Research updates on vitamin D, spearmint, omega-3, lutein, and zeaxanthin
The advancing worldwide prevalence of cognitive decline and dementia is a global health concern. World Health Organization (WHO) estimates from 2013 suggested that more than 35 million individuals worldwide were living with dementia; the WHO noted it expected that number to almost double every 20 years, reaching 115.4 million by 2050.1
Dietary and nutritional factors impact cognitive status and likely contribute to these staggering numbers. Studies, for instance, show that dietary protocols such as The Mediterranean Diet may benefit cognitive health. Moreover, a recent review led by Arrigo Cicero from the University of Bologna (Bologna, Italy) looked at studies published between 1970 and 2017 and concluded that the use of herbs and phytochemicals for delaying the onset of cognitive decline shows significant promise.2
Nutrition and diet can play a significant role in helping to support cognitive health. Some recent studies investigating the effects of herbs and nutrients on cognition are summarized here.
1. Mavrodaris A et al., “Prevalences of dementia and cognitive impairment among older people in sub-Saharan Africa: a systematic review,” Bulletin of the World Health Organization, vol. 91, no. 10 (October 1, 2013): 773-783
2. Cicero AFG et al., “Botanicals and phytochemicals active on cognitive decline: the clinical evidence,” Pharmacological Research. Published online Dec 28, 2017.
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Vitamin D Enhances Visual Memory
Epidemiological studies have previously found an association between vitamin D and cognitive health. To assess the effect of vitamin D supplementation on cognitive function in a healthy population, Jacqueline Petterson of the University of Northern British Columbia (Canada) conducted an intervention study.3
In the randomized trial, 82 healthy adults from British Columbia were asked to supplement with high-dose (4,000 IU per day) or low-dose (400 IU per day) vitamin D3 for 18 weeks. All participants had vitamin D levels ≤100 nmol/L (≤40 ng/ml) at baseline. Cognitive performance was assessed with the Symbol Digit Modalities Test, verbal fluency, digit span, and the CANTAB computerized battery, a validated digital cognitive function test developed at the University of Cambridge (United Kingdom).
According to researchers, serum vitamin D levels increased significantly more in the high-dose vitamin D group than in the low-dose group. Improvements in visual (non-verbal) memory were also noted with high-dose vitamin D supplementation. In those with baseline vitamin D levels <75 nmol/L (<30 ng/ml), the high-dose vitamin D supplement led to highly significant improvement. No such improvement was noted in the low-dose group, indicating that vitamin D supplementation is important for aspects of higher-level cognitive functioning.
3. Pettersen JA., “Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults,” Experimental Gerontology, vol. 90 (April 2017): 90-97
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Spearmint Bolsters Working Memory
A proprietary extract of spearmint that is high in polyphenols, including rosmarinic acid, was recently investigated for its effects on cognitive health. In a study led by Kelly Herrlinger from ingredients firm Kemin (Des Moines, IA), researchers aimed to evaluate the benefits of the extract, branded Neumentix, in adults with age-associated memory impairment.4
In the double-blind, placebo-controlled study, 90 adults with an average age of 59.4 years were divided into three groups: one group received a placebo while the other two received either 600 mg or 900 mg per day of the Neumentix spearmint extract for 90 days. Cognitive assessments included the validated Cognitive Drug Research (CDR) system, while additional evaluations included the Leeds Sleep Evaluation Questionnaire (LSEQ) and the Profile of Mood States (POMS) ratings scale.
After 90 days, significant benefits were seen in the group taking 900 mg of spearmint extract daily, including improved quality of working memory and spatial working memory. Additionally, 900 mg/day of the spearmint extract led to significant improvement versus placebo in the LSEQ, specifically as related to the “ease of getting to sleep” parameter. These results suggest that the Neumentix polyphenol-rich spearmint extract may be beneficial for those with age-associated memory impairment.
4. Herrlinger KA et al., “Spearmint extract improves working memory in men and women with age-associated memory impairment,” The Journal of Alternative and Complementary Medicine, vol. 24, no. 1 (January 2018): 37-47
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Omega-3s for Mild Cognitive Impairment
The importance of omega-3 fatty acids-and particularly docosahexaenoic acid (DHA)-for brain development is widely known. Several epidemiological studies support the benefits of higher omega-3 intakes for brain-health maintenance. However, the clinical effects of omega-3 supplementation are less clear.
Researchers from Zhengzhou University (Zhengzhou, China) recently conducted a randomized, double-blind, placebo-controlled study in 86 adults with mild cognitive impairment in which individuals received supplements containing 480 mg DHA and 720 mg EPA daily, or a placebo, for 6 months.5 Changes to cognitive function were assessed using the Basic Cognitive Aptitude Test (BCAT).
Based on the parameters assessed, omega-3 supplementation led to statistically significant improvements in total BCAT scores, perceptual speed, working memory, and spatial imagery efficiency, but not in mental arithmetic efficiency or recall. The results indicate that omega-3 fatty acid supplementation may be beneficial in supporting cognitive function in individuals with mild cognitive impairment.
5. Bo Y et al., “The n-3 polyunsaturated fatty acids supplementation improved the cognitive function in the Chinese elderly with mild cognitive impairment: a double-blind randomized controlled trial,” Nutrients, vol. 9, no. 1 (January 10, 2017)
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Lutein and Zeaxanthin
The macular carotenoids lutein and zeaxanthin are well-known for their eye- and macular-health benefits. However, recent studies have shown that these carotenoids are important for more than just the eyes. Two trials led by Lisa Renzi-Hammond and Billy Hammond from the University of Georgia (Athens, GA) suggest that lutein and zeaxanthin supplementation can support several aspects of cognitive function in both young and mature adults. The studies were conducted on Lutemax 2020, an ingredient from OmniActive Health Technologies (Morristown, NJ).
In one randomized, double-blind, placebo-controlled trial, researchers included 51 healthy young adults aged 18-30.6 Participants were asked to supplement with 10 mg of lutein plus 2 mg of zeaxanthin daily, or a placebo, for one year. Macular pigment optical density (MPOD) and cognitive function using the CNS Vital Signs computerized test battery were assessed every four months. MPOD levels significantly improved over the course of the year compared to placebo, and the team found corresponding significant improvements in spatial memory, reasoning ability, and complex attention, indicating the benefits of supplementation for cognitive function in a young population.
In a second, double-blind, placebo-controlled trial, 62 adults with an average age of 73 were randomized to supplement with 10 mg of lutein and 2 mg of zeaxanthin daily, or a placebo, for a year.7 Researchers noted significant improvements in MPOD, and the CNS Vital Signs assessment showed significant improvements in complex attention as well as cognitive flexibility. In the male participants, significant improvements were additionally seen in composite memory, suggesting that supplementation with lutein and zeaxanthin is beneficial for enhancing aspects of cognition in this population as well.
6. Renzi-Hammond LM et al., “Effects of a lutein and zeaxanthin intervention on cognitive function: a randomized, double-masked, placebo-controlled trial of younger healthy adults,” Nutrients, vol. 9, no. 11 (November 14, 2017)
7. Hammond BR Jr et al., “Effects of lutein/zeaxanthin supplementation on the cognitive function of community dwelling older adults: a randomized, double-masked, placebo-controlled trial,” Frontiers in Aging Neuroscience. Published online August 3, 2017.
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