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The Effects of Black Tea Consumption on Intestinal Microflora-A Randomized Single-Blind Parallel-Group, Placebo-Controlled Study.
Tomioka, R, Tanaka, Y, Suzuki, M, Ebihara, S
Journal of nutritional science and vitaminology. 2023;69(5):326-339
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Tea from the leaves of the tea plant (Camelia sinensis) is consumed around the world. Tea has many health benefits, and in part, this is due to its rich content in compounds classed as polyphenols. Through the fermentation process, black tea is particularly high in polyphenols. Previous studies around respiratory infections indicated that regular consumption of black tea appeared to improve immune defence mechanisms that protect mucous membranes, called mucosal immunity. As this mucosal immunity is closely influenced by gut bacteria, the authors speculated whether the previously seen impact of improved mucosal immunity is related to the ability of black tea to also modulate bacteria in the gut. A previously run randomised single-blinded, placebo-controlled trial with 72 Japanese participants who consumed three cups of black tea (2g) or a placebo of barley tea for 12 weeks provided the data for this study. Data gathered included gut flora analysis, short-chain fatty acids (SCFAs) levels - fats that play a role in maintaining gut health, and saliva IgA (SIgA) concentrations - which are antibodies made in the lymph tissue of the gut. The results showed that black tea consumption led to a significant increase in the abundance of Prevotella bacteria, which mediate SCFA production and are involved in normalising immune function. Furthermore, tea increased butyrate-producing bacteria. Butyrate is associated with improved barrier function of the gut walls but also helps to manage pathogens and immune responses. Black tea consumption also increased salivary SIgA concentration - a type of antibody on the mucous membranes that prevents pathogens from entering the body -, and a decrease in stool acetic acid concentration, which may be due to the increase in butyrate-producing bacteria which use acetic acid to make butyrate. Notably, participants with low salivary SIgA levels at the start had a more pronounced positive change in total bacteria, after consuming black tea compared to the placebo group. The authors concluded that regular consumption of black tea may help to improve mucosal immunity by increasing the abundance of beneficial bacteria in the gut.
Abstract
We previously reported that black tea consumption for 12 wk reduced the risk of acute upper respiratory tract inflammation, and improved secretory capacity in individuals with low salivary SIgA levels (Tanaka Y et al. 2021. Jpn Pharmacol Ther 49: 273-288). These results suggested that habitual black tea consumption improves mucosal immunity. Therefore, in this study we evaluated the effect of black tea intake on gut microbiota, which is known to be involved in mucosal immunity, by analyzing the bacterial flora and the short-chain fatty acids (SCFAs) concentration of feces collected during the above clinical study. The clinical design was a randomized, single-blind, parallel-group, placebo-controlled study with 72 healthy Japanese adult males and females, who consumed three cups of black tea (Black Tea Polymerized Polyphenols 76.2 mg per day) or placebo per day for 12 wk. In all subjects intake of black tea significantly increased abundance of Prevotella and decreased fecal acetic acid concentration. Particularly in the subjects with low salivary SIgA levels, the change over time of total bacteria, Prevotella, and butyrate-producing bacteria, which are involved in normalizing immune function, were higher in the black tea group than in the placebo group. In subjects with low abundance of Flavonifractor plautii a butyrate-producing bacteria, black tea consumption significantly increased salivary SIgA concentration and the absolute number of Flavonifractor plautii. In conclusion, our results suggest that improvement of mucosal immunity via an increase in butyrate-producing bacteria in the gut may partly contribute to the suppressive effect of black tea consumption on acute upper respiratory tract inflammation observed in our previous report.
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Human milk miRNAs associate to maternal dietary nutrients, milk microbiota, infant gut microbiota and growth.
