Writing in Nutrients, Japanese scientists from Tohoku University and the Lion Corporation report that 10 mg per day of lutein for twelve months is consistently associated with improvements in visual episodic memory, verbal episodic memory, inhibition, and attention.
For astaxanthin, the scientists presented data to support a potential benefit for memory performance, but could not reach a firm conclusion because of a small number of studies.
“It is clear that the positive effects of these carotenoids on cognitive functions were determined on the basis of supplementation rather than normal daily consumptions,” wrote the authors. “These results indicate that it is not easy to take enough lutein and astaxanthin to affect cognitive functions from daily consumption. The supplementation of lutein or astaxanthin led to improvements of cognitive functions in the RCT.”
Lutein and brain health
The link between lutein and eye health was first reported in 1994 by Dr Johanna Seddon and her co-workers at Harvard University, who found a link between the intake of carotenoid-rich food, particularly dark green leafy vegetables like spinach, and a significant reduction in age-related macular degeneration (AMD) (JAMA, Vol. 272, pp. 1413-1420).
Numerous studies with data from primates, children, middle-aged people, and the elderly now support the importance of lutein in brain health, which is unsurprising given that the eyes and the brain are connected.
Indeed, recent findings from pediatric brain tissue studies have shown that about 60% of the total carotenoids in the pediatric brain tissue is lutein, and yet NHANES data show that lutein is only about 12% of the carotenoids in the diets, so there is a preference for lutein in the brain (Vishwanathan et al. J Pediatr Gastroenterol Nutr. 2014).
A 2017 study by scientists from Queens University Belfast and the Macular Pigment Research Group at the Waterford Institute of Technology found that higher blood levels of lutein and zeaxanthin may be associated with better cognition, memory, and executive function (Journal of Gerontology, Series A).
The new review from Japan included five lutein studies and two astaxanthin studies.
Overall, lutein was associated with improvements in visual episodic memory, verbal episodic memory, inhibition, and attention, compared to placebo, but no benefits were reported for working memory, reasoning, shifting, and processing speed, said the scientists.
“These results suggest that consumption of lutein would have a positive effect on cognitive functions in healthy adults,” they stated.
“Lutein and its isomers can cross the blood-brain barrier (BBB). Therefore, their anti-oxidant and anti-inflammatory functions would directly act in the human brain. Notably, lutein is selectively distributed in the frontal cortex, visual cortex, and hippocampus. The concentration level of lutein and its isomers in the prefrontal cortex was higher than that in other regions,” they added.
“The medial temporal lobe, which included the hippocampus and parahippocampus, has an important role for memory functions. These results suggest that lutein and its isomer would affect the memory and inhibition related brain regions.”
2020, 12(3). E617. doi: 10.3390/nu12030617
“Effects of Lutein and Astaxanthin Intake on the Improvement of Cognitive Functions among Healthy Adults: A Systematic Review of Randomized Controlled Trials”
Authors: R. Nouchi et al.