Methods and compositions are disclosed for delivering lutein or other antioxidant to target tissues such as the eye, in bioactive form, while protecting the antioxidant from degradation. The antioxidant is encapsulated in nanoparticles comprising a protein such as zein or a polymer such as poly(lactic-co-glycolic acid) (PLGA). Preferably a surfactant is associated with the nanoparticles as well, further helping to protect the antioxidant. After the nanoparticles are administered to the target tissue, bioactive antioxidant is released to the tissue over time. Optionally, the nanoparticles are admixed with a thermosensitive, bioadhesive gel to promote slow release of antioxidant. The methods and compositions are useful for treating or preventing conditions such as age-related macular degeneration or cataracts.
