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Mixed Tree Nuts, Cognition, and Gut Microbiota: A 4-Week, Placebo-Controlled, Randomized Crossover Trial in Healthy Nonelderly Adults.
Haskell-Ramsay, CF, Dodd, FL, Smith, D, Cuthbertson, L, Nelson, A, Lodge, JK, Jackson, PA
The Journal of nutrition. 2023;152(12):2778-2788
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Cognitive impairment is a growing worldwide health concern as our population ages. In the absence of effective pharmaceutical treatments, modifiable lifestyle factors such as nutrition represent crucial targets in preventing cognitive decline. The aim of this study was to investigate the cognitive and mood effects of mixed tree nut supplementation in healthy non-elderly adults aged 18 to 49 years. This study is a randomised, placebo-controlled, double-blind, counterbalanced crossover design. Participants (n = 81) were randomly assigned to one of the two groups; the treatment or placebo group. Results showed that nut consumption led to improved picture recognition in terms of increased accuracy and faster reaction time. Furthermore, there was an enrichment of an unclassified type of bacterial community (Lachnospiraceae) but limited changes to the urinary metabolome. On the other hand, supplementation with mixed nuts failed to evince effects on mood. Authors conclude by pointing out that their findings are attributed to a sample of healthy and nonelderly participants. Thus, more profound effects may be shown with higher quantities of nuts or in those at risk, such as those experiencing cognitive decline or in those suffering gut dysbiosis.
Abstract
BACKGROUND Beneficial effects of nut supplementation on cognitive function have previously been demonstrated in young and older adults. Alterations to gut microbiota have also been shown following tree nut consumption. However, no data exists on the effects of nuts on cognition and intestinal microbial communities assessed within the same study. OBJECTIVES The study aimed to examine the effects of daily consumption of tree nuts for 4 wk on cognitive function (primary outcome), mood, metabolomics, and gut microbial species (secondary outcomes) in healthy, nonelderly adults. METHODS This randomized, placebo-controlled, double-blind, counterbalanced crossover study assessed the effects of 4 wk of supplementation with 30 g/d mixed tree nuts versus placebo on cognition and mood in 79 healthy adults aged 18-49 y. Metabolic responses, gut bacterial community structure, and the potential for these to impact cognition were explored using a multi-omic approach. Bacterial community analysis was conducted in Quantitative Insights Into Microbial Ecology 2 (QIIME2). RESULTS Mixed model analysis indicated that nut consumption led to significant improvements to accuracy (placebo M = 92.2% compared with NUTS M = 94.5%; P = 0.019) and speed of response (placebo M = 788 ms compared with NUTS M = 757 ms; P = 0.004) on a picture recognition task. No significant changes to bacterial community α or β diversity were observed when comparing nut consumption to the placebo arm. However, an unclassified Lachnospiraceae amplicon sequence variant (ASV) was significantly enriched in participants when supplemented with nuts (P = 0.015). No correlations were observed between the changes to picture recognition and the changes to the unclassified Lachnospiraceae ASV. There were no significant changes to the urinary metabolome. CONCLUSIONS These findings indicate a positive effect of nut on cognition following only 4 wk of consumption in a healthy nonelderly sample, as well as upregulation of a microbial taxa associated with gut health. The effects appear to be independent of one another, but further exploration is required in those experiencing cognitive decline and/or gut dysbiosis.
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Wild blueberry (poly)phenols can improve vascular function and cognitive performance in healthy older individuals: a double-blind randomized controlled trial.
Wood, E, Hein, S, Mesnage, R, Fernandes, F, Abhayaratne, N, Xu, Y, Zhang, Z, Bell, L, Williams, C, Rodriguez-Mateos, A
The American journal of clinical nutrition. 2023;117(6):1306-1319
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The risk of developing both cardiovascular and neurodegenerative diseases increases with aging. Growing evidence from epidemiological and human intervention trials indicates that (poly)phenols may have cardioprotective properties as well as the ability to improve cognitive function. The aim of this study was to investigate the effects of daily wild blueberry (WBB) (poly)phenol consumption on vascular function and cognitive performance in healthy older individuals. This study was a randomised, double-blinded, placebo-controlled parallel design study. A total of 61 healthy older individuals were recruited and randomly assigned to one of the two arms; placebo intervention or blueberry intervention group. Results showed that long-term consumption of a dietary achievable amount of WBB enhanced vascular and cognitive function in older adults. Authors conclude that gut microbiota and vascular blood flow may play important roles in mediating the cognitive benefits shown by the consumption of (poly)phenol-rich foods.
