Dietary Magnesium May Help Prevent Development of Type 2 Diabetes

[Guest guest]

Laurie Barclay, MD

Dec. 23, 2003 — Magnesium-containing foods can prevent development

of type 2 diabetes in both men and women, according to the results

of a large cohort trial published in the January issue of Diabetes

Care. A second cohort study in the same issue showed a similar

benefit, especially for overweight women. The editorialist suggests

that there is now compelling evidence to support randomized

controlled trials.

" Our findings suggest a significant inverse association between

magnesium intake and diabetes risk, " write Ruy -Ridaura, MD,

and colleagues from Harvard Medical School in Boston,

Massachusetts. " This study supports the dietary recommendations to

increase consumption of major food sources of magnesium, such as

nuts, whole grains, and green leafy vegetables. "

The study population consisted of 85,060 women and 42,872 men with

no history of diabetes, cardiovascular disease, or cancer at

baseline. Using a validated food frequency questionnaire every two

to four years, the investigators determined dietary magnesium

intake. During follow-up of 18 years in women and 12 years in men,

there were 4,085 incident cases of type 2 diabetes in women and

1,333 cases in men.

Comparing the highest with the lowest quintile of total magnesium

intake, the relative risk (RR) of type 2 diabetes, after adjustment

for age, body mass index (BMI), physical activity, family history of

diabetes, alcohol consumption, and history of hypertension and

hypercholesterolemia at baseline, was 0.66 (95% confidence interval

[CI], 0.60-0.73) in women and 0.67 in men (95% CI, 0.56-0.80; P for

trend < .001 in both sexes).

Further adjustments for other dietary variables did not affect the

inverse association between magnesium intake and reduced diabetes

risk, nor did subgroup analysis according to BMI, physical activity,

or family history of diabetes.

Study limitations include inability to screen for blood glucose,

resulting in failure to diagnose some cases of diabetes, and

possible residual confounding.

" Higher magnesium intake is likely more beneficial among individuals

with some degree of magnesium deficiency, " the authors write. " This

effect of magnesium supplementation in general or high-risk

populations requires further research, ideally in randomized

clinical trials. "

The National Institutes of Health and the National Institutes of

Diabetes and Digestive and Kidney Diseases supported this study.

In a separate study of a cohort from the Women's Health Study,

higher magnesium intake reduced diabetes risk by about 10% overall,

or by about 20% in overweight women.

In an accompanying editorial, Jerry L. Nadler, MD, from the

University of Virginia Health Science System in Charlottesville,

suggests that there is now compelling evidence to support randomized

controlled trials. " If increased magnesium intake is beneficial, it

could provide a new, cost-effective way to reduce development of

type 2 diabetes, " he writes.

Diabetes Care. 2003;27:134-140,59-65,270-271