Vitamin D insufficiency together with high serum levels of vitamin A increases the risk for osteoporosis in postmenopausal women

Postmenopausal women who were vitamin D deficient and had high serum levels of retinol had an eight times higher risk of having osteoporosis. A high retinol level together with vitamin D deficiency/insufficiency is an additional risk factor for osteoporosis. Purpose The aim of this study was to evaluate the association between vitamin D deficiency/insufficiency and excess of vitamin A intake as an osteoporosis risk factor in healthy postmenopausal women Design The design is a cross-sectional study of 232 healthy postmenopausal women. Methods Bone mass was evaluated by dual energy X-ray absorptiometry. Serum calcium, albumin phosphorus, creatinine, total high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and triglycerides analyzed by standard methods and retinol and 25-hydroxyvitamin D [25 (OH) D] measured by an online solid-phase extraction coupled with high-pressure liquid chromatography-ultraviolet detection. Results Prevalence of vitamin D deficiency [25(OH) D<20 ng/mL] was 70.1 %; 14.3 % had a 25(OH) D<10 ng/mL, and 23.6 % had insufficiency [25(OH) D 21-29 ng/mL]. Prevalence of high serum levels of retinol (>80 mu g/dL) was 36.4 %. Among subjects with 25(OH) D <20 ng/mL (n=152), 60.4 % (n=92) had serum levels of retinol> 80 mu g/dL. Bone density measurements revealed that the risk of osteoporosis was similar to 8 times higher in women with the highest retinol levels, as compared with women with the lowest retinol levels. In women with 25(OH) D<20 ng/mL, the risk for osteoporosis increased substantially in women who had the highest blood levels of retinol compared to the women with lowest retinol levels. Conclusions Higher retinol levels together with vitamin D deficiency could be a significant additional risk factor for osteoporosis, underscoring the need for improved physician and public education regarding optimization of vitamin D status in postmenopausal women and developing policies to avoid high serum levels of vitamin A.