Abstract
BACKGROUND Evidence suggests that the intake of blueberry (poly)phenols is associated with improvements in vascular function and cognitive performance. Whether these cognitive effects are linked to increases in cerebral and vascular blood flow or changes in the gut microbiota is currently unknown. METHODS A double-blind, parallel randomized controlled trial was conducted in 61 healthy older individuals aged 65-80 y. Participants received either 26 g of freeze-dried wild blueberry (WBB) powder (302 mg anthocyanins) or a matched placebo (0 mg anthocyanins). Endothelial function measured by flow-mediated dilation (FMD), cognitive function, arterial stiffness, blood pressure (BP), cerebral blood flow (CBF), gut microbiome, and blood parameters were measured at baseline and 12 wk following daily consumption. Plasma and urinary (poly)phenol metabolites were analyzed using microelution solid-phase extraction coupled with liquid chromatography-mass spectrometry. RESULTS A significant increase in FMD and reduction in 24 h ambulatory systolic BP were found in the WBB group compared with the placebo group (0.86%; 95% CI: 0.56, 1.17, P < 0.001; -3.59 mmHg; 95% CI: -6.95, -0.23, P = 0.037; respectively). Enhanced immediate recall on the auditory verbal learning task, alongside better accuracy on a task-switch task was also found following WBB treatment compared with placebo (P < 0.05). Total 24 h urinary (poly)phenol excretion increased significantly in the WBB group compared with placebo. No changes in the CBF or gut microbiota composition were found. CONCLUSIONS Daily intake of WBB powder, equivalent to 178 g fresh weight, improves vascular and cognitive function and decreases 24 h ambulatory systolic BP in healthy older individuals. This suggests that WBB (poly)phenols may reduce future CVD risk in an older population and may improve episodic memory processes and executive functioning in older adults at risk for cognitive decline. Clinical Trial Registration number in clinicaltrials.gov: NCT04084457.
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Probiotic intervention benefits multiple neural behaviors in older adults with mild cognitive impairment.
Fei, Y, Wang, R, Lu, J, Peng, S, Yang, S, Wang, Y, Zheng, K, Li, R, Lin, L, Li, M
Geriatric nursing (New York, N.Y.). 2023;51:167-175
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Mild cognitive impairment (MCI) is an intermediate stage between the normal cognitive changes associated with aging and dementia. Recent research shows that probiotic supplementation can regulate the balance of the intestinal flora and improve self-care ability and cognition in older adults. The aim of this study was to explore the effects and the underlying mechanisms of probiotic supplementation on MCI older adults. This study was a pilot randomised controlled trial (RCT) to investigate the effects of 12 weeks of probiotic supplementation in patients with MCI. Participants were randomly assigned to the probiotic group or control group. Results demonstrated the beneficial effects of probiotic supplementation intervention on multiple neural behaviours by regulating the homeostasis of the gut microbiota in older MCI patients. Authors conclude that this study provided new insights into nutrition interventions in older MCI patients. However, further trials with larger cohorts should be conducted to confirm the effects of probiotic intervention in MCI patients and provide more clinical evidence for its preventive and therapeutic effects.
Abstract
Probiotic supplements were shown to improve cognitive function in Alzheimer's disease (AD) patients. However, it is still unclear whether this applies to older individuals with mild cognitive impairment (MCI). We aimed to explore the effects of probiotic supplementation on multiple neural behaviors in older adults with MCI. Forty-two MCI patients (age > 60 years) were randomly divided into two groups and consumed either probiotics (n=21) or placebo (n=21) for 12 weeks. Various scale scores, gut microbiota measures and serological indicators were recorded pre- and posttreatment. After 12 weeks of intervention, cognitive function and sleep quality were improved in the probiotic group compared with those in the control group, and the underlying mechanisms were associated with changes in the intestinal microbiota. In conclusion, our study demonstrated that probiotic treatment enhanced cognitive function and sleep quality in older MCI patients, thus providing important insights into the clinical prevention and treatment of MCI.
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PRO-DEMET Randomized Controlled Trial on Probiotics in Depression-Pilot Study Results.
