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Anxiety, Depression, and the Microbiome: A Role for Gut Peptides.
Lach, G, Schellekens, H, Dinan, TG, Cryan, JF
Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 2018;15(1):36-59
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Hormones released in the gut can have an impact in the brain through a bidirectional relationship, known as the gut-brain axis. The release of these hormones may be controlled by the gut microbiota, however exact mechanisms are not fully understood. Most hormones originating in the gut may have a role in obesity development, which is often associated with psychiatric disorders. Understanding the relationship between gut microbiota and depression through gut derived signalling molecules may be of benefit and was the focus of this review. Diversity and stability of the gut microbiota is important for health, which is disrupted during depression and anxiety. The gut microbiota serves to produce brain, hormone and immune signals that can travel to the brain, and can be affected by poor gut health. For those with depression, side effects of anti-depressants can be a disruption of the gut microbiota, however how this impacts symptoms is not fully understood. It was concluded that although there is strong research on the gut microbiota and depression it is still in its infancy. The role of gut microbiota on signalling with the brain and the rest of the body seems to be important for depression and anxiety. This study could be used by healthcare professionals to understand how the gut microbiota can play a role in depression.
Abstract
The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.
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Recognizing Depression from the Microbiota⁻Gut⁻Brain Axis.
Liang, S, Wu, X, Hu, X, Wang, T, Jin, F
International journal of molecular sciences. 2018;19(6)
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Emerging research indicates that major depression is not just a mental disorder but also a systemic disease. In depression, the brain-gut axis, the bidirectional pathway that connects the brain and gut, is thought to be disturbed. This disruption is hypothesised to be a major pathological basis of depression. The aim of this paper is to explore this hypothesis by reviewing the current literature. According to the current literature, the authors found research stating the gut microbiota of depressed patients is significantly different from that of healthy controls. Additionally, disturbances or abnormalities in the gut can influence the susceptibility of onset of depression, while restoration of the gut will alleviate depression. Based on these findings, the authors conclude depression is closely related with the condition of the brain-gut axis, and that restoring the normal condition of gut microbiota may aid in the therapy of depression. The authors expect therapies that target gut microbiota will play an important role in the treatment and prevention of depression in the future.
Abstract
Major depression is one of the leading causes of disability, morbidity, and mortality worldwide. The brain⁻gut axis functions are disturbed, revealed by a dysfunction of the brain, immune system, endocrine system, and gut. Traditional depression treatments all target the brain, with different drugs and/or psychotherapy. Unfortunately, most of the patients have never received any treatment. Studies indicate that gut microbiota could be a direct cause for the disorder. Abnormal microbiota and the microbiota⁻gut⁻brain dysfunction may cause mental disorders, while correcting these disturbance could alleviate depression. Nowadays, the gut microbiota modulation has become a hot topic in treatment research of mental disorders. Depression is closely related with the health condition of the brain⁻gut axis, and maintaining/restoring the normal condition of gut microbiota helps in the prevention/therapy of mental disorders.
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Metabolic and Microbiota Measures as Peripheral Biomarkers in Major Depressive Disorder.
Horne, R, Foster, JA
Frontiers in psychiatry. 2018;9:513
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Though the connection between the gut microbiome, physical health and mental health is becoming more established, there remains a lack of understanding around the underlying cause of major depressive disorder (MDD). There is a need to identify biomarkers in MDD in order to help identify individual differences and improve treatment outcomes. The aim of this review is to investigate the link between metabolic biomarkers and the gut microbiota in individuals experiencing MDD. The current literature points to two potential biomarkers, leptin and ghrelin, which play a role in both metabolic disease and depression. Based on these findings, the authors conclude these biomarkers may help researchers and clinicians establish subgroups in depressed individuals in order to better predict treatment responses and develop more targeted therapies.
