-
1.
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
-
-
-
Free full text
Plain language summary
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.
-
2.
Gut Microbiota-Derived Metabolites and Cardiovascular Disease Risk: A Systematic Review of Prospective Cohort Studies.
Sanchez-Gimenez, R, Ahmed-Khodja, W, Molina, Y, Peiró, OM, Bonet, G, Carrasquer, A, Fragkiadakis, GA, Bulló, M, Bardaji, A, Papandreou, C
Nutrients. 2022;14(13)
-
-
-
Free full text
Plain language summary
Cardiovascular disease (CVD) remains a major public health issue. Identification of circulating biomarkers with prognostic value may help to both identify pathophysiological processes relevant to CVD development and improve preventive cardiovascular risk reduction efforts. The aim of this study was to identify the association of circulating levels of microbial metabolites with CVD incidence. This study is a systematic review of twenty-one studies of which 19 were prospective cohort studies, one study included one nested case-control study and one study included two nested case–control studies. Results show that: - associations of trimethylamine N-oxide (TMAO) [molecular metabolite derived from the gut flora] and subsequent risk of CV outcomes were supported by some but not all prospective studies. - inconsistent results were also obtained for secondary bile acids in relation to CVD and related outcomes, and CVD/all-cause mortality. - with regards to branched-chain amino acids (BCAAs), their associations with CV outcomes were robust amongst most of the studies. Authors conclude that their findings show inconsistent results for TMAO and bile acids but robust ones for the relationships between BCAAs and CVD. Thus, further studies are needed to investigate whether circulating microbial metabolites could be an intervention target for CVD.
Abstract
Gut microbiota-derived metabolites have recently attracted considerable attention due to their role in host-microbial crosstalk and their link with cardiovascular health. The MEDLINE-PubMed and Elsevier's Scopus databases were searched up to June 2022 for studies evaluating the association of baseline circulating levels of trimethylamine N-oxide (TMAO), secondary bile acids, short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), tryptophan and indole derivatives, with risk of cardiovascular disease (CVD). A total of twenty-one studies were included in the systematic review after evaluating 1210 non-duplicate records. There were nineteen of the twenty-one studies that were cohort studies and two studies had a nested case-control design. All of the included studies were of high quality according to the "Newcastle-Ottawa Scale". TMAO was positively associated with adverse cardiovascular events and CVD/all-cause mortality in some, but not all of the included studies. Bile acids were associated with atrial fibrillation and CVD/all-cause mortality, but not with CVD. Positive associations were found between BCAAs and CVD, and between indole derivatives and major adverse cardiovascular events, while a negative association was reported between tryptophan and all-cause mortality. No studies examining the relationship between SCFAs and CVD risk were identified. Evidence from prospective studies included in the systematic review supports a role of microbial metabolites in CVD.
-
3.
Vegan diet in young children remodels metabolism and challenges the statuses of essential nutrients.
Hovinen, T, Korkalo, L, Freese, R, Skaffari, E, Isohanni, P, Niemi, M, Nevalainen, J, Gylling, H, Zamboni, N, Erkkola, M, et al
EMBO molecular medicine. 2021;13(2):e13492
-
-
-
Free full text
-
Plain language summary
As vegan diets gain popularity amongst families, there is little known about the impact of strict plant-based diets on metabolism and micronutrient status in children, apart from reduced average growth within the norm. This small study looked at 40 Finnish children from one day centre, and compared children following an omnivore or vegetarian diet to those raised on a vegan diet. The diets were analysed, and biomarkers and metabolites were measured. The metabolic profile and nutrient status of children who followed a vegan diet from birth were distinctively different to other diet patterns, including vegetarians. The authors suggest that little animal source foods are enough to shift the metabolism of children. Dietary analysis showed that vegan children had higher folate consumption and lower protein and saturated fats intake. Despite intake appearing adequate, serum markers for fat-soluble vitamins A and D were low. While the fatty acid ALA was higher compared to omnivores, DHA and overall cholesterol were decreased. The authors concluded that the bodies own cholesterol production does not seem to compensate for a lack of dietary cholesterol in this case and it remains to be established whether lower cholesterol in vegan children are negative to health. Furthermore, the circulating amino acids pool was decreased in vegan children, particularly branch chained amino acids. The most distinct difference, however, was seen in the variance of bile acid patterns. The physiological functions of bile acids go beyond digestion, yet the consequences of diverging bile acid profiles in children’s health are unknown. In conclusion, the data shows that a strict vegan diet affects the metabolism of healthy children, but much of the long-term impact on health is currently still unclear. This article highlights some of the differences, risks and uncertainties that come with raising young children on a strictly vegan diet.
