According to Science Daily, exposure to space rays can make veggies grown during spaceflight healthier for their consumers. There is a fear in the future that long spaceflights could cause damage to astronauts' eyesight since harmful radiation can damage eyes.  That said, the carotenoid, zeaxanthin, is known to promote better eye health and protect eyesight.  Zeaxanthin can be found primarily in green leafy vegetables, and can also be made into a supplement.

NASA has spent a long time studying the possibilities of growing a garden for long distance space travel, as the healthy foods would both build morale and keep astronauts fighting fit. These tests have been primarily to make giant veggies in limited space with limited equipment in order to get the most bang for the astronauts' buck. But a study from the University of Colorado at Boulder has found that a smaller plant might pack more nutrients, and that exposing it to space rays may get the plant to produce more of the zeaxanthin that's good for astronauts' eyesight. 

The rays stress the plants out, making them want to produce more of the zeaxanthin that protects them from light rays. The zeaxanthin acts as a defensive nutrient, one that the human body can't produce on its own. The team had set out to see if they could get the best of both worlds, and produce a large plant that had the maximum nutrients required. 

The team found short bursts might be the best. Barbara Demmig-Adams, professor in the Department of Ecology and Evolutionary Biology, says that the key might be in duping the plants into thinking that they'll be dosed in light. "When they get poked a little bit with light that's really not a problem, they get the biomechanical machine ready, and I imagine them saying, 'Tomorrow there may be a huge blast and we don't want to be unprepared,' " she said.

The atmosphere of the Earth filters out a great deal of the solar radiation that would normally hurt our eyes, but in space, the astronauts are without such defensive measures. The zeaxanthin would help greatly in keeping their eyes from being damaged by space rays and background radiation.