MONDAY, March 8 (HealthDay News) -- Fluorescent lighting in grocery stores might increase the nutritional value of fresh spinach, a new study suggests.

Many food stores display fresh spinach in clear plastic containers, kept at around 39 degrees Fahrenheit in coolers exposed to fluorescent light 24 hours a day. In the study, researchers exposed fresh spinach leaves to continuous fluorescent light or darkness for three to nine days.

After just three days, the spinach stored under the lights had significantly higher levels of vitamins C, K, E and folate, as well as higher levels of lutein and zeaxanthin, which are healthful plant pigments. After nine days of continuous exposure to the lights, levels of folate increased 84 to 100 percent, and levels of vitamin K increased 50 to 100 percent, depending on the spinach variety.

Spinach stored in continuous darkness had declining or unchanged levels of nutrients, the study found.

The finding could lead to improved methods of preserving and boosting the nutritional value of spinach and other fresh vegetables, the researchers stated in a news release from the American Chemical Society.

The study findings were published in the Journal of Agricultural and Food Chemistry.

More information

The U.S. Centers for Disease Control and Prevention explains the health benefits of vegetables and fruits.