Abstract
Vegan diets are gaining popularity, also in families with young children. However, the effects of strict plant-based diets on metabolism and micronutrient status of children are unknown. We recruited 40 Finnish children with a median age 3.5 years-vegans, vegetarians, or omnivores from same daycare centers-for a cross-sectional study. They enjoyed nutritionist-planned vegan or omnivore meals in daycare, and the full diets were analyzed with questionnaires and food records. Detailed analysis of serum metabolomics and biomarkers indicated vitamin A insufficiency and border-line sufficient vitamin D in all vegan participants. Their serum total, HDL and LDL cholesterol, essential amino acid, and docosahexaenoic n-3 fatty acid (DHA) levels were markedly low and primary bile acid biosynthesis, and phospholipid balance was distinct from omnivores. Possible combination of low vitamin A and DHA status raise concern for their visual health. Our evidence indicates that (i) vitamin A and D status of vegan children requires special attention; (ii) dietary recommendations for children cannot be extrapolated from adult vegan studies; and (iii) longitudinal studies on infant-onset vegan diets are warranted.
-
4.
Type 2 diabetes preventive effects with a 12-months sardine-enriched diet in elderly population with prediabetes: An interventional, randomized and controlled trial.
Díaz-Rizzolo, DA, Serra, A, Colungo, C, Sala-Vila, A, Sisó-Almirall, A, Gomis, R
Clinical nutrition (Edinburgh, Scotland). 2021;40(5):2587-2598
-
-
-
Free full text
Plain language summary
Older people have a higher risk of developing Type 2 diabetes (T2D) due to the possibility of β-cell dysfunction due to ageing. Sardines are believed to be protective against the development of T2D. Therefore, this randomised controlled trial evaluated the preventative effects of a sardine-rich diet in elderly prediabetic patients. For one year, both the sardine group (SG) and control group (CG) followed a T2D prevention diet, with the SG consuming 200 g of sardines each week. Both groups improved body weight, BMI, waist and hip circumference, and body composition. Taurine, EPA, DHA, omega-3 fatty acid, calcium, iodine, zinc, phosphorous and fluoride, vitamin B12 and D, and lycopene and tocopherols were found to be higher in the SG than the CG, indicating the sardines were protective against T2D. In SG, HDL cholesterol and adiponectin levels were significantly increased, and blood pressure and triglycerides were decreased, signalling a reduced risk of T2D and cardiovascular disease. In addition, SG showed a reduction in HOMA-IR and an Omega-3 fatty acid was substituted for Omega-6 fatty acids in the erythrocyte membrane, suggesting a reduced risk of T2D. Further robust research is required to confirm the protective effect of a sardine-enriched diet against T2D. It may be useful to healthcare providers to comprehend how a sardine-enriched diet could improve obesity, T2D and CVD markers in pre-diabetic elderly patients.
