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The Association between Total Protein, Animal Protein, and Animal Protein Sources with Risk of Inflammatory Bowel Diseases: A Systematic Review and Meta-Analysis of Cohort Studies.
Talebi, S, Zeraattalab-Motlagh, S, Rahimlou, M, Naeini, F, Ranjbar, M, Talebi, A, Mohammadi, H
Advances in nutrition (Bethesda, Md.). 2023;14(4):752-761
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Expert Review
Conflicts of interest:
None
Take Home Message:
- According to the researchers, the effect of the high consumption of meat in increasing the risk of IBD is not related to the type of protein contained in it but could be due to cooking meat at high temperatures
- Other studies have reported that the consumption of animal proteins, especially processed and red meat, increases the risk of IBD
- Other studies related to dairy intake have been contradictory. There is also evidence reported of a positive effect from dairy exclusion in IBD patients.
- Further research is required to corroborate the findings of this systematic review.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
The authors conducted a dose-dependent meta-analysis of prospective cohort studies which examined the relation between total protein, animal protein, and animal protein sources with inflammatory bowel disease (IBD) in adults because the prevalence and incidence of IBD have exceeded globally.
Methods
Cochrane methodology was undertaken for the systematic review. Data from 11 prospective cohort studies with 8067 cases and 4,302,554 participants was extracted by 2 independent investigators. Evaluation of the quality and possible biases of included studies was performed. Risk ratios (RR) with 95% confidence intervals were chosen as the effect estimate. Various subgroup analyses were undertaken as well as metaregression analyses.
Results
- Seven cohort studies (7232 cases, 1,097,040 participants) were included in the analysis of dairy intake. Higher intakes of dairy was associated with a lower risk of IBD (RR: 0.81; 95% CI: 0.72, 0.90; n = 7)
- Consumption of protein from dairy products was found to be protective against IBD risk (RR = 0.77; 95% CI: 0.68, 0.88)
- Three prospective cohort studies with 1214 cases of IBD among a total of 535,738 subjects were included in the total meat analyses. Higher dietary total meat intake was not associated with the risk of IBD (RR: 1.24; 95% CI: 0.90, 1.70; n = 4)
- A positive linear association was found between total meat intake and risk of IBD. 100 g/d increment in dietary total meat consumption was associated with a 38% greater risk of IBD (RR: 1.38, 95% CI: 1.13, 1.68)
- Three prospective cohorts, among 492,497 participants and 4025 cases were included in the analysis of egg consumption. No association was found between egg consumption and IBD risk (RR: 0.92; 95% CI: 0.81, 1.04; n = 4).
Conclusion
The findings indicated no notable correlation between the intake of the majority of dietary protein sources and the incidence of IBD. IBD risk only escalated with higher total meat consumption, while the intake of protein from dairy products emerged as a protective factor against the risk of IBD.
Clinical practice applications:
- Dairy product consumption may be protective against IBD. However the studies included with statistically significant results did not control for alcohol intake and other confounding factors. The type of dairy product consumed, as well as a personalised approach, should be considered
- This study did not find any association between red or processed meat consumption and risk of IBD. However the subgroup analysis did find a significant association between red meat intake and IBD risk. This difference in results may be caused by differences in cooking methods, genetic factors, amount of meat consumption, confounding factors, and other environmental factors
- Total meat intake, as well as type of meat intake, and how meat is cooked, should be reviewed in clients with IBD, Crohn's Disease and Ulcerative Colitis.
Considerations for future research:
- Intervention studies would need to be conducted to corroborate the findings of this systematic review
- Future research should fully consider cofounding factors, such as alcohol intake and body mass index (BMI)
- Future studies should further consider types of protein as well as dose and cooking implications.
Abstract
We aimed to conduct this dose-dependent meta-analysis to examine the relation between total protein, animal protein, and its sources with inflammatory bowel disease (IBD). We searched databases, comprising PubMed/Medline, Web of Science (ISI), Embase, and Google Scholar, for the published studies up to 28 March 2023. Prospective cohort study designs that investigated associations between dietary intake of various animal protein sources and with risk of IBD in the general population were identified. Eleven prospective cohort studies with 4,302,554 participants and 8067 cases were considered eligible. Findings indicated that higher intake of dairy was significantly associated with a lower risk of IBD (relative risk [RR]: 0.81; 95% confidence interval [CI]: 0.72, 0.90), Crohn disease (RR: 0.69; 95% CI: 0.56, 0.86), and ulcerative colitis (RR: 0.84; 95% CI: 0.75, 0.94). There was no association between different sources of animal protein and the risk of IBD. The dose-response analysis suggested that each 100 g/d increment in dietary total meat consumption was associated with a 38% greater risk of IBD. Moreover, a positive linear association was found between total meat intake and risk of IBD (Pnonlinearity = 0.522, Pdose-response = 0.005). Overall, among the dietary sources of protein, the risk of IBD increased only with increasing total meat intake, and the consumption of protein from dairy products was found to be a protective factor against the IBD risk. This trial was registered at PROSPERO as CRD42023397719.
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Physical Training and Healthy Diet Improved Bowel Symptoms, Quality of Life, and Fatigue in Children With Inflammatory Bowel Disease.
