Lifecoursedeterminants of bone mass accrual in atransitional rural community in South India:the Andhra Pradesh Children and Parents Study(APCAPS)

Abstract

Abstract In urbanizing rural communities in India, bone development in children and adolescents may be affected by nutrition transition. This thesis work used a lifecourse approach to investigate the combined effects of early life undernutrition and urbanized lifestyles in late adolescence on bone mass accrual in a rural area in southern India that has been undergoing socioeconomic development over the past decade. The analyses used data from a prospective cohort study near Hyderabad city in India, the Andhra Pradesh Children and Parents Study (APCAPS). Research Paper 1 The first study examined bone mass in the population of APCAPS. Over 50% of female and 30% of male participants aged 50 years and above had osteopenia or osteoporosis. Peak bone mass was low in this lean rural population (hip BMD in 2029 year old female: 0.84±0.1; male: 0.95±0.11 g/cm2) in comparison to the reference values from a healthy Indian population in the same age group (female: 0.90±0.11; male: 0.99±0.13). There was clearer evidence of positive association between hip BMD and lean mass than fat mass in this population. Research Paper 2: The second study examined longitudinal effects of early life proteinenergy supplementation on bone mass in young adulthood, adjusting for current body size and lifestyles. There was no clear evidence for a longterm positive effect of prenatal and infant exposure to modest proteinenergy supplementation on bone mass accrual in this rural community. Greater lean mass in young adulthood was associated with higher hip and lumbar spine BMD. Weightbearing physical activity was positively associated with hip, LS, and wholebody BMD in males. Research Paper 3: The third study assessed longitudinal effects of low body mass index (BMI) during adolescence on bone mass in young adulthood. When adjusted for current BMI, there was no clear evidence for association of hip and LS BMD in young adulthood with adolescent BMI. Controlling for adolescent BMI, greater increase in BMI during adolescence was associated with higher BMD in young adulthood, although it was 3 still suboptimal in comparison to a healthy young Indian population. Concluding remarks In this transitional rural community from south India, the prevalence of osteopenia and osteoporosis was high, especially among females. Although neither modest early life supplementation nor weight gain in late adolescence was sufficient to achieve optimal peak bone mass, increase in body size in late adolescence and young adulthood was beneficial for bone mass accrual in this young population. There is a need to develop strategies to take advantage of, and also prevent any detrimental effects of, nutrition transition to improve peak bone mass in transitional rural communities in India.