Abstract
BACKGROUND Fish could play a role in preventing type 2 diabetes (T2D) but there has been little specification about the type of fish and the preventive mechanism involved in its health claim. The sardine is a source of omega-3 and taurine that, in isolation or in synergy, would produce T2D-delaying through different molecular mechanism. HYPOTHESIS The consumption of twice a week of sardine, during one year would reduce T2D-developing risk in a population with prediabetes (preDM) and old age. DESIGN 152 subjects with fasting glucose between 100-124 mg/dL aged ≥65 yo were recruited from three primary care centers in Barcelona and were randomly distributed among two interventional groups: control group (CG) and sardine group (SG). Both groups received same T2D-prevention nutritional during a year but only SG had to add 200 g of sardine per week. All variables were collected before to start and at the end of the diet. (ClinicalTrials.gov: NCT03557541). RESULTS 152 people were randomized into CG (n=77) and SG (n=75) with 18 and 12 drop outs respectively. Subjects in SG, significantly compared to CG, decreased percentage classified-individuals in a very high risk group to develop T2D according to FINDRISC (p=0.035). In addition to increasing HDL-cholesterol and adiponectin and decreasing triglycerides (p<0.05) and blood pressure (<0.05), SG showed a lower HOMA-IR (p=0.032). The consumption of sardine characteristics nutrients as omega-3, EPA and DHA, vitamin D, fluorine and taurine were higher for SG (p<0.05). These results agreed with the increased of taurine, fatty acid (FA) omega-3 and bile acids circulating metabolites (p<0.05). Changes erythrocyte membrane FA were detected only in SG with a decrease of 5 omega-6 FA (p<0.001) and an increase of 3 omega-3 FA types (p<0.001). CONCLUSION We conclude that a year T2D-prevention diet with sardine supplementation has a greater protective effect against developing T2D and CV events.
-
5.
Alternate Day Fasting Improves Physiological and Molecular Markers of Aging in Healthy, Non-obese Humans.
Stekovic, S, Hofer, SJ, Tripolt, N, Aon, MA, Royer, P, Pein, L, Stadler, JT, Pendl, T, Prietl, B, Url, J, et al
Cell metabolism. 2019;30(3):462-476.e6
-
-
-
-
Free full text
Plain language summary
Intermittent fasting and calorie restriction are believed to reduce cardiometabolic risk factors and increase longevity. Fasting alternate days (ADF) involves fasting for 36 hours and eating ad libitum for 12 hours. Thirty healthy participants were randomly assigned to a long-term ADF intervention group for ≥6 months against sixty participants in the control group. After completing the cross-sectional study arm, sixty healthy participants in the control group were randomly assigned to either a four-week short-term ADF intervention group or a control group with an ad libitum diet. Study participants adhered well to the fasting regimen. Both short-term and long-term ADF intervention groups showed a significant reduction in calorie intake, improvements in anthropometric and cardiovascular parameters including reduced BMI, substantial reduction in trunk fat, lower heart rate, increased serum β-hydroxybutyrate which is cardioprotective and anti-ageing, reduced circulating triiodothyronine (fT3) levels which indicate longevity. Short-term ADF reduced systolic and diastolic pressure, mean arterial pressure, pulse pressure, and pulse wave velocity. Long-term ADF intervention reduced circulating total cholesterol, low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and triglycerides, the age-related biomarker sICAM-1 for disease and inflammation, and improved lipid and amino acid metabolites. ADF did not affect insulin sensitivity. Although red blood cells and iron levels were altered, ADF interventions were not associated with iron deficiency. Healthcare professionals can use the results of this study to understand the cardioprotective and anti-ageing properties of ADF. However, further long-term robust studies are required to evaluate the effect of long-term ADF on bone health.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Short duration (<4 weeks) alternate day fasting may be an effective way to implement caloric restriction, improve body composition and reduce cardiovascular disease risk in healthy non-overweight adults.
- >6 months alternate fasting does not appear to be associated with reduced bone mass, bone mineral density of the lumbar spine region, white blood cell counts, ferritin and transferrin when compared to healthy controls.
- Both short term and long term alternate day fasting may reduce triiodothyronine in healthy adults. Low levels of fT3 without thyroid gland dysfunction has been associated with longevity in humans.
- Alternate day fasting should be performed alongside a trained clinician to reduce the risk of adverse effects due to critical medical conditions.
