In a study published in the journal Limits in nutritionResearchers in the United Kingdom examined the impact of 90-day supplementation of a multi-ingredient herbal supplement on the cognitive abilities and gut microbiota of elderly patients who showed subjective memory decline. They found that the intervention resulted in memory impairment in the participants, but improved the speed of cognitive tasks, which coincided with a higher concentration of tyrosine in the urine and reduced levels of three bacterial species in the intestines.
Study: Chronic supplementation of a multi-ingredient herbal supplement increases the rate of cognitive task performance in addition to changes in urinary dopamine metabolism and the gut microbiome in cognitively intact older adults experiencing subjective memory loss: a randomized, placebo-controlled, parallel-group trial. Image credits: lupvaliu / Shutterstock
Although the effects of specific individual herbs on brain function have been studied, there is limited research on the ingestion of combinations of herbal compounds. Combination products are typically formulated to enhance the effects of individual ingredients through the potential synergy between all the ingredients, which may not be apparent when the compounds are taken individually.
Evidence suggests that phytochemicals such as phenolics, terpene, micro- and macronutrients, and polysaccharide groups may support brain function by potentially conferring 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, in the current study researchers evaluated the effect of a multi-ingredient supplement on the cognitive function, urinary metabolome, and gut microbiome of older adults experiencing subjective memory decline.
About the study
The current randomized, placebo-controlled, double-blind, parallel-group intervention study was conducted for 90 days in 128 participants between 55 and 75 years old. The participants self-reported age-related memory loss compared to their twenties and were otherwise healthy.
Participants were randomized to receive two capsules of 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 leaf, reishi (full spectrum), rosemary, cardamom, green tea, holy basil and sea green. The first and last doses were taken in the laboratory on test days, the intermediate doses were taken by the participants at home.
The tests were conducted using a series of cognitive tasks that participants performed once on day 1 (acute), twice on day 90 of treatment (chronic), and once a week in the interim. Mental performance was assessed using an automated smartphone-based system (Cognim app) regarding 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 their visit to 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 analyzes were performed using various tools. The urine metabolome was characterized using liquid chromatography of the urine samples collected in the laboratory prior to treatment.
results and discussion
The post-dose compliance range was found to be 84.6–112.1%. Compared to baseline, placebo participants showed significantly better attentional accuracy, quality of memory, episodic memory, memory speed, and overall accuracy and speed. Furthermore, memory impairments 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 on the following tasks: choice reaction time, numerical working memory and Stroop tasks, with fewer errors on the fast visual information processing task.
The gut microbiome analysis showed that Shannon diversity was greater in the treatment group than in the placebo group. Interestingly, although the gut bacteria abundance 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. Furthermore, the treatment group showed a significant reduction in the abundance of three types of intestinal bacteria viz Anaerostipes spp., Sutterella, And Blautia, before and after completing the dose. A lower abundance of Sutterella appeared 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 findings show that the multi-ingredient supplement helped improve cognitive speed in the participants, possibly modulated by increased dopaminergic activity, while additionally improving their bowel movements. 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 needed to explain the supplement’s unexpected effects on memory and the potential usefulness of combination supplements in improving brain function in older adults.