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Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial.
Ni Lochlainn, M, Bowyer, RCE, Moll, JM, García, MP, Wadge, S, Baleanu, AF, Nessa, A, Sheedy, A, Akdag, G, Hart, D, et al
Nature communications. 2024;15(1):1859
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Humans lose skeletal muscle with advancing age, and this can progress to sarcopenia. Dietary protein is crucial for maintaining skeletal muscle health; however, several factors can lead to reduced protein intake in older age. The aim of this study was to test whether the addition of gut microbiome modulation could augment established muscle function improvements from combined protein (branched chain amino acids [BCAA]) and resistance exercise. This study was based on the PROMOTe (effect of PRebiotic and prOtein on Muscle in Older Twins) trial which was a randomised controlled trial in which twin pairs (n= 72) were randomised, one twin to each study arm. Results showed that prebiotics improved cognition but did not impact muscle strength and function, compared with placebo. Furthermore, gut microbiome modulation via prebiotic supplementation in the context of ageing-muscle research is feasible and well tolerated, with clear responses noted in the gut microbiota composition and function. Authors concluded that cheap and readily available gut microbiome interventions hold promise for improving cognitive frailty in our ageing population.
Abstract
Studies suggest that inducing gut microbiota changes may alter both muscle physiology and cognitive behaviour. Gut microbiota may play a role in both anabolic resistance of older muscle, and cognition. In this placebo controlled double blinded randomised controlled trial of 36 twin pairs (72 individuals), aged ≥60, each twin pair are block randomised to receive either placebo or prebiotic daily for 12 weeks. Resistance exercise and branched chain amino acid (BCAA) supplementation is prescribed to all participants. Outcomes are physical function and cognition. The trial is carried out remotely using video visits, online questionnaires and cognitive testing, and posting of equipment and biological samples. The prebiotic supplement is well tolerated and results in a changed gut microbiome [e.g., increased relative Bifidobacterium abundance]. There is no significant difference between prebiotic and placebo for the primary outcome of chair rise time (β = 0.579; 95% CI -1.080-2.239 p = 0.494). The prebiotic improves cognition (factor score versus placebo (β = -0.482; 95% CI,-0.813, -0.141; p = 0.014)). Our results demonstrate that cheap and readily available gut microbiome interventions may improve cognition in our ageing population. We illustrate the feasibility of remotely delivered trials for older people, which could reduce under-representation of older people in clinical trials. ClinicalTrials.gov registration: NCT04309292.
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L-Arginine is a feasible supplement to heal chronic anal fissure via reducing internal anal sphincter pressure: a randomized clinical trial study.
Khalighi Sikaroudi, M, Sedaghat, M, Shidfar, F, Talebi, S, Hosseini-Baharanchi, FS, Masoodi, M, Farahani, SV
Amino acids. 2023;55(2):193-202
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An anal fissure is a condition resulting from a superficial open wound or tear in the anus mucosa with a sharp pain that can extend from the anal canal to the periphery. The aim of this study was to evaluate the effect of oral L-arginine as a safer method with better performance on clinical symptoms, quality of life, and internal anal sphincter pressure in patients with chronic anal fissure. This study is a randomised, double-blind, placebo-controlled trial with parallel design conducted in the 4-week intervention and the 8-week follow-up. The study recruited 76 adult men and women who were aged between 18 and 65 years of age and were diagnosed with chronic fissures. Participants were assigned to two groups: 3000 mg l-arginine, or a placebo filled with Maltodextrin. Results show that supplementation with l-arginine may relieve clinical symptoms, especially pain and bleeding, and improve the quality of life of patients with chronic anal fissure. In addition, analysis of anal internal sphincter pressures evaluated by manometry and balloon showed the significant reduction of sphincter pressure in these patients. Authors conclude that l-arginine supplementation may relieve clinical symptoms and improve the quality of life, anxiety, and depression in patients with chronic anal fissures.