Evidence Category:
-
X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
Introduction
Animal models have consistently demonstrated the healthspan and lifespan benefits of caloric restriction. However, chronic caloric restriction in humans has proven difficult to maintain.
Intermittent fasting may serve as a more manageable alternative to continuous caloric restriction. This randomised controlled trial and cross sectional analysis aimed to investigate the effects of alternate day fasting (ADF) on heart rate, blood pressure, cholesterol levels, CVD risk, body composition, and the metabolome and proteome of healthy, non-overweight adults (cohort median age between 48 and 52 years).
Methods
Prior to the enrollment of the study a cross sectional analysis was conducted on healthy adults engaged in long term (>6 months) alternate day fasting (n=30) and a control group (n=60).
The 60 participants from the cross sectional analysis control group were then randomised to either a 4 week ADF group or a control group. In both the >6 months and 4 weeks of ADF groups, participants were instructed to eat every second-day ad libitum, but to completely exclude solid and liquid foods and caloric beverages on fasting days.
Results
The cross sectional analysis identified that the alternate day fasting group:
- Consumed fewer calories vs the control group (−28.56%, p=0.0002).
- Had lower levels of circulating total cholesterol (p=0.004), LDL (p=0.011), VLDL (p=0.009), triglycerides (p=0.010) and a lower heart rate (p=0.040) vs the control group.
- Lower levels of soluble intercellular adhesion molecule-1 (sICAM-1) (p value 0.048), an age-associated inflammatory marker.
- Reduced circulating triiodothyronine (p<0.001) compared to the control group.
- In the metabolome, 54 out of 113 detected significantly modified metabolites (p value < 0.05) were at least 20% higher after 36 h of fasting, of which the majority (>95%) were lipids or free fatty acids, including polyunsaturated free fatty acids (PUFAs), α-tocopherol, and a type of vitamin E. 49 metabolites were at least 20% lower, consisting mainly (44.9%) of amino acids or related metabolites. Low levels of circulating amino acids have been found to increase lifespan in model organisms. The authors concluded that the elevation in fatty acids may be due to increased lipolysis from adipose tissue while the reduction in amino acids may be the result of increased gluconeogenesis.
- 13 out of 2,089 significantly (p value < 0.05) modulated protein hits within the PBMC proteome showed an increase of ≥15%, while the remaining proteins were downregulated after 36 h of fasting. Gene set enrichment analysis (GSEA) performed on the PBMC proteome unveiled changes in pathways related to lipid metabolism, pathways related to energy metabolism and stress response.
Following the 4 week intervention the alternate day fasting group demonstrated:
- Reduced caloric intake from baseline vs. the control group (−37.40% vs. −8.22%, p=0.0012).
- Greater reductions in body weight (−3.5kg vs −0.2kg, p<0.0001), BMI (−1.23kg/m2 vs −0.02kg/m2, p<0.0001) and improvements in their fat to lean mass ratio (−6.3% ± 5.0 percentage points, p value < 0.0001).
- Reduced systolic (−4.5mmHg, p=0.006) and diastolic (−2.5mmHg, p=0.03) blood pressure, heart rate (-4.5 b/min, p=0.0019), arterial (−3mmHg, p=0.0087) and pulse pressure (−2.5mmHg, p=0.0088) as well as pulse wave velocity (−1.538%, p=0.0362). Pulse wave velocity measures the rate at which pressure moves down the vessel wall and is a measure of arterial stiffness.
- Reduced circulating triiodothyronine (p<0.001) from baseline values.
Clinical practice applications:
The cross sectional analysis did not identify any differences in the long-term (>6 months) alternate day fasting group and control group in bone mass, bone mineral density of the lumbar spine region, white blood cell counts, ferritin and transferrin when compared to healthy controls. RBC counts and iron metabolism markers in the blood plasma (hematocrit, haemoglobin, iron, and transferrin saturation), were lower in the >6 months of ADF group but stayed within the reference range.
The randomised controlled trial demonstrated that alternate day fasting may be an effective intervention to reduce caloric intake, improve body composition and reduce cardiovascular disease risk in healthy non-overweight adults within 4 weeks.
