In Reply We appreciate the interest and the comments written by Meagher et al regarding our study and the methods used.
Lutein and zeaxanthin concentrations in the plasma of patients with AMD were analyzed via normal-phase high-performance liquid chromatography using an NH2 column at 40°C. We searched for a carotenoid, which occurs only in traces in plasma. Furthermore, its peak should be adequately distinguishable from the other peaks in the method used. Astaxanthin ([3S,3′S]-3,3′-dihydroxy-β,β-carotene-4,4′-dione) met these requirements. In random checks, the concentrations of astaxanthin in the plasma of the participants were well below the limit of quantification. Besides that, astaxanthin is structurally related to lutein and zeaxanthin and therefore exhibits a similar behavior against outside influences during sample preparation. Additionally, the participants were instructed to abstain from dietary supplements. Those reporting a consumption of supplements were excluded from the study.
Christin Arnold, Susanne Jentsch, Dietrich Schweitzer, Volker Böhm. Regarding Macular Xanthophylls and ω-3 Long-Chain Polyunsaturated Fatty Acids in Age-Related Macular Degeneration—Reply. JAMA Ophthalmol. 2014;132(2):231–232. doi:10.1001/jamaophthalmol.2013.6340