Retinol, retinol-binding protein 4, abdominal fat mass, peak bone mineral density, and markers of bone metabolism in men: the Northern Osteoporosis and Obesity (NO2) Study

Abstract

Context: The association between retinol and bone mineral density (BMD) in males after puberty has not been fully investigated previously. Objective: To investigate the association between retinol, retinol-binding protein-4 (RBP-4), BMD (g/cm 2 ), abdominal fat mass, and markers of bone metabolism in young men. Design: Longitudinal study. Participants: Seventy-eight healthy males with a mean age of 22.6G0.7 years at baseline. A follow-up was conducted in 73 of the participants 2.0G0.4 years later. Main outcome measures: Associations between serum concentrations of retinol and RBP-4, and BMD of the total body, lumbar spine, and hip, serum concentrations of osteocalcin, and carboxy terminal telopeptide of type 1 collagen (CTX), were investigated. Results: Both retinol and RBP-4 showed an inverse relationship with that of osteocalcin (rZK0.23 to K0.25, P!0.05). Levels of RBP-4 (rZ0.26, PZ0.02) and osteocalcin (rZK0.23, PZ0.04) were also related to abdominal fat mass, and the relationship between RBP-4, retinol, and osteocalcin disappeared after adjusting for this influence of abdominal fat mass. Neither retinol nor RBP-4 concentrations were associated with BMD at any site, CTX as baseline, or changes in BMD during the 2-year follow-up period. Levels of RBP-4 showed a strong association with levels of retinol (rZ0.61, P!0.001). Conclusion: We found a negative association between the bone formation marker osteocalcin with retinol and RBP-4. The association disappeared when adjusting for the influence of abdominal fat mass. Neither retinol nor RBP-4 were associated with peak BMD in young men. 158 765-770 European Journal of Endocrinology

Retinol May Counteract the Negative Effect of Cadmium on Bone

“…The concentrations are similar to those observed in women in the US and Europe (15)(16)(17)34) but somewhat lower than those reported for Swedish men (13,20). Also, the urinary cadmium concentrations were in the range of those observed in women of a similar age in the US and Europe (6,7,35,36).…”

“…Null or weak associations have previously been observed for serum retinol or retinyl esters in relation to BMD or fracture risk (15)(16)(17)(18)20,(37)(38)(39). Some studies have found retinol to be associated with higher BMD or have shown that women with osteoporosis have lower retinol concentrations.…”

“…However, normal bone metabolism can only be maintained with adequate vitamin A status (14). Vitamin A deficiency has been associated with lower BMD and increased risk of osteoporosis and fractures at different sites (15)(16)(17)(18), but data are not conclusive (9,19,20). Thus, vitamin A deficiency as well as excess intake are proposed risk factors for low BMD and fractures (21,22).…”

Bone damage in type 2 diabetes mellitus

“…In this context a possible role for adipokines (leptin and adiponectin) [49], fetuin-A [50], and retinol-binding protein 4 [51] has been identified.…”

Time-Course Changes in Bone Turnover Markers and Fat-Soluble Vitamins After Obesity Surgery

“…Evidence includes the negative association between osteocalcin (a bone formation marker) and retinol [11], the association between carotenoid intake and loss of bone mineral density [12], and the in vitro, animal, and human evidence suggesting a unique anabolic effect on bone calcification and osteoporosis prevention of β-cryptoxanthin [13]. Additionally, high oxidative stress is associated with reduced BMD and bone metabolism markers in hypercholesterolemic subjects [14] and elderly men [15], and serum α-tocopherol levels seem to modify the association between urinary 8-iso-PGF2α and BMD in the elderly [15].…”