Yeruva, L, Mulakala, BK, Rajasundaram, D, Gonzalez, S, Cabrera-Rubio, R, Martínez-Costa, C, Collado, MC
Clinical nutrition (Edinburgh, Scotland). 2023;42(12):2528-2539
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Human milk is a source of nutrition during the early stages of development. Human milk contains nutritive and non-nutritive bioactives such as microRNAs (miRNAs or miRs). These bioactives likely program an infant's growth, development, and physiological systems (i.e., immune system, brain, liver). The aim of this study was to examine the potential impact of maternal diet on human milk miRNAs profile and the link to microbiota. This study was an observational study which included a subset of 60 healthy lactating women (n = 30 milk samples in each cluster). Results showed that that: - human milk miRNA's profile was altered based on maternal dietary protein source (plant or animal protein). - miRNA features were distinct based on maternal diet intake and correlated with dietary plant polyphenols, and milk microbiota. - milk miRNAs, irrespective of maternal dietary source, have a strong correlation with infant gut microbiota early in life as well as to infant anthropometric measures. Authors concluded that their findings extend current knowledge that milk miRNAs are differentially expressed based on maternal protein source, associate with specific set of milk microbiota and maternal intake of polyphenols, and infant microbiota for optimal growth and development.
Abstract
BACKGROUND Maternal diet influences the milk composition, yet little information is available on the impact of maternal diet on milk miRNAs expression. Further, the association of human milk miRNAs to maternal diet and milk microbiota is not explored. In addition, the role of milk miRNAs on the infant gut microbiota, infant growth and development has not been investigated. METHODS Milk samples were collected from 60 healthy lactating women at ≤15d post-partum, HTG transcriptome assay was performed to examine milk miRNA profile. Maternal clinical and dietary clusters information were available and infant anthropometric measures were followed up to one year of age. Milk and infant microbiota were analyzed by 16S rRNA gene sequencing and integrative multi-omics data analysis was performed to identify potential association between microRNA, maternal dietary nutrients and microbiota. RESULTS Discriminant analysis revealed that the milk miRNAs were clustered into groups according to the maternal protein source. Interestingly, 31 miRNAs were differentially expressed (P adj < 0.05) between maternal dietary clusters (Cluster 1: enriched in plant protein and fibers and Cluster 2: enriched in animal protein), with 30 miRNAs downregulated in the plant protein group relative to animal protein group. Pathway analysis revealed that the top enriched pathways (P adj < 0.01) were involved in cell growth and proliferation processes. Furthermore, significant features contributing to the clustering were associated with maternal dietary nutrients and milk microbiota (r > 0.70). Further, miR-378 and 320 family miRNAs involved in adipogenesis were positively correlated to the infant BMI-z-scores, weight, and weight for length-z-scores at 6 months of age. CONCLUSIONS Maternal dietary source impacts the milk miRNA expression profile. Further, miRNAs were associated with maternal dietary nutrients, milk microbiota and to the infant gut microbiota and infant growth and development. CLINICAL TRIAL The study is registered in ClinicalTrials.gov. The identification number is NCT03552939.
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Impact of Blueberry Consumption on the Human Fecal Bileacidome: A Pilot Study of Bile Acid Modulation by Freeze-Dried Blueberry.
