Effectiveness of Partially Hydrolyzed Guar Gum on Cognitive Function and Sleep Efficiency in Healthy Elderly Subjects in a Randomized, Double-Blind, Placebo-Controlled, and Parallel-Group Study

What Was Reviewed?

The study reviewed the effectiveness of partially hydrolyzed guar gum (PHGG), a water-soluble prebiotic dietary fiber, on cognitive function, sleep efficiency, and overall mental health in elderly individuals. The research specifically focused on assessing the impact of PHGG supplementation on cognitive domains such as visual memory and simple attention, sleep quality parameters like sleepiness on rising, and mood states including vigor and confusion. The study also considered the safety and tolerability of PHGG in the target population. The review encompasses the potential mechanisms through which PHGG may exert its effects, particularly its role in modulating the gut microbiome and the production of short-chain fatty acids (SCFAs), which are implicated in the gut-brain axis and neuroprotection.

Who Was Reviewed?

The subjects of the review were 66 healthy elderly Japanese individuals aged 60 years or older. These participants were free from cognitive impairment (as indicated by a Mini Mental State Examination score of 24 or higher) and were not undergoing treatment for chronic diseases that could influence the outcomes. The participants were randomly assigned to receive either PHGG supplementation (5 g/day) or a placebo for a duration of 12 weeks. The study specifically targeted an elderly population to investigate whether PHGG could mitigate age-related cognitive decline and improve sleep quality, given that these issues are particularly prevalent in this demographic.

What Were the Most Important Findings of This Review?

Cognitive Function:

The most significant finding was the improvement in visual memory observed in the PHGG group after 12 weeks of supplementation. Visual memory scores were significantly higher in the PHGG group compared to the placebo group, suggesting that PHGG has a positive effect on this critical cognitive domain. Improvements in simple attention were also noted at 8 weeks, although this was less emphasized.

Sleep Quality:

The PHGG group demonstrated significant improvements in sleep quality, particularly in the domain of “sleepiness on rising,” after 8 weeks of supplementation. This improvement indicates better sleep efficiency and mental clarity upon waking, which are essential for maintaining daily function in the elderly.

Mood and Mental Health:

Although no significant intergroup differences were observed, within-group analyses revealed that PHGG supplementation led to increased vigor and reduced confusion, suggesting a potential benefit of PHGG on mood states, although these findings were more exploratory.

Safety:

The study confirmed the safety of PHGG, as no adverse events were reported, making it a viable supplement for elderly populations.

What Are the Greatest Implications of This Review?

Potential Role of PHGG in Cognitive Health:

The study suggests that PHGG supplementation could serve as a functional food intervention to enhance cognitive function, particularly visual memory, in elderly individuals. This finding is significant as visual memory is crucial for daily activities and maintaining independence in aging populations. The positive effects observed may indicate that PHGG could be a valuable tool in preventing or delaying cognitive decline.

Enhancement of Sleep Quality:

Improved sleep quality, as evidenced by reduced sleepiness on rising, has broad implications for overall health and well-being in the elderly. Sleep disturbances are common in aging, and interventions like PHGG that can improve sleep efficiency are likely to contribute to better cognitive function, mood, and quality of life.

Implications for the Gut-Brain Axis:

The study reinforces the concept that the gut microbiome, modulated by prebiotic interventions like PHGG, plays a crucial role in brain health. By promoting the production of SCFAs and improving gut health, PHGG may influence brain function through the gut-brain axis, offering a non-pharmacological approach to support cognitive and mental health in the elderly.

Foundation for Future Research:

While the study provides promising data, it also highlights the need for further research with larger sample sizes, longer durations, and objective assessments. The findings lay the groundwork for more comprehensive studies that could explore the long-term effects of PHGG on cognitive decline, its mechanisms of action, and its potential to prevent dementia.