Gawlik-Kotelnicka, O, Margulska, A, Skowrońska, A, Strzelecki, D
Nutrients. 2023;15(6)
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Depression often coexists with metabolic abnormalities, and metabolic syndrome (MetS) is diagnosed in 30% of depressed subjects. Importantly, both obesity and MetS have been found to be independently associated with depressive symptoms and inflammation. The aim of this study was to investigate the effect of probiotics in the treatment of depressive disorders with possible comorbid MetS and its components. This study was an internal feasibility study based on the main randomised study - a single-centre, parallel-group, prospective, randomised, double-blind, placebo-controlled pilot trial. Adult patients (≥18 years) with depressive disorders were randomly assigned (1:1) into either the placebo or probiotic group. Results showed a positive association between probiotics supplementation and psychometric parameters together with the metabolic profile, serum inflammation markers, and biomarkers of metabolic-associated fatty liver disease in patients with depressive disorders. Authors conclude that the findings of their study would be suitable for determining the potential clinical use of probiotics and assessing certain key factors such as potential biomarkers of response.
Abstract
There is a pressing need to identify new treatment options for depression and its comorbidities. Depression often coexists with metabolic complications, and the two may share a pathophysiological overlap, including inflammation and microbiota changes. Microbiota interventions (e.g., probiotics) may represent a safe and easy-to-use treatment option as an adjunctive therapy in patients only partially responsive to pharmacologic treatment. (1) Objective: The paper presents the results of a feasibility and pilot study. The study is an internal part of a randomized controlled trail (RCT) of the effect of probiotic supplementation on psychometric, anthropometric, metabolic, and inflammatory parameters in adult patients with depressive disorders depending on the presence of metabolic syndrome. (2) Methods: The trial has a four-arm, parallel-group, prospective, randomized, double-blind, controlled design. Sixty participants received a probiotic preparation containing Lactobacillus helveticus Rosell®-52 and Bifidobacterium longum Rosell®-175 over 60 days. The feasibility of the study design was assessed, as well as the rates of recruitment, eligibility, consent, and study completion. The following were assessed: depressive, anxiety and stress symptoms, quality of life, blood pressure, body mass index and waist circumference, complete blood count with differential, serum levels of C-reactive protein, high-density lipoprotein cholesterol, triglycerides, fasting glucose, some secondary markers of inflammation and metabolic health, as well as noninvasive biomarkers of liver fibrosis (APRI and FIB-4). (3) Results: The study was found to be generally feasible. The eligibility rate was 52% of recruited participants with 80% completing the study protocol. No differences in sociodemographic or anthropometric factors or basic laboratory findings were found between the placebo and probiotic group at the start of the intervention period. Importantly, the proportion of recruited participants fulfilling the criteria of metabolic syndrome was too low. (4) Conclusions: Whilst the whole study protocol was feasible, some different timepoint procedures require modification. The major weakness of the recruitment methods was that the percentage of metabolic arms participants was insufficient. Overall, the full RCT design on probiotics in depression with vs. without metabolic syndrome was shown to be feasible with little modification.
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A Randomized, Double-Blind, Placebo-Controlled Study of an Anthocyanin-Rich Functional Ingredient on Cognitive Function and Eye Dryness in Late Adulthood Volunteers: Roles of Epigenetic and Gut Microbiome Modulations.
Wattanathorn, J, Tong-Un, T, Thukham-Mee, W, Paholpak, P, Rangseekhajee, P
Nutrients. 2023;15(16)
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The global market of functional foods targeting wellness promotion, disease risk reduction, and quality of life promotion has been increasing. Due to this demand, the development of novel functional ingredients is essential when producing new fortified foods and beverages. The aim of this study was to determine the effect of the eight-week consumption of a functional soup containing “Anthaplex” [a novel functional ingredient consisting of the extracts of purple waxy corn (Zea mays) and coloured sticky rice (Oryza sativa)] on cognitive function and eye dryness in healthy volunteers in late adulthood. This study was an 8-week, 3-arm, randomised, double-blind, placebo-controlled study. A total of 69 participants were randomly assigned to placebo, D2 (2g of Anthaplex), or D4 (4g of Anthaplex) treatment group. Results showed that “Anthaplex” can improve cognitive function and working memory together with eye dryness. Authors concluded that “Anthaplex” could be a new functional ingredient for supplements aiming to improve cognitive function and eye dryness.