Gagnon, W, Garneau, V, Trottier, J, Verreault, M, Couillard, C, Roy, D, Marette, A, Drouin-Chartier, JP, Vohl, MC, Barbier, O
Nutrients. 2022;14(18)
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Primary bile acids (BAs) are made in the liver from cholesterol. They are released into the small intestine, where they aid fat digestion and absorption. Most BAs are reabsorbed from the gut, yet a small amount gets modified by the gut bacteria, forming secondary BAs destined for faecal excretion. Excess secondary BAs have negative health consequences. The different types of primary BAs influence many physiological functions. Such as glucose regulation, fat metabolism and absorption, intestinal inflammation and immunity, as well as gut bacteria diversity. For optimal BA metabolism, they are tightly regulated by the body, as minimal changes in BA pool and composition can have a significant impact on overall health. The composition of the BA pool can be influenced by gut bacteria, metabolic disorders, pathologies of the liver and gut, and diet. Dietary polyphenols, a plant-based compound, have been of particular interest here. This study sought to investigate the impact of supplementary freeze-dried blueberry powder (BBP), a rich polyphenol source, on the faecal BA pool composition in people at risk of metabolic syndrome. For this 11 men and 13 women were supplemented for 8 weeks. When compared to the data before the intervention, no significant changes in total BAs were observed. However, the composition of the BA pool changed leading to the accumulation of particular BAs and a reduction in secondary BA levels. This suggested that the consumption of blueberries can be considered a potential clinical intervention to aid the elimination of toxic secondary BAs. As the mechanisms leading to such modifications and their consequences for human health are complex, the authors advocate for investigation in larger population groups and also alert that such changes may be subject to interindividual variability and health status.
Abstract
Cholesterol-derived bile acids (BAs) affect numerous physiological functions such as glucose homeostasis, lipid metabolism and absorption, intestinal inflammation and immunity, as well as intestinal microbiota diversity. Diet influences the composition of the BA pool. In the present study, we analyzed the impact of a dietary supplementation with a freeze-dried blueberry powder (BBP) on the fecal BA pool composition. The diet of 11 men and 13 women at risk of metabolic syndrome was supplemented with 50 g/day of BBP for 8 weeks, and feces were harvested before (pre) and after (post) BBP consumption. BAs were profiled using liquid chromatography coupled with tandem mass spectrometry. No significant changes in total BAs were detected when comparing pre- vs. post-BBP consumption samples. However, post-BBP consumption samples exhibited significant accumulations of glycine-conjugated BAs (p = 0.04), glycochenodeoxycholic (p = 0.01), and glycoursodeoxycholic (p = 0.01) acids, as well as a significant reduction (p = 0.03) in the secondary BA levels compared with pre-BBP feces. In conclusion, the fecal bileacidome is significantly altered after the consumption of BBP for 8 weeks. While additional studies are needed to fully understand the underlying mechanisms and physiological implications of these changes, our data suggest that the consumption of blueberries can modulate toxic BA elimination.
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Dietary macronutrients and the gut microbiome: a precision nutrition approach to improve cardiometabolic health.
Jardon, KM, Canfora, EE, Goossens, GH, Blaak, EE
Gut. 2022;71(6):1214-1226
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The global rise in the prevalence of obesity is strongly associated with an increase in the incidence and prevalence of cardiometabolic diseases, including insulin resistance (IR) and type 2 diabetes mellitus. In recent years, advancements have been made in understanding the involvement of the gut microbiome in obesity and related cardiometabolic complications as regulator of host energy and substrate metabolism. This study is a review that discusses the latest research describing interactions between dietary composition, the gut microbiome and host metabolism. Results show that current evidence for developing optimal dietary interventions targeting bodyweight control and IR via the gut microbiota is still in its infancy and does not capture the complexity of the integration of a whole-diet approach, the microbial and the host’s metabolic phenotype. Furthermore, implementation of targeted, precision nutrition intervention strategies or dietary guidelines for individuals or subgroups in public health requires further insight in the mechanisms involved in (non-)response to dietary intervention. Authors conclude that future studies are needed and these should focus on assessing detailed individual phenotyping and gaining insight into the balance between carbohydrate and protein fermentation by the gut microbiota as well as the site of fermentation in the colon.