Scheffers, LE, Vos, IK, Utens, EMWJ, Dieleman, GC, Walet, S, Escher, JC, van den Berg, LEM
Journal of pediatric gastroenterology and nutrition. 2023;77(2):214-221
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Inflammatory bowel disease (IBD), including Crohn disease and ulcerative colitis, are chronic inflammatory diseases of the gastrointestinal tract, characterised by periods of remission and relapse of symptoms. The aim of this study was to assess the effects of a tailored lifestyle intervention on physical fitness (maximal and submaximal exercise capacity, strength, and core stability), the patient-reported outcomes (quality of life, fatigue, and fear), clinical disease activity, and nutritional status. This study was a prospective single-centre randomised semi-crossover-controlled trial. Children were randomized into group A (start exercise) or group B (start control period). Results showed improved physical fitness, quality of life, and parent-reported fatigue. Additionally, a combination of lower clinical disease activity scores accompanied by fewer IBD symptoms suggests positive effects on intestinal inflammation. Authors concluded that based on the findings of their study, children and adolescents with IBD should be motivated and supported to acquire and maintain a healthy lifestyle.
Expert Review
Conflicts of interest:
None
Take Home Message:
- IBD is a chronic inflammatory disease of the gastrointestinal tract, characterised by periods of abdominal pain, severe diarrhoea, and fatigue
- This clinical trial suggests that a 12-week program of physical training plus personalised healthy dietary advice may improve physical fitness, quality of life, and fatigue in children with IBD.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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X
B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A randomised semi-crossover controlled trial was conducted to investigate the impact of a 12-week lifestyle program (3 physical training sessions per week plus personalised healthy dietary advice) in children with Inflammatory Bowel Disease (IBD).
Method
- Sixteen children with a median age of 15 [IQR: 12–16]) that were diagnosed with IBD (CD, UC, or IBD-unclassified) were randomized to group A (start exercise) or group B (start control period). Group A started the intervention immediately after the first assessment and did not have a control period. Group B started after a control period (this was planned to last for 6 weeks but due to the COVID-19 lockdown extended to 6 months)
- The lifestyle intervention lasted 12 weeks and consisted of 3 physiotherapist-supervised training sessions per week, lasting 60 minutes each. In addition, all participants received a recommended caloric intake per day based on measured rest energy expenditure and a brochure regarding healthy diet in children
- Endpoints were physical fitness (maximal and submaximal exercise capacity, strength, and core stability), patient-reported outcomes (quality of life, fatigue, and fears for exercise), clinical disease activity (faecal calprotectin and disease activity scores), and nutritional status (energy balance and body composition)
- A total of 15 out of 16 participants (93%) completed the program, one patient dropped out after one training session due to motivational problems.
Results
The primary findings of this study were as follows:
- While medical treatment remained unchanged, Paediatric Crohn's Disease Activity Index decreased versus the control period (15 [3–25] vs 2.5 [0–5], P = 0.012)
- The number of patients in clinical remission increased from 5 to 12 (P < 0.001), compared to the control period
- Quality of life (IMPACT-III) improved on 4 out of 6 domains and the total score (+13 points) versus the control period including a large improvement in bowel-related symptoms, P= 0.029)
- Fecal calprotectin decreased, but not compared to the control period, mainly due to relatively large intra-patient fluctuations (400 μg/g [57.1–1662.7] vs 128 μg/g [23.8–642.3], P = 0.016)
- Parents reported an improvement in the quality of life versus the control period on the child health questionnaire and total fatigue score (PedsQoL • Multidimensional Fatigue Scale) (+14 points, P = 0.048)
- Walking distance improved after the 12-week program, compared to the control period (P = 0.001).
Conclusion
This study revealed that a 12-week physical training program and personalised dietary advice improved bowel symptoms, quality of life, and fatigue in children with IBD.
Clinical practice applications:
- The mechanism behind the anti-inflammatory effects of exercise has not been clarified
- Multiple theories have been suggested in previously published studies such as a reduced release of adipokines due to less visceral fat, increased secretion of anti-inflammatory cytokines such as interleukin (IL)-6, and reduced transient stool time
- This clinical trial demonstrated that a 12-week program of physical training sessions plus personalised healthy dietary advice resulted in improved physical fitness, quality of life, and parent-reported fatigue.
Considerations for future research:
- A sample size calculation was not provided in the study report and it is therefore assumed that the sample size of 16 children in this trial was too small to draw a definite conclusion. A larger study over a longer period is therefore needed across diverse age and ethnic population groups to draw better conclusions
- This study did not measure mucosal inflammation before and after the intervention due to the invasive nature of the procedure. It would however be useful that future research investigate this to gain more insight into the effect of lifestyle interventions on IBD.
Abstract
OBJECTIVES Physical activity programs have been suggested as adjunctive therapy in adult inflammatory bowel disease (IBD) patients. We assessed the effects of a 12-week lifestyle intervention in children with IBD. METHODS This study was a randomized semi-crossover controlled trial, investigating a 12-week lifestyle program (3 physical training sessions per week plus personalized healthy dietary advice) in children with IBD. Endpoints were physical fitness (maximal and submaximal exercise capacity, strength, and core stability), patient-reported outcomes (quality of life, fatigue, and fears for exercise), clinical disease activity (fecal calprotectin and disease activity scores), and nutritional status (energy balance and body composition). Change in maximal exercise capacity (peak VO 2 ) was the primary endpoint; all others were secondary endpoints. RESULTS Fifteen patients (median age 15 [IQR: 12-16]) completed the program. At baseline, peak VO 2 was reduced (median 73.3% [58.8-100.9] of predicted). After the 12-week program, compared to the control period, peak VO 2 did not change significantly; exercise capacity measured by 6-minute walking test and core-stability did. While medical treatment remained unchanged, Pediatric Crohn's Disease Activity Index decreased significantly versus the control period (15 [3-25] vs 2.5 [0-5], P = 0.012), and fecal calprotectin also decreased significantly but not versus the control period. Quality of life (IMPACT-III) improved on 4 out of 6 domains and total score (+13 points) versus the control period. Parents-reported quality of life on the child health questionnaire and total fatigue score (PedsQoL Multidimensional Fatigue Scale) also improved significantly versus the control period. CONCLUSIONS A 12-week lifestyle intervention improved bowel symptoms, quality of life, and fatigue in pediatric IBD patients.
