A team of plant physiologists has developed a method of producing redder- and thus healthier, anti-oxidant-richer - lettuce using ultraviolet light-emitting diodes (LEDs).

To create red leaf lettuce plants enriched with these compounds, Britz purchased low-power LEDs that shine with UVB light, a component of natural sunlight.

Britz exposed the plants to levels of UVB light comparable to those that a beach goer would feel on a sunny day, approximately 10 milliwatts per square meter.

After 43 hours of exposure to UVB light, the growing lettuce plants were noticeably redder than other plants that only saw white light. Though the team has yet to quantify this effect, it appears to increase as the intensity of the light increases. The effect also seems to be particularly sensitive to the wavelength used - peaking at 282 and 296 nanometers, and absent for longer wavelength UV. "We've been pleasantly surprised to see how effective the LEDs are, and are now testing how much exposure is required, and whether the light should be pulsed or continuous," says Britz.

This research will be presented at the 2009 Conference on Lasers and Electro Optics/International Quantum Electronics Conference (CLEO/IQEC). Catch "Shedding light on nutrition," by Steven Britz, 10:30 a.m., Tuesday, June 2.