BACKGROUND: The mechanism and clinical significance of low circulating 25-hydroxyvitamin D [25(OH)D] in obese people are unknown. Low total 25(OH)D may be due to low vitamin D-binding proteins (DBPs) or faster metabolic clearance. However, obese people have a higher bone mineral density (BMD), which suggests that low 25(OH)D may not be associated with adverse consequences for bone. OBJECTIVE: We sought to determine whether 1) vitamin D metabolism and 2) its association with bone health differ by body weight. DESIGN: We conducted a cross-sectional observational study of 223 normal-weight, overweight, and obese men and women aged 25-75 y in South Yorkshire, United Kingdom, in the fall and spring. A subgroup of 106 subjects was also assessed in the winter. We used novel techniques, including an immunoassay for free 25(OH)D, a stable isotope for the 25(OH)D3 half-life, and high-resolution quantitative tomography, to make a detailed assessment of vitamin D physiology and bone health. RESULTS: Serum total 25(OH)D was lower in obese and overweight subjects than in normal-weight subjects in the fall and spring (geometric means: 45.0 and 40.8 compared with 58.6 nmol/L, respectively; P < 0.001) but not in the winter. Serum 25(OH)D was inversely correlated with body mass index (BMI) in the fall and spring and in the winter. Free 25(OH)D and 1,25-dihydroxyvitamin D [1,25(OH)2D] were lower in obese subjects. DBP, the DBP genotype, and the 25(OH)D3 half-life did not differ between BMI groups. Bone turnover was lower, and bone density was higher, in obese people. CONCLUSIONS: Total and free 25(OH)D and 1,25(OH)2D are lower at higher BMI, which cannot be explained by lower DBP or the shorter half-life of 25(OH)D3 We speculate that low 25(OH)D in obesity is due to a greater pool of distribution. Lower 25(OH)D may not reflect at-risk skeletal health in obese people, and BMI should be considered when interpreting serum 25(OH)D as a marker of vitamin D status.
BACKGROUND: The mechanism and clinical significance of low circulating 25-hydroxyvitamin D [25(OH)D] in obese people are unknown. Low total 25(OH)D may be due to low vitamin D-binding proteins (DBPs) or faster metabolic clearance. However, obese people have a higher bone mineral density (BMD), which suggests that low 25(OH)D may not be associated with adverse consequences for bone. OBJECTIVE: We sought to determine whether 1) vitamin D metabolism and 2) its association with bone health differ by body weight. DESIGN: We conducted a cross-sectional observational study of 223 normal-weight, overweight, and obesemen and women aged 25-75 y in South Yorkshire, United Kingdom, in the fall and spring. A subgroup of 106 subjects was also assessed in the winter. We used novel techniques, including an immunoassay for free 25(OH)D, a stable isotope for the 25(OH)D3 half-life, and high-resolution quantitative tomography, to make a detailed assessment of vitamin D physiology and bone health. RESULTS: Serum total 25(OH)D was lower in obese and overweight subjects than in normal-weight subjects in the fall and spring (geometric means: 45.0 and 40.8 compared with 58.6 nmol/L, respectively; P < 0.001) but not in the winter. Serum 25(OH)D was inversely correlated with body mass index (BMI) in the fall and spring and in the winter. Free 25(OH)D and 1,25-dihydroxyvitamin D [1,25(OH)2D] were lower in obese subjects. DBP, the DBP genotype, and the 25(OH)D3 half-life did not differ between BMI groups. Bone turnover was lower, and bone density was higher, in obese people. CONCLUSIONS: Total and free 25(OH)D and 1,25(OH)2D are lower at higher BMI, which cannot be explained by lower DBP or the shorter half-life of 25(OH)D3 We speculate that low 25(OH)D in obesity is due to a greater pool of distribution. Lower 25(OH)D may not reflect at-risk skeletal health in obese people, and BMI should be considered when interpreting serum 25(OH)D as a marker of vitamin D status.
Authors: Janice B Schwartz; J Christopher Gallagher; Rolf Jorde; Vivian Berg; Jennifer Walsh; Richard Eastell; Amy L Evans; Simon Bowles; Kim E Naylor; Kerry S Jones; Inez Schoenmakers; Michael Holick; Eric Orwoll; Carrie Nielson; Martin Kaufmann; Glenville Jones; Roger Bouillon; Jennifer Lai; Davide Verotta; Daniel Bikle Journal: J Clin Endocrinol Metab Date: 2018-09-01 Impact factor: 5.958
Authors: Shinyoung Jun; Alexandra E Cowan; Anindya Bhadra; Kevin W Dodd; Johanna T Dwyer; Heather A Eicher-Miller; Jaime J Gahche; Patricia M Guenther; Nancy Potischman; Janet A Tooze; Regan L Bailey Journal: Public Health Nutr Date: 2020-05-29 Impact factor: 4.022
Authors: John J Lima; Mario Castro; Tonya S King; Jason E Lang; Victor E Ortega; Stephen P Peters; Loren C Denlinger; Elliot Israel; Christine A Sorkness; Michael E Wechsler; Sally E Wenzel; Lewis J Smith Journal: Ann Allergy Asthma Immunol Date: 2018-06-14 Impact factor: 6.347