The same natural compounds that give plants and vegetables their vibrant colour could enhance brain function in older adults, finds a study from the University of Georgia. Study participants with lower level of certain carotenoid had to rely on more brain power to complete memory-oriented tasks.
What foods have carotenoids?
Carotenoids are a family of yellow, orange and red pigments produced by plants. They include beta-carotene (e.g., carrots, sweet potato, dark leafy greens), lycopene (e.g., tomato juice, tomato sauce, pink grapefruit), lutein and zeaxanthin (e.g., spinach, kale, collards) and alpha-carotene (e.g., pumpkin, carrots, winter squash, leafy greens).
Higher levels of lutein + zeaxanthin enhanced brainpower
For the study, researchers used functional MRIs (fMRI) to gauge the brain activity of more than 40 older adults (aged 65 to 86 years) while they attempted to recall word pairings they were taught earlier.
They then analyzed the brain activity while the participants were in the fMRI machine, and found that people with higher levels of lutein and zeaxanthin in their bloodstream and eyes didn't require as much brain activity to complete the task. (Lutein and zeaxanthin are concentrated in the retina where they protect against free radical damage.)
Participants with lower levels of lutein and zeaxanthin had to use more brain power and relied more heavily on different parts of the brain in order to remember the word pairings they were taught. People with higher levels, on the other hand, were able to minimize the amount of brain activity necessary to complete the task.
When it came to what was actually going on in the brain, there were significant differences related to participants’ carotenoid levels.
The participants weren't randomly selected and the total sample size is small, but the amount of variation in brain functioning within the group was significant.
The next step is to study whether changing one's diet to include more vegetables containing the carotenoids or by adding nutritional supplements could boost individuals' neurocognitive performance.
Best food sources of lutein + zeaxanthin
While there is no official recommmened intake for lutein + zeaxanthin, experts suggest a daily intake of six to 15 milligrams is beneficial. Per one-half cup cooked, you'll find 12 mg of lutein in kale, 10 mg in spinach, 10 mg in Swiss chard, 7.5 mg in turnip greens, 7 mg in mustard greens, 7 mg in collard greens and 5 mg in dandelion greens.
You’ll get more lutein if you eat your greens cooked rather than raw. That’s because cooking breaks down cell walls, increasing the amount of the phytochemical that's available to your body for absorption.
Source: Journal of the International Neuropsychological Society, October 25, 2016.
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