The zeaxanthin serum test measures the level of zeaxanthin, a dietary xanthophyll carotenoid, in the blood. Zeaxanthin is a fat-soluble antioxidant found mainly in brightly colored fruits and vegetables, such as corn, orange peppers, and goji berries, and is a structural isomer of lutein. In the human body, it is selectively stored in eye tissues, especially the macula of the retina, where it helps protect photoreceptor cells from light-induced oxidative stress and supports clear vision. Measuring serum zeaxanthin provides valuable insight into carotenoid levels and the effectiveness of diet or supplements in promoting retinal health and systemic antioxidant defenses.
Zeaxanthin is one of the two main macular carotenoids—along with lutein—that help form macular pigment. This pigment acts as an optical filter, absorbing harmful blue light and preventing it from reaching the deeper layers of the retina. In this role, zeaxanthin helps prevent age-related macular degeneration (AMD), a leading cause of vision loss in older adults. Besides its light-protective role, zeaxanthin also has potent antioxidant activity by quenching singlet oxygen and scavenging free radicals produced through photooxidative and metabolic processes. Its presence in the blood indicates the availability of zeaxanthin to the eye and other tissues, reflecting recent dietary intake and systemic distribution.
The serum concentration of zeaxanthin is affected by various factors, including dietary intake, bioavailability, lipid status, and overall metabolic health. Elevated serum levels are usually seen after regular consumption of zeaxanthin-rich foods or carotenoid supplements. These higher levels are often viewed as beneficial, especially for those aiming to maintain macular health or lower the risk of degenerative eye diseases. On the other hand, low serum zeaxanthin levels may indicate insufficient intake of carotenoid-rich fruits and vegetables, poor lipid absorption, or increased use due to systemic oxidative stress. People with gastrointestinal disorders, such as celiac disease, Crohn’s disease, or chronic pancreatitis, may have lower serum levels due to decreased absorption of fat-soluble nutrients. In individuals with chronic inflammation, smoking, or high oxidative stress, serum zeaxanthin levels can also be reduced as antioxidant stores are depleted more quickly.
Measuring serum zeaxanthin is a valuable biomarker for evaluating antioxidant and nutritional status, particularly in relation to visual health, macular pigment density, and systemic resilience against oxidative damage. Since zeaxanthin cannot be produced endogenously, its serum level offers a direct and dynamic measure of dietary sufficiency and carotenoid-based protective ability.
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Last updated: 29/06/2025
