Supplemental Calcium in Overweight People

An estimated 97 million people in the United States are overweight or obese, and therefore have an increased risk for a number of other obesity-related co-morbid conditions (such as hypertension, dyslipidemia, and Type 2 Diabetes) as well as for all-cause mortality. The total cost attributable to obesity amounted to $99.2 billion in the US in 1995 and this figure, like the prevalence of increased body mass, is rising at an alarming rate. At the same time calcium intake in the US adult population is far below the RDA (recommended daily allowance) and much below the daily optimal calcium intake recommended by the 1994 NIH consensus conference. An analysis of the NHANES III database suggests a strong inverse association between relative risk of obesity and calcium intake. Further, both prospective studies in animal models, and retrospective analyses of human studies suggest calcium supplementation may play a role in minimizing yearly weight gain, and may possibly induce small weight losses. In order to test the relationship between calcium intake and body weight, we propose to conduct a 2-year, randomized, double-blind, placebo-controlled trial of calcium supplementation (1500 mg/day of supplementary calcium vs. placebo) in adults with a BMI greater than or equal to 25 kg/m(2). We will study the effects of supplemental calcium on body weight, body composition, and obesity-related comorbid conditions, such as insulin sensitivity and lipids. The effects of such supplementation on blood pressure will also be systematically evaluated. A control group of untreated, healthy, adults will also be enrolled for comparisons to study subjects.