Compliance rate was high with only 1 drop out in the alternate day fasting group of the randomised controlled trial.
Both the 4 week intervention and long-term (>6 month) analysis identified a reduction in triiodothyronine amongst the ADF groups. Low levels of triiodothyronine in absence of thyroid gland dysfunction has been associated with longevity in humans.
Considerations for future research:
- Future larger studies in non-healthy and/or overweight/obese populations would be useful to determine safety and efficacy of alternate day fasting within that population group.
- Further studies comparing alternate day fasting with continuous caloric restriction would be useful to identify which intervention is most beneficial for body composition and cardioprotection.
- Subgroup analysis of diet composition and diet quality may help to identify the most appropriate/inappropriate diet to compliment alternate day fasting.
- Longer duration randomised controlled trials are needed to identify any health risks or deficiencies which may develop with long term caloric restriction and alternate day fasting.
Abstract
Caloric restriction and intermittent fasting are known to prolong life- and healthspan in model organisms, while their effects on humans are less well studied. In a randomized controlled trial study (ClinicalTrials.gov identifier: NCT02673515), we show that 4 weeks of strict alternate day fasting (ADF) improved markers of general health in healthy, middle-aged humans while causing a 37% calorie reduction on average. No adverse effects occurred even after >6 months. ADF improved cardiovascular markers, reduced fat mass (particularly the trunk fat), improving the fat-to-lean ratio, and increased β-hydroxybutyrate, even on non-fasting days. On fasting days, the pro-aging amino-acid methionine, among others, was periodically depleted, while polyunsaturated fatty acids were elevated. We found reduced levels sICAM-1 (an age-associated inflammatory marker), low-density lipoprotein, and the metabolic regulator triiodothyronine after long-term ADF. These results shed light on the physiological impact of ADF and supports its safety. ADF could eventually become a clinically relevant intervention.
-
6.
Does the microbiome and virome contribute to myalgic encephalomyelitis/chronic fatigue syndrome?
Newberry, F, Hsieh, SY, Wileman, T, Carding, SR
Clinical science (London, England : 1979). 2018;132(5):523-542
-
-
-
Free full text
-
Plain language summary
Myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) (ME/CFS) is a disabling and debilitating disease. Several studies have shown alterations in the gut microbiome (dysbiosis) in patients with ME/CFS. However, in focusing on the bacterial components of the microbiome, the viral component of the microbiome (known as the virome) has been neglected. Viruses can change the microbiome which can influence the health. This area is therefore important for research into ME/CFS. This article provides a comprehensive review of the current evidence supporting microbiome alterations in ME/CFS patients. Additionally, the challenges associated with microbiome studies are discussed. A literature search was done and 11 papers were found that had examined the microbiome ME/CFS patients, dating from 1998 to 2017. It was not possible to compare the studies statistically but from looking at each one individually there is sufficient evidence to support the claim of an altered intestinal microbiome in ME/CFS patients. ME/CFS is multifactorial and potential dysbiosis should be considered to be only part of the picture. Future studies are needed to adopt standardized techniques and analyses. As research increases, it is becoming clear that the virome can directly and indirectly affect host health, and may play a role in the pathogenesis of ME/CFS.
Abstract
Myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) (ME/CFS) is a disabling and debilitating disease of unknown aetiology. It is a heterogeneous disease characterized by various inflammatory, immune, viral, neurological and endocrine symptoms. Several microbiome studies have described alterations in the bacterial component of the microbiome (dysbiosis) consistent with a possible role in disease development. However, in focusing on the bacterial components of the microbiome, these studies have neglected the viral constituent known as the virome. Viruses, particularly those infecting bacteria (bacteriophages), have the potential to alter the function and structure of the microbiome via gene transfer and host lysis. Viral-induced microbiome changes can directly and indirectly influence host health and disease. The contribution of viruses towards disease pathogenesis is therefore an important area for research in ME/CFS. Recent advancements in sequencing technology and bioinformatics now allow more comprehensive and inclusive investigations of human microbiomes. However, as the number of microbiome studies increases, the need for greater consistency in study design and analysis also increases. Comparisons between different ME/CFS microbiome studies are difficult because of differences in patient selection and diagnosis criteria, sample processing, genome sequencing and downstream bioinformatics analysis. It is therefore important that microbiome studies adopt robust, reproducible and consistent study design to enable more reliable and valid comparisons and conclusions to be made between studies. This article provides a comprehensive review of the current evidence supporting microbiome alterations in ME/CFS patients. Additionally, the pitfalls and challenges associated with microbiome studies are discussed.