Abstract
The hypertonicity of internal anal sphincter resting pressure is one of the main causes of chronic anal fissure. Therefore, the aim of this study was to assess the effect of oral administration of L-arginine on the improvement of the anal fissures by relaxing the internal anal sphincter. Seventy-six chronic anal fissure patients (aged 18-65 years) who were referred to Rasoul-e-Akram Hospital, Tehran, Iran from February 2019 to October 2020 participated in this randomized, double-blind, placebo-controlled trial. Participants were allocated into treatment (L-arginine) and placebo groups. They took a 1000 mg capsule three times a day for 1 month, and then we followed them at the end of the first and third months after the intervention. Clinical symptoms, anal sphincter resting pressure, and quality of life (QoL) were completed at baseline and the end of the study. The analysis of data showed a significant decrease in bleeding, fissure size, and pain for each group; however, in the L-arginine group was more than the control group at the end of the study (P values < 0.001). Following that, a significant increase in QoL was seen just in patients treated with L-arginine (P value = 0.006). In addition, the comparison of anal pressures at baseline and, between groups at the end of the study showed a significant reduction in sphincter pressure in patients treated with L-arginine (P value < 0.001, = 0.049; respectively). The oral administration of 3000 mg L-arginine can heal chronic anal fissures by reducing internal anal sphincter pressure with more negligible side effects. However, we recommend long-term study with more extended follow-up.Clinical trial registry: IRCT20190712044182N1 at Iranian clinical trials, date: 2019-08-27.
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The Influence of n-3PUFA Supplementation on Muscle Strength, Mass, and Function: A Systematic Review and Meta-Analysis.
Santo André, HC, Esteves, GP, Barreto, GHC, Longhini, F, Dolan, E, Benatti, FB
Advances in nutrition (Bethesda, Md.). 2023;14(1):115-127
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Omega 3 polyunsaturated fatty acids (n-3PUFA) are long-chain polyunsaturated fatty acids essential to human health. They play a role in cell membrane integrity, immune and inflammation regulation, cognition and neuromuscular function. As the human body cannot make these fatty acids, they need to be obtained through diet or supplementation. Regarding skeletal muscle, recent research showed that n-3PUFAs may increase the uptake of amino acids by increasing the membrane fluidity in the muscle, and by activating pathways that inhibit protein breakdown. This led to the hypothesis that n-3PUFAs may enhance muscle mass gain and strength. This systematic review sought to gather all available evidence about the impact of n-3PUFA supplementation on muscle mass, strength, and function in healthy young and older adults. The review included 14 studies with a total of 1443 participants. The authors found that n-3PUFA supplementation had no significant effect on muscle mass or muscle function in healthy young and older adults, however, a very small but significant positive effect was noted regarding muscle strength. In the discussion section, the authors explain the challenges of their review and how these findings integrate with the current understanding and other research findings. They concluded more research is needed to get a better insight into the effects of n-3PUFA on muscle function and the variants.
Abstract
The effects of omega 3 polyunsaturated fatty acids (n-3PUFA) supplementation on skeletal muscle are currently unclear. The purpose of this systematic review was to synthesize all available evidence regarding the influence of n-3PUFA supplementation on muscle mass, strength, and function in healthy young and older adults. Four databases were searched (Medline, Embase, Cochrane CENTRAL, and SportDiscus). Predefined eligibility criteria were determined according to Population, Intervention, Comparator, Outcomes, and Study Design. Only peer-reviewed studies were included. The Cochrane RoB2 Tool and the NutriGrade approach were used to access risk of bias and certainty in evidence. Effect sizes were calculated using pre-post scores and analyzed using a three-level, random-effects meta-analysis. When sufficient studies were available, subanalyses were performed in the muscle mass, strength, and function outcomes according to participant's age (<60 or ≥60 years), supplementation dosage (<2 or ≥2 g/day), and training intervention ("resistance training" vs. "none or other"). Overall, 14 individual studies were included, total 1443 participants (913 females; 520 males) and 52 outcomes measures. Studies had high overall risk of bias and consideration of all NutriGrade elements resulted in a certainty assessment of moderate meta-evidence for all outcomes. n-3PUFA supplementation had no significant effect on muscle mass (standard mean difference [SMD] = 0.07 [95% CI: -0.02, 0.17], P = 0.11) and muscle function (SMD = 0.03 [95% CI: -0.09, 0.15], P = 0.58), but it showed a very small albeit significant positive effect on muscle strength (SMD = 0.12 [95% CI: 0.006, 0.24], P = 0.04) in participants when compared with placebo. Subgroup analyses showed that age, supplementation dose, or cosupplementation alongside resistance training did not influence these responses. In conclusion, our analyses indicated that n-3PUFA supplementation may lead to very small increases in muscle strength but did not impact muscle mass and function in healthy young and older adults. To our knowledge, this is the first review and meta-analysis investigating whether n-3PUFA supplementation can lead to increases in muscle strength, mass, and function in healthy adults. Registered protocol: doi.org/10.17605/OSF.IO/2FWQT.
