magnesium matters

Journal of the American Geriatrics Society
Volume 53 Issue 11 Page 1875 – November 2005
doi:10.1111/j.1532-5415.2005.53561.x
Volume 53 Issue 11

Magnesium Intake from Food and Supplements Is Associated with Bone Mineral Density in Healthy Older White Subjects
Kathryn M. Ryder, MD, MS*, Ronald I. Shorr, MD, MS, Andrew J. Bush, PhD, Stephen B. Kritchevsky, PhD, Tamara Harris, MD, MPH§, Katie Stone, PhD, Jane Cauley, DrPH¶, and Frances A. Tylavsky, DrPH
Objectives: To determine whether magnesium intake from supplemental and dietary sources is associated with bone mineral density (BMD) in older men and women.

Design: Cross-sectional.

Setting: Memphis, Tennessee, and Pittsburgh, Pennsylvania.

Participants: Two thousand thirty-eight older black and white men and women aged 70 to 79 at baseline enrolled in the Health, Aging and Body Composition Study.

Measurements: Dietary intake of magnesium was assessed using a semiquantitative food frequency questionnaire, and supplement data were collected based on a medication inventory. BMD of the whole body was obtained using a fan-beam densitometer. Additional covariates included age, body mass index (BMI), smoking status, alcohol use, physical activity, estrogen use, and supplemental calcium (Ca) and vitamin D use.

Results: In white, but not black, men and women, magnesium intake was positively associated with BMD of the whole body after adjustment for age, self-report of osteoporosis or fracture in adulthood, caloric intake, Ca and vitamin D intake, BMI, smoking status, alcohol intake, physical activity, thiazide diuretic use, and estrogen use in women (P=.05 for men and P=.005 for women). BMD was 0.04 g/cm2 higher in white women and 0.02 g/cm2 higher in white men in the highest than in the lowest quintile of magnesium intake.

Conclusion: Greater magnesium intake was significantly related to higher BMD in white women and men. The lack of association observed in black women and men may be related to differences in Ca regulation or in nutrient reporting.

2 COMMENTS

  1. Scand J Clin Lab Invest. 2005;65(8):659-70. Related Articles, Links

    Ionized magnesium levels and the ratio of ionized calcium to magnesium in asthma patients before and after treatment with magnesium.

    Sinert R, Spektor M, Gorlin A, Doty C, Rubin A, Altura BT, Altura BM.

    Department of Emergency Medicine, State University of New York, Downstate Medical Center, Brooklyn, NY, USA.

    Objective. Prior studies have been equivocal about the efficacy of magnesium therapy in acute asthma exacerbations. We hypothesize that pretreatment ionized magnesium (Mg(2+)) levels and/or the ratio of ionized calcium to ionized magnesium (Ca(2+)/Mg(2+)) may have been confounding variables in these previous studies. Here, we report on the incidence of abnormal divalent ion levels in our asthma population. Material and methods. The study was designed as a randomized, double-blind, placebo-controlled trial of intravenous magnesium. Inclusion criteria were: age >18 years, percentage predicted forced expiratory volume (FEV(1)) <75 % after an initial beta-agonist. African-American patients (AA) at an urban university hospital were randomized to 2 g IV Mg or placebo. Mg(2+) and Ca(2+)/Mg(2+) levels were measured pre- and post-infusion. Data were reported as means+/-SD. Student's t-test and Fisher's exact test were used where appropriate (alpha = 0.05, two tailed) Results. Fifty-five AA patients (mean age of 42.7 years+/-15.6 years, range18-75 years) were studied. A significantly (p<0.05) lower level of Mg(2+) was found in asthma (AS) patients compared with that in the AA group, by 0.03 mmol/L (95 % CI, 0.007-0.053 mmol/L). The AS group had a mean increase in Ca(2+)/Mg(2+) ratios over the AA group, of 0.27 (95 % CI, 0.16-0.38); 100 % of patients with abnormal divalent ion levels were corrected with IV magnesium. Conclusions. We identified a subgroup of asthmatic patients with significant abnormalities in their divalent ion concentrations, which was corrected with IV magnesium.

  2. Am J Epidemiol. 2005 Nov 30; [Epub ahead of print] Related Articles, Links

    Magnesium Intake and Reduced Risk of Colon Cancer in a Prospective Study of Women.

    Folsom AR, Hong CP.

    Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN.

    A recent prospective study among Swedish women suggested an inverse association of dietary magnesium intake with incidence of colorectal cancer. The authors assessed this association in a cohort of 35,196 Iowa women initially free of cancer and aged 55-69 years in 1986. Intakes of magnesium and other nutrients were assessed by food frequency questionnaire at baseline. Over 17 years of follow-up through 2002, 1,112 women developed colorectal cancer. After adjustment for age, energy, other nutrients, and risk factors for colorectal cancer, the hazard ratios of colorectal cancer across quintiles of magnesium intake were 1.00, 0.96, 0.83, 0.87, and 0.80 (95% confidence interval: 0.62, 1.03; ptrend = 0.06). The association was largely absent for rectal cancer but, for colon cancer, the hazard ratios were 1.00, 1.00, 0.88, 0.85, and 0.77 (95% confidence interval: 0.58, 1.03; ptrend = 0.04). These findings offer further evidence that a diet high in magnesium may reduce the occurrence of colon cancer among women. If replicated by other observational studies, a clinical trial would be needed to determine whether it is magnesium, specifically, and not other aspects of the contributing foods, that may offer benefit.

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