Measurement of skin carotenoids and their association with diseases: a narrative review.

Skin carotenoids are highly correlated with blood carotenoid concentrations and can be measured noninvasively using optical methods. Skin carotenoid levels are widely used in nutritional education as indicators of fruit and vegetable intake; however, research on their use as biomarkers for disease prevention is limited. This narrative review outlines methods for measuring skin carotenoid levels and describes the diseases in which the relationship between skin carotenoids and diseases has been examined, including atherosclerotic cardiovascular disease, metabolic syndrome, pediatric asthma, age-related macular degeneration, and cognitive impairment.