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Effects of a Synbiotic on Plasma Immune Activity Markers and Short-Chain Fatty Acids in Children and Adults with ADHD-A Randomized Controlled Trial.
Yang, LL, Stiernborg, M, Skott, E, Xu, J, Wu, Y, Landberg, R, Arefin, S, Kublickiene, K, Millischer, V, Nilsson, IAK, et al
Nutrients. 2023;15(5)
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Attention deficit hyperactivity disorder (ADHD) is a common childhood-onset neurodevelopmental psychiatric disorder. The core symptoms of the disorder are inattention and hyperactivity/impulsivity. The aim of this study was to explore the effects of Synbiotic 2000 on concentrations of plasma immune activity markers and short-chain fatty acids (SCFAs) in ADHD. This study is a double-blind randomised controlled trial over a period of 9-weeks. Patients (n= 248) were randomly allocated to one of the two treatments: Synbiotic 2000 or placebo. Results show that there was no statistically significant overall effect of Synbiotic 2000 compared to placebo on any analyte analysing all the paediatric and all adult participants as one group. However, age-group stratified analyses showed that plasma levels of several of the analytes were at baseline different in the children compared to in the adults. Authors conclude that Synbiotic 2000, in children with ADHD, reduces markers of intestinal and vascular inflammation, the latter in part through increasing SCFAs levels. Furthermore, they suggest that the findings warrant further studies to determine if persons with ADHD would benefit inflammation-wise from dietary intake of Synbiotic 2000 or a similar synbiotic.
Abstract
Synbiotic 2000, a pre + probiotic, reduced comorbid autistic traits and emotion dysregulation in attention deficit hyperactivity disorder (ADHD) patients. Immune activity and bacteria-derived short-chain fatty acids (SCFAs) are microbiota-gut-brain axis mediators. The aim was to investigate Synbiotic 2000 effects on plasma levels of immune activity markers and SCFAs in children and adults with ADHD. ADHD patients (n = 182) completed the 9-week intervention with Synbiotic 2000 or placebo and 156 provided blood samples. Healthy adult controls (n = 57) provided baseline samples. At baseline, adults with ADHD had higher pro-inflammatory sICAM-1 and sVCAM-1 and lower SCFA levels than controls. Children with ADHD had higher baseline sICAM-1, sVCAM-1, IL-12/IL-23p40, IL-2Rα, and lower formic, acetic, and propionic acid levels than adults with ADHD. sICAM-1, sVCAM-1, and propionic acid levels were more abnormal in children on medication. Synbiotic 2000, compared to placebo, reduced IL-12/IL-23p40 and sICAM-1 and increased propionic acid levels in children on medication. SCFAs correlated negatively with sICAM-1 and sVCAM-1. Preliminary human aortic smooth-muscle-cell experiments indicated that SCFAs protected against IL-1β-induced ICAM-1 expression. These findings suggest that treatment with Synbiotic 2000 reduces IL12/IL-23p40 and sICAM-1 and increases propionic acid levels in children with ADHD. Propionic acid, together with formic and acetic acid, may contribute to the lowering of the higher-than-normal sICAM-1 levels.
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Dietary Strawberries Improve Serum Metabolites of Cardiometabolic Risks in Adults with Features of the Metabolic Syndrome in a Randomized Controlled Crossover Trial.
Basu, A, Izuora, K, Hooyman, A, Scofield, HR, Ebersole, JL
International journal of molecular sciences. 2023;24(3)
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Metabolic syndrome has been identified as a major risk factor for type 2 diabetes and its cardiovascular complications. Several dietary strategies, especially the use of different forms of dietary supplements, continue to be investigated for the prevention and management of this condition. The aim of this study was to examine the serum metabolites (targeted and untargeted) that may be affected by strawberry supplementation. This study was a randomised, double-blind, controlled crossover trial which enrolled adult participants with one or more features of metabolic syndrome. Participants were assigned to one of the three arms for four weeks separated by a one-week washout period. Results show that several targeted and untargeted serum metabolites were modulated with strawberry supplementation. In fact, strawberry supplementation improved the serum metabolic profiles which are associated with decreased risks of insulin resistance and diabetes, as well as endothelial dysfunction in adults with features of metabolic syndrome. Authors conclude that adding whole strawberries to the habitual diet may be a beneficial and feasible strategy to improve the cardiometabolic health in adults.