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3.
Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial.
Katayoshi, T, Uehata, S, Nakashima, N, Nakajo, T, Kitajima, N, Kageyama, M, Tsuji-Naito, K
Scientific reports. 2023;13(1):2786
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Nicotinamide adenine dinucleotide (NAD+) is a coenzyme that plays a crucial role in energy metabolism and different biological processes. Sirtuins (SIRT1) are NAD+-dependent deacetylases, an enzyme that plays a key role in enhancing metabolic efficiency. Nicotinamide mononucleotide (NMN) is a precursor to NAD+. NMN supplementation may help to reduce the risk of developing metabolic diseases and cardiovascular diseases. This randomised, double-blinded, and placebo-controlled, parallel trial investigated the effects of 12 weeks of 125 mg NMN supplementation on metabolic health parameters, including CVD risk factors, blood NAD+ metabolites level, and SIRT1 expression in middle-aged men and women. Serum nicotinamide was significantly higher and arterial stiffness was lower in the NMN test group of middle-aged men and women after 12 weeks of NMN supplementation. The results of the study indicate that the administration of 250mg of nicotinamide mononucleotide (NMN) daily for an extended period is considered safe and well-tolerated. Healthcare professionals can use this finding to understand the significant implications of the use of NMN as a potential therapeutic agent in individuals seeking to improve their metabolic and cardiovascular health. Further robust studies are required to evaluate the effects of NMN supplementation due to the limitations and high baseline variability between the participants of this study.
Expert Review
Conflicts of interest:
None
Take Home Message:
- As we age, NAM levels decline, which could have a negative effect on cardiovascular health.
- Middle-aged adults may like to consider NMN supplementation to improve NAM metabolism and arterial stiffness.
- However, without data on CVD events, it is difficult to determine actual risk reductions.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
- Nicotinamide adenine dinucleotide (NAD+) is a coenzyme involved in metabolism. When we age, NAD+ levels decline resulting in poorer metabolism and age-related disease such as cardiovascular disease (CVD). Nicotinamide mononucleotide (NMN) is a precursor in the biosynthesis of NAD+.
- This double-blind, randomised control trial aimed to determine the effect of supplementing NMN on NAD+ levels, CVD risk factors and sirtuin 1 (SIRT1) expression, which relies on NAD+ for adequate functioning.
Methods
- 36 healthy male and female individuals aged between 40-65 years of age were assigned to either NMN (125mg/day) or placebo for 12 weeks.
- One capsule was taken twice per day after meals.
- Serum nicotinamide (NAM), NAD+, NMN, advanced glycation end products (AGES), 8-hydroxydeoxyguanosine (8-OHdG) and SIRT1 mRNA expression were measured.
- The condition of blood vessels (arterial stiffness) was also assessed using the ankle brachial index (ABI).
- In a sub-analysis, individuals with hypertension, above average body mass index (BMI), or blood glucose level were also assessed for blood vessel condition using the ABI.
Results
- The results showed that from baseline serum NAM decreased in the placebo group (P=0.014), whereas it increased in the NMN group (P=0.006). This resulted in an increase in the NMN group compared to placebo (P=0.037).
- Interestingly serum NAM was lower in the NMN group compared to placebo at baseline (P=0.001).
- There was no statistically significant difference in ABI with NMN supplementation.
- Amongst those with hypertension there was also no change in ABI. However, those with high BMI or blood glucose, there was an improvement in vascular condition compared to placebo (P=<0.007 and P=0.019 respectively).
- 8-OHdG, SIRT1 mRNA and AGEs remained unchanged by NMN supplementation
Conclusion
- NMN supplementation enhanced NAD+ metabolism in middle-aged adults.
- It also relieved arterial stiffness and reduced CVD risk factors.
Clinical practice applications:
- Apparently healthy middle-aged adults who would like to activate NAD metabolism and decrease their risk for CVD, should consider 12-week supplementation with NMN (125mg/day).
- ABI should be monitored to ensure desired effects.
- It is unclear as to the effects of NMN supplementation after 12-weeks.
Considerations for future research:
- Future research should consider longer supplementation duration and/or adding in a follow-up period to determine duration of effect.
- Different supplemental doses should also be researched to determine an optimal dose.
Abstract
Many animal studies have shown that oral administration of the nicotinamide adenine dinucleotide (NAD+) precursor nicotinamide mononucleotide (NMN) prevents the reduction of NAD+ levels in organs and tissues, helping alleviate aging-related diseases. However, there are very few clinical reports of NMN supplementation in humans. Thus, this study aimed to investigate the influence of a 12-week NMN oral supplementation on biochemical and metabolic health parameters. A 12-week randomized, double-blind, placebo-controlled, parallel-group clinical trial was conducted. A total of 36 healthy middle-aged participants received one capsule of either 125 mg NMN or placebo twice a day. Among the NAD+ metabolites, the levels of nicotinamide in the serum were significantly higher in the NMN intake group than in the placebo group. Pulse wave velocity values indicating arterial stiffness tended to decrease in the NMN intake group. However, no significant difference was found between the two groups. Long-term NMN supplementation at 250 mg/day was well tolerated and did not cause adverse events. NMN safely and effectively elevated NAD+ metabolism in healthy middle-aged adults. Additionally, NMN supplementation showed potential in alleviating arterial stiffness.
