Effect of oral supplementation with enzymatically synthesized glycogen (ESG) on cognitive function: a randomized, double-blind, placebo-controlled study.

Background: There is a well-established correlation between aging and decreasing cognitive performance in healthy adults. Furthermore, with increasing levels of stress in modern societies, cognitive decline is a growing concern. With our focus on these concens, we prepared enzymatically synthesized glycogen (ESG) from starch, and aimed to examine whether ESG supplementation improved cognitive functions in humans. Methods: In a randomized, double-blind, placebo-controlled, cross-over trial, 40 healthy participants were administered 5.0 g of ESG or maltodextrin (placebo) beverages for 4 weeks, respectively. A washout period of 4 to 5 weeks was set between treatments. The primary endpoint was the effect of orally administered ESG on cognitive function, which was assessed by using the CogHealth test battery. In addition, the fatigue VAS (visual analog scale) score and salivary levels of anti-fatigue factors (such as cortisol and secretory IgA) were determined. Results: Two participants dropped out for personal reasons, therefore data for the remaining 38 subjects was analyzed. It was found that visual discrimination and long-term memory were significantly potentiated by the ingestion of ESG for 2-4 weeks compared with placebo treatment. On the other hand, the fatigue VAS score and salivary levels of anti-fatigue factors showed no significant differences between the ESG group and the placebo group. Conclusions: Our study shows that oral administration of ESG significantly potentiates the cognitive performance of healthy volunteers. We speculate that glycogen is not only a vital energy source, but is also involved in enhancement of cognitive function. Keywords: Glycogen, ESG, cognitive performance, CogHealth, long-term memory, visual discrimination .