-
7.
The microbiome of professional athletes differs from that of more sedentary subjects in composition and particularly at the functional metabolic level.
Barton, W, Penney, NC, Cronin, O, Garcia-Perez, I, Molloy, MG, Holmes, E, Shanahan, F, Cotter, PD, O'Sullivan, O
Gut. 2018;67(4):625-633
-
-
-
Free full text
-
Plain language summary
The human gut microbiome is known to actively influence metabolism, immunity and development. It has been shown that increased physical activity and healthy diet is associated with positive changes in faecal microbial diversity and composition compared with sedentary individuals. The aim of this study was to assess the metabolic activity of the microbiota between extremely active and sedentary individuals. Metabolic and genetic factors of the gut microbiome were analysed in 40 professional rugby players and 46 sedentary controls. This study found significant differences in faecal microbiota between athletes and sedentary controls at the functional metabolic level, providing deeper insight into the link between sustained physical activity and metabolic health. Based on these results, the authors conclude exercise may be an effective way to manipulate the gut microbiome and suggest further controlled trials be done to better understand the relationship between diet, exercise and the gut microbiome.
Abstract
OBJECTIVE It is evident that the gut microbiota and factors that influence its composition and activity effect human metabolic, immunological and developmental processes. We previously reported that extreme physical activity with associated dietary adaptations, such as that pursued by professional athletes, is associated with changes in faecal microbial diversity and composition relative to that of individuals with a more sedentary lifestyle. Here we address the impact of these factors on the functionality/metabolic activity of the microbiota which reveals even greater separation between exercise and a more sedentary state. DESIGN Metabolic phenotyping and functional metagenomic analysis of the gut microbiome of professional international rugby union players (n=40) and controls (n=46) was carried out and results were correlated with lifestyle parameters and clinical measurements (eg, dietary habit and serum creatine kinase, respectively). RESULTS Athletes had relative increases in pathways (eg, amino acid and antibiotic biosynthesis and carbohydrate metabolism) and faecal metabolites (eg, microbial produced short-chain fatty acids (SCFAs) acetate, propionate and butyrate) associated with enhanced muscle turnover (fitness) and overall health when compared with control groups. CONCLUSIONS Differences in faecal microbiota between athletes and sedentary controls show even greater separation at the metagenomic and metabolomic than at compositional levels and provide added insight into the diet-exercise-gut microbiota paradigm.
-
8.
Heat-stabilised rice bran consumption by colorectal cancer survivors modulates stool metabolite profiles and metabolic networks: a randomised controlled trial.
Brown, DG, Borresen, EC, Brown, RJ, Ryan, EP
The British journal of nutrition. 2017;117(9):1244-1256
-
-
-
Free full text
-
Plain language summary
Colorectal cancer (CRC) is the third most common cancer in the world. Rice bran is high in phytochemicals, fibre and other bioactive compounds that may have potential to reduce cancer formation. Rice bran consumption has been shown to reduce CRC growth in mice, as well as alter the stool microbiome in humans. This alteration of the gut microbiome and the metabolic end products produced by it is thought to provide positive health benefits in terms of CRC development. This randomised controlled trial with CRC survivors included daily consumption of 30g/day of rice bran for 28 days in the intervention group, consisting of 9 participants. No rice bran was consumed in the control group of 10 participants. The aim of the study was to identify changes in metabolites that may have potential to reduce the risk of CRC, in the stool samples given by the participants after consuming rice bran, as well as to understand the differences in stool metabolites in the intervention and control groups. The authors found that rice bran consumption led to changes in 93 metabolites, 33 of which increased, while 60 metabolites decreased after 4 weeks of consumption. Metabolic pathways affected included advanced glycation end products, steroid metabolism, primary bile acid metabolism, leucine, isoleucine and valine metabolism, methionine, cysteine, S-adenosyl methionine and taurine metabolism, inositol metabolism, vitamin B6 metabolism and benzoate metabolism. The authors hypothesise that these metabolic changes may have potential for the prevention of cancer and they should be further explored in larger studies.