Abstract
Advances in understanding the role of the microbiome in physical and mental health are at the forefront of medical research and hold potential to have a direct impact on precision medicine approaches. In the past 7 years, we have studied the role of microbiota-brain communication on behavior in mouse models using germ-free mice, mice exposed to antibiotics, and healthy specific pathogen free mice. Through our work and that of others, we have seen an amazing increase in our knowledge of how bacteria signal to the brain and the implications this has for psychiatry. Gut microbiota composition and function are influenced both by genetics, age, sex, diet, life experiences, and many other factors of psychiatric and bodily disorders and thus may act as potential biomarkers of the gut-brain axis that could be used in psychiatry and co-morbid conditions. There is a particular need in major depressive disorder and other mental illness to identify biomarkers that can stratify patients into more homogeneous groups to provide better treatment and for development of new therapeutic approaches. Peripheral outcome measures of host-microbe bidirectional communication have significant translational value as biomarkers. Enabling stratification of clinical populations, based on individual biological differences, to predict treatment response to pharmacological and non-pharmacological interventions. Here we consider the links between co-morbid metabolic syndrome and depression, focusing on biomarkers including leptin and ghrelin in combination with assessing gut microbiota composition, as a potential tool to help identify individual differences in depressed population.
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Normalization of Plus Size and the Danger of Unseen Overweight and Obesity in England.
Muttarak, R
Obesity (Silver Spring, Md.). 2018;26(7):1125-1129
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In the United Kingdom more than 25% of adults are classified as clinically obese, thus leading to a normalisation of overweight and obesity. As being 'plus size' becomes more common, there is an increase in weight status misperception that can potentially undermine the recognition of being overweight and its health consequences. The aim of this study was to explore the trends and socio-demographic factors underlying perceived weight status among the overweight or obese population in England. A cross-sectional study was done to collect data through face-to-face interviews and a self-completion questionnaire. The findings of this study showed that there is an increasing trend in misperceiving weight status between both men and women. The authors’ conclude this is possibly reflective of the normalisation of overweight and obesity and that it is vital for obesity prevention programs to consider socioeconomic inequalities for program effectiveness.
Abstract
OBJECTIVE This study aimed to investigate trends and sociodemographic factors underlying weight misperception in adults with overweight and obesity in England. METHODS This study used descriptive and logistic regression analyses based on a pooled nationally representative cross-sectional survey, Health Survey for England, for the years 1997, 1998, 2002, 2014, and 2015 of individuals with BMI ≥ 25 (n = 23,459). The main outcomes were (1) weight misperception and (2) weight-loss attempts as well as the associations with demographic and socioeconomic characteristics and health status. RESULTS The proportion of individuals with overweight and obesity misperceiving their weight status increased over time between 1997 and 2015 (37% to 40% in men; 17% to 19% in women). There were socioeconomic disparities in the misperception of weight status, with lower-educated individuals from poorer-income households and members of minority ethnic groups being more likely to underestimate their weight. Those underestimating their overweight and obesity status were 85% less likely to try to lose weight compared with people who accurately identified their weight status. CONCLUSIONS The upward trend in underassessment of overweight and obesity status in England is possibly a result of the normalization of overweight and obesity. Obesity prevention programs need to consider differential sociodemographic characteristics associated with underassessment of weight status.
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Comparison of two low-fat diets, differing in protein and carbohydrate, on psychological wellbeing in adults with obesity and type 2 diabetes: a randomised clinical trial.
