Abstract
[Purpose] The purpose of this study was to assess the possible role of physical
activities, calcium consumption and lifestyle factors in both bone mineral density and
bone metabolism indices in 350 young adult volunteers. [Subjects and Methods] All
volunteers were recruited for the assessment of lifestyle behaviors and physical activity
traits using validated questioners, and bone mineral density (BMD), serum osteocalcin
(s-OC), bone-specific alkaline phosphatase (BAP), and calcium were estimated using
dual-energy X-ray absorptiometry analysis, and immunoassay techniques. [Results] Male
participants showed a significant increase in BMD along with an increase in bone
metabolism markers compared with females in all groups. However, younger subjects showed a
significant increase in BMD, OC, BAP, and calcium compared with older subjects.
Osteoporosis was more common in older subjects linked with abnormal body mass index and
waist circumference. Bone metabolism markers correlated positively with BMD, physically
activity and negatively with osteoporosis in all stages. Also, moderate to higher calcium
and milk intake correlated positively with higher BMD. However, low calcium and milk
intake along with higher caffeine, and carbonated beverage consumption, and heavy
cigarette smoking showed a negative effect on the status of bone mineral density. Stepwise
regression analysis showed that life style factors including physical activity and
demographic parameters explained around 58–69.8% of the bone mineral density variation in
young adults especially females. [Conclusion] body mass index, physical activity, low
calcium consumption, and abnormal lifestyle have role in bone mineral density and
prognosis of osteoporosis in young adults.