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The Efficacy of Self-Management Strategies for Females with Endometriosis: a Systematic Review.
Mardon, AK, Leake, HB, Hayles, C, Henry, ML, Neumann, PB, Moseley, GL, Chalmers, KJ
Reproductive sciences (Thousand Oaks, Calif.). 2023;30(2):390-407
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Endometriosis is a gynaecological condition with symptoms of pelvic pain, fatigue, and stress. Decreased quality of life, impaired fertility and hinderances to carry out day to day tasks are all associated with endometriosis. Treatment options involve medications and surgery; however, both are associated with poorer outcomes than the initial disease itself. Self-management strategies that the individual can perform themselves, such as lifestyle changes, meditation, and rest have all been used to improve the quality of life of individuals with endometriosis, however their effectiveness has not been determined. This systematic review and meta-analysis aimed to determine the effectiveness of self-management strategies for the management of endometriosis. The study showed that many self-management strategies were no more effective than placebo or hormonal therapies for the management of endometriosis. It was concluded that many self-management strategies were no more effective than hormonal treatment at reducing endometriosis symptoms and the studies that did show a benefit were insufficient to base recommendations on due to poor design. This study could be used by healthcare professionals to understand that currently the research on self-management strategies of endometriosis is poor and whilst some may be of benefit to individuals who cannot or do not want to take hormone therapy, more research is warranted.
Expert Review
Conflicts of interest:
None
Take Home Message:
It is not possible to generalise the findings of this systematic review for the self-management of endometriosis due to the poor quality of evidence. Further studies of higher quality are needed.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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X
B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
Endometriosis is an inflammatory condition where endometrial-like tissue is found outside of the uterus. Diagnosis of endometriosis is made in around 6-10% of females of reproductive age. Endometriosis can adversely affect fertility, psychological well being and quality of life (QoL). Conventional interventions can have side effects and limited effectiveness. The aim of this systematic review (SR) was to evaluate the efficacy of self-management interventions for pain-related symptoms and QoL.
Methods
Fifteen experimental studies were included in this SR. Ten evaluated dietary supplements, three evaluated dietary modifications, one evaluated over-the-counter (OTC) medication, and one evaluated exercise. Outcome measures were self-reported for dysmenorrhoea, dyspareunia, overall pain, non-menstrual pelvic pain, use of medications and QoL.
Results
- Most dietary supplements were no more effective than placebo or frequently recommended medical interventions, at reducing pain-related outcomes.
- Melatonin (one RCT n=30) performed better than placebo for managing dysmenorrhoea and overall pain but not for non-menstrual pelvic pain. PEA-transploydatin (one RCT n=20) performed better than placebo for dysmenorrhoea and non-menstrual pelvic pain but not better than medical intervention.
- Resveratrol (one RCT n=22 & one intervention study n=12) plus the oral contraceptive pill (OCP) was more effective than the OCP alone for managing dysmenorrhoea.
- In one observational study, 75% of participants (n=295) reported a reduction in ‘high’ intensity pain scores following a 12-month gluten-free diet (p- value =<0.005). Similarly, a full dietary modification (one non randomised controlled trial , n=30) found less participants reporting pain at ‘high intensity’ (18%) compared to linseed and calcium oil supplements (41%) and placebo (62%).
- A metal trace element supplement was more effective than placebo for managing overall pain (one RCT p- value<0.001).
- Naproxen (one cross over trial, n=11) performed better than placebo at managing dysmenorrhoea (83% vs 41%, p- value 0.008).
- Hatha yoga (one RCT n=12) was found to be effective at reducing overall pain and improving QoL compared to no yoga (p-value <0.05).
Conclusion
Due to limited, low-quality evidence, high risk of bias and high levels of heterogeneity between studies, it was not possible to generalise the findings of the studies included in this systematic review. Further research of high-quality is needed in order to make self-management recommendations for females with endometriosis.
Notes: The authors reported no conflicts of interest.
Clinical practice applications:
Evidence-based self-management interventions are considered critical for the management of endometriosis. However, the quality of evidence in this SR was considered of poor quality. Further high-quality research is needed in order to be able to make recommendations. Strategies that showed potential benefits included:
- Dietary modifications and a gluten-free diet may be effective for reducing the intensity of pain associated with endometriosis.
- Hatha yoga may be effective at reducing overall pain and supporting psychological wellbeing and QoL.
Considerations for future research:
High quality studies are needed as well as a ‘gold standard’ definition for self-management criteria. Understanding potential barriers to self-management interventions may also be beneficial.
