Valentini A, Perrone MA, Cianfarani MA, Tarantino U, Massoud R, Merra G, Bernardini S, Morris HA, Bertoli A. Obesity, vitamin D status and physical activity: 1,25(OH)2D as a potential marker of vitamin D deficiency in obese subjects.
Panminerva Med 2021;
62:83-92. [PMID:
32515572 DOI:
10.23736/s0031-0808.20.03770-2]
[Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND
Obesity has been regarded to be protective against fracture in spite of its association with low levels of vitamin D. Vitamin D is the key regulator of bone metabolism and its deficiency contributes to higher level of parathyroid hormone (PTH), leading to the activation of bone turnover.
METHODS
We studied 161 subjects of which 65 were young healthy subjects and 96 were elderly subjects. We measured creatinine, 25(OH)D, 1,25(OH)2D, PTH, albumin, and calcium plasma levels, we evaluated physical activity, and we calculated BMI. A sub-cohort of elderly subjects also underwent DXA scans.
RESULTS
Overweight and obese subjects, as well as underweight ones, had lower levels of vitamin D but normal serum concentrations of 1,25(OH)2D and PTH was higher in underweight and obese subjects. Moreover, we found a nonlinear relationship between body mass index (BMI) and PTH with a significant U-shaped exponential regression. Regardless of BMI, 25(OH)D mean levels were higher in subjects who practice physical activity.
CONCLUSIONS
These findings suggest that physical activity and BMI had a significant effect on the metabolism of bone and vitamin D, but the effect of BMI was different in underweight, normal weight or obese subjects. In obesity the real vitamin D deficiency could be estimate by serum 1,25(OH)2D concentrations whose lower levels contribute to the higher PTH production and consequently to bone loss and to a greater fracture risk.
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