Watson, NA, Dyer, KA, Buckley, JD, Brinkworth, GD, Coates, AM, Parfitt, G, Howe, PRC, Noakes, M, Murphy, KJ
Nutrition journal. 2018;17(1):62
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The psychological burden of living with type 2 diabetes (T2D) has far reaching effects, negatively impacting quality of life, physical health and emotional wellbeing. It has been suggested that health-related quality of life (HRQoL) changes in response to weight status however this has not yet been explored in individuals with T2D. The aim of this randomised controlled study was to compare the effects of high protein and high carbohydrate diets, combined with moderate intensity exercise, on psychological wellbeing and HRQoL in 61 overweight adults with T2D. Participants enrolled in a 12-week weight loss period followed by a 12-week weight maintenance phase and blood glucose levels and various quality of life factors were assessed. This trial found in overweight adults with T2D, improvements in several psychological wellbeing and HRQoL were seen in response to modest weight loss and improvements in blood sugar levels. Improvements were seen in both high protein and high carbohydrate group, though a high protein diet may be better for maintaining control of blood glucose levels thus improving feelings of vitality. Based on this study, the authors conclude that it is imperative to address and support the psychological aspects of patients managing T2D.
Abstract
BACKGROUND Although higher-protein diets (HP) can assist with weight loss and glycemic control, their effect on psychological wellbeing has not been established. The objective of this study was to compare the effects of a HP and a higher-carbohydrate diet (HC), combined with regular exercise, on psychological wellbeing both during weight loss (WL) and weight maintenance phases (WM). METHODS In a parallel RCT, 61 adults with T2D (mean ± SD: BMI 34.3 ± 5.1 kg/m2, aged 55 ± 8 years) consumed a HP diet (29% protein, 34% carbohydrate, 31% fat) or an isocaloric HC diet (21%:48%:24%), with moderate intensity exercise, for 12 weeks of WL and 12 weeks of WM. Secondary data evaluating psychological wellbeing was assessed using: Problems Areas in Diabetes (PAID); Diabetes-39 Quality of Life (D-39); Short Form Health Survey (SF-36); Perceived Stress Scale-10 (PSS-10) and the Leeds Sleep Evaluation Questionnaire (LSEQ) at Weeks 0, 12 and 24 and evaluated with mixed models analysis. RESULTS Independent of diet, improvements for PAID; D-39 diabetes control; D-39 severity of diabetes; SF-36 physical functioning and SF-36 general health were found following WL (d = 0.30 to 0.69, P ≤ 0.04 for all) which remained after 12 weeks of WM. SF-36 vitality improved more in the HP group (group x time interaction P = 0.03). Associations were seen between HbA1c and D-39 severity of diabetes rating (r = 0.30, P = 0.01) and SF-36 mental health (r = - 0.32, P = 0.003) and between weight loss and PAID (r = 0.30, P = 0.01). CONCLUSION Several improvements in diabetes-related and general psychological wellbeing were seen similarly for both diets following weight loss and a reduction in HbA1c with most of these improvements remaining when weight loss was sustained for 12 weeks. A HP diet may provide additional increases in vitality. TRIAL REGISTRATION The trial was prospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN 12613000008729 ) on 4 January 2013.
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Harnessing the Power of Microbiome Assessment Tools as Part of Neuroprotective Nutrition and Lifestyle Medicine Interventions.
Toribio-Mateas, M
Microorganisms. 2018;6(2)
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This is a practical review written by a clinician for other clinicians. It draws from an extensive body of evidence on the links between the gut microbes (bacteria amongst them), called the microbiota, both in health and in a variety of human diseases. The author, who is also a researcher in the communication between the gut and the brain (the gut-brain axis), focuses on the translation of science into simple clinical applications that result in measurable health outcomes, and in particular in neurodegenerative conditions such as Alzheimer's and Parkinson's, but also other less well studied such as Chronic Fatigue Syndrome (CFS). The paper also covers mental health / mood conditions such as anxiety, and depression. Practitioners who work in the area of gut health and use stool tests to assess various imbalances their patients may be experiencing will get the most out this paper. The author takes a look at the physiological processes that influence gastrointestinal as well as brain health and discusses how tools such as the characterisation or "mapping" of commensal bacteria (the bacteria that lives inside our guts normally), along with the identification of potential opportunistic and pathogenic bacteria and parasites, together with knowledge of molecules such as short chain fatty acids or zonulin can enable better clinical decision making by nutrition and lifestyle medicine practitioners. The paper also includes a valuable discussion on patient-reported outcome measures (PROMs), and particularly on the use of MYMOP by practitioners as a validated tool to collect insight from exposure to real world data in clinical practice.
