TABLE 2.

Brief overview of spectroscopy-based skin carotenoid devices¹

Spectroscopy method	Type of spectroscopy device used	Number of validation studies meeting the eligibility criteria of review	Number of validation studies with multiple racial/ethnic groups included	Number of validation studies with infants and/or children	Number of validation studies using plasma or serum carotenoids	Number of validation studies using dietary intake	Number of validation studies using both plasma or serum carotenoids and dietary intake
Resonance Raman spectroscopy (RRS)	NuSkin BioPhotonic Scanner® (Pharmanex)	7 (52, 55, 56, 58, 60, 63, 64)	2 (55, 56)	3 (52, 55, 56)	2 (63, 64)	3 (52, 55, 58)	2 (56, 60)
	Custom-built scanner	13 (15, 22, 26, 38–41, 50, 51, 53, 54, 57, 61)	4 (38, 54, 57, 61)	6 (38, 41, 51, 53, 54, 57)	7 (15, 39–41, 50, 51, 61)	3 (22, 54, 57)	3 (26, 38, 53)
Pressure-mediated reflection spectroscopy (RS)	Veggie Meter®(Longevity Link Corporation)	2 (59, 62)	1 (59)	0	1 (62)	0	1 (59)
Spectrophotometer	CM700D (Konica Minolta)	4 (23, 25, 27, 28)	0	0	1 (28)	3 (23, 25, 27)	0
	Spectro-Guide 450 Gloss 6801 (BYK-Gardner)	1 (24)	0	0	0	1 (24)	0
	CM2600D (Konica Minolta)	2 (29, 30)	0	0	0	2 (29, 30)	0

¹Reference citation numbers in parentheses.