CALCIUM SUPPLEMENT LINK TO INCREASED BONE DENSITY IN ADOLESCENT GIRLS
This article was originally published in The Tan Sheet
CALCIUM SUPPLEMENT LINK TO INCREASED BONE DENSITY IN ADOLESCENT GIRLS is shown in a study conducted by Tom Lloyd, PhD, Pennsylvania State University, et al., published in the Aug. 18 issue of the Journal of the American Medical Association. The study of 94 Caucasian 12-year-old females found that girls receiving 500 mg calcium citrate maleate (two 250 mg tablets) daily for 18 months had greater increases in lumbar spine bone density, lumbar spine bone mineral content, total body bone mineral density and 24-hour calcium excretion than adolescent girls given placebo. Over the 18-month period, the supplemented group compared with the placebo group had an 18.7% versus a 15.8% increase in lumbar spine bone density, a 39.4% versus a 34.7% increase in lumbar spine bone mineral content, a 9.6% versus an 8.3% increase in total body bone mineral density, and a 90.4 mg/d versus a 72.9 mg/d increase in urinary calcium excretion, Lloyd et al. noted. Adolescent girls were the focus of the study, the researchers explained, because "general consensus is that peak bone mass of premenopausal women is a major determinant of osteoporosis later in life." Based on the findings, Lloyd et al. concluded that calcium supplementation of 12-year-old girls "resulted in significant gains in total body and spinal bone density." The "modest increase," the authors speculated, "may ensure optimal development of peak bone mass, which could lower the risk of osteoporotic fracture later in life." To determine the effect of calcium supplementation on bone acquisition, the researchers observed 48 girls given calcium supplements and 46 given placebo at six-month intervals during which the subjects were measured for bone mineral content and bone mineral density using a bone absorptiometer. Urine specimens also were collected. Three-day diet records were completed at baseline and at each six-month period to obtain dietary calcium intake measurements. Lloyd et al. emphasized that "the placebo and the supplemented groups did not differ at study entry with respect to any of the variables measured." The average dietary calcium intake by the two groups was similar at about 960 mg, or 80% of the Recommended Daily Allowance of 1,200 mg per day for girls and women aged 11-24 and for pregnant and breastfeeding women. The RDA for all other groups is 800 mg per day. "However, the supplemented group received approximately 40% more calcium daily [than the placebo controls] from the supplement," the researchers noted, bringing their average total daily intake to 115% of the RDA. "Bone acquisition during the study period was significantly greater in the supplemented group than in the placebo group," the researchers found. For example, lumbar spine bone mineral density was .14 g/cm versus .11 g/cm, lumbar spine bone mineral content was 11.9 g versus 10.4 g, total body bone mineral density was .09 g/cm versus .07 g/cm, and total body bone mineral content was 404 g versus 368 g. Measured on a per year basis, the daily intake of an additional 354 mg of calcium by the supplemented group was associated with increases of 12.5% in lumbar spine bone mineral density, 6.4% in total body bone mineral density, and 26.3% in lumbar spine bone mineral density. In comparison, the placebo group registered per year increases of 10.5% in lumbar spine bone mineral density, 5.5% in total body bone mineral density, and 23.1% in lumbar spine bone mineral density. Longitudinal analysis of total body bone mineral density and lumbar spine bone mineral density "indicates the presence of a treatment effect," the authors said. Longitudinal analysis of lumbar spine bone mineral content and total body bone mineral content also "showed greater total skeletal mineral acquisition by the supplemented group during the 18 months." "It is unclear whether greater gains in bone density could have been achieved with greater calcium intakes, and we do not know if gains in bone density will persist in the absence of a continued greater intake of calcium," Lloyd et al. stated. "Additional longitudinal studies will be necessary," they continued, "to determine whether the observed increases in skeletal bone acquisition result in increased peak bone mass or an acceleration of bone mineralization." The Lloyd et al. study was supported by grants from the Public Health Service and Procter & Gamble, which supplied the calcium supplements and placebos for the trial. P&G is currently using calcium citrate maleate -- a type of calcium the researchers maintained "has been shown to be well absorbed in children and young adults and to retard bone loss in older postmenopausal women" -- in its Sunny Delight Plus Calcium and Hawaiian Punch Plus Calcium beverage products. Other recently published studies have, in contrast, warned of the negative aspects of calcium supplementation rather than its benefits. A recent study in the American Journal of Public Health, for instance, found that 25% of 70 brands of calcium supplements exceeded the provisional total tolerable daily intake of six micrograms of lead for children six years and under ("The Tan Sheet" Aug. 16, p. 8). Another recent study warned that calcium supplements and antacids containing lead and other trace metals can pose health hazards to older people ("The Tan Sheet" April 12, p. 9).
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