Abstract
An extensive body of evidence documents the importance of the gut microbiome both in health and in a variety of human diseases. Cell and animal studies describing this relationship abound, whilst clinical studies exploring the associations between changes in gut microbiota and the corresponding metabolites with neurodegeneration in the human brain have only begun to emerge more recently. Further, the findings of such studies are often difficult to translate into simple clinical applications that result in measurable health outcomes. The purpose of this paper is to appraise the literature on a select set of faecal biomarkers from a clinician’s perspective. This practical review aims to examine key physiological processes that influence both gastrointestinal, as well as brain health, and to discuss how tools such as the characterisation of commensal bacteria, the identification of potential opportunistic, pathogenic and parasitic organisms and the quantification of gut microbiome biomarkers and metabolites can help inform clinical decisions of nutrition and lifestyle medicine practitioners.
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Bacillus coagulans MTCC 5856 for the management of major depression with irritable bowel syndrome: a randomised, double-blind, placebo controlled, multi-centre, pilot clinical study.
Majeed, M, Nagabhushanam, K, Arumugam, S, Majeed, S, Ali, F
Food & nutrition research. 2018;62
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Bacillus coagulans, also known as Lactobacillus sporogenes, is a probiotic bacterium in spore form that "opens up" in the small intestine, thereby enduring minimal damage by the acidity of the stomach pH. Bacillus coagulans MTCC 5856 supplemented orally in doses of 2 billion spores twice per day (a total of 4 billion per day) has been shown previously to help in the management of diarrhoea. The current study is randomised and controlled, and focused on finding out what effect this probiotic would have on the depressive symptoms often experienced by people with irritable bowel syndrome or IBS. A total of 40 participants were randomised to the probiotic group, which means that 20 of them just took an empty capsule without any Bacillus coagulans to figure out whether the effects of the supplementation were just due to chance or placebo. Neither the clinician administering the probiotic or the participants knew whether they were taking the probiotic or an empty capsule. The study lasted for 90 days. Those who did take the probiotic at 4 billion spores per day (2 billion morning and 2 billion evening) experienced an improvement in both depression and IBS symptoms that was statistically significant and clinically meaningful. Even though this was a small study, it is worth taking into account that the safety of supplementation with Bacillus coagulans has been documented in previous studies. Therefore, nutrition and lifestyle practitioners looking to support their patients' mental health by working upstream from the gut may wish to consider adding this probiotic bacterium to their recommendations on the basis of its potential psychobiotic properties.
Abstract
BACKGROUND The modification of microbial ecology in human gut by supplementing probiotics may be an alternative strategy to ameliorate or prevent depression. OBJECTIVE The current study was conducted to assess the safety and efficacy of the probiotic strain Bacillus coagulans MTCC 5856 for major depressive disorder (MDD) in IBS patients. METHOD Patients (n = 40) diagnosed for MDD with IBS were randomized (1:1) to receive placebo or B. coagulans MTCC 5856 at a daily dose of 2 × 109 cfu (2 billion spores) and were maintained to the end of double-blind treatment (90 days). Changes from baseline in clinical symptoms of MDD and IBS were evaluated through questionnaires. RESULTS Significant change (p = 0.01) in favour of the B. coagulans MTCC 5856 was observed for the primary efficacy measure Hamilton Rating Scale for Depression (HAM-D), Montgomery-Asberg Depression Rating Scale (MADRS), Center for Epidemiological Studies Depression Scale (CES-D) and Irritable bowel syndrome quality of life questionnaire (IBS-QOL). Secondary efficacy measures i.e. Clinical Global Impression-Improvement rating Scale (CGI-I), Clinical Global Impression Severity rating Scale (CGI-S), Gastrointestinal Discomfort Questionnaire (GI-DQ) and Modified Epworth Sleepiness Scale (mESS) also showed significant results (p = 0.01) in B. coagulans MTCC 5856 group compared to placebo group except dementia total reaction scoring. Serum myeloperoxidase, an inflammatory biomarker was also significantly reduced (p < 0.01) when compared with the baseline and end of the study. All the safety parameters remained well within the normal clinical range and had no clinically significant difference between the screening and at the end of the study. CONCLUSION B. coagulans MTCC 5856 showed robust efficacy for the treatment of patients experiencing IBS symptoms with major depressive disorder. The improvement in depression and IBS symptoms was statistically significant and clinically meaningful. These findings support B. coagulans MTCC 5856 as an important new treatment option for major depressive disorder in IBS patients.
