Serum retinyl esters are not elevated in postmenopausal women with and without osteoporosis whose preformed vitamin A intakes are high.

BACKGROUND

Recent observational studies suggest that preformed vitamin A (VA) intakes of 1500-2000 microg/d may increase the risk of osteoporosis and hip fracture. However, few studies have examined associations between biologic indicators of VA and osteoporosis.

OBJECTIVE

This study characterized VA intake, serum VA, and bone turnover markers in postmenopausal women with and without osteoporosis.

METHODS

Bone density was measured by dual-energy X-ray absorptiometry. Subjects were separated into those with osteoporosis (n = 30) and those with normal bone density (n = 29). Women with osteopenia were excluded. Complete blood chemistries were obtained. Serum was analyzed for retinol, retinyl esters, and metabolites. Assays for 3 bone turnover markers were performed by using commercially available kits. Diet records were quantified. Logistic regression was used to test for an association between dietary and serum variables and osteoporosis.

RESULTS

Dietary VA did not differ significantly between the groups but was nearly twice the Recommended Dietary Allowance in both groups. Body mass index (BMI) and serum triacylglycerols were significantly lower in the osteoporosis group. Retinyl esters were not elevated in either group, but a trend existed for the association of serum retinyl esters as a percentage of total VA with osteoporosis (P = 0.070) after adjustment for BMI and triacylglycerols in the statistical model. Milk, fruit, and vegetable intakes were below the current recommendations.

CONCLUSIONS

Serum retinyl esters were not elevated in these postmenopausal women despite intakes of total VA that were nearly two-fold the Recommended Dietary Allowance. However, retinyl ester concentration (percentage of total VA) was marginally associated with osteoporosis and should be further investigated.