Nutrient Sensitivity and the Eye

The eye has developed a shifting sensitivity to dietary intake of various nutrients to not only support its function but also to preserve its health, according to a new review (Prog Retin Eye Res. ePub 4 Feb 2011. DOI: 10.1016/j.preteyeres.2011.01.001)

Eric Lien, from the Department of Food Science and Human Nutrition at the University of Illinois, with a colleague from the Vision Sciences Laboratory at the University of Georgia, Athens, noted studies have found a “fundamental paradox" about the eye. Namely, the organ itself is damaged by its operation, making it vulnerable because it responds to visible light and because its internal structures have special metabolic and structural needs.

For example, the high concentrations of diet-derived long-chain polyunsaturated fatty acids in the photoreceptor membranes are prone to peroxidation due to the high oxygen tension in the outer retina; however, the retina and lens are particularly rich in antioxidants including vitamins C and E and the macular carotenoids, which fight light-induced oxidative damage. Also, nutrients that support essential function and protection operate in an integrated manner, with Lien citing the ability of vitamin E to protect the DHA-rich membranes, to regenerate itself by reacting with vitamin C, and being distributed in complement with lutein and zeaxanthin. The macular lutein and zeaxanthin also work not only as antioxidant nutrients, but also directly impact visual performance.

Lien also noted age impacts the vulnerabilities and sensitivities of the eye. While infants have higher metabolic activity and clearer—thus more vulnerable—retinas, the eyes of the elderly are more vulnerable due to their increased levels of inflammatory stress and cascading oxidative effects. The team therefore concluded the eye, more than most other organs, “has evolved an exquisite and shifting sensitivity to dietary intake throughout the lifespan, not just for its basic operation (e.g., Vitamin A for transduction), but also for its very preservation."

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