Abstract
Dietary strawberries have been shown to improve cardiometabolic risks in multiple clinical trials. However, no studies have reported effects on serum metabolomic profiles that may identify the target pathways affected by strawberries as underlying mechanisms. We conducted a 14-week randomized, controlled crossover study in which participants with features of metabolic syndrome were assigned to one of the three arms for four weeks separated by a one-week washout period: control powder, 1 serving (low dose: 13 g strawberry powder/day), or 2.5 servings (high dose: 32 g strawberry powder/day). Blood samples, anthropometric measures, blood pressure, and dietary and physical activity data were collected at baseline and at the end of each four-week phase of intervention. Serum samples were analyzed for primary metabolites and complex lipids using different mass spectrometry methods. Mixed-model ANOVA was used to examine differences in the targeted metabolites between treatment phases, and LASSO logistic regression was used to examine differences in the untargeted metabolites at end of the strawberry intervention vs. the baseline. The findings revealed significant differences in the serum branched-chain amino acids valine and leucine following strawberry intervention (high dose) compared with the low-dose and control phases. Untargeted metabolomic profiles revealed several metabolites, including serum phosphate, benzoic acid, and hydroxyphenyl propionic acid, that represented improved energy-metabolism pathways, compliance measures, and microbial metabolism of strawberry polyphenols, respectively. Thus, dietary supplementation of strawberries significantly improves the serum metabolic profiles of cardiometabolic risks in adults.
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Absence of Effects of L-Arginine and L-Citrulline on Inflammatory Biomarkers and Oxidative Stress in Response to Physical Exercise: A Systematic Review with Meta-Analysis.
Porto, AA, Gonzaga, LA, Benjamim, CJR, Valenti, VE
Nutrients. 2023;15(8)
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L-citrulline is a non-essential amino acid that acts as a precursor to L-arginine. L-arginine is a semi-essential amino acid used for nitric oxide production which is crucial for maintaining physiological function and immune regulation. Previous research has shown that L-citrulline and L-arginine supplementation may offer antioxidant and anti-inflammatory benefits in reducing exercise-related oxidative stress and inflammation. This systematic review and meta-analysis included seven randomised controlled trials to investigate the effect of L-citrulline and L-arginine on antioxidants, oxidative stress, and inflammatory and anti-inflammatory markers. This systematic review and meta-analysis showed no significant improvements in oxidative stress and inflammation followed by the supplementation of L-citrulline and L-arginine before exercise. However, further robust studies that include different dosages and exercise intensities are required to assess the beneficial effects of L-citrulline and L-arginine supplements to support physical exercise-induced oxidative stress and inflammation due to the heterogeneity of the included studies. Healthcare professionals can use the results of this study to understand the potential benefits of L-citrulline and L-arginine supplementation in people prone to producing proinflammatory cytokines.
Abstract
The repercussions on oxidative and inflammatory stress markers under the effects of arginine and citrulline in response to exercise are not fully reached. We completed a systematic review to investigate the effects of L-Citrulline or L-Arginine on oxidative stress and inflammatory biomarkers following exercise. EMBASE, MEDLINE (PubMed), Cochrane Library, CINAHL, LILACS, and Web of Science databases were used to record the trials. This study includes randomized controlled trials (RCTs) and non-RCTs with subjects over 18 years old. Those under the intervention protocol consumed L-Citrulline or L-Arginine, and the controls ingested placebo. We recognized 1080 studies, but only 7 were included (7 studies in meta-analysis). We observed no difference between pre- vs. post-exercise for oxidative stress (subtotal = -0.21 [CI: -0.56, 0.14], p = 0.24, and heterogeneity = 0%. In the sub-group "L-Arginine" we found a subtotal = -0.29 [-0.71, 0.12], p = 0.16, and heterogeneity = 0%. For the "L-Citrulline" subgroup we observed a subtotal = 0.00 [-0.67, 0.67], p = 1.00, and heterogeneity was not applicable. No differences were observed between groups (p = 0.47), and I² = 0%) or in antioxidant activity (subtotal = -0.28 [-1.65, 1.08], p = 0.68, and heterogeneity = 0%). In the "L-Arginine" sub-group, we found a subtotal = -3.90 [-14.18, 6.38], p = 0.46, and heterogeneity was not applicable. For the "L-Citrulline" subgroup, we reported a subtotal = -0.22 [-1.60, 1.16], p = 0.75, and heterogeneity was not applicable. No differences were observed between groups (p = 0.49), and I² = 0%), inflammatory markers (subtotal = 8.38 [-0.02, 16.78], p = 0.05, and heterogeneity = 93%. Tests for subgroup differences were not applicable, and anti-inflammatory markers (subtotal = -0.38 [-1.15, 0.39], p = 0.34 and heterogeneity = 15%; testing for subgroup differences was not applicable). In conclusion, our systematic review and meta-analysis found that L-Citrulline and L-Arginine did not influence inflammatory biomarkers and oxidative stress after exercise.