Abstract
Due to the rising demand for supplements targeting cognitive enhancement and dry eye together with the health benefits of anthocyanins, we have developed a functional soup containing an anthocyanin-rich functional ingredient, or "Anthaplex," and assessed the effects on cognitive function and eye dryness together with the possible mechanisms. A total of 69 male and female health volunteers were randomized and divided into placebo, D2, and D4 groups. All subjects consumed 120 mL of placebo or functional soup containing "Anthaplex" either at 2 or 4 g per serving per day within 5 min in the morning for eight weeks. The cognitive function, working memory, dry eye, AChE, MAO, MAO-A, MAO-B, and GABA-T activities, BDNF, HAC, HDAC, and DNMT activities, pH, and amount of lactic acid-producing bacteria, particularly Lactobacillus and Bifidobacterium spp. in feces, were determined before intervention and after eight weeks of consumption. Subjects who consumed the "Anthaplex" soup had improved cognitive function, working memory, eye dryness, histone acetylation, ACh E suppression, and BDNF with increased Bifidobacterium spp. but decreased pH in feces. These data suggest that "Anthaplex" improves cognitive function and eye dryness via the modulations of the histone acetylation process, gut microbiome, and cholinergic function.
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Modulating the Gut Microbiome in Multiple Sclerosis Management: A Systematic Review of Current Interventions.
Tsogka, A, Kitsos, DK, Stavrogianni, K, Giannopapas, V, Chasiotis, A, Christouli, N, Tsivgoulis, G, Tzartos, JS, Giannopoulos, S
Journal of clinical medicine. 2023;12(24)
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Multiple sclerosis (MS) is an autoimmune disease caused by the altered immune system mistakenly attacking the central nervous system. While genetics play a leading causative role in the manifestation of this disease, other contributing environmental factors can also exist, such as a disruption in the intestinal microbial composition. Previous research has shown that the bidirectional communication between the brain's and gut's health, also known as the gut-brain axis, may contribute to the prognosis of MS. Modulating gut microbial composition can be a therapeutic strategy in MS patients to manage symptoms and prevent disease progression. This systematic review assessed different protocols for modulating gut microbial composition, including dietary modifications, probiotic use, intermittent fasting, and faecal microbial transplantation. The review included thirteen studies that compared the effects of the above gut microbial modulation intervention protocols in MS patients with healthy participants. While different dietary modification strategies improved MS symptoms, probiotic supplementations and intermittent fasting reduced inflammation, and faecal microbial transplantation showed promising positive effects in a few reports. Due to the methodological limitations of the included studies, further robust studies are required to evaluate the beneficial effects of gut microbial modulation strategies in reducing the symptoms of MS patients. However, healthcare professionals can use the results of this study to understand the benefits of gut microbial modulation in MS patients.
Abstract
This review attempted to explore all recent clinical studies that have investigated the clinical and autoimmune impact of gut microbiota interventions in multiple sclerosis (MS), including dietary protocols, probiotics, fecal microbiota transplantation (FMT), and intermittent fasting (IF). Methods: Thirteen studies were held between 2011 and 2023 this demonstrated interventions in gut microbiome among patients with MS and their impact the clinical parameters of the disease. These included specialized dietary interventions, the supply of probiotic mixtures, FMT, and IF. Results: Dietary interventions positively affected various aspects of MS, including relapse rates, EDSS disability scores, MS-related fatigue, and metabolic features. Probiotic mixtures showed promising results on MS-related fatigue, EDSS parameters, inflammation; meanwhile, FMT-though a limited number of studies was included-indicated some clinical improvement in similar variables. IF showed reductions in EDSS scores and significant improvement in patients' emotional statuses. Conclusions: In dietary protocols, clinical MS parameters, including relapse rate, EDSS, MFIS, FSS, and MSQoL54 scales, were significantly improved through the application of a specific diet each time. Probiotic nutritional mixtures promote a shift in inflammation towards an anti-inflammatory cytokine profile in patients with MS. The administration of such mixtures affected disability, mood levels, and quality of life among patients with MS. FMT protocols possibly demonstrate a therapeutic effect in some case reports. IF protocols were found to ameliorate EDSS and FAMS scores. All interventional means of gut microbiome modulation provided significant conclusions on several clinical aspects of MS and highlight the complexity in the relationship between MS and the gut microbiome.
