Quantitative Ultrasound and Dual X-Ray Absorptiometry as Indicators of Bone Mineral Density in Young Women and Nutritional Factors Affecting It †

Young adulthood is an important stage in the accrual of bone mass. Young women are often unaware of the need, and how to optimize modifiable risk factors, particularly intake of nutrients associated with good bone health. In this study, an accessible way to estimate osteoporosis risk, quantitative ultrasound (QUS), is compared to the gold-standard technique dual X-ray absorptiometry (DXA) in a group of 54 healthy young women (18–26 years) from Manawatu, New Zealand, and the relationship with nutrient intake is investigated. Broadband ultrasound attenuation and speed of sound (BUA, SOS) were assessed by QUS calcaneal scans and bone mineral concentration/density (BMC/BMD) were determined by DXA scans of the lumbar spine and hip (total and femoral neck). Dietary intake of energy, protein, and calcium was estimated using three-day food diaries and questionnaires. DXA mean Z-scores (>−2.0) for the hip (0.19) and spine (0.2) and QUS mean Z-scores (>−1.0) (0.41) were within the expected ranges. DXA (BMD) and QUS (BUA, SOS) measurements were strongly correlated. Median intakes of protein and calcium were 83.7 g/day and 784 mg/day, respectively. Protein intake was adequate and, whilst median calcium intake was higher than national average, it was below the Estimated Average Requirement (EAR). No significant relationship was found between dietary intake of calcium or protein and BMD or BMC. To conclude, QUS may provide a reasonable indicator of osteoporosis risk in young women but may not be an appropriate diagnostic tool. Increased calcium intake is recommended for this group, regardless of BMD.