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Effect of soy isoflavones supplementation on migraine characteristics, mental status and calcitonin gene-related peptide (CGRP) levels in women with migraine: results of randomised controlled trial.
Babapour, M, Khorvash, F, Rouhani, MH, Ghavami, A, Ghasemi-Tehrani, H, Heidari, Z, Karbasi, M, Moradi, F, Askari, G
Nutrition journal. 2022;21(1):50
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Migraine is considered as an intense unilateral throbbing headache, often accompanied by nausea, vomiting, photophobia and phonophobia, which can be exacerbated by routine physical activity. It has been shown that cytokines levels are altered in migraineurs. Cytokines are inflammatory mediators that can stimulate calcitonin gene-related peptide (CGRP) [amino acid] transcription. The aim of this study was to investigate the effects of soy isoflavones supplementation on migraine headache characteristics, mental status, quality of life and CGRP concentration in adult women with migraine. This study is a double-blind, placebo-controlled clinic trial. Participants (n=88 women) were randomly assigned to one of the two groups: intervention or placebo groups (1:1). Patients in the intervention group received one tablet containing 50 mg isoflavones. Results indicate that consumption of 50 mg/day soy isoflavones supplementation for 8 weeks led to significant reduction in frequency, duration, and clinical indices of migraine and improved quality of life and CGRP levels. However, severity of migraine headache and mental status including depression, stress and anxiety were not affected by supplementation. Authors conclude that even though their findings were promising, further studies focusing on the mental status dimensions including depression, stress and anxiety are needed.
Abstract
BACKGROUND Literature suggests a relationship between estrogen levels and migraine headache pathogenesis. However, the effect of soy isoflavones on migraine characteristic remains unclear. This study aimed to investigate the effect of soy isoflavones on migraine characteristics and calcitonin gene-related peptide (CGRP) levels in women with migraine. METHODS Eighty-three participants completed a randomized double-blind controlled trial, receiving 50 mg per day soy isoflavones or placebo supplementation for 8 weeks. Migraine severity, migraine days per month, frequency and duration of attacks, mental status, quality of life and serum CGRP levels were measured at baseline and the end of the intervention. Bivariate comparison and intention-to-treat (ITT) were used for analysis. RESULTS Soy isoflavones intake resulted in a significant decrease in mean frequency (-2.36 vs -0.43, P < 0.001), duration (-2.50 vs -0.02, P < 0.001) of migraine attacks and CGRP level (-12.18 ng/l vs -8.62, P = 0.002) in compared to placebo group. Also, a significant improvement was found in quality of life (16.76 vs 2.52, P < 0.001). Although, reduction in the migraine severity and mental status did not reach a statistically significant level (P > 0.05). CONCLUSION soy isoflavones supplementation may be considered as a complementary treatment for women with migraine to improve migraine characteristics and reduce the burden of disease.
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Energy Drinks and Sleep among Adolescents.
Tomanic, M, Paunovic, K, Lackovic, M, Djurdjevic, K, Nestorovic, M, Jakovljevic, A, Markovic, M
Nutrients. 2022;14(18)
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Sleep deprivation is a common problem among adolescents. There has been an increase in the consumption of energy drinks among adolescents in recent years. It is well known that energy drinks contain caffeine, sugar, and amino acids such as taurine, B vitamins, Ginseng, and guarana, which have psychoactive properties and disrupt the circadian rhythm. Insufficient sleep can affect genes involved in circadian rhythm and serotonin pathways, resulting in a higher risk of developing mental health problems. Therefore, researchers accessed the data from a population-based cross-sectional study to evaluate the effect of an energy drink on sufficient sleep in male and female adolescents. This study found that high energy drink consumption negatively affected sufficient sleep in male and female adolescents, with boys consuming energy drinks more frequently. The intake of vegetables and water, as well as regular physical activity, were positively correlated with adequate sleep in male adolescents. Physical activity and sufficient sleep were positively correlated in girls. Girls who used sedatives were less likely to get sufficient sleep. In order to determine how the different ingredients of energy drinks affect the sleep quality and neurodevelopment of adolescents individually and synergistically, further robust studies are required. The results of this study may help healthcare professionals to understand the adverse effects of energy drinks on adolescents.
