Effects of Lutein and Astaxanthin Intake on the Improvement of Cognitive Functions among Healthy Adults: A Systematic Review of Randomized Controlled Trials

Abstract

Background: Fruits and vegetables are generally rich in antioxidants such as carotenoids. Consumption of carotenoids is expected to have benefits on cognitive functions in humans. However, previous randomized controlled trials (RCT) using carotenoids have reported inconsistent results. Therefore, this systematic review (SR) aimed to summarize the effect of carotenoid intake on cognitive functions in humans. Method: PubMed, Cochrane Library, Web of Science, and PsychoINFO were searched for research papers on carotenoid intake with the criteria that 1) oral carotenoid intake was evaluated using RCTs, 2) participants were healthy young, middle-aged, or older, and 3) cognitive functions were measured using RCTs. Results: Five studies using lutein and two studies using astaxanthin met the inclusion criteria. Consumption of lutein and its isomer showed consistent results in selective improvement of visual episodic memory in young and middle-aged adults while inhibition was observed in middle-aged and older adults. One of the two included astaxanthin studies reported a significant improvement of verbal episodic memory performance in middle-aged adults. Conclusion: This SR showed that the 10 mg lutein per day for twelve months can lead to improvement of cognitive functions. Due to the small number of studies, it is difficult to conclude whether astaxanthin would have a positive effect on cognitive functions.

Lutein Has a Positive Impact on Brain Health in Healthy Older Adults: A Systematic Review of Randomized Controlled Trials and Cohort Studies

“…The methodological quality ratings of the studies were conducted based on previous studies [ 18 , 33 ]. The quality assessment scores ranged from 7 to 10 (see the Supplementary Table S4 ), indicating that all studies had adequate methodological quality.…”

“…It is important to consider the potential biological mechanisms underlying the effects of lutein on the human brain. Based on the previous hypothesis [ 18 ], we inferred the mechanisms by which lutein and its isomers affect brain activity and structure. Lutein and its isomer have antioxidant and anti-inflammatory effects in vivo [ 34 ] and traverse the blood-brain barrier [ 35 ].…”

“…Meta-analyses and systematic reviews have revealed that regular lutein consumption reduces health problems such as cancer and eye disease (e.g., age-related macular degeneration) [ 13 , 14 , 15 , 16 , 17 ]. Moreover, a recent systematic review of randomized controlled trials (RCTs) indicated that lutein has a positive effect on cognition in young and older adults [ 18 ]. Notably, several neuroimaging studies have shown that lutein intake affects brain activity and brain structures [ 19 , 20 , 21 , 22 ].…”

Benefits of VR Physical Exercise on Cognition in Older Adults with and without Mild Cognitive Decline: A Systematic Review of Randomized Controlled Trials

“…The quality of each study was assessed using the modified Delphi list [ 34 ]. These quality assessment criteria were based on previous systematic review papers [ 35 , 36 ].…”

Astaxanthin: An algae-based natural compound with a potential role in human health-promoting effect: An updated comprehensive review

“…El-Agamy et al have shown the significant effect of ASX as a protective shield to doxorubicin which induces the impairment of cognitive functions [46]. A systematic review of RCTs demonstrated that in middle-aged adults, ASX significantly improved verbal episodic memory performance [47].…”