Dietary Intake and Bone Mineral Density in Young-Adult Females

Abstract

The late second and early third decades of life are critical periods for bone health due to the attainment of peak bone mass during this time, yet little is known about relationships between lifestyle factors and bone health among young-adult females. Therefore, anthropometric, body composition, and nutritional variables were examined in relation to bone mineral density (BMD) and biochemical markers of bone turnover in a group of 60 healthy, young-adult females aged 18 to 25 years. Body weight, body mass index (BMI), fat-free soft tissue mass (FFST), and fat mass had statistically significant and positive associations with BMD. Mean daily dietary protein, magnesium, and iron intakes had statistically significant and negative associations with BMD. A second study compared dietary intake, BMD, and biochemical markers of bone turnover in young-adult females with chronic dieting habits to nondieters. Anthropometric and body composition variables between chronic dieters and nondieters were not statistically different; however, chronic dieters had statistically significantly lower average daily dietary intakes of energy, macronutrients, and selected micronutrients compared to nondieters. Chronic dieters had statistically significantly higher whole body (WB) BMD compared to nondieters. Moderate effects were observed for WB, lumbar spine, trochanter, and total proximal femur BMD such that chronic dieters possessed greater BMD compared to nondieters. It appears that among young-adult females, total body weight, particularly FFST mass, has an important association with BMD. Although nutritional inadequacies among young-adult females raise concerns, overconsumption of nutrients may increase the likelihood of nutrient-nutrient interactions that may have a less than optimal impact on BMD. Future investigations of dietary intake and BMD among young-adult females are warranted.