The relationship between dietary intakes assessed by duplicate portion sampling method and bone health in female students: a cross-sectional study

Purpose Osteoporosis is increasingly affecting the young female adults of the Iranian population. The role of nutrition and physical activity on bone mineral content (BMC) and bone mineral density (BMD) in young female students has not been fully examined. This study aims to assess the dietary intake of several nutrients, such as calcium, phosphorus and protein; serum concentrations of vitamin D; and physical activity and their relationship with BMC and BMD in young female students. Design/methodology/approach Three-day dietary intakes of 67 female students were measured via duplicate portion sampling (DPS) method. Calcium and phosphorus content of the food samples were determined using atomic absorption spectrophotometer. Protein intake was determined by Kjeldahl method. Serum 25(OH) D concentrations were measured using enzyme-linked immunosorbent assay. Lumbar spine and femoral neck BMD were measured using dual-energy X-ray absorptiometry (DEXA). Findings The mean ±SD dietary intake of protein, calcium and phosphorus was 58.8 ± 16.9 g/day, 388 ± 135 mg/day and 1884 ± 682 mg/day, respectively. Significant positive correlation was found between serum vitamin 25(OH) D concentrations and BMC of lumbar spine (r = 0.28, p = 0.016) and BMD of femoral neck (r = 0.29, p = 0.016). Moreover, the authors observed a significant positive correlation between physical activity and femoral neck BMC (r = 0.26, p = 0.03) and BMD (r = 0.28, p = 0.02). This study found no significant associations between dietary intakes of protein, calcium and phosphorus and bone density measurements. Originality/value In this study, the authors measured the dietary intake of protein, calcium and phosphorus using DPS method. This study highlights the role of physical activity and serum vitamin 25(OH) D concentrations in female students’ bone health.