Abstract
Self-management is critical for the care of endometriosis. Females with endometriosis frequently use self-management strategies to manage associated symptoms; however, the efficacy of such strategies is unknown. The aim of this review was to systematically appraise the evidence concerning efficacy of self-management strategies for endometriosis symptoms. Electronic databases, including Medline, Embase, Emcare, Web of Science Core Collection, Scopus, and the Cochrane Central Register of Controlled Trials, were searched from inception to March 2021. We included peer-reviewed experimental studies published in English evaluating the efficacy of self-management strategies in human females laparoscopically diagnosed with endometriosis. Studies underwent screening, data extraction, and risk of bias appraisal (randomised studies: Risk of Bias 2 tool; non-randomised studies: Risk Of Bias In Non-randomized Studies - of Interventions tool). Of the fifteen studies included, 10 evaluated dietary supplements, three evaluated dietary modifications, one evaluated over-the-counter medication, and one evaluated exercise. Most studies had a high-critical risk of bias. Many self-management strategies were not more effective at reducing endometriosis symptoms compared to placebo or hormonal therapies. Where studies suggest efficacy for self-management strategies, no recommendations can be made due to the poor quality and heterogeneity of evidence. High-quality empirical evidence is required to investigate the efficacy of self-management strategies for females with endometriosis.
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5.
Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials.
Zheng, Y, Zhang, Z, Tang, P, Wu, Y, Zhang, A, Li, D, Wang, CZ, Wan, JY, Yao, H, Yuan, CS
Frontiers in immunology. 2023;14:1143548
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Intestinal barrier function is closely related to the pathogenesis of various immune and inflammatory diseases. The intestinal microbiota plays an essential role in maintaining gut homeostasis and functionality in the presence of pro-inflammatory and anti-inflammatory microbes. The aim of this study was to comprehensively evaluate the role of probiotics in contributing to intestinal barrier function, and the related immune function, inflammatory status, and gut microbiota composition. This study was a systematic review of 28 articles (qualitative synthesis), and a meta-analysis of 26 randomised controlled trials. Results showed that probiotics could significantly improve intestinal barrier function according to specific indicators. The meta-analysis also indicated that probiotic supplementation could reduce inflammatory factors. Furthermore, it also demonstrated that probiotics could modulate gut microbiota compositions by elevating the abundances of Bifidobacterium and Lactobacillus. Authors conclude that probiotics could improve intestinal barrier function to some extent, but more high-quality randomised controlled studies are needed to reach a solid conclusion.
Expert Review
Conflicts of interest:
None
Take Home Message:
The probiotics Bifidobacterium and Lactobacillus may be beneficial for health by addressing imbalances in gut bacteria (dysbiosis), reducing inflammation in the gut and improving the integrity and function of the gut barrier
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
Probiotics are microorganisms that are considered beneficial to health. The aim of this study was to assess the role of probiotics in protecting intestinal barrier function as well as their effects on the composition of gut microbiota, inflammatory status, and immune function for reducing the risk of related diseases.
Methods
26 randomised controlled trials (RCTs) published between 2005-2021 with a total population of n=1891 (n = 955 Intervention, n = 936 controls)) were included in the meta-analysis. Outcome measures were categorised under indicators relating to intestinal barrier function, inflammatory markers, immune function and microbiota composition. Studies were conducted worldwide with participants being healthcare patients or athletes. Study durations ranged from 3 days to 6 months. Different dosages and forms of probiotics were used. Data was pooled for Bifidobacterium, Lactobacillus, Enterobacteriaceae and Enterococcus species.
Results
Gut barrier function in the probiotic groups was improved as measured by transepithelial resistance (TER) mean difference (MD) 5.27 {95% CI, 3.82 to 6.72, p = < 0.00001], lipopolysaccharide (LPS) standardised mean difference (SMD) -0.47 (95% CI, -0.85 to -0.09, p = 0.02), serum zonulin SMD -1.58 (95% CI,-2.49 to -0.66, p = 0.0007), and endotoxin SMD -3.20 (95% CI, -5.41 to - 0.98, p = 0.005).
The inflammatory markers interleukin 6 (IL-6), C-reactive protein (CRP) and tumour necrosis factor-alpha (TNF-a) were also improved compared to control groups. Lactobacillus (95% CI p=0.02) and Bifidobacterium (95% CI, p=0.01) enhanced microbial composition, however, Enterobacteriaceae and Enterococcus species did not. Immune function as measured by Immunoglobulin A (IgA), Immunoglobulin G IgG and Immunoglobulin M (IgM) were not improved.
Conclusion
The findings of this study suggest that intestinal barrier function and microbial composition could be improved using probiotics. They were also found to help alleviate inflammation. Further studies of high quality are however needed to confirm these results.
No conflicts of interest were reported.
Clinical practice applications:
The use of the probiotics Bifidobacterium and Lactobacillus may be beneficial for:
- supporting the integrity of gut barrier function
- improving the composition of gut microbiota
- lowering inflammation
Considerations for future research:
High heterogeneity between studies may affect the applicability of the results. Future research development should focus on the following areas:
- testing methods
- study durations
- measuring indicators
- the type and dose of probiotics
Abstract
BACKGROUND Probiotics play a vital role in treating immune and inflammatory diseases by improving intestinal barrier function; however, a comprehensive evaluation is missing. The present study aimed to explore the impact of probiotics on the intestinal barrier and related immune function, inflammation, and microbiota composition. A systematic review and meta-analyses were conducted. METHODS Four major databases (PubMed, Science Citation Index Expanded, CENTRAL, and Embase) were thoroughly searched. Weighted mean differences were calculated for continuous outcomes with corresponding 95% confidence intervals (CIs), heterogeneity among studies was evaluated utilizing I2 statistic (Chi-Square test), and data were pooled using random effects meta-analyses. RESULTS Meta-analysis of data from a total of 26 RCTs (n = 1891) indicated that probiotics significantly improved gut barrier function measured by levels of TER (MD, 5.27, 95% CI, 3.82 to 6.72, P < 0.00001), serum zonulin (SMD, -1.58, 95% CI, -2.49 to -0.66, P = 0.0007), endotoxin (SMD, -3.20, 95% CI, -5.41 to -0.98, P = 0.005), and LPS (SMD, -0.47, 95% CI, -0.85 to -0.09, P = 0.02). Furthermore, probiotic groups demonstrated better efficacy over control groups in reducing inflammatory factors, including CRP, TNF-α, and IL-6. Probiotics can also modulate the gut microbiota structure by boosting the enrichment of Bifidobacterium and Lactobacillus. CONCLUSION The present work revealed that probiotics could improve intestinal barrier function, and alleviate inflammation and microbial dysbiosis. Further high-quality RCTs are warranted to achieve a more definitive conclusion. CLINICAL TRIAL REGISTRATION https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=281822, identifier CRD42021281822.