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Effects of Lactiplantibacillus plantarum OLL2712 on Memory Function in Older Adults with Declining Memory: A Randomized Placebo-Controlled Trial.
Sakurai, K, Toshimitsu, T, Okada, E, Anzai, S, Shiraishi, I, Inamura, N, Kobayashi, S, Sashihara, T, Hisatsune, T
Nutrients. 2022;14(20)
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On the Alzheimer’s disease spectrum, which is the most common cause of dementia, the typical symptom at onset is impaired memory. As the disease progresses, other cognitive domains, such as language, visuospatial cognition, and executive function, are impaired, gradually making it impossible to maintain independence in daily life. The aim of this study was to test the protective effects of 12 weeks of supplementation with heat-treated Lactiplantibacillus OLL2712 cells on memory function in older adults. This study was a double-blind placebo-controlled trial in which participants were randomly assigned to the active or placebo group. Results showed that OLL2712 consumption had a protective effect on memory function in older adults. However, there was no significant effect of OLL2712 intake on verbal memory in either of the analyses. Furthermore, in the gut microbiota analysis, the bacterial composition of the active group showed significantly lower abundance ratios of bacterial species linked to inflammation (Lachnoclostridium, Monoglobus, and Oscillibacter). Authors conclude that continuous intake of OLL2712 may be an effective approach to protect memory function in older adults.
Abstract
The use of probiotics is expected to be an intervention in neurodegenerative conditions that cause dementia owing to their ability to modulate neuroinflammatory responses via the microbiome-gut-brain axis. Therefore, we selected Lactiplantibacillus plantarum OLL2712 (OLL2712), the optimal anti-inflammatory lactic acid bacteria strain with high IL-10-inducing activity in immune cells, and aimed to verify its protective effects on memory function in older adults. A 12-week, randomized, double-blind, placebo-controlled trial was performed with older adults over the age of 65 years with declining memory. The participants consumed either powder containing heat-treated OLL2712 cells or placebo. Memory function was assessed using a computer-assisted cognitive test, Cognitrax. Daily dietary nutrient intake was assessed using the Brief-type Self-administered Diet History Questionnaire (BDHQ). The composition of the gut microbiota was analyzed by fecal DNA extraction and 16S rDNA sequencing. Data from 78 participants who completed the entire procedure were analyzed, and significant improvements in composite memory and visual memory scores were observed in the active group, after accounting for the effect of daily nutritional intake (p = 0.044 and p = 0.021, respectively). In addition, the active group had a lower abundance ratio of Lachnoclostridium, Monoglobus, and Oscillibacter genera, which have been reported to be involved in inflammation. The present study suggests that OLL2712 ingestion has protective effects against memory function decline in older adults.
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Probiotic Bifidobacterium longum BB68S Improves Cognitive Functions in Healthy Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial.
Shi, S, Zhang, Q, Sang, Y, Ge, S, Wang, Q, Wang, R, He, J
Nutrients. 2022;15(1)
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Probiotics, live microorganisms that provide health benefits when administered regularly in the host, substantially affect the composition as well as metabolic output of the gut microbiome. Probiotics can impact brain health and host behaviours through the microbiota-gut-brain axis. The aim of this study was to investigate the effects of Bifidobacterium longum BB68S (BB68S) [probiotics] on the cognitive function of healthy elderly people aged 60–75 years. This study was a randomised, double-blind, placebo-controlled trial. The subjects (n=60) were evenly and randomly allocated to the probiotic or placebo groups. Results showed that the subjects had good tolerance to the probiotic intervention in this study and no side effects were reported. The BB68S intervention significantly improved cognitive function compared to that of controls. Amongst the 12 items, list learning, story memory, figure copy, line orientation, coding, story recall, and figure recall scores of the probiotic group improved significantly. Among the 5 domains, only language did not significantly improve. Authors conclude that BB68S could improve cognitive function thus probiotics may be used as an alternative strategy to advance cognitive aging and promote healthy aging.
