Vitamin D Status and Bone Health Among Young Adult Women

Background: Osteoporosis is estimated to affect 200 million women in the world, affecting 10% of women aged 60, 20% of women aged 70, 40% of women aged 80 and 67% of women aged 90. Osteoporosis is characterized by low bone density and increases the risk for fractured bones; however, it may be prevented with modifiable factors such as supplements, diet, and physical activity. Vitamin D deficiency leads to bone mineral density loss, as Vitamin D3 is responsible for calcium absorption into the bones. Bone consolidation is believed to occur between 20 and 30 years old; thus, attaining peak bone mass is critical during pre-menopause. Methods: The relationship between vitamin D and bone mineral density has predominately been studied in postmenopausal populations. Therefore, we examined this association among 18-30 year old participants (n=271) in the cross-sectional UMass Vitamin D Status Study. The modified version of the Harvard Food Frequency Questionnaire was used to assess the average intake of vitamin D foods and supplements. Serum 25(OH)D3 concentrations were assayed from blood samples. Bone mineral content and bone area were measured by dual-energy X-ray absorptiometry scan. Bone mineral content (BMC), as measured in grams, provides a measure of bone mass. Bone area (BA), as measured in cm2, reflects a two-dimensional area, which is characterized by the periphery of a bone region. We used multivariable linear regression to model the relationship between bone mineral density and bone area with sources of vitamin D after adjusting for dietary and lifestyle factors. Results: In the present study, the mean and standard deviation of vitamin D is 372.7 IU and 285.8 IU, respectively. For vitamin D from supplements, the mean is 140.9 IU with a standard deviation of 232.3 IU. Finally, for vitamin D from food, the mean is 231.8 IU with a standard deviation of 182.0 IU. Compared to reference values of 600 IU, these data are below the recommended daily allowance. We did not observe an association between total vitamin D or vitamin D from foods sources with either BMC or BA. We also did not observe an association between serum 25-hydroxyvitamin D levels and BMC or BA. Conclusion: Future studies with larger sample sizes are warranted to validate this association among young premenopausal women