A critical insight into the physicochemical stability of macular carotenoids with respect to their industrial production, safety profile, targeted tissue delivery, and bioavailability

Abstract

Lutein, zeaxanthin, and mesozeaxanthin, collectively termed as macular pigments, are key carotenoids integral to optimized central vision of the eye. Therefore, nutraceuticals and functional foods have been developed commercially using carotenoid rich flowers, such as marigold and calendula or single celled photosynthetic algae, such as the Dunaliella. Industrial formulation of such products enriched in macular pigments have often suffered from serious bottlenecks in stability, delivery, and bioavailability. The two chief factors largely responsible for decreasing the shelf-life have been solubility and oxidation of these pigments owing to their strong lipophilic nature and presence of conjugated double bonds. In this regard, oil-based formulations have often been found to be more suitable than powder-based formulations in terms of shelf life and targeted delivery. In some cases, addition of phenolic acids in the formulations have also augmented the product value by enhancing micellization. In this regard, a novel proprietary formulation of these pigments has been developed in our laboratory utilizing marigold extracts in a colloidal solution of extra virgin olive oil and canola oil fortified with antioxidants like thyme oil, tocopherol, and ascorbyl palmitate. This review article presents an updated insight into the stability and bioavailability of industrially manufactured macular carotenoids together with their safety and solubility issues.