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6.
Effects of Diet on 10-Year Atherosclerotic Cardiovascular Disease Risk (from the DASH Trial).
Jeong, SY, Wee, CC, Kovell, LC, Plante, TB, Miller, ER, Appel, LJ, Mukamal, KJ, Juraschek, SP
The American journal of cardiology. 2023;187:10-17
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Determining the 10-year risk of heart disease can be used as tool to determine appropriate treatment plans. This study of 459 adults aged 22-75 years with obesity aimed to compare the effects on the 10-year risk for the development heart disease of an 8-week dietary approaches to stop hypertension (DASH) diet, with the standard American diet (AD) and a diet high in fruits and vegetables (F/V). The results showed that the DASH diet significantly improved risk factors such as systolic blood pressure and total cholesterol. However, the F/V diet had an improvement in good cholesterol, which the DASH diet did not. This equated to a similar 10% reduction in the 10-year heart disease risk compared to the AD. It was concluded that compared to a typical AD, DASH and F/V diets reduced the risk for heart disease over a 10-year period. However, the actual risk reduction was only small and individuals with obesity may need to reduce their risk further with other therapies. This study could be used by healthcare professionals to recommend a DASH diet or a diet high in fruits and vegetables to reduce the long-term risk for heart disease alongside other proven therapies or methods to reduce risk.
Expert Review
Conflicts of interest:
None
Take Home Message:
- DASH and F/V diets may be of benefit to obese individuals to decrease their risk for ASCVD
- The DASH diet did reduce HDL cholesterol and recommendations should be made to limit this effect (e.g. exercise and more fruit and vegetables in the diet).
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
This study aimed to determine the effect of the Dietary Approaches to Stop Hypertension (DASH) diet compared to a standard American diet (AD) and a diet emphasising fruits and vegetables (F/V) on the 10-year risk of atherosclerotic cardiovascular disease (ASCVD) and how adopting these diets affect specific risk factors (e.g systolic blood pressure (SBP), diastolic blood pressure (DBP) and blood lipids).
Methods
- Secondary analysis from the DASH trial which ran for 8 weeks in 459 adults aged 22-75 years with obesity
- All meals were provided and dietary intake was adjusted to prevent weight loss
- The primary outcome was an absolute and relative difference in 10-year ASCVD risk from baseline.
Participants were randomised to one of three diets:
1) DASH diet
2) F/V diet, similar to AD but with more fruits and vegetables and higher potassium and magnesium
3) Standard AD.
Results
- DASH significantly lowered SBP, total cholesterol, and HDL cholesterol compared to F/V (absolute difference SBP: -2.8, (95% confidence interval [CI]-4.5, -1.2), total cholesterol: 9.3 (-14.7, 3.9), and HDL cholesterol: -3.5 (-5.0, -2.1) P=<0.05 for all)
- DASH significantly lowered SBP, total cholesterol, and HDL cholesterol compared to AD (absolute difference SBP: -5.3 (-7.0, -3.7), total cholesterol: -13.1 (-18.5, -7.7), and HDL cholesterol: -3.8 (-5.2, -2.4) P=<0.05 for all)
- Compared to AD, DASH and F/V diets reduced 10-year ASCVD relative risk by -10.3%
( −14.4 to −5.9) and −9.9% ( −14.0 to −5.5) respectively
- This translated into low actual risk reductions of -0.21% for the F/V diet and -0.17% for the DASH diet
- Although DASH improved SBP, and total cholesterol compared to F/V, no differences in ASCVD risk between DASH and F/V were apparent. This was attributable to the detrimental effect of the DASH diet on HDL cholesterol, which was not seen in the F/V diet
- The effects of the DASH diet were more pronounced in black participants and in women.
Conclusion
Compared to the AD, DASH and F/V reduced 10-year ASCVD risk by approximately 10% over 8-weeks. The DASH diet was more effective for women and black adults.
Clinical practice applications:
- DASH and F/V diets decrease risk factors and an individual’s risk of ASCVD, and should be encouraged in individuals with obesity, especially women and black adults
- However, these diets do still leave obese individuals at risk for ASCVD.
Considerations for future research:
- Research on these diets in combination with weight loss regimes may give more pronounced results
- It may also be interesting to understand the mechanisms behind why the DASH diet reduces HDL cholesterol.
