Of the 600 carotenoids responsible for the rainbow of colors seen in fruits and vegetables, only two--lutein and zeaxanthin--accumulate in the retina of the human eye, giving rise to the “macula lutea” or “yellow spot.” These macular pigments, or color filters, serve as internal sunglasses. Athletes who consume more of these two important xanthophylls may experience:
- Reduced visual discomfort. Picture an outfielder in baseball catching a fly ball on a partly cloudy day. Staring into bright, unclouded sections of sky is hard on the eyes. Small increases in macular pigments from lutein and zeaxanthin supplementation reduce visual discomfort (Stringham et al. 2010).
- Improved photostress recovery. If you’ve ever felt blinded by a bright light, you’ve experienced photostress. Intense glare bleaches photopigments in the eyes, extending the time required to recover visual function. Photostress recovery improves with increased macular pigmentation and lutein and zeaxanthin supplementation (Stringham & Hammond 2008).
- Increased visibility. Peak light absorbance of macular pigments happens at the same wavelength as sky light. Macular pigments reduce “blue haze,” thus improving how far and how well we can view outdoor objects that are obscured by airborne particulates (Stringham et al. 2010).
- Enhanced contrast. Yellow filters help us define object edges through color differences. For example, when a baseball is viewed in the sky, the eye distinguishes the white ball from the blue sky through color differences. This contrast effect is enhanced with yellow filters, so macular pigments may improve visual contrast (Lien & Hammond 2011).
Spinach and kale contain lots of lutein but zero zeaxanthin. Good sources of both include egg yolks and corn tortillas. Orange peppers are a rich source of zeaxanthin. (Perry et al 2009). Adding a spinach salad with egg yolks and a few orange pepper slices to your daily diet might help you keep your eye on the ball!
Lien, E.L, & Hammond, B.R. 2011. Nutritional influences on visual development and function. Progress in Retinal and Eye Research, 30, (3), 188-203.
Perry, A., Rasmussen, H., & Johnson, E.A. 2009. Xanthophyll (lutein and zeaxanthin) content in fruits, vegetables and corn and egg products. Journal of Food Composition and Analysis, 22,(1), 9-15.
Stringham, J.M., & Hammond, B.R. 2008. Macular pigment and visual performance under glare conditions. Optometry and Vision Science, 85 (2), 82-88.
Stringham, J.M., et al. 2010. The influence of dietary lutein and zeaxanthin on visual performance. Journal of Food Science, 75 (1), R24-29.