Many people, however, experience a decline in cognitive function with time. In the US, 24% of men and 30% of the women who are 85 or older have moderate to severe memory impairment, and the population in this age group is expected to grow from 6 million in 2014 to 20 million by 2060.1
Recent studies have demonstrated that natural astaxanthin can support cognitive health in later life, enabling individuals to stay sharp and do the things they value for as long as possible.
How oxidative stress affects the brain
There is growing recognition that reactive oxygen species (ROS) and free radicals play a role in many neurological diseases.2
These unstable molecules can damage cells and tissues by oxidation. Each cell in the human body can form 20 trillion ROS per day through normal metabolism and be attacked by these reactive molecules 10,000 times per day.3The brain is particularly vulnerable to oxidative damage because of several physiological, anatomical and functional factors, such as higher oxygen availability, modest antioxidant defences, limited regenerative capacity and multiple neurological cell types.2
In a healthy human body, the antioxidant defence system keeps the generation of ROS and free radicals under control. However, these defences grow weaker as people age, making them more susceptible to health conditions associated with oxidative stress. Therefore, supplementation with dietary antioxidants can help support the body’s defences and mitigate the harmful effects of ROS.
What is astaxanthin?
Astaxanthin is a natural antioxidant that is attracting great interest in the cognitive health category. Sourced from the microalgae Haematococcus pluvialis, astaxanthin is one of the most powerful natural antioxidants known. It has numerous health benefits that are supported by extensive scientific research, including more than 50 human studies and 1400 peer-reviewed papers.4
A comparative study has shown that natural astaxanthin is 6000 times more powerful than vitamin C, 100 times more powerful than vitamin E, and five times more powerful than ß-carotene in trapping energy from singlet oxygen, one of the most common ROS in the body.5 In addition, astaxanthin can neutralise harmful ROS without generating pro-oxidants, which is a common side-effect of other antioxidants.6
Furthermore, research on mice has shown that astaxanthin can cross the blood-retinal and blood-brain barriers with no adverse effects, enabling this antioxidant to prevent, delay and/or ameliorate damage to the central nervous system caused by free radicals.7
Astaxanthin supports brain health
There is a growing body of peer-reviewed research focusing on the general health benefits of astaxanthin supplementation, including the effects on cognitive function and brain health. Below is a summary of key findings from recent human studies.
Nakagawa et al. conducted a randomised, double-blind, placebo-controlled human trial to test for the effects of astaxanthin supplementation on phospholipid hydroperoxide (PLOOH).8 PLOOH accumulates abnormally in the erythrocytes of dementia patients, and astaxanthin is hypothesised to prevent the accumulation.
After 12 weeks of treatment with 6 µg/d or 12 µg/d of astaxanthin, erythrocyte and plasma PLOOH concentrations were lower in the astaxanthin groups than in the placebo group. The authors concluded that astaxanthin supplementation resulted in improved erythrocyte antioxidant status and decreased PLOOH levels, which may contribute to the prevention of dementia.
In another randomised, double-blind, placebo-controlled human trial, Katagiri et al. studied the effects of astaxanthin supplementation on cognitive function.9
Ninety six, healthy, middle-aged and elderly subjects with some level of age-related forgetfulness were included in the study and received either astaxanthin (6 or 12 µg/d) or a placebo during the course of 12 weeks. Changes in cognitive performance were assessed using two standardised memory tests.
The CogHealth test is a computer-based test of memory and thinking capacity, and the Groton Maze Learning Test (GMLT) measures executive function using a maze learning paradigm. CogHealth scores improved in the 12 µg/d group compared with other treatments, and GMLT scores improved earlier in the 6 µg/d and 12 µg/d group than the placebo group. Together, these results indicate that astaxanthin supplementation improves cognitive function in healthy, aged individuals.
Satoh et al. conducted an open-label trial with 10 male subjects aged 50–69 that presented symptoms of mild cognitive impairment.10
The study lasted for 12 weeks and tested an astaxanthin dose size of 12 µg/d. Cognitive health parameters (CogHealth and P300) were assessed before administration, after 6 weeks and finally after 12 weeks.
The CogHealth test battery comprises seven tasks that assess a range of cognitive functions such as signal detection, working memory, simple learning and associative learning.
The P300 refers to the event-related potential component elicited in the process of decision making, which is a parameter used as a measure of the efficacy of various treatments on cognitive function. The authors concluded that administration of astaxanthin might improve higher brain function, including cognition, attention, memory, information processing and resultant behaviour in older persons.
Zanotta et al. performed an exploratory study to assess the effects of a particular dietary supplement on subjects with mild cognitive impairment (MCI).11
The supplement in question contained 2 µg of astaxanthin, extracts of Bacopa monnieri, phosphatidylserine and vitamin E. One hundred and two men and women aged 71.2 ± 9.9 years were enrolled in the study that lasted 60 days. Subjects had been diagnosed with MCI based on results of a mini-mental state examination (MMSE), where the mean score was 26.0 ± 2.0 and all scores were between 22 and 28 (total scale goes from 0 to 30).
They underwent the Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) test and the clock-drawing test at the baseline and upon completion of the trial.
The results showed that total ADAS-cog scores improved from 13.7 ± 5.8 at the baseline to 9.7 ± 4.9 on day 60, and the clock-drawing test scores improved from 8.5 ± 2.3 to 9.1 ± 1.9. The authors therefore concluded that dietary supplementation with the tested compound showed the potential to counteract cognitive impairment in subjects with mild cognitive impairment.
In addition to these human clinical trials, several other studies have shown evidence for the beneficial effects of astaxanthin supplementation.12
For example, Chang et al. hypothesised that astaxanthin could be used as a neuron protectant and in early stage Alzheimer’s disease therapy, and Lobos et al. found that astaxanthin protects neurons from noxious effects of amyloid- peptide oligomers on mitochondrial ROS production.13,14
Conclusion
Together, these and other recent scientific findings demonstrate that natural astaxanthin, as an extremely potent scavenger of ROS, can help to support cognitive function in later life.
Moreover, the interest in astaxanthin as an ingredient in the healthy category is growing and will continue to grow as the relative ratio of older consumers increases. This development creates an opportunity for manufacturers to develop dietary supplements that can help people live longer and more active lives.
References
1. https://agingstats.gov/docs/LatestReport/Older-Americans-2016-Key-Indicators-of-WellBeing.pdf.
2. M. Patel, Trends in Pharmacological Sciences 37, 768–778 (2016).
3. K.K Niyogi, et al., Proc. Natl Acad. Sci. USA 94, 14162–14167 (1997).
4. www.ncbi.nlm.nih.gov/pubmed.
5. Y.M. Nishida, Carotenoid Science 11, 16–20 (2007).
6. S. Beutner, et al., Journal of the Science of Food and Agriculture 81(6), 559–568 (2001).
7. www.google.com/patents/US5527533.
8. K. Nakagawa, et al., British Journal of Nutrition 105, 1563–1571 (2011).
9. M. Katagiri, et al., J. Clin. Biochem. Nutr. 51, 102–107 (2012).
10. A. Satoh, et al., J. Clin. Biochem. Nutr. 44, 280–284 (2009).
11. D. Zanotta, et al., Neuropsychiatric Disease and Treatment 10, 225–230 (2014).
12. B. Grimmig, et al., GeroScience 39, 19–32 (2017).
13. C. Chang, et al., Journal of Medicinal Food 13, 548–556 (2010).
14. P. Lobos, et al., Neural Plasticity, epub http://dx.doi.org/10.1155/2016/3456783 (2016).
