participants completed food frequency questionnaires every 4 years for dietary intake assessment.

Through 28 years of follow-up, researchers observed 17,130 incident cases of type 2 diabetes. The risk for incident type 2 diabetes was 41% lower in NHS, 45% lower in NHS2 and 41% lower in the Health Professionals’ Follow-up Study with the highest category of total magnesium intake (average, 390-470 mg per day) compared with the lowest category (average, 229-280 mg per day; P for trend < .0001) after adjustment for age and energy intake.

The risk for type 2 diabetes was 15% lower with the highest total magnesium intake compared with the lowest intake in pooled estimates of the fully adjusted model from all three cohorts (pooled HR = 0.85; 95% CI, 0.8-0.91). The risk for developing diabetes was 4% lower with each additional 50 mg per day of magnesium intake (pooled HR = 0.96; 95% CI, 0.95-0.98).

No significant interaction between magnesium and glycemic load was found, but there were statistically significant interactions between magnesium and cereal fiber and between magnesium and glycemic index (P for interaction < .0001). – by Amber Cox

Disclosures: The authors report no relevant financial disclosures.

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Alpana Shukla

Magnesium is recognized as a shortfall nutrient with nearly 50% of the U.S. population reported to have inadequate magnesium intake. Hypomagnesemia and lower magnesium intake are linked to higher incidence of prediabetes and type 2 diabetes, plausibly through insulin resistance pathways. In this study, Hruby and colleagues have used three large longitudinal cohorts with 28 years’ follow-up and repeated measures of dietary intake to analyze the joint effect of magnesium intake and carbohydrate quality on incidence of diabetes. This study confirms previous observational findings of inverse correlation between magnesium intake and incident diabetes: Those with the highest magnesium intake had 15% lower risk for type 2 diabetes compared with those with the lowest intake. In addition, the study shows that the benefit of higher magnesium intake in mitigating the risk of diabetes is modestly higher in the context of low-quality carbohydrate intake (high glycemic index or low cereal fiber). An interesting trend observed over the study period is that while average magnesium intakes have increased over time, the contribution from dietary sources, such as vegetables and leafy greens, has declined and the contribution from supplements has increased. Taken together with what is already known about the effects of high glycemic index carbohydrate on incident diabetes and metabolic risk, these data reinforce current nutritional guidelines for prevention of diabetes that emphasize intake of vegetables, leafy greens, whole grains and nuts, which are rich sources of dietary magnesium.

Alpana Shukla, MD, MRCP

Assistant Professor of Research in Medicine
Director of Clinical Research
Comprehensive Weight Control Center
Division of Endocrinology, Diabetes and Metabolism
Weill Cornell Medicine

Disclosure: Shukla reports no relevant financial disclosures.