Optical assessment of skin carotenoid status as a biomarker of vegetable and fruit intake

Authors: ERMAKOV, IGOR - Longevity Link Corporation; ERMAKOVA, MAIA - Longevity Link Corporation; SHARIFZADEH, MOHSEN - Longevity Link Corporation; GORUSUPUDI, ARUNA - University Of Utah; FARNSWORTH, KELLIANN - University Of Utah; BERNSTEIN, PAUL - University Of Utah; STOOKEY, JODI - San Francisco Department Of Public Health; EVANS, JANE - San Francisco Department Of Public Health; ARANA, TITO - San Francisco Department Of Public Health; TAO-LEW, LISA - San Francisco Department Of Public Health; ISMAN, CARLY - San Francisco Department Of Public Health; CLAYTON, ANNA - San Francisco Department Of Public Health; OBANA, AKIRA - Seirei Hamamatsu General Hospital; WHIGHAM, LEAH - The Paso Del Norte Institute For Healthy Living; REDELFS, ALISHA - The Paso Del Norte Institute For Healthy Living; Jahns, Lisa; GELLERMANN, WERNER - Longevity Link Corporation

Submitted to: Archives of Biochemistry and Biophysics
Publication Type: Review Article
Publication Acceptance Date: 3/26/2018
Publication Date: 5/15/2018
Publication URL: http://handle.nal.usda.gov/10113/5929379
Citation: Ermakov, I.V., Ermakova, M., Sharifzadeh, M., Gorusupudi, A., Farnsworth, K., Bernstein, P.S., Stookey, J., Evans, J., Arana, T., Tao-Lew, L., Isman, C., Clayton, A., Obana, A., Whigham, L., Redelfs, A., Jahns, L.A., Gellermann, W. 2018. Optical assessment of skin carotenoid status as a biomarker of vegetable and fruit intake. Archives Of Biochemistry and Biophysics. 646:46-54. https://doi.org/10.1016/j.abb.2018.03.033.
DOI: https://doi.org/10.1016/j.abb.2018.03.033

Interpretive Summary: High consumption of vegetables and fruits is associated with beneficial health outcomes, but Americans do not consume enough of them. Carotenoids are pigments found in the skins of many brightly-colored vegetables and fruits and may also be beneficial for health. Public health researchers and professionals implement studies to increase consumption of vegetables and fruits, but it is very difficult to measure their effectiveness as most studies rely upon self-reported intake, which is subject to forgetting or over-estimation. A new method to measure the effectiveness of these interventions is by skin carotenoid concentrations. There are two methods used to measure skin carotenoid concentrations; resonance Raman spectroscopy (RRS) and reflection spectroscopy (RS). RRS is an older, well-validated method and RS is newer and has several advantages over the RRS. It is more portable, faster, and adjusts for melanin in the skin, making it ideal as a biomarker of vegetable and fruit intake. We present results from eight studies that investigated different aspects of validity of RS and RRS, including how similar they are to each other. We found that RS is highly correlated with blood carotenoids, and with the more thoroughly validated RRS. We found that RS provides useful measurements in a wide variety of age groups and race/ethnicities, indicating that the scores are independent of melanin content of the skin. We also found that women have higher measurement scores than men, that smokers have reduced scores, and that there is no difference by age. In conclusion, we show that RS, and RRS, are valid measurements that can be used to detect differences among people in carotenoid intake.

Technical Abstract: Resonance Raman spectroscopy (RRS) and reflection spectroscopy (RS) are optical methods applicable to the non-invasive detection of carotenoids in human skin. RRS is the older, more thoroughly validated method, whereas RS is newer and has several advantages. Since collective skin carotenoid levels serve as a biomarker for vegetable and fruit intake, both methods hold promise as convenient screening tools for assessment of dietary interventions and correlations between skin carotenoids and health and disease outcomes. In this manuscript, we describe the most recent optimized device configurations and compare their use in various clinical and field settings. Both RRS and RS devices yield a wide range of skin carotenoid levels between subjects, which is a critical feature for a biomarker. Repeatability of the methods is 3-15% depending on the subject’s skin carotenoid level and the uniformity of its local distribution. For 54 subjects recruited from an ophthalmology clinic, we first checked the validity of the relatively novel RS methodology via biochemical serum carotenoid measurements, the latter carried out with high performance liquid chromatography (HPLC). A high correlation between RS skin and serum HPLC carotenoid levels was established (R = 0.81; p < 0.001). Also, a high correlation was found between RS and RRS skin levels (R = 0.94 p < 0.001). Subsequent comparisons of skin carotenoid measurements in diverse age groups and ethnicities included 569 Japanese adults, 947 children with ages 2-5 screened in 24 day care centers in San Francisco, and 49 predominantly Hispanic adults screened at an outdoor health fair event. Depending on the particular subject group, correlation coefficients between the RRS and RS methods ranged between R ~ 0.80 and R ~ 0.96. Analysis of the Japanese screening showed that, on average, skin carotenoid levels are higher in women compared to men, skin levels do not depend on age, tobacco smokers have reduced levels versus non-smokers, and skin carotenoid levels are not correlated with diabetes. For the two most ethnically diverse groups with widely varying melanin levels, we investigated the effect of dermal melanin on RS and RRS skin carotenoid levels. The analysis revealed that large variations in skin carotenoid levels remain detectable independent of the particular melanin index. This behavior is consistent with the absence of melanin effects on the skin carotenoid levels generated with the instrument configurations. The RS method has an advantage over RRS in its relative simplicity. Due to its detection of skin reflection over a wide spectral range from the near UV to the near IR, it has the unique ability to quantify each of the major tissue chromophores and take them into account in the derivation of skin carotenoid levels.