Abstract
Rice bran (RB) consumption has been shown to reduce colorectal cancer (CRC) growth in mice and modify the human stool microbiome. Changes in host and microbial metabolism induced by RB consumption was hypothesised to modulate the stool metabolite profile in favour of promoting gut health and inhibiting CRC growth. The objective was to integrate gut microbial metabolite profiles and identify metabolic pathway networks for CRC chemoprevention using non-targeted metabolomics. In all, nineteen CRC survivors participated in a parallel randomised controlled dietary intervention trial that included daily consumption of study-provided foods with heat-stabilised RB (30 g/d) or no additional ingredient (control). Stool samples were collected at baseline and 4 weeks and analysed using GC-MS and ultra-performance liquid chromatography-MS. Stool metabolomics revealed 93 significantly different metabolites in individuals consuming RB. A 264-fold increase in β-hydroxyisovaleroylcarnitine and 18-fold increase in β-hydroxyisovalerate exemplified changes in leucine, isoleucine and valine metabolism in the RB group. A total of thirty-nine stool metabolites were significantly different between RB and control groups, including increased hesperidin (28-fold) and narirutin (14-fold). Metabolic pathways impacted in the RB group over time included advanced glycation end products, steroids and bile acids. Fatty acid, leucine/valine and vitamin B6 metabolic pathways were increased in RB compared with control. There were 453 metabolites identified in the RB food metabolome, thirty-nine of which were identified in stool from RB consumers. RB consumption favourably modulated the stool metabolome of CRC survivors and these findings suggest the need for continued dietary CRC chemoprevention efforts.
-
9.
Circadian Rhythms, Metabolism, and Chrononutrition in Rodents and Humans.
Johnston, JD, Ordovás, JM, Scheer, FA, Turek, FW
Advances in nutrition (Bethesda, Md.). 2016;7(2):399-406
-
-
-
Free full text
-
Plain language summary
Chrononutrition is an emerging field that links the body’s metabolism to its endogenous circadian rhythm. It is now recognised that numerous circadian clocks are found within all major tissues and most cells of the body. This complex network of clocks influences a wide range of biological processes including neuronal, endocrine, metabolic and behavioural function. When there is a disruption in a single circadian clock, whole-organism homeostasis can be impacted, potentially resulting in the development of disease. This review explains the potential mechanisms by which circadian clocks influence biological processes through transgenic animal studies, and how they are being translated to human genetics and metabolomics. The principles of chrononutrition are clinically significant factors that should be considered when managing and treating metabolic disease, as well as maintaining health in the general population.
Abstract
Chrononutrition is an emerging discipline that builds on the intimate relation between endogenous circadian (24-h) rhythms and metabolism. Circadian regulation of metabolic function can be observed from the level of intracellular biochemistry to whole-organism physiology and even postprandial responses. Recent work has elucidated the metabolic roles of circadian clocks in key metabolic tissues, including liver, pancreas, white adipose, and skeletal muscle. For example, tissue-specific clock disruption in a single peripheral organ can cause obesity or disruption of whole-organism glucose homeostasis. This review explains mechanistic insights gained from transgenic animal studies and how these data are being translated into the study of human genetics and physiology. The principles of chrononutrition have already been demonstrated to improve human weight loss and are likely to benefit the health of individuals with metabolic disease, as well as of the general population.