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Carotenoids may help enhance cognitive function
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Speakers at the Brain and Ocular Nutrition Conference in Cambridge, England, presented a wealth of research supporting a link between carotenoid intake and improvement in cognition and reduced incidence of Alzheimer’s disease and dementia.
Carotenoid-cognitive function research
“As a result of the past 10 years of research, we now know that carotenoids are preferentially placed in the brain (frontal and occipital cortex), particularly lutein and zeaxanthin,” Elizabeth J. Johnson, PhD, from the Jean Mayer USDA Human Nutrition Center on Aging at Tufts University in Boston, said at the conference.
What does this mean for the brain’s functioning? The theory is that lutein improves cognition, and the research over the last 10 years shows that improving carotenoid consumption improves cognition. Johnson described 14 research papers proving the association of lutein with improved cognitive function over the past decade and marveled that there were another 14 papers in a PubMed search covering just the last 2 years, signifying a significant acceleration in research of carotenoids and improved brain function.
Kang and colleagues found that women who consumed more green leafy vegetables showed less cognitive declines as they aged. Johnson and colleagues (2008) found that women who were supplemented with a combination of lutein and docosahexaenoic acid (DHA) performed better on executive function, learning and short-term memory tests and better than those with the same nutrients alone. Nolan and colleagues found in The Irish Longitudinal Study on Aging study that education is positively associated with macular pigment optical density in an Irish population.
Further, Johnson and colleagues (2013) found in the Centenarian Study that while lutein, zeaxanthin, cryptoxanthin, beta-carotene and lycopene are all found in serum concentrations, lutein, zeaxanthin and cryptoxanthin were found in the brain tissues at much higher levels than beta-carotene and lycopene. So we now understand that the brain preferentially takes up lutein over beta-carotene, in fact, more than three times the amount found in the blood supply. Vishwanathan and colleagues found lutein in infant brains in amounts far in excess of other carotenoids in the brain (occipital cortex, auditory cortex, hippocampus and frontal cortex).
Nutrition intervention, cognition, Alzheimer’s
A study from Riona Mulcahy, MB, BAO, BCh, consultant physician at the University Hospital Waterford, Ireland, demonstrated the need to add DHA to carotenoid supplements to reduce Alzheimer’s disease (AD) progression. Considering the increased incidence of AD around the world and the fact that no new medication has been approved for the disease since 2003, nutritional intervention success may be a huge victory for aging people everywhere.
Mulcahy presented a summary of studies from Waterford featuring nutrition intervention to enhance cognitive function and prevent AD. She previewed her talk by prefacing the importance of finding a way to reduce the incidence and effects of AD due to the exponential numbers of people who will be affected by the disease.
She stated that by the year 2020, there will be more people in the world older than 65 years than younger than 5 years, and by 2050, more than 20% of the population will be older than 65 – with an estimated 131 million with AD. Of those older than 85 years, nearly half will be affected by AD. Current drug therapy for AD is focused on neurotransmitter activity cholinesterase inhibitors and memantine, NMDA [N-methyl-D-aspartate] receptor antagonists that reduce the amount of glutamate.
George Perry, PhD, dean of the College of Sciences at the University of Texas, San Antonio, and editor-in-chief of the Journal of Alzheimer’s Disease, gave a keynote lecture at the meeting. He commented on Mulcahy’s lecture: “It is really a dramatic effect you had [in this study]. There have been attempts with antioxidants like vitamin E that have had no results [of decreasing dementia or AD]. These are really the first promising results. Your data suggests that [carotenoids], together with fatty acids, could be a therapeutically valid point to intervene with.”
A new and promising area of research is now taking place in nutritional prevention with carotenoids. Lutein and zeaxanthin deposits not only in the eye, but in the pons, hippocampus, pre-frontal and frontal lobes (short-term memory and higher mental professing), cerebellum and temporal lobes. In the CREST Cognition Study, increasing carotenoids to normal patients showed a significant improvement of episodic memory (Power et al.).
A study comparing 30 participants with AD to 30 without AD over a 6-month placebo-controlled trial found that people with AD have significantly poorer vision, which can lead to mobility issues such as falling (Nolan et al., 2014). The bottom-line finding was a relative lack of macular pigment optical density (MPOD) and higher incidence of age-related macular degeneration with lower serum concentrations of carotenoids.
