Objective: Lack of mental energy is one of the leading reasons adults turn to dietary supplements, with three out of ten supplement users hoping to improve their energy level; even more consume caffeine-containing products for the same reason. Despite this interest from consumers, there is no consensus scientific definition of mental energy or sole validated instrument for measuring it. We performed this review to summarize main findings from research regarding the influence of natural dietary compounds on three aspects of mental energy: cognition (vigilance), motivation (to do mental work), and mood (feelings of energy and/or absence of feelings of fatigue).Methods: A narrative review of key papers.Results: In addition to caffeine, a number of other compounds, including the polyphenols, which are found in all plant-derived products, and the phytochemicals in culinary herbs and herbal products such as Panax ginseng and Ginkgo biloba, have been shown in animal models to modulate neurotransmitter activity potentially relevant to mental energy. Inadequate intake of B vitamins could also potentially have a negative effect on mental energy due to their role in overall energy production, as precursors of key cofactors in the citric acid cycle, as well as their role in brain function and neurotransmitter synthesis. Consumption of some of these products may have direct or indirect effects on one or more elements of mental energy.Conclusion: Large, prospective clinical trials of these products using appropriate, validated instruments designed to measure mental energy may be worthwhile if sufficient evidence exists to justify such trials.
Keywords: B vitamins; Cognition; Ginkgo biloba; Panax ginseng; caffeine; mood; motivation.
Do specific dietary constituents and supplements affect mental energy? Review of the evidence.Nutr Rev. 2010 Dec;68(12):697-718. doi: 10.1111/j.1753-4887.2010.00340.x. Nutr Rev. 2010. PMID: 21091914 Review.
Phytochemicals for Improving Aspects of Cognitive Function and Psychological State Potentially Relevant to Sports Performance.Sports Med. 2019 Feb;49(Suppl 1):39-58. doi: 10.1007/s40279-018-1007-0. Sports Med. 2019. PMID: 30671903 Free PMC article. Review.
Modulation of cognition and mood following administration of single doses of Ginkgo biloba, ginseng, and a ginkgo/ginseng combination to healthy young adults.Physiol Behav. 2002 Apr 15;75(5):739-51. doi: 10.1016/s0031-9384(02)00665-0. Physiol Behav. 2002. PMID: 12020739 Clinical Trial.
The effects of ginseng, ephedrine, and caffeine on cognitive performance, mood and energy.Nutr Rev. 2001 Apr;59(4):91-102. doi: 10.1111/j.1753-4887.2001.tb06995.x. Nutr Rev. 2001. PMID: 11368507 Review.
Screening for Cognitive Impairment in Older Adults: An Evidence Update for the U.S. Preventive Services Task Force [Internet].Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Nov. Report No.: 14-05198-EF-1. Agency for Healthcare Research and Quality (US). 2013. PMID: 24354019 Free Books & Documents. Review.