Abstract
Although modern risk estimators, such as the American College of Cardiology/American Heart Association Pooled Cohort Equation, play a central role in the decisions of patients to start pharmacologic therapy to prevent atherosclerotic cardiovascular disease (ASCVD), there is limited evidence to inform expectations for 10-year ASCVD risk reduction from established lifestyle interventions. Using data from the original DASH (Dietary Approaches to Stop Hypertension) trial, we determined the effects of adopting the DASH diet on 10-year ASCVD risk compared with adopting a control or a fruits and vegetables (F/V) diet. The DASH trial included 459 adults aged 22 to 75 years without CVD and not taking antihypertensive or diabetes mellitus medications, who were randomized to controlled feeding of a control diet, an F/V diet, or the DASH diet for 8 weeks. We determined 10-year ASCVD risk with the American College of Cardiology/American Heart Association Pooled Cohort Equation based on blood pressure and lipids measured before and after the 8-week intervention. Compared with the control diet, the DASH and F/V diets changed 10-year ASCVD risk by -10.3% (95% confidence interval [CI] -14.4 to -5.9) and -9.9% (95% CI -14.0 to -5.5) respectively; these effects were more pronounced in women and Black adults. There was no difference between the DASH and F/V diets (-0.4%, 95% CI -6.9 to 6.5). ASCVD reductions attributable to the difference in systolic blood pressure alone were -14.6% (-17.3 to -11.7) with the DASH diet and -7.9% (-10.9 to -4.8) with the F/V diet, a net relative advantage of 7.2% greater relative reduction from DASH compared with F/V. This was offset by the effects on high-density lipoprotein of the DASH diet, which increased 10-year ASCVD by 8.8% (5.5 to 12.3) compared with the more neutral effect of the F/V diet of -1.9% (-5.0 to 1.2). In conclusion, compared with a typical American diet, the DASH and F/V diets reduced 10-year ASCVD risk scores by about 10% over 8 weeks. These findings are informative for counseling patients on both choices of diet and expectations for 10-year ASCVD risk reduction.
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7.
An Energy-Reduced Mediterranean Diet, Physical Activity, and Body Composition: An Interim Subgroup Analysis of the PREDIMED-Plus Randomized Clinical Trial.
Konieczna, J, Ruiz-Canela, M, Galmes-Panades, AM, Abete, I, Babio, N, Fiol, M, Martín-Sánchez, V, Estruch, R, Vidal, J, Buil-Cosiales, P, et al
JAMA network open. 2023;6(10):e2337994
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The Mediterranean diet (MedDiet), which focuses on whole grains, lean meat, fruits, vegetables, and low amounts of minimally processed foods has been shown in previous research to improve body composition and decrease fat storage around the middle. This randomised control trial of 1556 older adults aimed to determine the effects of combining a 30% lower energy version of the MedDiet in combination with physical exercise on body composition. After 3 years, the results showed that compared to a normal MedDiet without exercise, the lower energy version in combination with exercise improved body composition by decreasing total fat, and the fat stored around the organs and increasing muscle mass. However, benefits were more pronounced after 1 year and decreased slightly at 3 years. It was concluded that a low energy MedDiet in combination with physical activity may be able to improve the body composition of overweight and older adults with obesity. This study could be used by healthcare professionals to recommend a low energy MedDiet to older adults to promote weight loss, whilst attenuating muscle loss associated with ageing.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The addition of exercise to an energy-reduced diet, which focuses on whole grains, healthy fats, lean protein, and fruits and vegetables can emphasise positive effects on body composition in older adults.
- However, there is a loss of lean mass associated with this type of diet (contrary to author conclusions) and measures should be taken to monitor and increase protein intake to prevent or limit this loss.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
This study aimed to determine the long-term effects of an energy reduced MedDiet in combination with physical activity on body composition.
Methods
- This is a predetermined 3-year interim analysis of a 6-year single-blind, randomised control trial of 1556 individuals aged 55-75 who are overweight or obese with metabolic syndrome.
- 760 individuals on 30% energy reduced MedDiet with limited processed foods, plus 45 minutes walking 6 days per week and behavioural and motivational support. [Intervention group]
- 761 on standard MedDiet without physical activity. [Control]
Results
Within group comparisons showed that individuals in the intervention group lost (P value represents baseline vs year 3):
- Total fat mass percentage (1-year vs baseline, −1.14%; 95% CI, −1.32% to −0.96%; 3-year vs baseline, −0.52%; 95% CI, −0.71% to −0.33% P=<0.001)
- Absolute visceral fat (1-year vs baseline, −154 g; 95% CI, −191 to −116 g; 3-year vs baseline, −75.1 g, 95% CI, −115 to −35.3 g P=<0.001)
- Absolute total fat after 1 year (mean change at 1 year vs baseline, −1677 g; 95% CI, −1930 to −1424 g) but regained some at year 3 (mean change at 3 years vs baseline, −1018 g; 95% CI, −1280 to −756 g P=<0.001)
- Absolute lean mass (mean change at 1 year vs baseline −300 g; 95% CI, −439 to −162 g) with further losses at year 3 (−626 g; 95% CI, −770 to −483 g P=0.001).
Within group comparisons also showed significantly increased:
- Total lean mass percentage, which was greater at year 1 than year 3 (1-year vs baseline, 1.07%; 95%CI, 0.90%-1.25%; 3-year vs baseline, 0.47%; 95% CI, 0.29%-0.65% P=<0.001).
As a result of total fat loss and some lean mass in the intervention group, the lean:fat mass ratio improved and was unchanged in the control group (between group differences (P=<0.001).
Compared to women, men may find the MedDiet + exercise more beneficial as it was shown that body composition changes were slightly more pronounced in men.
Conclusion
An energy-reduced MedDiet plus exercise emphasised positive changes to body composition compared to standard MedDiet in older adults who are overweight or have obesity.
Clinical practice applications:
- The recommendation of a reduced energy MedDiet in combination with physical activity to older people who are overweight or obese may improve body composition.