Abstract
Probiotics could improve cognitive functions in patients with neurological disorders such as Alzheimer’s disease, but the effects on cognitive function in healthy older adults without cognitive impairment need further study. The purpose of this study was to investigate the effect of Bifidobacterium longum BB68S (BB68S) on cognitive functions among healthy older adults without cognitive impairment. A randomized, double-blind, placebo-controlled trial was conducted with 60 healthy older adults without cognitive impairment who were divided into probiotic or placebo groups and required to consume either a sachet of probiotic (BB68S, 5 × 1010 CFU/sachet) or placebo once daily for 8 weeks. The Montreal Cognitive Assessment (MoCA) was used as an inclusion screening tool to screen elderly participants with healthy cognitive function in our study, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was used to assess cognitive function in subjects before and after intervention as an assessment tool. BB68S significantly improved subjects’ cognitive functions (total RBANS score increased by 18.89 points after intervention, p < 0.0001), especially immediate memory, visuospatial/constructional, attention, and delayed memory domains. BB68S intervention increased the relative abundances of beneficial bacteria Lachnospira, Bifidobacterium, Dorea, and Cellulosilyticum, while decreasing those of bacteria related to cognition impairment, such as Collinsella, Parabacteroides, Tyzzerella, Bilophila, unclassified_c_Negativicutes, Epulopiscium, Porphyromonas, and Granulicatella. In conclusion, BB68S could improve cognitive functions in healthy elderly adults without cognitive impairment, along with having beneficial regulatory effects on their gut microbiota. This study supports probiotics as a strategy to promote healthy aging and advances cognitive aging research.
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Consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomized controlled trial.
Shin, JH, Kim, CS, Cha, L, Kim, S, Lee, S, Chae, S, Chun, WY, Shin, DM
The Journal of nutritional biochemistry. 2022;99:108854
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Disturbances in a person’s mood interrupts their personal well-being and the ability to participate in social interactions, leading to physical health problems such as chronic diseases. The role of diet as a mood regulator has received a great deal of interest. Certain dietary components have been shown to reduce anxiety and depression and improve quality of life. The aim of this study was to investigate the effects of dark chocolate intake on mood in everyday life, with special emphasis on the gut-brain axis. This study is a randomized controlled trial. Participants who met the criteria for eligibility were randomly assigned to one of three groups: (1) control group (CON, n=14); 2) 85% cocoa chocolate group (DC85, n=18); and 3) 70% cocoa chocolate group (DC70, n=16). Results show that daily intake of dark chocolate significantly reduced negative affect in the DC85, but not in the DC70. Furthermore, gut microbial diversity was significantly higher in DC85 than the CON. Authors conclude that dark chocolate has prebiotic effects by restructuring the diversity and composition of the gut microbiome, which may in turn improve mood via the gut-brain axis.
Expert Review
Conflicts of interest:
None
Take Home Message:
- To highlight the potential benefits of high cocoa content dark chocolate in relation to mental states
- To promote more awareness of how dietary habits may impact emotional wellbeing
- To emphasise the importance of microbiota and the gut-brain axis regarding dietary habits.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Background
The authors highlight that dark chocolate has been continually identified for its effects on mood. However, there is a dearth of evidence concerning the emotional impact of daily consumption of dark chocolate. Hence, the impact of dark chocolate consumption on daily mood, focusing on the gut-brain axis, is being investigated in this study.
Objectives
- To evaluate the correlation between the effect on emotional state after consuming dark chocolate and the gut microbiota in healthy adults
- To identify alterations in the composition and diversity of the microorganisms in the gastrointestinal tract on account of dark chocolate intake.
Study Design
A randomised controlled trial was performed at Seoul National University from July to December 2017, This involved. consumption of two types of dark chocolate (70% and 85% cocoa content). Subjects in the treatment groups were blinded although investigators and the control cohort were unblinded.
Participants
117 individuals were screened. However, 48 healthy males and females aged 20-30 years were eligible at baseline.
Interventions
- Subjects (n=16): Consumed 30g/day of 70% cocoa chocolate for 3 weeks
- Participants (n=18): Consumed 30g/day of 85% cocoa chocolate for 3 weeks
- Participants (n=14): The control group consumed no chocolate for 3 weeks.
