In a study published in Limits in nutrition, researchers from the United Kingdom investigated the effects of a 90-day intake of a multicomponent herbal supplement on the cognitive abilities and gut microbiota of elderly patients showing subjective memory decline. They found that the intervention resulted in memory deficits in the participants, but improved speed on cognitive tasks, coinciding with a higher concentration of tyrosine in the urine and reduced levels of three types of bacteria in the gut.
Study: Chronic supplementation of a multicomponent herbal supplement increases cognitive task performance along with changes in urinary dopamine metabolism and gut microbiome in cognitively intact older adults experiencing subjective memory decline: a randomized, placebo-controlled, parallel-group trial. Image credit: lupvaliu / Shutterstock
Background
Although the effects of specific individual herbs on brain function have been studied, there is limited research on taking combinations of herbal compounds. Combination products are usually formulated to enhance the effects of the individual ingredients through the potential synergy between all ingredients that may not be apparent when the compounds are taken individually.
Evidence suggests that phytochemicals such as phenols, terpenes, micro- and macronutrients, and polysaccharide groups may support brain function by potentially providing neuroprotection, interacting with neurotransmitter systems, supporting metabolism, and mediating communication in the gut-brain axis. Given the lack of research on a combination of these ingredients, researchers in the current study evaluated the effect of a multi-ingredient supplement on cognitive function, urinary metabolome, and gut microbiome of older adults experiencing subjective memory decline.
About the research
The present randomized, placebo-controlled, double-blind, parallel-group intervention study was conducted over 90 days in 128 participants aged between 55-75 years. Participants self-reported age-related memory decline compared to their 20s and were otherwise healthy.
Participants were randomized to receive two capsules of either the magnesium stearate (placebo) or the herbal supplement called “Turmeric Brainwave” with their daily breakfast. The supplement was a combination of ingredients including Bacopa monnieri, turmeric, gotu kola leaves, reishi (full spectrum), rosemary, cardamom, green tea, holy basil and sea vegetables. The first and last doses were taken on testing days in the laboratory, and intermediate doses were taken by participants at home.
Testing was performed using a battery of cognitive tasks performed by participants once on day 1 (acute), twice on day 90 of treatment (chronic), and once weekly in between. Mental performance was assessed using a computerized smartphone-based system (Cognim app) on attentional speed and accuracy, memory quality, episodic memory, memory speed, 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 diluted bacterial richness were assessed and statistical analysis was performed using various tools. The urinary metabolome was characterized using liquid chromatography of the urine samples collected before treatment in the laboratory.
Results and discussion
The range of compliance after the intervention dose was found to be 84.6–112.1%. Compared to baseline, placebo participants showed significantly better attentional accuracy, memory quality, episodic memory, memory speed, and overall accuracy and speed. Furthermore, 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 tasks. Specifically, speed was found to be significantly higher in the following tasks: choice reaction time, numerical working memory, and Stroop tasks, with fewer errors in the rapid visual processing task.
When analyzing the gut microbiome, Shannon diversity was found to be greater in the treatment group than in the placebo group. Interestingly, although the abundance of gut bacteria of participants in the placebo group was significantly affected by age, dietary habits, alcohol and caffeine consumption, and concomitant medication use, this effect was not observed in the treatment group. Additionally, the treated group showed a significant reduction in the abundance of three types of gut bacteria viz Anaerostipes spp., basement, and Blautia, before and after completing the dose. Less abundant than The basement was shown to coincide with reduced constipation and improved bowel movements in the treatment group.
Analysis of the relative abundance of urinary metabolites revealed increased levels of tyrosine in the treatment group, indicating a role for dopamine in the observed increase in cognitive speed.
Conclusion
In conclusion, the study findings show that the multi-ingredient supplement helped improve participants’ cognitive speed, modulated potentially by increased dopaminergic activity, while further improving their gut experience. However, the study is limited by uneven randomization of participants to treatment group before and after the coronavirus disease 2019 (COVID-19) pandemic. Further research is needed to explain the unexpected effects of the supplement on memory and the potential benefit of combined supplements to improve brain function in older adults.
