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220 Cha pte r Se v e n

perfect correlation between Raman and HPLC data, as evidenced by
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a correlation coefficient R as high as 0.95. The results show excellent
linearity of RRS-derived carotenoid levels over a wide range of phys-
iological skin carotenoid concentrations, and provide a direct valida-
tion of the skin carotenoid RRS detection approach.
Measurements of large populations with the Raman device reveal
a bell-shaped distribution of carotenoid levels, as shown in Fig. 7.17b
for a group of 1375 healthy volunteer subjects that could be screened
with the RRS method within a period of a few weeks. 26,32 Analysis of
the data confirmed a pronounced positive relationship between self-
reported fruit and vegetable intake (a source of carotenoids) and skin
Raman response. Furthermore, the study showed that people with
habitual high-sunlight exposure have significantly lower skin carot-
enoid levels than people with little sunlight exposure, independent of
their carotenoid intake or dietary habits, and that smokers had dramat-
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ically lower levels of skin carotenoids as compared to nonsmokers.
Importantly, is also showed that RRS detection can track the increase of
skin carotenoid levels occurring in subjects with low-skin carotenoid
levels within a relat ively short time frame of weeks as a result of dietary
supplementation with carotenoid-containing multi-vitamins.
Based on these capabilities, the RRS detection method has already
found commercial application in the nutritional supplement indus-
try, (BioPhotonic Scanner™, Pharmanex LLC, Provo, Utah), which
has placed thousands of portable instruments with their customers
for rapid optical measurements of dermal carotenoid levels, and
which has further developed the instrumentation for rugged field
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use. For medical applications, the method had found initial interest
in dermatology, where a tentative correlation was demonstrated
between certain types of cancerous lesions and depleted carotenoid
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levels. Quantitative RRS measurements in these tissues, however,
which extend to layers beyond the stratum corneum, are more com-
plicated due to additional absorption and scattering caused by other
layers and chromophores, and need to be further refined for future
studies. In the field of epidemiology, the RRS method has recently
been applied to subjects with increased bitter taste sensitivities. Mea-
suring the stratum corneum layer of palm tissue, an inverse relation-
ship was observed between taste sensitivity and fruit and vegetable
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uptake, a finding that may be helpful to promote healthy behavioral
patterns of dietary change in large populations. In neonatology, skin
carotenoid RRS measurements are in progress to investigate correla-
tions of carotenoid levels with retinopathy of prematurely born
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infants. Measuring the sole of the foot, it could be shown that reti-
nopathy is influenced by the carotenoids in human milk-fed infants,
and that it appears likely that carotenoids are important nutrients in
decreasing the severity of the disease.
In all previous RRS measurements of dermal carotenoids we
measured the total concentration of all long-chain carotenoid species