Can foods, beverages or dietary supplements really increase your mental energy? Scientists at the Life Sciences Research Organization (LSRO) recently reported the results of a review of the scientific evidence for such claims regarding ginkgo biloba, ginseng, glucose and omega-3 polyunsaturated fatty acids. They defined mental energy as consisting of mood (transient feelings about the presence of fatigue or energy), motivation (determination and enthusiasm) and cognition (sustained attention and vigilance).
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The numbers of marketing claims and food, beverage and drug products claiming to increase mental energy have risen rapidly, thus increasing the need for scientific specificity in marketing and food label claims, noted researchers Michael C. Falk, PhD, and colleagues in Nutrition Reviews.
Falk and colleagues initially identified more than 35 food ingredients, dietary supplements, dietary constituents and dietary factors thought to benefit mental energy, and pored over some 2,500 studies. But they concluded that insufficient evidence is available to evaluate mental-energy claims for most products and very few studies attempted to study motivation. Ultimately, their review focused on evaluating the effects on mood and cognition of four dietary supplements or constituents to illustrate the state of the available evidence: ginkgo biloba, ginseng, glucose, and omega-3 fatty acids.
Ginkgo biloba-A 2007 Cochrane Review concluded that the evidence ginkgo biloba is effective against dementia was not convincing, and subsequent major studies of this traditional Chinese herb against dementia and cognitive decline were negative (see the March 2009 and February 2010 Healthletter). Nonetheless, the LSRO review found that ginkgo biloba extract consistently improved mental processing speed in both younger and healthy or non-demented older adults, and appears to have a favorable effect on attention. Falk and colleagues added, Conflicting evidence prohibits any clear association from being made between ginkgo biloba and memory in healthy participants.
What about mood? Several studies suggest ginkgo biloba may improve aspects of mood, Falk and colleagues reported, including alertness and calmness in healthy subjects.
Ginseng-Another Chinese herbal remedy, ginseng root has been claimed to have many benefits including improvements in mental energy. But the LSRO review found the scientific evidence for such claims regarding mood and cognition inconsistent.
Glucose-This simple sugar is the main energy source for your brain, so it would seem to make sense (as TV candy commercials often dramatize) that glucose would improve mental energy. The evidence for such a link, however, turns out not to be as strong as you might expect. The LSRO review noted, A variety of studies have explored the relationship between glucose and memory, but the results are inconsistent-in part because of study variations in timing, dosing and population makeup. Other potentially relevant cognitive tasks, such as attention and vigilance, have not been substantially evaluated. The elderly and those with poor blood-sugar regulation are most likely to show improvement after glucose intake.
As for mood, there is little evidence linking glucose intake to enhanced mood-despite the TV commercials.
Omega-3s-These polyunsaturated fatty acids, such as those found in fish oil, have been shown to have heart-health benefits. But the presence of the omega-3 DHA in the neuronal membranes of the brains gray matter has led to speculation it may also play a role in brain health and cognition. The reviewers noted some evidence that fish consumption and omega-3s might delay or prevent cognitive decline in the elderly. But they concluded, At this time, there is not enough evidence to determine if omega-3s alter mood in healthy adults.
Given all these maybes, is there anything that definitely does improve mental energy? Try a cup of coffee or tea. The evidence that caffeine perks up mental function in a dose-dependent way-that is, the more you consume, the greater the effect-is so strong that Falk and colleagues didnt bother to include it in their review.
TO LEARN MORE: Nutrition Reviews, December 2010; abstract at dx.doi.org/10.1111/j.1753- 4887.2010.00340.x.