Factors that influence peak bone mass formation: a study of calcium balance and the inheritance of bone mass in adolescent females

Article Abstract:

Osteoporosis is a decrease in bone density which can lead to fractures and is a serious health problem, particularly among postmenopausal white women. Many factors are thought to be related to development of osteoporosis, including extent of skeletal mass acquisition during adolescence, familial factors, and hormonal factors, which influence the rate of bone loss after menopause. Most treatments of established osteoporosis are rather ineffective, so prevention of osteoporosis has become a more important treatment goal. Achievement of a maximum bone mass at the time of skeletal maturation is thought to be the most important factor in preventing later bone loss, but little is known about the mechanisms by which peak bone density can be achieved. It is possible that nutrition, specifically calcium intake, as well as age, sex, and genetically determined factors, may influence peak bone mass. Calcium balance, bone density, and the effect of two years of calcium supplementation were studied in 31 adolescent females, and the bone densities of their biological parents were evaluated as well. Calcium balance, the amount of calcium retained in the body, was determined by calcium ingestion, since the level of urinary calcium did not increase with increased intake. At the start of the study, 29 percent of subjects were consuming less than the RDA (recommended dietary allowance) of calcium. The group given calcium supplements for two years had about twice the calcium intake of the unsupplemented group. Bone mass and density increased over two years in both groups. The supplemented group had greater increases, but these were not significant, possibly because of studying too few subjects. Bone size, mass, and density correlated well between daughters and their parents. The bone mass of daughters at age 14 was 80 to 85 percent of that of their mothers, and this increased to 90 to 97 percent by age 16. The results suggest that calcium intake may exert a significant influence on peak bone mass and thus on later development of osteoporosis. Calcium supplementation should be considered for adolescent women. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Calcium metabolism and calcium requirements during skeletal modeling and consolidation of bone mass

Article Abstract:

The human skeleton continues to grow and develop during infancy, childhood and adolescence, until the maximal amount of bone mass (peak bone mass) is achieved. Peak bone mass is usually achieved by age 30. After this time, bone mass is lost gradually and the skeleton becomes more susceptible to fractures. Calcium plays an important role in the growth and development of bones. More than 99 percent of the calcium in the body is found in bones. During infancy, the amount of calcium in the body increases at a faster rate than during any other period of development. During childhood, the rate of growth slows down. Between the ages of two and eight, the annual increase in height decreases from nine centimeters per year to five and a half centimeters per year (from about 4 inches to 2 inches). During this time, the amount of calcium retained in the body also decreases. However, children still need two to four times more calcium than adults. Studies have shown that calcium supplements can improve growth and health in children. The body requires the most calcium during puberty and adolescence (ages 9 to 17). This is when bone mass increases at the greatest rate. At this time, more calcium is retained in the body than during infancy or childhood. In young adulthood, the bones stop growing. The amount of calcium retained in the body is lower during this period than during any of the previous periods of growth. By age 30, the bones have reached their maximum strength, and after this time a loss of bone mass begins. It is the loss of bone mass that increases the likelihood of bone fractures in the elderly. (Consumer Summary produced by Reliance Medical Information, Inc.)

Aging, Physiological aspects, Calcium metabolism

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Influence of calcium intake and growth indexes on vertebral bone mineral density in young females

Article Abstract:

Osteoporosis (bone thinning with loss of calcium content) is a major health problem, with 1.2 million bone fractures resulting from the disorder every year in the US. It is a particular problem for older women, since one third of the women over 65 years of age have spinal osteoporosis. Because osteoporosis is so common, it is important to identify preventive actions that would maximize peak bone density of early adulthood and help to maintain bone structure. Almost half of adult bone is produced during adolescence, and this time of life is thus thought to be a key period for consumption of dietary calcium. Low calcium intake may thus be a factor limiting adult peak bone density. Current calcium intake was evaluated in 49 preadolescent and adolescent girls (aged 8 to 18 years) to determine if this dietary factor was a major influence on vertebral (spinal) bone mineral density (V-BMD). The recommended dietary allowance (RDA) for calcium was met by 67 percent of girls aged 8 to 10 and by 16 percent of girls aged 11 to 18. Variations in V-BMD was significantly related to SMR, age, and calcium intake. The study indicates that although SMR and age also influence BMD in adolescents, calcium intake is the only factor influencing BMD which is amenable to change. (Consumer Summary produced by Reliance Medical Information, Inc.)

Teenage girls, Food and nutrition, Bone densitometry

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