A study links a plant compound to intelligence in older adults. The study, reported in the Frontiers in Aging Neuroscience, suggests that consumption of a pigment found in leafy greens may help preserve “crystallized intelligence”. This is the ability to use skills and knowledge one has acquired over a lifetime.
Lutein is a naturally occurring carotenoid, and one of several plant pigments that humans acquire through the diet. Foods rich in lutein include broccoli, spinach, kale, kiwi fruit, and avocado. The compound accumulates in the brain, embedding in cell membranes, where it plays “a neuroprotective role”.
The study involved 122 participants aged between 65 and 75, who solved problems and answered questions on a standard test of crystallized intelligence. The researchers also collected blood samples to determine serum levels of lutein. They also imaged participant’s brain via MRI to measure the volume of different brain structures.
While serum lutein levels reflect only recent dietary intake of this compound, they are associated with brain concentrations of it in older adults, which reflect long-term dietary intake.
The researchers focused on the temporal cortex brain region of the brain that is linked to crystallized intelligence. They found that participants with higher blood serum levels of lutein tended to do better on tests of crystallized intelligence.
During the study it was found that participants with lower levels of the carotenoids lutein and zeaxanthin had to use more brain power to remember word pairings they were taught. They also relied more heavily on different parts of the brain.
People with higher levels, on the other hand, were able to minimize the amount of brain activity necessary to complete the task. In other words, they were more “neurally efficient.”
This means that brains of people with higher levels of lutein (and zeaxanthin) worked more efficiently than compared to brains of people with lower levels.
Interestingly, those with higher serum lutein levels also tended to have thicker gray in the parahippocampal cortex. Like crystallized intelligence, this brain region is preserved in healthy aging.
Carotenoids, particularly lutein and zeaxanthin, have been shown in previous research to boost cognitive health as well as eye health.