John E. Lewis*, Jillian Poles, Delaney P. Shaw, Elisa Karhu, Sher Ali Khan, Annabel E. Lyons, Susana Barreiro Sacco, H. Reginald McDaniel

Lewis et al. J Clin Transl Res 2021; 7(4):14

Published online: August 4, 2021


Background and aim: Brain health is becoming more important to the average person as the number of people with cognitive impairments, such as Alzheimer’s disease, is rising significantly. The current FDA-approved pharmacotherapeutics for dementia neither cure nor halt cognitive decline; they just delay the worsening cognitive impairment. This narrative review summarizes the effects of nutrients and phytonutrients on cognitive function.
Methods: A comprehensive literature search of PubMed was performed to find clinical trials in humans that assessed the effects of nutrients and phytonutrients on cognitive function published in English between 2000 and 2021. Six independent reviewers evaluated the articles for inclusion in this review.
Results: Ninety-six articles were summarized in this narrative review. In total 21 categories of nutrients and phytonutrients were included, i.e., α-lipoic acid, Bacopa monnieri, B vitamins, cholinergic precursors, vitamin D, vitamin E, Ginkgo biloba, ginseng, lion’s mane mushroom, N-acetyl cysteine, omega-3 fatty acids, aloe polysaccharides, Rhodiola rosea, rosemary, saffron, tart cherries, turmeric, wild yam, Withania somnifera, xanthines, and zinc. Particular noteworthy effects on cognition included memory, recollection, attention, intelligence, vocabulary, recognition, response inhibition, arousal, performance enhancement, planning, creative thinking, reaction time, vigilance, task switching, orientation to time, place, and person, reading, writing, comprehension, accuracy, learning, information processing speed, executive function, mental flexibility, daily functioning, decrease in mental fatigue, and freedom from distractibility. Some nutrients and phytonutrients also improved mood and contentedness and reduced anxiety and the need for caregiving. These effects are not completely consistent or ubiquitous across all patient populations or health statuses. Adverse effects were minimal or nonexistent.
Conclusion: Due to the growing population of people with cognitive impairment and the lack of effective pharmacotherapeutics, it is prudent for those afflicted or their caregivers to find alternative treatments. Our narrative review shows that many of these nutrients and phytonutrients may be promising for treating some aspects of cognitive impairment, especially for people afflicted with Alzheimer’s disease.
Relevance for patients: As demonstrated in a number of clinical trials, healthy adults and patients with various health challenges (e.g., Alzheimer’s disease, mild cognitive impairment, multiple sclerosis, and Parkinson’s disease) exhibiting a wide range of severity in cognitive defects would be best served to consider multiple nutrients and phytonutrients to improve aspects of their cognitive function.


Author affiliation

1. Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
2. Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
3. Institute of Human Nutrition, Vagelos College of Physicians & Surgeons, Columbia University, New York, NY, USA
4. Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA
5. Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
6. School of Nursing and Health Studies, University of Miami, Coral Gables, FL, USA
7. Department of Internal Medicine, Mount Sinai Medical Center Miami Beach, FL, USA
8. Wellness Quest, LLC, Grand Prairie, TX, USA

*Corresponding author
John E. Lewis
Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, 1120 NW, 14th Street, Suite #1482A (D28), Miami, FL 33136
Phone: +1 305-243-6227
Fax: +1 305-243-1619

Handling editor:
Michal Heger
Department of Pharmaceutics, Utrecht University, the Netherlands
Department of Pharmaceutics, Jiaxing University Medical College, Zhejiang, China


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