ABSTRACT
Osteoporosis is a disease typically affecting the elderly but onset can occur at any age. The prevalence of osteoporosis is growing in Canada, with a current two million Canadians diagnosed (Osteoporosis Canada, 2010). This disease is characterized by low bone density and increased fracture risk and has its antecedents in childhood; although the two major factors affecting bone accrual in childhood are exercise and diet, recently there has been increased interest in the effects of oral contraception (OC) usage. Bone accrues during adolescence by the action of continuous resorption and formation of bone cells. While 25 % of adult bone mass is accrued during the adolescent growth spurt (Bailey, 1999), up to 50 % increase in total bone mass occurs between the ages of 12–18 years (Cromer et al., 2008). This is of interest since bone mass peaks at approximately 18 years of age in females and starts to decline after the third decade of life (Frost, 1997; Busen, 2004), with the largest loss of bone occurring at the time of menopause. Therefore, with the age-related reductions in bone mass, women are at high risk for osteoporosis if they do not lay down enough bone during the growing years to survive the impact of bone loss in later life. As such, it is important for girls to accrue as much bone as possible in their youth, in order to ward off osteoporotic bone levels later in life (Busen, 2004).