Main Health Outcomes Measured
- Mood states were quantified via the Positive and Negative Affect Schedule in tandem with Microbiota analysis pre- and post-experiment
- Body composition analysis and dietary assessment were also conducted pre- and post-intervention
- Faecal 16S rRNA sequencing analysis of bacterial genomic DNA was conducted for the cohort who consumed 85% cocoa chocolate and the control arm to evaluate the association between the mood-altering effects of dark chocolate and the gut microbiota
- Statistical tests were performed based on intention-to-treat analysis. The Chi-squared test, Kruskal-Wallis test, one-way ANOVA, unpaired t-test and Mann-Whitney U test were employed for inter-group analysis. Spearman's correlation analysis was used to assess the association between gut microbiota composition and mood scores and P<.05 was considered statistically significant.
Results
- Daily intake of dark chocolate substantially diminished negative emotional states in the cohort consuming 85% cocoa content, but not in the 70% cocoa treatment arm
- Gut microbial diversity was substantially greater in the 85% cacao cohort than the control group (P<.05)
- Blautia obeum levels were significantly elevated and Faecalibacterium prausnitzii levels were decreased in the 85% cacao cohort than the control arm (P<.05).
- Furthermore, it was observed that changes in negative affect scores were inversely correlated with diversity and relative abundance of Blautia obeum (P<.05).
Conclusions
The observations suggest that consumption of dark chocolate with a higher cocoa content may induce prebiotic effects due to its capacity to restructure the diversity and composition of the gut microbiota. Furthermore, consuming dark chocolate with a higher cocoa might exert a positive effect on negative emotional states through the gut-brain axis.
Clinical practice applications:
- To inform practitioners of the benefits of 30g/day high (85%) cocoa chocolate consumption and its potential positive impact on mood through the gut-brain axis
- To educate clients regarding the potential benefits of daily high cocoa content chocolate consumption and its possible favourable effect on emotional states associated with gut microbiota.
Considerations for future research:
- More extensive research could investigate interventions of a longer period
- Further studies could evaluate if any difference exists between cocoa and cacao consumption and emotional states via the gut-brain axis, and the strength of any associations
- Interventions could investigate which strains of bacteria that high cocoa content dark chocolate may affect.
Abstract
Dark chocolate has long been recognized for its mood-altering properties; however, the evidence regarding the emotional effects of daily dark chocolate intake is limited. Therefore, we aimed to investigate the effects of dark chocolate intake on mood in everyday life, with special emphasis on the gut-brain axis. Two different dark chocolates (85% and 70% cocoa content) were tested in this study. In a randomized controlled trial, healthy adults (20-30 y) consumed either 30 g/d of 85% cocoa chocolate (DC85, n=18); 70% cocoa chocolate (DC70, n=16); or no chocolate (control group, CON; n=14); for 3 weeks. Mood states were measured using the Positive and Negative Affect Schedule (PANAS). Daily consumption of dark chocolate significantly reduced negative affect in DC85, but not in DC70. To assess the association between the mood-altering effects of dark chocolate and the gut microbiota, we performed fecal 16S rRNA sequencing analysis for the DC85 and CON groups. Gut microbial diversity was significantly higher in DC85 than CON (P<.05). Blautia obeum levels were significantly elevated and Faecalibacterium prausnitzii levels were reduced in DC85 compared to CON (P<.05). Furthermore, we found that the observed changes in negative affect scores were negatively correlated with diversity and relative abundance of Blautia obeum (P<.05). These findings indicate that dark chocolate exerts prebiotic effects, as evidenced by its ability to restructure the diversity and abundance of intestinal bacteria; thus, it may improve negative emotional states via the gut-brain axis.
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Feed your microbes to deal with stress: a psychobiotic diet impacts microbial stability and perceived stress in a healthy adult population.
Berding, K, Bastiaanssen, TFS, Moloney, GM, Boscaini, S, Strain, CR, Anesi, A, Long-Smith, C, Mattivi, F, Stanton, C, Clarke, G, et al
Molecular psychiatry. 2022
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Psychobiotic describe any exogenous intervention that leads to a bacterially mediated impact on the brain. Probiotics and prebiotics have shown promising results as psychobiotic agents in both animal and human studies. The aim of this study was to investigate the potential of a whole diet psychobiotic approach to modulate the microbiota composition and function, affect responses to and feelings of stress and improve mood in a healthy population. This study is a single-blind, randomized, controlled study which recruited healthy adult (male and female) participants with poor dietary habits, aged 18–59 years. Participants were block randomized (block of 4, stratified by gender) into either intervention or control group using randomly permuted blocks and were instructed to follow their respective diet for 4 weeks. Results show that a short term psychobiotic dietary intervention improved perceived stress in a healthy population, while eliciting specific metabolic changes in the gut microbiota. Authors conclude that underlying microbial influences need to be investigated and future preclinical experiments are required to explore causality and decipher mechanistic pathways.
