Older adults who eat a pigment commonly found in leafy greens better retain their skills and knowledge, a new study finds.

The substance in question — lutein — appears to play a “neuroprotective role,” said Marta Zamroziewicz, a University of Illinois graduate student. Zamroziewicz led the study with Illinois psychology professor Aron Barbey, Ph.D.

For the study, 122 healthy participants aged 65 to 75 solved problems and answered questions on a standard test that measures crystallized intelligence. Researchers also collected blood samples to determine blood serum levels of lutein and imaged participants’ brains via magnetic resonance imaging to measure the volume of different brain structures.

The researchers found that participants with higher blood serum levels of lutein tended to test better.

“Lutein accumulates in the gray matter of brain regions known to underlie the preservation of cognitive function in healthy brain aging,” Zamroziewicz said.

Full findings appear in the journal Frontiers in Aging Neuroscience.