Calcium retention in relation to calcium intake and postmenarcheal age in adolescent females

Abstract

Achievement of maximal calcium retention during adolescence may influence the magnitude of peak bone mass and subsequently lower the risk of osteoporosis. Calcium retention is generally considered to reach a plateau at a certain calcium intake. To test this hypothesis, calcium balance was measured in 35 females with a mean (+/-SD) age of 12.7 +/- 1.2 y (range: 12-15 y) who consumed from 841 +/- 153 to 2173 +/- 149 mg Ca/d. Subjects ate a basal diet that included a fortified beverage containing different amounts of calcium citrate malate. Twenty-one subjects were studied at two dietary calcium intakes with use of a crossover design. Results from a previous study in 14 subjects who were studied at only one calcium intake were included in the data analysis. Calcium retention was modeled as a nonlinear function of calcium intake that included a parameter representing mean maximal retention. Mean maximal calcium retention was 473 mg/d (95% CI: 245, 701 mg Ca/d). At higher postmenarcheal ages, maximal calcium retention was lower but the intake required to achieve this was not affected. Calcium intake explained 79% and 6%, respectively, of the variation in fecal and urinary calcium excretion. Intake of 1200 mg Ca/d, the recommended dietary allowance for calcium published in 1989, resulted in a mean calcium retention that was 57% of the maximal value (95% CI: 25%, 89%). Intake of 1300 mg Ca/d was the smallest intake that allowed some adolescent females to achieve 100% of maximal calcium retention (95% CI: 26%, 100%). These data support the idea that calcium retention plateaus at a certain calcium intake although it continues to increase at intakes > 2 g/d.

Osteoporosis, Nutrition and Adolescence

“…Thus, if calcium intake is below 500 mg/day in childhood, more than 50% of ingested calcium must be retained in order to obtain adequate mineral accretion (Mølgaard et al, 1999). Balance studies carried out in adolescents support that calcium retention is associated with calcium intake, but at intakes up to 1300 mg/day a plateau is reached (Jackman et al, 1997). Therefore, calcium is a threshold nutrient, i.e., at suboptimal intake the body's ability to store calcium as bone tissue is limited by the intake of the mineral, but increasing calcium intake above the body's requirements does not result in further increases of stores .…”

Optimizing Bone Health and Calcium Intakes of Infants, Children, and Adolescents

“…At intakes below this level, the skeleton may receive less calcium than it can use, and peak bone mass may not be achieved. 4,[31][32][33] Virtually all the data used to establish this intake level are from white children. Few data are available from other racial groups.…”

“…Multiple approaches are used to assess calcium requirements in children. These approaches include (1) measurement of calcium balance with various levels of calcium intake with or without use of calcium stable isotopes methodology, 32,33,45 (2) measurement of bone mineral content by dual-energy x-ray absorptiometry or other radiographic techniques in groups of children before and after calcium supplementation, 46,47 and (3) epidemiologic studies of the association of fracture incidence in children with bone mineral content or relating bone mass and/or fracture risk in adults to childhood calcium intake. [10][11][12][13][14][15]48,49 None of these approaches are useful in the office setting.…”

Ingestão de cálcio e indicadores antropométricos entre adolescentes

“…A menor ingestão desse mineral pelos adolescentes pré-púberes merece ainda maior destaque, tendo em vista a maior necessidade de cálcio nessa fase, para garantir o crescimento adequado. A reduzida ingestão desse mineral nesta fase resulta em menor mineralização óssea, quando comparada a indivíduos da mesma faixa etária que tiveram ingestão adequada de cálcio 26 .…”