ASK PIRATES second baseman Neil Walker (hitting) for the most important qualities of his game, and he won't talk about catching or hitting. "You can't do those things without good vision," he says.
Ocular workouts and vision drills on computers have become ubiquitous around MLB, and now players are also eating their way to improved sight. In a 2014 study published in The Archives of Biochemistry and Biophysics, researchers from the University of Georgia found evidence linking visual processing speed and reaction time with the daily intake of zeaxanthin, a nutrient found in many deeply pigmented vegetables and paprika. A year later all 30 major league teams have started experimenting with the nutrient.
Walker tried zeaxanthin in spring 2014 after experiencing dry eyes and struggling with glare. "After taking it every day, I felt like my contrast was better, and I wasn't squinting as much," says Walker, 29. "It was like internal sunglasses, especially during day games."
Zeaxanthin works in the macula, the small, cone-packed area of the retina that provides high-acuity vision, says optometrist Graham Erickson. Naturally occurring phytonutrients (the pigments that give food its colors) are distributed throughout the body when digested, but zeaxanthin concentrates in the macula. "Because the eye can process light faster," says Erickson, "there can be improvements to reaction time and coincidence anticipation, like timing the arrival of the ball from a pitch."
As more players start to use zeaxanthin, nutritionists learn more about optimizing dosages and timing, but for now, Walker is happy with the results. "I get that [the improvement] is something that's hard to measure," he says. "But when you're trying to track baseballs at the plate or in the field for a living, that's kind of your own little test."
Most teams use zeaxanthin in supplement form—Rays assistant athletic trainer Paul Harker keeps it next to the multivitamins and fish oil—which is available at health and nutrition stores. The nutrient is also found naturally in several foods that can be incorporated into anyone's diet for similar effects.
Swap iceberg and romaine for dark leafy greens like kale, spinach, collard greens and dandelion greens.
Zeaxanthin is derived from the chili pepper that produces paprika, but red bell or spicy cayenne peppers are also good sources, as are goji berries.
Egg yolks have a high concentration of zeaxanthin and lutein, another naturally occurring nutrient that improves vision.
For more athlete training profiles and tips, go to SI.com/edge
CHARLES LECLAIRE/USA TODAY SPORTS (WALKER)
Batters need to pick up the spin of the seams on a ball going 90 mph.
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