In a study published in the journal Frontiers in Nutrition, researchers in the United Kingdom investigated the impact of the 90-day supplementation of a multi-ingredient herbal supplement on the cognitive abilities and gut microbiota of elderly patients showing a subjective memory decline. They found that the intervention resulted in memory deficits in the participants but improved the speed of cognitive tasks, coinciding with a higher concentration of tyrosine in the urine and reduced levels of three bacterial species in the gut.
Study: Chronic supplementation of a multi-ingredient herbal supplement increases speed of cognitive task performance alongside changes in the urinary metabolism of dopamine and the gut microbiome in cognitively intact older adults experiencing subjective memory decline: a randomized, placebo controlled, parallel groups investigation. Image Credit: lupvaliu / Shutterstock
Although the effects of specific individual herbs on brain function have been investigated, there is limited research on the intake of combinations of herbal compounds. Combination products are typically formulated to enhance the effects of individual ingredients through the potential synergy among all the ingredients, which may not be evident when the compounds are taken in isolation.
Evidence suggests that phytochemicals such as phenolics, terpene, micro- and macro-nutrients, and polysaccharide groups may support brain function by potentially conferring neuroprotection, interacting with neurotransmitter systems, supporting metabolism, and mediating the communication in the gut-brain axis. Given the lack of research on a combination of these ingredients, researchers in the present study evaluated the effect of a multi-ingredient supplement on the cognitive function, urinary metabolome, and gut microbiome of older adults experiencing a subjective memory decline.
About the study
The present randomized, placebo-controlled, double-blind, parallel-group intervention trial was conducted for 90 days on 128 participants between 55–75 years of age. The participants self-reported an age-related memory decline compared to their 20s and were otherwise healthy.
The participants were randomized to receive two capsules of either the magnesium stearate (placebo) or the herbal supplement named "Turmeric Brainwave" with their daily breakfast. The supplement was a combination of ingredients, including Bacopa monnieri, turmeric, gotu kola leaf, reishi (full spectrum), rosemary, cardamom, green tea, holy basil, and sea greens. The first and last doses were taken on testing days in the laboratory, and the interim doses were taken by the participants at home.
The testing was done using a battery of cognitive tasks performed by participants once on day 1 (acute), twice on day 90 of the treatment (chronic), and once every week in the interim. The mental performance was assessed using a computerized, smartphone-based system (Cognim app) concerning speed and accuracy of attention, quality of memory, episodic memory, speed of memory, and overall speed and accuracy. The gut microbiome was analyzed by examining participants' stool samples collected within 18 hours of visiting the laboratory. Libraries of 16S-ribosomal ribonucleic acid (16S-rRNA) sequences were prepared and analyzed. Shannon diversity and rarefied bacterial richness were estimated, and statistical analysis was performed using various tools. The urine metabolome was characterized using liquid chromatography of the urine samples collected prior to treatment in the laboratory.
Results and discussion
The post-dose compliance range of the intervention was found to be 84.6–112.1%. Compared to baseline, placebo participants showed significantly better accuracy of attention, quality of memory, episodic memory, speed of memory, and overall accuracy and speed. Additionally, memory deficits were observed even after 90 days of treatment with the multi-ingredient supplement. However, the treatment group showed a significant improvement in the speed of cognitive task performance. Specifically, speed was found to be significantly higher in the following tasks: choice reaction time, numeric working memory, and Stroop tasks, with fewer errors in the rapid visual information processing task.
In the gut microbiome analysis, Shannon diversity was found to be greater in the treatment group than in the placebo group. Interestingly, although the gut bacterial abundance of the placebo group participants was impacted significantly by age, dietary habits, alcohol and caffeine consumption, and concomitant medication use, this effect was not observed in the treatment group. Additionally, the treatment group showed a significant reduction in the abundance of three gut bacterial species, namely Anaerostipes spp., Sutterella, and Blautia, before and after the dose completion. A lower abundance of Sutterella was shown to coincide with reduced constipation and improved bowel movements in the treatment group.
The analysis of the relative abundance of metabolites in the urine revealed increased tyrosine levels in the treatment group, indicating the role of dopamine in the observed increase in cognitive speed.
In conclusion, the study's findings demonstrate that the multi-ingredient supplement helped improve cognitive speed in the participants, modulated potentially by increased dopaminergic activity, while additionally improving their bowel experience. However, the study is limited by the unequal randomization of participants into the treatment group before and after the coronavirus disease 2019 (COVID-19) pandemic. Further research is required to explain the unanticipated effects of the supplement on memory and the potential utility of combination supplements in improving brain function in older adults.