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Intestinal microbiome-gut-brain axis and irritable bowel syndrome.
Moser, G, Fournier, C, Peter, J
Wiener medizinische Wochenschrift (1946). 2018;168(3-4):62-66
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The gut-brain-microbiota axis connects the nervous system with the metabolic, hormonal and immune functions of the intestines. Irritable bowel syndrome (IBS) is a functional gut disorder that commonly presents with psychological co-morbidities, and while animal studies show strong associations between stress and gut microbiota, studies in humans are rare. This review assesses the current literature on intestinal microbiome and its association with stress, anxiety and depression in patients with IBS. Based on existing studies, the authors found the gut microbiota forms a crucial link between the intestine and nervous system. Therapies targeted at both modulating the gut microbiome and psychological interventions are recommended. The authors conclude further randomised clinical trials are needed to better understand which therapies work best for patients with IBS.
Abstract
Psychological comorbidity is highly present in irritable bowel syndrome (IBS). Recent research points to a role of intestinal microbiota in visceral hypersensitivity, anxiety, and depression. Increased disease reactivity to psychological stress has been described too. A few clinical studies have attempted to identify features of dysbiosis in IBS. While animal studies revealed strong associations between stress and gut microbiota, studies in humans are rare. This review covers the most important studies on intestinal microbial correlates of psychological and clinical features in IBS, including stress, anxiety, and depression.
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Patient-Reported Outcome Measures 2 Years After Standard and Distal Gastric Bypass-a Double-Blind Randomized Controlled Trial.
Svanevik, M, Risstad, H, Karlsen, TI, Kristinsson, JA, Småstuen, MC, Kolotkin, RL, Søvik, TT, Sandbu, R, Mala, T, Hjelmesæth, J
Obesity surgery. 2018;28(3):606-614
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Bariatric surgery may induce weight loss, improvement of weight-associated comorbidities, and improved health and well-being. The aim of the study is to compare the effects of standard and distal Rou-en-Y gastric bypass on obesity-specific health related quality of life, weight-related symptoms, eating behaviour, anxiety and depression. The study is a double-blind, parallel-group randomised controlled trial. The participants’ age ranged from 18 to 60 years of age with a BMI of 50 to 60 kg/m2. Results indicated improvements in most patient-reported outcome measures after both surgeries, but no significant difference between groups after surgery in relation to obesity-specific health related quality of life, weight-related symptoms, anxiety and depression, or eating behaviour. Authors conclude that both surgeries lead to sustained weight loss and improved health related quality of life 2 years after surgery in patients with a BMI 50-60kg/m2.