Abstract
Accumulating evidence indicates that the gut microbiome is an important regulator of body weight, glucose and lipid metabolism, and inflammatory processes, and may thereby play a key role in the aetiology of obesity, insulin resistance and type 2 diabetes. Interindividual responsiveness to specific dietary interventions may be partially determined by differences in baseline gut microbiota composition and functionality between individuals with distinct metabolic phenotypes. However, the relationship between an individual's diet, gut microbiome and host metabolic phenotype is multidirectional and complex, yielding a challenge for practical implementation of targeted dietary guidelines. In this review, we discuss the latest research describing interactions between dietary composition, the gut microbiome and host metabolism. Furthermore, we describe how this knowledge can be integrated to develop precision-based nutritional strategies to improve bodyweight control and metabolic health in humans. Specifically, we will address that (1) insight in the role of the baseline gut microbial and metabolic phenotype in dietary intervention response may provide leads for precision-based nutritional strategies; that (2) the balance between carbohydrate and protein fermentation by the gut microbiota, as well as the site of fermentation in the colon, seems important determinants of host metabolism; and that (3) 'big data', including multiple omics and advanced modelling, are of undeniable importance in predicting (non-)response to dietary interventions. Clearly, detailed metabolic and microbial phenotyping in humans is necessary to better understand the link between diet, the gut microbiome and host metabolism, which is required to develop targeted dietary strategies and guidelines for different subgroups of the population.
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The effects of Aronia berry (poly)phenol supplementation on arterial function and the gut microbiome in middle aged men and women: Results from a randomized controlled trial.
Le Sayec, M, Xu, Y, Laiola, M, Gallego, FA, Katsikioti, D, Durbidge, C, Kivisild, U, Armes, S, Lecomte, M, Fança-Berthon, P, et al
Clinical nutrition (Edinburgh, Scotland). 2022;41(11):2549-2561
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Over the last decades, Aronia melanocarpa, or black chokeberry, has gained increased attention for its high content of (poly)phenols, and potential protection against chronic diseases such as cardiovascular disease and diabetes. The aim of this study was to investigate the effects of 12-week aronia berry (poly)phenol consumption on cardiometabolic health and gut microbiome composition in prehypertensive middle-aged adults. This study was a 2-arm, double-blind, parallel randomised controlled trial. Participants (n = 102; 47 men and 55 women) were assigned randomly to Aronia or control groups. Results showed that there were no significant effects in blood pressure (primary outcome), endothelial function or blood lipids. However, there was a significant improvement in 24-hour ambulatory arterial indices and significant changes in gut microbiome richness, functions and composition between Aronia and control groups. Authors conclude that future studies should be conducted to investigate whether aronia supplementation may be effective in other at-risk populations such as hypertensives or people with cardiovascular disease risk.
Abstract
BACKGROUND AND AIMS Berry (poly)phenol consumption has been associated with cardioprotective benefits, however little is known on the role the gut microbiome may play on such health benefits. Our objective was to investigate the effects of aronia berry (poly)phenol consumption on cardiometabolic health and gut microbiome richness and composition in prehypertensive middle-aged men and women. METHODS A total of 102 prehypertensive participants were included in a parallel 12-week randomized double-blind placebo-controlled trial. Volunteers were randomly allocated to daily consume an encapsulated (poly)phenol-rich aronia berry extract (Aronia, n = 51) or a matched maltodextrin placebo (Control, n = 51). Blood pressure (BP) and arterial function (office and 24 h), endothelial function (measured as flow-mediated dilation), serum biochemistry (including blood lipids), plasma and urine (poly)phenol metabolites as well as gut microbiome composition through shotgun metagenomic sequencing were monitored over the study period. Relationships between vascular outcomes, (poly)phenol metabolites and gut microbiome were investigated using an integrated multi-levels approach. RESULTS A significant improvement in arterial indices measured as augmentation index (AIx) and pulse wave velocity (PWV) was found in the Aronia compared to Control group (awake Δ PWV = -0.24 m/s; 95% CI: -0.79, -0.01 m/s, P < 0.05; 24 h peripheral Δ AIx = -6.8; -11.2, -2.3, %, P = 0.003; 24 h central Δ AIx = -3.3; -5.5, -1.0, %, P = 0.006). No changes in BP, endothelial function or blood lipids were found following the intervention. Consumption of aronia (poly)phenols led to a significant increase in gut microbiome gene richness and in the abundance of butyrate-producing species such as Lawsonibacter asaccharolyticus and Intestinimonas butyriciproducens species, compared to Control group. Results from an approach including metabolomic, metagenomic and clinical outcomes highlighted associations between aronia-derived phenolic metabolites, arterial stiffness, and gut microbiome. CONCLUSIONS Aronia berry (poly)phenol consumption improved arterial function in prehypertensive middle-aged individuals, possibly via modulation of gut microbiome richness and composition based on the associations observed between these parameters. CLINICAL TRIAL REGISTRY The National Institutes of Health (NIH)-randomized trial records held on the NIH ClinicalTrials.gov website (NCT03434574). Aronia Berry Consumption on Blood Pressure.
