Associations between blood antioxidant levels and femoral neck strength.

BACKGROUND: Studies have confirmed that antioxidants contribute to a lower risk of osteoporosis, which is an independent factor for femoral neck fracture (FNF). However, the associations between blood antioxidant levels and femoral neck strength remain unclear.

OBJECTIVE: Our aim was to test the hypothesis that levels of blood antioxidants are positively associated with composite indices of bone strength in femoral neck, which integrate the bending strength index (BSI), compressive strength index (CSI), and impact strength index (ISI), in a population of middle-aged and elderly individuals.

METHODS: This cross-sectional study utilized data from the Midlife in the United States (MIDUS) study. Blood levels of antioxidants were measured and analyzed.

RESULTS: In total, data from 878 participants were analyzed. Results of Spearman correlation analyses indicated that blood levels of 6 antioxidants (total lutein, zeaxanthin, alpha-carotene, 13-cis-beta-carotene, trans-beta-carotene and total lycopene) were positively associated with CSI, BSI, or ISI in middle-aged and elderly individuals. Conversely, blood gamma-tocopherol and alpha-tocopherol levels were negatively associated with CSI, BSI, or ISI scores. Furthermore, linear regression analyses suggested that only blood zeaxanthin levels remained positively associated with CSI (odds ratio, OR 1.27; 95% CI: 0.03, 2.50; p = 0.045), BSI (OR, 0.54; 95% CI: 0.03-1.06; p = 0.037), and ISI (OR, 0.06; 95% CI: 0.00, 0.13; p = 0.045) scores in the study population after adjusting for age and sex.

CONCLUSIONS: Our results indicated that elevated blood zeaxanthin levels were significantly and positively associated with femoral neck strength (CSI, BSI, or ISI) in a population of middle-aged and elderly individuals. These findings suggest that zeaxanthin supplementation may reduce FNF risk independently.