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Journal: Archives of Internal Medicine. 2007; 167(9): 893-902.

PMID: 17502530

Authors and affiliation: Caan B, Neuhouser M, Aragaki A, Lewis CB, Jackson R, Leboff MS, Margolis KL, Powell L, Uwaifo G, Whitlock E, Wylie-Rosett J, Lacroix A. Division of Research, Kaiser Permanente Northern California, Oakland, USA. [E-Mail: bette.caan@dor.kaiser.org ]

Background: Obesity in the United States has increased significantly during the past several decades. The role of calcium in the maintenance of a healthy body weight remains controversial.

Methods: A randomized, double-blinded, placebo-controlled trial was performed with 36,282 postmenopausal women, aged 50 to 79 years, who were already enrolled in the dietary modification and/or hormone therapy arms of the Women's Health Initiative clinical trial. Women were randomized at their first or second annual visit to receive a dose of 1000 mg of elemental calcium plus 400 IU of cholecalciferol (vitamin D) or placebo daily. Change in body weight was ascertained annually for an average of 7 years.

Results: Women receiving calcium plus cholecalciferol supplements vs. women receiving placebo had a minimal but consistent favorable difference in weight change (mean difference, -0.13 kg; 95% confidence interval, -0.21 to -0.05; P = .001).

After 3 years of follow-up, women with daily calcium intakes less than 1200 mg at baseline who were randomized to supplements were 11% less likely to experience small weight gains (1 to 3 kg) and 11% less likely to gain more moderate amounts of weight (more than 3 kg) (P for interaction for baseline calcium intake = .008). [1 kilogram = 2.2 pounds]

Conclusion: Calcium plus cholecalciferol supplementation has a small effect on the prevention of weight gain, which was observed primarily in women who reported inadequate calcium intakes.

Trial Registration clinicaltrials.gov Identifier: NCT00000611.