Abstract
BACKGROUND The preferred surgical procedure for treating morbid obesity is debated. Patient-reported outcome measures (PROMs) are relevant for evaluation of the optimal bariatric procedure. METHODS A total of 113 patients with BMI from 50 to 60 were randomly assigned to standard (n = 57) or distal (n = 56) Roux-en-Y gastric bypass (RYGB). Validated PROMS questionnaires were completed at baseline and 2 years after surgery. Data were analyzed using mixed models for repeated measures and the results are expressed as estimated means and mean changes. RESULTS Obesity-related quality of life improved significantly after both procedures, without significant between-group differences (- 0.4 (95% CI = - 8.4, 7.2) points, p = 0.88, ES = 0.06). Both groups had significant reductions in the number of weight-related symptoms and symptom distress score, with a mean group difference (95% CI) of 1.4 (- 0.3, 3.3) symptoms and 5.0 (2.9. 12.8) symptom distress score points. There were no between-group differences for uncontrolled eating (22.0 (17.2-26.7) vs. 28.9 (23.3-34.5) points), cognitive restraint (57.4 (52.0-62.7) vs. 62.1 (57.9-66.2) points), and emotional eating (26.8 (20.5-33.1) vs. 32.6 (25.5-39.7) points). The prevalence of anxiety was 33% after standard and 25% after distal RYGB (p = 0.53), and for depression 12 and 9%, respectively (p = 0.76). CONCLUSIONS There were no statistically significant differences between standard and distal RYGB 2 years post surgery regarding weight loss, obesity-related quality of life, weight-related symptoms, anxiety, depression, or eating behavior. TRIAL REGISTRATION Clinical Trials.gov number NCT00821197.
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The Effect of a High-Dose Vitamin B Multivitamin Supplement on the Relationship between Brain Metabolism and Blood Biomarkers of Oxidative Stress: A Randomized Control Trial.
Ford, TC, Downey, LA, Simpson, T, McPhee, G, Oliver, C, Stough, C
Nutrients. 2018;10(12)
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A diet rich in vitamins and micronutrients, particularly B vitamins, is essential for body and brain functionality. B vitamin supplementation has been found to reduce depression, enhance mood, lessen anxiety and improve cognition. New neuroimaging techniques have shed light on the relationship between blood and neural biomarkers, connecting diet quality and brain function. The aim of this randomised, placebo-controlled, double-blind trial was to investigate the effect of 6-month high-dose B-vitamin supplementation on neural and blood biomarkers of metabolism in 32 healthy adults. Participants were randomised to consume either B-vitamin supplementation or placebo pills twice a day for six months and underwent blood tests and brain imaging before and after supplementation. This study found supplementation effectively increased vitamin B6 and B12 levels and reduced homocysteine with no changes in folate as compared with placebo. Supplementation promoted neural metabolic pathways and reduced oxidative stress and inflammation. Based on these findings, the authors conclude B-group vitamins are important for maintaining brain health in healthy adults and may play a role in prevention and alleviation of neural disease and disability.
Abstract
A diet rich in B-group vitamins is essential for optimal body and brain function, and insufficient amounts of such vitamins have been associated with higher levels of neural inflammation and oxidative stress, as marked by increased blood plasma homocysteine. Neural biomarkers of oxidative stress quantified through proton magnetic spectroscopy (1H-MRS) are not well understood, and the relationship between such neural and blood biomarkers is seldom studied. The current study addresses this gap by investigating the direct effect of 6-month high-dose B-group vitamin supplementation on neural and blood biomarkers of metabolism. Using a randomized, double-blind, placebo-controlled design, 32 healthy adults (20 female, 12 male) aged 30⁻65 years underwent blood tests (vitamin B6, vitamin B12, folate, and homocysteine levels) and 1H-MRS of the posterior cingulate cortex (PCC) and dorsolateral prefrontal cortex (DLPFC) before and after supplementation. Results confirmed the supplement was effective in increasing vitamin B6 and vitamin B12 levels and reducing homocysteine, whereas there was no change in folate levels. There were significant relationships between vitamin B6 and N-acetylaspartate (NAA), choline, and creatine, as well as between vitamin B12 and creatine (ps < 0.05), whereas NAA in the PCC increased, albeit not significantly (p > 0.05). Together these data provide preliminary evidence for the efficacy of high-dose B-group supplementation in reducing oxidative stress and inflammation through increasing oxidative metabolism. It may also promote myelination, cellular metabolism, and energy storage.