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  • Lutein, Zeaxanthin, and Omega-3-fatty acids: Sources, Intakes, Bioavailability, and Associated risk for Age-related Macular Degeneration
    (2023) Kalu, Arua
    Thesis
    There is overwhelming evidence supporting lutein and zeaxanthin as beneficial to eye health. Age-related Macular Degeneration (AMD), one of the leading causes of blindness in Australia and globally, has been associated with inadequate dietary lutein (L) and zeaxanthin (Z) intakes. This study aimed to assess dietary L+Z intakes and sources, the cooking effect on carotenoids L, including the relative bioavailability of these carotenoids when consumed with omega-3 supplements. Consequently, the potential health benefit associated with increased carotenoids L+Z intakes and lower AMD risk. This study had 3 phases; Phase 1 assessed dietary L+Z intakes using dietary questionnaires (24-h recall and DQES), and background characteristics, while serum L+Z and omega-3 status were determined using HPLC and GC-MS. Carotenoid L+Z sources (raw vs. cooked) in subjects’ dietary reports were analyzed, including other food sources from major supermarket outlets, and levels were quantified using HPLC (Phase 2). The relative bioavailability of L+Z were examined when consumed with omega-3 supplements over a 19-d period (Phase 3). This study revealed evidence supporting the achievable mean levels of serum L and estimated dietary L +Z levels among 19 – 52 yr Australian adults with and without a family history of AMD. The preliminary data linked ethnic origin and residency status duration (>10 yr) with dietary intakes of L+Z and omega-3-FA. Overall, dietary L+Z intakes were below the reported range (≈3 – 5 mg/day) considered for recommended intakes. Also, participants achieved serum L and Z levels that were consistent (34-60 µg/dL) and inconsistent (<34 µg/dL) with reported literature evidence. Further, data analysis revealed that RBC EPA/AA ratio, seafood, supplement use (non-AMD related), and residency status influenced serum L and omega-3-FA status. Dietary L+Z intakes reported by subjects were quantified, and sweet corn, asparagus, chili habanero, and plum were determined (raw form) to be good L contributors. This study estimated L levels before and after cooking. The effect of cooking across foods was variable in terms of observed changes and will require further investigation using different heating methods. After cooking, carotenoid L increased (+19.74 % to +68.43 %) in brussel sprout, coriander, and spring onion. Further, the 19-d bioavailability trial revealed the additional benefit of omega-3-FA inclusion in L+Z supplement intakes among human subjects. Omega-3-addition significantly increased serum L+Z levels without significantly affecting oxidative stress levels. L+Z concentrations were 68% more relatively bioavailable when consumed with omega-3 supplements. Observed changes were achieved after supplementation with 540 mg/d EPA+ 360 mg/d DHA and/ or 12 mg/d (10 mg L+ 2 mg Z) over the 19-d period. Overall, this research demonstrates the additional benefit of omega-3-dietary or supplement intakes with L+Z, good food sources of L+Z, and the effect of cooking on these carotenoids.