Expert Review
Conflicts of interest:
None
Take Home Message:
Eating foods known to have a positive influence on gut microbial composition could elicit benefits in terms of reducing perceived stress and improving sleep quality.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
This RCT explored the impact of a psychobiotic diet, compared to a control diet, on perceived stress, sleep and gut microbiota.
A high psychobiotic diet is one high in prebiotic and fermented foods. In this study, a psychobiotic diet included daily recommended consumption and servings of the following:
- High prebiotic fruit & veg (6-8)
- Grains (5-8)
- Fermented foods (2-3)
- Legumes (3-4 per week)
Methodology:
- A single-blind, randomised, controlled study
- 45 healthy adults (18-59 years) with poor dietary habits
- Sample size determined by previous microbiome research - target not reached due to introduction of covid restrictrictions
- Active intervention (n=24) received dietitian advice to follow psychobitoic diet
- Control intervention (n=21) received dietitian advice largely based on the Irish Healthy Eating Guidelines food pyramid
- Intervention duration 4 weeks.
- Assessed on questionnaire measures of perceived stress and sleep, pre and post-intervention (no primary outcome defined)
- Shotgun microbiome analysis on stool samples, pre and post-intervention
Results:
- Perceived stress improved in the psychobiotic diet group
- Subjective sleep quality improved in the psychobiotic diet group
- Only subtle changes in microbial composition and function
- More stable microbiota throughout the study (regardless of diet) was correlated with greater changes in perceived stress
- Neither cortisol awakening response nor measured immune markers were affected by dietary intervention
Conclusions:
- Using a diet targeted to positively modulate gut-brain communication may have the potential for reducing stress and improving sleep
- Although improvements in stress were only observed for the intervention group – the post-intervention stress levels were not significantly different between the groups.
- Thus, we should interpret the results with some caution
Clinical practice applications:
- Providing advice on dietary intake of foods known to positively impact gut microbiota may be helpful for individuals affected by stress or sleep problems
- The inclusion of the following foods may be helpful:
- High prebiotic fruit & veg (6-8 per day)
- Grains (5-8 per day)
- Fermented foods (2-3 per day)
- Legumes (3-4 per week)
Considerations for future research:
- Important to replicate these results in a larger sample
- It might be helpful to investigate individual aspects of the diet separately, to assess their individual impact
- Objective measures of sleep (such as actigraphy recordings) might provide additionally useful findings
- It would be interesting to explore the effect of the psychobiotic diet in other conditions
- Chronobiology or chrononutrition - i.e. looking at timing of the foods proposed in the section above
Abstract
The impact of diet on the microbiota composition and the role of diet in supporting optimal mental health have received much attention in the last decade. However, whether whole dietary approaches can exert psychobiotic effects is largely understudied. Thus, we investigated the influence of a psychobiotic diet (high in prebiotic and fermented foods) on the microbial profile and function as well as on mental health outcomes in a healthy human population. Forty-five adults were randomized into either a psychobiotic (n = 24) or control (n = 21) diet for 4 weeks. Fecal microbiota composition and function was characterized using shotgun sequencing. Stress, overall health and diet were assessed using validated questionnaires. Metabolic profiling of plasma, urine and fecal samples was performed. Intervention with a psychobiotic diet resulted in reductions of perceived stress (32% in diet vs. 17% in control group), but not between groups. Similarly, biological marker of stress were not affected. Additionally, higher adherence to the diet resulted in stronger decreases in perceived stress. While the dietary intervention elicited only subtle changes in microbial composition and function, significant changes in the level of 40 specific fecal lipids and urinary tryptophan metabolites were observed. Lastly, microbial volatility was linked to greater changes in perceived stress scores in those on the psychobiotic diet. These results highlight that dietary approaches can be used to reduce perceived stress in a human cohort. Using microbiota-targeted diets to positively modulate gut-brain communication holds possibilities for the reduction of stress and stress-associated disorders, but additional research is warranted to investigate underlying mechanisms, including the role of the microbiota.