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The effects of phosphocreatine disodium salts plus blueberry extract supplementation on muscular strength, power, and endurance.
Anders, JPV, Neltner, TJ, Smith, RW, Keller, JL, Housh, TJ, Daugherty, FJ, Tempesta, MS, Dash, AK, Munt, DJ, Schmidt, RJ, et al
Journal of the International Society of Sports Nutrition. 2021;18(1):60
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The effects of polyphenols and phosphocreatine supplementation on exercise performance, muscular strength, power, and endurance are largely unknown. This randomised, double-blinded, placebo-controlled, parallel-design trial aimed to differentiate the effects of a blend of 5 grams of phosphocreatine disodium salts plus 200 mg blueberry extract (PCDSB), 3 grams of Creatinine monohydrate (CM), and placebo on measures of muscular strength, power, and endurance. PCDSB contained 60 grams of phenols and 2.5 grams of pure creatine, and CM contained 2.4 grams of pure creatin. During this trial, thirty-three men took random supplements for 28 days and kept up their regular exercise regimen. In both PCDSB and CM, Peak torque (PT) and Average power (AP) increased after 28 days of supplementation with no effect on fatigue-induced PT% and AP% or body mass. Additionally, a greater proportion of participants showed a meaningful increase in muscular strength to PCDSB than to CM. To evaluate the additive effects of ingredients in the PCDSB supplement, longer-term studies are needed with larger supplementation doses. The study provides insight into the ergogenic effects of PCDSB and CM for healthcare practitioners.
Abstract
BACKGROUND Numerous studies have demonstrated the efficacy of creatine supplementation for improvements in exercise performance. Few studies, however, have examined the effects of phosphocreatine supplementation on exercise performance. Furthermore, while polyphenols have antioxidant and anti-inflammatory properties, little is known regarding the influence of polyphenol supplementation on muscular strength, power, and endurance. Thus, the purpose of the present study was to compare the effects of 28 days of supplementation with phosphocreatine disodium salts plus blueberry extract (PCDSB), creatine monohydrate (CM), and placebo on measures of muscular strength, power, and endurance. METHODS Thirty-three men were randomly assigned to consume either PCDSB, CM, or placebo for 28 days. Peak torque (PT), average power (AP), and percent decline for peak torque (PT%) and average power (AP%) were assessed from a fatigue test consisting of 50 maximal, unilateral, isokinetic leg extensions at 180°·s- 1 before and after the 28 days of supplementation. Individual responses were assessed to examine the proportion of subjects that exceeded a minimal important difference (MID). RESULTS The results demonstrated significant (p < 0.05) improvements in PT for the PCDSB and CM groups from pre- (99.90 ± 22.47 N·m and 99.95 ± 22.50 N·m, respectively) to post-supplementation (119.22 ± 29.87 N·m and 111.97 ± 24.50 N·m, respectively), but no significant (p = 0.112) change for the placebo group. The PCDSB and CM groups also exhibited significant improvements in AP from pre- (140.18 ± 32.08 W and 143.42 ± 33.84 W, respectively) to post-supplementation (170.12 ± 42.68 W and 159.78 ± 31.20 W, respectively), but no significant (p = 0.279) change for the placebo group. A significantly (p < 0.05) greater proportion of subjects in the PCDSB group exceeded the MID for PT compared to the placebo group, but there were no significant (p > 0.05) differences in the proportion of subjects exceeding the MID between the CM and placebo groups or between the CM and PCDSB groups. CONCLUSIONS These findings indicated that for the group mean responses, 28 days of supplementation with both PCDSB and CM resulted in increases in PT and AP. The PCDSB, however, may have an advantage over CM when compared to the placebo group for the proportion of individuals that respond favorably to supplementation with meaningful increases in muscular strength.
