Magnesium Intake, C-Reactive Protein, and the Prevalence of Metabolic Syndrome in Middle-Aged and Older U.S. Women

  1. Yiqing Song, MD123,
  2. Paul M. Ridker, MD, MPH14,
  3. JoAnn E. Manson, MD, DRPH12,
  4. Nancy R. Cook, SCD12,
  5. Julie E. Buring, SCD125 and
  6. Simin Liu, MD, SCD12
  1. 1Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusettes
  2. 2Department of Epidemiology, Harvard School of Public Health, Boston, Massachusettes
  3. 3Department of Nutrition, Harvard School of Public Health, Boston, Massachusettes
  4. 4Center for Cardiovascular Disease Prevention and the Donald Reynolds Center for Cardiovascular Research, Division of Cardiovascular Diseases, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusettes
  5. 5Department of Ambulatory Care and Prevention, Harvard Medical School, Boston, Massachusetts
  1. Address correspondence and reprint requests to Yiqing Song, MD, Division of Preventive Medicine, Brigham and Women’s Hospital, 900 Commonwealth Ave. East, Boston, MA 02215. E-mail: ysong{at}


OBJECTIVE—The aim of this study was to examine whether and to what extent magnesium intake is related to systemic inflammation and the metabolic syndrome.

RESEARCH DESIGN AND METHODS—We performed a cross-sectional analysis on data from 11,686 women ≥45 years of age participating in the Women’s Health Study who were initially free of cardiovascular disease and cancer and had no use of postmenopausal hormones.

RESULTS—In age- and BMI-adjusted analyses, magnesium intake was inversely associated with plasma C-reactive protein (CRP) concentrations; CRP concentrations were 12% lower in the highest intake quintile than in the lowest (P for trend <0.0001). This association was not appreciably altered by further adjustment for other potential confounding variables including dietary factors; the mean CRP concentrations for ascending quintiles of magnesium intake were 1.50, 1.39, 1.35, 1.34, and 1.31 mg/l (P for trend = 0.0003). This inverse association was stronger for women with a BMI ≥25 kg/m2 (P < 0.0001 for interaction) and those who were current or past smokers (P = 0.0009 for interaction). After adjustment for confounding lifestyle and dietary factors, women in the highest quintile of magnesium intake had 27% lower risk of the metabolic syndrome (defined according to the National Cholesterol Education Program criteria) compared with those in the lowest quintile of intake (odds ratio 0.73 [95% CI 0.60–0.88], P for trend = 0.0008).

CONCLUSIONS—Our results suggest that magnesium intake is inversely associated with systemic inflammation and the prevalence of the metabolic syndrome in middle-aged and older women.


  • P.M.R. has received grant/research support from AstraZeneca, Bristol-Myers Squibb, and Novartis.

    A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

    • Accepted February 16, 2005.
    • Received January 16, 2005.
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