An early study of AD patients who were supplemented carotenoids were found to have better vision and increased MPOD, but no improvement in cognition (Nolan et al., 2015).
Mapstone and colleagues worked on using serum phospholipids to diagnose AD in a blood test. Albert Koulman, PhD, Cambridge University, found that serum samples of people with AD who had carotenoids also had low phospholipids (EPA and DHA). His work led to the theory that phospholipids need to be supplemented in addition to carotenoids.
In a study led by the Nutrition Research Centre Ireland in collaboration with University Hospital Waterford (Nolan et al., 2018), subjects with AD were divided into two groups; the first was given only carotenoids (10 mg lutein, 10 mg mesozeaxanthin, 2 mg zeaxanthin) and the second was given both phospholipids consisting of 450 mg DHA and the carotenoid formulation. A third (control) group of patients without AD were given the carotenoid-only formulation. After 18 months of supplementation, those who were given the carotenoid formulation and 450 mg of DHA had a significant increase in serum concentration of carotenoids. Most importantly, this same group supplemented with both fish oils and carotenoids also had improved cognitive function based on cognitive tests performed independently. The group of AD patients given only carotenoids continued progression of AD.
A new, larger-scale, double-masked, placebo-controlled study is in progress. The Memory Intervention with Nutrition for Dementia is evaluating 120 patients diagnosed with mild to moderate AD. Findings will be reported in 2020.
Centenarian study
Tufts University USDA Human Nutrition Research Center on Aging PhD student, Jirayu Tanprasertsuk, MS, presented the results of the Georgia Centenarian Study, which evaluated donated brain tissue samples. Of the 47 individuals, mostly female and average age of 102 years old, approximately half had dementia. Brain nutrient pattern analysis measured for vitamin E and K, monosaturated fatty acids (MUFAs), omega-3 and omega-6 polyunsaturated fatty acids (PUFAs), trans fatty acids (trans-FAs), saturated fatty acids (SFAs) and carotenoids (lutein, zeaxanthin, cryptoxanthin, beta-carotene and lycopene) and their correlations. In addition, they studied serum concentrations of tocopherols, total omega-3 PUFAs and n-6/n-3 PUFAs and found the ratio reflected brain concentrations. Older adults with no dementia were high in omega-3 fatty acids (PUFAs), saturated fatty acids and carotenoids (lutein, zeaxanthin trending). The same non-demented individuals were also low in vitamin A, MUFAs and trans-FAs.
- References:
- Brain and Ocular Nutrition Conference abstracts. J Alzheimers Dis. 2018;64(3).
- Johnson EJ, et al. Nutr Neurosci. 2008;doi:10.1179/147683008X301450.
- Johnson EJ, et al. J Aging Res. 2013;doi:10.1155/2013/951786.
- Kang JH, et al. Ann Neurol. 2015;doi:10.1002/ana.20476.
- Mapstone M, et al. Nat Med. 2014;doi:10.1038/nm.3466.
- Nolan JM, et al. Invest Ophthalmol Vis Sci. 2012;doi:10.1167/iovs.11-9367.
- Nolan JM, et al. J Alzheimers Dis. 2014;doi:10.3233/JAD-140507.
- Nolan JM, et al. J Alzheimers Dis. 2015; doi:10.3233/JAD-142265.
- Nolan JM, et al. J Alzheimers Dis. 2018;doi:10.3233/JAD-180160.
- Power R, et al. J Alzheimers Dis. 2018;doi:10.3233/JAD-170713.
- Tanprasertsuk J, et al. J Gerontol A Biol Sci Med Sci. 2018;doi:10.1093/gerona/gly125.
- Vishwanathan R, et al. J Pediatr Gastroenterol Nutr. 2014;doi:10.1097/MPG.0000000000000389.
- For more information:
- David W. Nelson, OD, MBA, is in a private group practice in Madison, Wis. He can be reached at amoptbddwn@aol.com.
Disclosure: Nelson reports he is a consultant for MacuHealth.