Abstract
Many adolescents worldwide have the problem of meeting recommended nightly sleep hours. The causes of sleep disturbance are multifactorial, but interest in food's effect on sleep has dramatically increased lately. In this study, we investigated the association between regular energy drink (ED) intake (weekly or more frequent) and sufficient sleep (SS) (≥8 h) in adolescents. Additional objectives were to examine the relationship between health-related behaviors and SS, stratified by gender. A population-based cross-sectional study was conducted during the 2019/2020 school year from 12 schools in Belgrade. There were 1287 students aged 15 to 19 who participated (37.4% male). We used a modified version of the food frequency questionnaire adapted for Serbian adolescents. Logistic regression revealed that regular ED consumption was an independent risk factor negatively related to SS in both sexes. Additionally, daily vegetable and water intake (≥2 L) showed a positive correlation with SS in boys, while in girls, the odds of realizing SS decreased with statements of sedative use. In conclusion, we show that ED intake is negatively associated with SS in both sexes; daily vegetable and water intake (≥2 L) may raise the odds of SS in boys, while sedative use may decrease the chances of SS in girls.
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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)
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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.
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The impact of nutrition on tendon health and tendinopathy: a systematic review.
Hijlkema, A, Roozenboom, C, Mensink, M, Zwerver, J
Journal of the International Society of Sports Nutrition. 2022;19(1):474-504
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Tendinopathy, which involves persistent tendon pain and loss of function related to mechanical loading, is common in athletes as well as in the general population. The aim of this study was to evaluate the impact of nutrition on the prevention and treatment of tendinopathy in a general human population. This study is a systematic review of nineteen studies. The number of people included in these studies ranged from 50 to 80,106. Results show that: - there wasn’t an association between any of the dietary parameters and Achilles tendon thickness. - despite inconsistent findings on the risk and severity of tendinopathy in humans, there is evidence that alcohol may inhibit collagen synthesis through toxic effects. - collagen seems to be beneficial in the treatment of tendinopathy, but conclusions about optimal dosage, timing, duration, and type of collagen supplementation cannot be drawn yet. - many other nutrients may contribute to collagen synthesis or may have anti-inflammatory effects, so most dietary supplements used in the different studies contained multiple substances. Authors conclude it is impossible to draw definitive conclusions and formulate dietary recommendations on the prevention and treatment of tendinopathy.
Abstract
BACKGROUND Tendinopathy is a painful condition that is prevalent in athletes as well as the general human population, and whose management is challenging. OBJECTIVE This systematic review aimed to evaluate the impact of nutrition on the prevention and treatment of tendinopathy. METHODS Searches were conducted in PubMed, EMBASE, Web of Science, and SPORTDiscus without restriction to year of publication. Studies examining the impact of exposure to nutrient intake in an adult human population on 1) prevalence/incidence of tendinopathy, 2) clinical outcomes of tendinopathy, 3) structural changes in the tendon by imaging modalities. Experimental and observational study designs written in English, Dutch, or German were eligible. RESULTS Nineteen studies met the inclusion criteria. The effects of the habitual diet were investigated in one study. Four studies examined the effects of exposure to alcohol. Alcohol consumption can be a potential risk factor associated with Achilles tendinopathy and rotator cuff tears, although findings were inconsistent. The use of dietary supplements was examined in fourteen studies. Among these, collagen-derived peptides were most often part of the supplements evaluated. Combining training and dietary supplements seems to induce better clinical and functional outcomes in tendinopathy. CONCLUSION This review demonstrates the paucity of high-quality studies and a wide variety among studies regarding nutrients, tendon location, study population, and reported outcome measures. Individual studies showed promising clinical implications for the use of dietary supplements, particularly those containing collagen-derived peptides. However, giving any definitive dietary recommendations on the prevention and treatment of tendinopathy remains elusive.