Carotenoid content in hen eggs according to rearing system: Analytical considerations and implications for dietary intake

Abstract

This manuscript examines how hen-rearing systems (categories 0, 1, 2, and 3) influence egg carotenoid content, with emphasis on lutein and zeaxanthin. The study combines an exploratory analysis of commercial eggs purchased in Madrid, Spain, with a literature review on the cognitive relevance of these carotenoids. Eggs from “free-range” (category 1) and “organic” (category 0) hens contain the highest total carotenoid levels (54.91 and 31.35 μg/g, respectively), as well as higher concentrations of lutein (21.31 and 14.53 μg/g) and zeaxanthin (11.95 and 10.68 μg/g), in the studied sample, attributed to hens having access to more diverse and natural diets. Eggs from barn-raised (category 2) and caged hens (category 3) show lower natural carotenoid levels (6.86 and 12.29 μg/g of lutein, and 6.39 and 7.47 μg/g of zeaxanthin, respectively), and their yolk color is often intensified through synthetic additives, which may lead consumers to associate deeper pigmentation with higher nutritional value. The literature indicates that lutein and zeaxanthin supplementation can support cognitive function, whereas findings on egg consumption remain inconsistent, likely due to variability in carotenoid content across production systems. Given their higher carotenoid concentrations, organic and free-range eggs may be more suitable for dietary strategies aimed at supporting cognitive health.