Data from 80 middle-aged overweight and obese adults indicated that the faster reaction times in the cognitive tests were associated with greater intake of lutein/zeaxanthin and choline “interactively, but not independently”.
“While both lutein and choline have been independently related to benefits for cognitive control, we did not observe the benefits of individualized consumption in the present study,” wrote researchers from the University of Illinois at Urbana-Champaign in Nutritional Neuroscience.
“Further, faster processing speed, as evidenced by faster RT, was only observed with the interaction of the two components (i.e. lutein and choline).”
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 Institute of Medicine (IOM) recognized choline - found naturally in beef and chicken liver, egg yolk, salmon, milk, and soybeans among other things - as an essential nutrient in 1998.
The adequate intake for choline is set at 550 mg per day for adult men and 425 mg/day for adult women (rising to 450 mg for pregnant women and 550 mg for breastfeeding women).
According to National Health and Nutrition Examination Survey (NHANES) data, while American infants are doing OK (choline is in breast milk and is added to infant formula), 90% of children, adults and pregnant women are not getting enough.
The University of Illinois scientists note that, while the potential brain health benefits of lutein/zeaxanthin and choline have been reported separately, only one study has examine if they have a combined, interactive effect on cognition (a study with six month-old children).
Data from the 80 middle-aged adults indicated that higher intake of lutein/zeaxanthin and choline was associated interactively with faster reaction time, but these results were not observed when the researchers considered the bioactives independently.
When they looked at the metabolites in the body, the researchers found that levels of phosphatidylcholine in the plasma was associated with higher accuracy on Switch trial types. On the other hand, no links were observed between serum lutein concentrations, MPOD, plasma free choline concentrations, nor plasma phosphatidylcholine levels for cognitive flexibility.
Commenting on the potential mechanism(s) of action, the researchers noted that choline can serve as a precursor for the neurotransmitter acetylcholine (ACh), while lutein, which acts as an antioxidant, may decrease activity of acetylcholinesterase, an enzyme that degrade Ach.
The researchers noted that the potential benefits derived from combined consumption of lutein and choline may be due to increases in ACh production in the brain, which could occur via choline consumption and lutein’s ability to attenuate acetylcholinesterase activity.
“Increased consumption of both of these dietary components may be beneficial for cognitive processing among individuals with overweight and obesity, who may be at a higher risk for cognitive decline in later life,” wrote the researchers.
“Future studies should therefore investigate the potential interactive properties of dietary components such as lutein and choline to inform dietary recommendations for cognitive and brain health,” they concluded.
Source: Nutritional Neuroscience
Published online ahead of print, doi: 10.1080/1028415X.2020.1866867
“Dietary lutein plus zeaxanthin and choline intake is interactively associated with cognitive flexibility in middle-adulthood in adults with overweight and obesity”
Authors: C.G. Edwards, et al.