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.
Much of the research has been led by Elizabeth Johnson, PhD, Scientist I in the Antioxidants Laboratory in the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Prof John Nolan and Prof Stephen Beatty from the Macular Pigment Research Group at the Waterford Institute of Technology in Ireland, and Billy Hammond, PhD, Professor in the Behavioral and Brain Sciences Program, Department of Psychology at the University of Georgia.
(For a 2012 review on the subject by Dr Johnson in the American Journal of Clinical Nutrition, please click HERE)
Dr Johnson told us recently that data 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, she noted (Vishwanathan et al. J Pediatr Gastroenterol Nutr. 2014).
The macula is a yellow spot of about five millimeters diameter on the retina. As we age, levels of the pigments in the macula decrease naturally, thereby increasing the risk of AMD. The yellow color is due to the content of the carotenoids lutein and zeaxanthin.
“There’s no link between beta-carotene or lycopene and cognitive measures,” she added. “It was only lutein.”
The mechanism of action for lutein is probably more than its action as an antioxidant, she said, since there is a lot more alpha-tocopherol (vitamin E) in the brain than lutein, but no link between alpha-tocopherol and cognitive function.
No surprise
“The eye and the brain are connected, so it’s no surprise lutein is important for brain health,” said Dick Roberts, PhD, principal manager of scientific affairs & technical services for Kemin’s Human Nutrition and Health Division.
“The current research shows that eye health and brain health are coming together as one,” he added.
Heather Richardson, global product manager for Kemin’s Human Nutrition and Health Division, said that cognitive health is definitely a priority for the strategic alliance of Kemin and DSM. She noted that infant nutrition is a key area of focus, with data showing that lutein is naturally deposited in the breast milk and passed on to the infant.
Biomarkers
In line with Dr Roberts’ statement about eye and brain health coming together, there is scientific evidence to indicate that the macular may act as a biomarker of lutein in the brain. A recently published paper by Billy Hammond’s group (Neurobiology of Aging, 2014, Vol. 35, pp. 1695-9) reported that macular pigment optical density (MPOD), which is representative of lutein and zeaxanthin status, was related to general cognition in people with mild cognitive impairment (MCI), while MPOD was only related to visual-spatial and constructional abilities in healthy older adults.
“The present data are the first to relate function in cognitively impaired individuals with an in vivo measure of lutein and zeaxanthin in central nervous system tissue and, to our knowledge, the first to relate function in MCI persons to lutein and zeaxanthin status,” they wrote.
The group of John Nolan and Stephen Beatty published results of an exploratory study in people with Alzheimer’s disease this month (Journal of Alzheimer’s Disease, 2014, doi: 10.3233/JAD-140507), which suggested that “brain carotenoid concentrations are positively related to macula pigment.
“There is a sound and biologically plausible rationale whereby lutein, zeaxanthin and meso-zeaxanthin may be important in the prevention and/or delay in the onset of Alzheimer’s disease,” wrote Nolan et al.
“Our main finding that Alzheimer’s disease patients have significantly less macula pigment and poorer vision when compared to controls merits further investigation, and a clinical trial designed to investigate the impact of macular carotenoid supplementation with respect to macula pigment, visual function and cognitive function among Alzheimer’s disease sufferers is merited.”
Dr Johnson explained that for lutein in the macula to be associated with cognitive function it would have to go from the diet to the circulation to the brain, and past the blood brain barrier. “It makes sense that lutein is linked to passing the blood brain barrier because it’s the same for the eye.”