This powerful carotenoid may help protect your brain function
It has long been known that lutein is one of the most prevalent carotenoids in the human eyes. And, extensive research has proven its benefits for the eye health, which range from acting as a sunscreen that filters blue and UV light to protect your eye cells from LED light and mobile screens' damage to preventing age-related macular degeneration, the leading cause of blindness and vision impairment.
As in the retina, lutein is the dominant carotenoid throughout human brain tissue  and together with zeaxanthin and meso-zeaxanthin (synthesized from lutein), they make up three-fourths of its carotenoids, specifically the areas responsible for cognitive function, data-processing and recall.
Lutein and brain health
It was only recently that scientists started to look into the effects of lutein on the brain health, especially after a study found an association between age-related eye disease and cognitive impairment.
In a four-month double-blind study, older women who were supplemented with lutein (12 mg/d), DHA (800 mg/d), or a combination had improved verbal fluency scores compared to a placebo group. Memory scores and rate of learning improved significantly in the combination treatment group, which also trended toward more efficient learning. The study in details:
Subjects and methods: The cognitive benefit of DHA and lutein in unimpaired elder women was explored in the context of a 4-month, double-blind, intervention trial of DHA and lutein supplementation for eye health. Forty-nine women (aged 60-80 years) were randomized to receive DHA (800 mg/day; n = 14), lutein (12 mg/day; n = 11), a combination of DHA and lutein (n = 14) or placebo (n = 10). Subjects underwent cognitive tests measuring verbal fluency, memory, processing speed and accuracy, and self-reports of mood at randomization and upon completion of the trial.
Results: Following supplementation, verbal fluency scores improved significantly in the DHA, lutein, and combined treatment groups (P < 0.03). Memory scores and rate of learning improved significantly in the combined treatment group (P < 0.03), who also displayed a trend toward more efficient learning (P = 0.07). Measures of mental processing speed, accuracy and mood were not affected by supplementation.
Conclusions: These exploratory findings suggest that DHA and lutein supplementation may have cognitive benefit for older adults.
Lutein and Alzheimer's Disease
Lutein is a very strong antioxidant that helps prevent the oxidation of lipids such as DHA, the oxidation of which has been observed in the brains of Alzheimer's disease and cognitively impaired patients. According to this study,
"Inhibition of DHA oxidation not only helps to maintain membrane structure and fluidity but also preserves DHA so it remains available for cleavage and conversion into anti-inflammatory molecules. Although the mechanisms by which lutein and DHA may function together is unclear, elevated DHA oxidation has been observed in the brains of Alzheimer’s disease and cognitively impaired patients; therefore, this potential lipid-protective action by lutein may, in part, explain the relationship between lutein and cognition."