Optical detection of carotenoid antioxidants in human bone and surrounding tissue.

Carotenoids are known to play an important role in health and disease state of living human tissue based on their antioxidant and optical filtering functions. In this study, we show that carotenoids exist in human bone and surrounding fatty tissue both in significant and individually variable concentrations. Measurements of biopsied tissue samples with molecule-specific Raman spectroscopy and high-performance liquid chromatography reveal that all carotenoids that are known to exist in human skin are also present in human bone. This includes all carotenes, lycopene, β-cryptoxanthin, lutein, and zeaxanthin. We propose quantitative reflection imaging as a noncontact optical method suitable for the measurement of composite carotenoid levels in bone and surrounding tissue exposed during open surgeries such as total knee arthroplasty, and as a proof of concept, demonstrate carotenoid measurements in biopsied bone samples. This will allow one to establish potential correlations between internal tissue carotenoid levels and levels in skin and to potentially use already existing optical skin carotenoid tests as surrogate marker for bone carotenoid status.