1 Clinical General Research Center, University of Cincinnati Medical Center 234 Goodman Street, Cincinnati, Ohio 45229
We have carefully reviewed the informative letter from Dr. Garry concerning the measurement of vitamin A and a non-vitamin A component, phytofluene. As indicated by Dr. Garry, our average vitamin A levels agreed with those published by Kahan1 and by Hansen and Warwick.2 As noted by Garry et al.3 and by Thompson et al.,4 unless corrected for by chromatography or calculated formula, phytofluene in plasma variable affects the "total" levels read as vitamin A (the sum of vitamin A and the non-vitamin A, phytofluene).