[Carotenoid levels measured by resonance Raman in vivo]

Carotenoid molecules are powerful antioxidants which can act as scavengers for free radicals, singlet oxygen, and other harmful reactive oxygen species in human body. Studies have shown an inverse correlation between the level of carotenoid and the risk of cancers, cardiovascular diseases, and degenerative diseases. High-performance liquid chromatography is used for measuring carotenoid levels as a standard method, but it is not noninvasive and real-time detecting. The authors have developed a novel noninvasive optical technology to measure carotenoid level in vivo by detecting the resonance Raman spectra, which can be used for high sensitivity and real-time detecting. When a low noise 473 nm laser with power less than the exposure limit set by ANSI Z136. 1-2000 standards, a clearly distinguishable low resonance Raman spectra superimposed on a strong fluorescence background is produced. The carotenoid level is assessed by measuring the resonance Raman intensity. Using penetrating tissue technology, the authors improved the signal-to-noise ratio in the setup. The experimental results from different volunteers confirmed that the carotenoid level is proportional to the intake of it. The technology provided important values for clinic applications and science research.