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Effect of Hesperidin on Cardiovascular Disease Risk Factors: The Role of Intestinal Microbiota on Hesperidin Bioavailability.
Mas-Capdevila, A, Teichenne, J, Domenech-Coca, C, Caimari, A, Del Bas, JM, Escoté, X, Crescenti, A
Nutrients. 2020;12(5)
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Cardiovascular diseases (CVDs) cause around 31% of all deaths worldwide. Certain dietary patterns have been associated with a reduction in CVDs and so the use of natural-based products has gained importance as a preventive strategy. Hesperidin is a bioactive compound found in high levels in citrus fruits. The reported beneficial properties include antitumor, antioxidant, anti-inflammatory; cholesterol and glucose lowering effects. Many animal studies show multiple beneficial effects but are inconclusive in human studies. The aim of this review is to describe the effects of hesperidin on CVD factors and to highlight the individual differences in its bioavailability and effectiveness. The gut bacteria play an important role in this. Hesperidin is not broken down by the normal digestive process and reaches the colon largely intact. It is the job of the gut bacteria to break it down into bioavailable substances that can be absorbed and utilised. The discrepancies observed in some of the results from human clinical trials may be partly due to individual differences, including that of the gut bacteria. Further clinical trials should be considered as well as classifying individuals according to individual differences in metabotypes.
Abstract
Recently, hesperidin, a flavonone mainly present in citrus fruits, has emerged as a new potential therapeutic agent able to modulate several cardiovascular diseases (CVDs) risk factors. Animal and in vitro studies demonstrate beneficial effects of hesperidin and its derived compounds on CVD risk factors. Thus, hesperidin has shown glucose-lowering and anti-inflammatory properties in diabetic models, dyslipidemia-, atherosclerosis-, and obesity-preventing effects in CVDs and obese models, and antihypertensive and antioxidant effects in hypertensive models. However, there is still controversy about whether hesperidin could contribute to ameliorate glucose homeostasis, lipid profile, adiposity, and blood pressure in humans, as evidenced by several clinical trials reporting no effects of treatments with this flavanone or with orange juice on these cardiovascular parameters. In this review, we focus on hesperidin's beneficial effects on CVD risk factors, paying special attention to the high interindividual variability in response to hesperidin-based acute and chronic interventions, which can be partly attributed to differences in gut microbiota. Based on the current evidence, we suggest that some of hesperidin's contradictory effects in human trials are partly due to the interindividual hesperidin variability in its bioavailability, which in turn is highly dependent on the α-rhamnosidase activity and gut microbiota composition.
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Potential Factors Influencing the Effects of Anthocyanins on Blood Pressure Regulation in Humans: A Review.
Vendrame, S, Klimis-Zacas, D
Nutrients. 2019;11(6)
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Anthocyanins (ACNs) are plant compounds belonging to the flavonoid group of polyphenols and are naturally occurring in a number of foods. They are responsible for the red, blue and purple pigmentation within plant foods, such as blueberries and raspberries and are known to contain therapeutic compounds. Several studies have investigated the anti-inflammatory, antioxidant and blood pressure modulation properties within ACNs, however, results for blood pressure modulation, unlike those for anti-inflammatory and antioxidant properties have been mixed and less consistent. This paper reviews 66 human intervention trials exploring the effects of various forms of ACNs, like whole berries, concentrates and freeze-dried powders in order to identify the singular variables related to blood pressure modulation in order to further investigate. Having looked at a number of variables within the trials, researchers concluded that ACNs do in fact contain blood pressure lowering properties, but further research into varying factors including dose effect, synergistic effects, absorption and metabolism and the functionality of the individuals gut microbiota is needed to clarify results further.
Abstract
Dietary intake of anthocyanins (ACNs) is associated with a reduced risk of cardiovascular and coronary heart disease. While the anti-inflammatory, antioxidant, and lipid-lowering effects of ACN consumption have been consistently reported, their effect(s) on blood pressure regulation is less consistent and results from human studies are mixed. The objective of this review is attempting to identify potential patterns which may explain the variability in results related to blood pressure. To do so, we review 66 human intervention trials testing the effects on blood pressure of purified ACN or ACN-rich extracts, or whole berries, berry juices, powders, purees and whole phenolic extracts, from berries that are rich in ACN and have ACNs as predominant bioactives. Several factors appear to be involved on the mixed results reported. In particular, the baseline characteristics of the population in terms of blood pressure and total flavonoid intake, the dose and duration of the intervention, the differential effects of individual ACN and their synergistic effects with other phytochemicals, the ACN content and bioavailability from the food matrix, and individual differences in ACN absorption and metabolism related to genotype and microbiota enterotypes.
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Mixed Spices at Culinary Doses Have Prebiotic Effects in Healthy Adults: A Pilot Study.
Lu, QY, Rasmussen, AM, Yang, J, Lee, RP, Huang, J, Shao, P, Carpenter, CL, Gilbuena, I, Thames, G, Henning, SM, et al
Nutrients. 2019;11(6)
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An increasing body of evidence suggests that the gut microbiota has a profound impact on human health. While the microbiome of a healthy individual is relatively stable, gut microbial dynamics can be influenced by host lifestyle and dietary choices. The aim of this study was to investigate the effects of mixed spices (cinnamon, oregano, ginger, black pepper, and cayenne pepper) at culinary doses consumed over 2 weeks in a standardized 5g capsule on the production of gut microbiota and short-chain fatty acids The study is a randomised, placebo-controlled, double-blind pilot study carried out with a total of 31 healthy women and men aged between 18 and 65. The subjects were randomly allocated to one of the two intervention groups. Results indicate that daily intake of 5g of mixed spices for 2 weeks in healthy subjects resulted in a significant reduction in the relative abundance of the phylum Firmicutes (bacteria), and a trend of increasing in phylum Bacteroidetes (bacteria) as compared with a matched control group. Authors conclude that a mixture of spices at culinary doses affects the composition of gut microbiota.
Abstract
Spices were used as food preservatives prior to the advent of refrigeration, suggesting the possibility of effects on microbiota. Previous studies have shown prebiotic activities in animals and in vitro, but there has not been a demonstration of prebiotic or postbiotic effects at culinary doses in humans. In this randomized placebo-controlled study, we determined in twenty-nine healthy adults the effects on the gut microbiota of the consumption daily of capsules containing 5 g of mixed spices at culinary doses by comparison to a matched control group consuming a maltodextrin placebo capsule. The 16S ribosomal RNA sequencing data were used for microbial characterization. Spice consumption resulted in a significant reduction in Firmicutes abundance (p < 0.033) and a trend of enrichment in Bacteroidetes (p < 0.097) compared to placebo group. Twenty-six operational taxonomic units (OTUs) were different between the spice and placebo groups after intervention. Furthermore, there was a significant negative correlation between fecal short-chain fatty acid propionate concentration and Firmicutes abundance in spice intervention group (p < 0.04). The production of individual fecal short-chain fatty acid was not significantly changed by spice consumption in this study. Mixed spices consumption significantly modified gut microbiota, suggesting a prebiotic effect of spice consumption at culinary doses.