- Although lean mass loss slowed between years 1 and 3, other practices should be employed to attenuate the loss of lean mass associated with an energy-reduced MedDiet and ageing.
Considerations for future research:
- The research has not yet concluded but when it does, it will address the incidence of cardiovascular disease along with body composition changes.
- It will also look at long-term effects of the diet to determine longevity.
- Future research could focus on how to limit lean mass loss through the possibility of changing the type of exercise that accompanies the MedDiet.
Abstract
IMPORTANCE Strategies targeting body composition may help prevent chronic diseases in persons with excess weight, but randomized clinical trials evaluating lifestyle interventions have rarely reported effects on directly quantified body composition. OBJECTIVE To evaluate the effects of a lifestyle weight-loss intervention on changes in overall and regional body composition. DESIGN, SETTING, AND PARTICIPANTS The ongoing Prevención con Dieta Mediterránea-Plus (PREDIMED-Plus) randomized clinical trial is designed to test the effect of the intervention on cardiovascular disease prevention after 8 years of follow-up. The trial is being conducted in 23 Spanish research centers and includes men and women (age 55-75 years) with body mass index between 27 and 40 and metabolic syndrome. The trial reported herein is an interim subgroup analysis of the intermediate outcome body composition after 3-year follow-up, and data analysis was conducted from February 1 to November 30, 2022. Of 6874 total PREDIMED-Plus participants, a subsample of 1521 individuals, coming from centers with access to a dual energy x-ray absorptiometry device, underwent body composition measurements at 3 time points. INTERVENTION Participants were randomly allocated to a multifactorial intervention based on an energy-reduced Mediterranean diet (MedDiet) and increased physical activity (PA) or to a control group based on usual care, with advice to follow an ad libitum MedDiet, but no physical activity promotion. MAIN OUTCOMES AND MEASURES The outcomes (continuous) were 3-year changes in total fat and lean mass (expressed as percentages of body mass) and visceral fat (in grams), tested using multivariable linear mixed-effects models. Clinical relevance of changes in body components (dichotomous) was assessed based on 5% or more improvements in baseline values, using logistic regression. Main analyses were performed in the evaluable population (completers only) and in sensitivity analyses, multiple imputation was performed to include data of participants lost to follow-up (intention-to-treat analyses). RESULTS A total of 1521 individuals were included (mean [SD] age, 65.3 [5.0] years; 52.1% men). In comparison with the control group (n=761), participants in the intervention arm (n=760) showed greater reductions in the percentage of total fat (between group differences after 1-year, -0.94% [95% CI, -1.19 to -0.69]; 3 years, -0.38% [95% CI, -0.64 to -0.12] and visceral fat storage after 1 year, -126 g [95% CI, -179 to -73.3 g]; 3 years, -70.4 g [95% CI, -126 to -15.2 g] and greater increases in the percentage of total lean mass at 1 year, 0.88% [95% CI, 0.63%-1.12%]; 3-years 0.34% [95% CI, 0.09%-0.60%]). The intervention group was more likely to show improvements of 5% or more in baseline body components (absolute risk reduction after 1 year, 13% for total fat mass, 11% for total lean mass, and 14% for visceral fat mass; after 3-years: 6% for total fat mass, 6% for total lean mass, and 8% for visceral fat mass). The number of participants needed to treat was between 12 and 17 to attain at least 1 individual with possibly clinically meaningful improvements in body composition. CONCLUSIONS AND RELEVANCE The findings of this trial suggest a weight-loss lifestyle intervention based on an energy-reduced MedDiet and physical activity significantly reduced total and visceral fat and attenuated age-related losses of lean mass in older adults with overweight or obesity and metabolic syndrome. Continued follow-up is warranted to confirm the long-term consequences of these changes on cardiovascular clinical end points. TRIAL REGISTRATION isrctn.org Identifier: ISRCTN89898870.
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8.
Comparative effects of vitamin and mineral supplements in the management of type 2 diabetes in primary care: A systematic review and network meta-analysis of randomized controlled trials.
Xia, J, Yu, J, Xu, H, Zhou, Y, Li, H, Yin, S, Xu, D, Wang, Y, Xia, H, Liao, W, et al
Pharmacological research. 2023;188:106647
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Type 2 diabetes mellitus (T2DM), characterised by sustained hyperglycaemia and insulin resistance, remains a severe driver of chronic metabolic diseases such as cardiovascular diseases. The aim of this study was to investigate and compare the efficacy of vitamin and mineral supplements in the management of glycaemic control and lipid metabolism for type 2 diabetic patients to inform clinical practice. This study is a systematic review and meta-analysis of one hundred and seventy articles with a total of 4223 adults with T2DM. Participants were randomised to either the placebo/no treatment group (n= 6345) or to the treatment group (n= 7878). Results show that: - chromium was the most effective micronutrient for decreasing fasting blood glucose and insulin resistance. - vitamin K was the top-ranked micronutrient in reducing haemoglobin A1C and fasting insulin levels. - vanadium was the top-ranked micronutrient in total cholesterol reductions. - niacin was ranked as the most effective in triglycerides reductions and increasing high-density lipoprotein cholesterol levels. - vitamin E was the top-ranked micronutrient in low-density lipoprotein cholesterol reductions. Authors conclude that micronutrient supplements especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more effective in the management of T2DM compared with other micronutrients.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Clinicians could consider the adjunctive effect of micronutrients supplements, such as chromium, vitamin E, vitamin K, vanadium, and niacin supplements in a nutrition protocol to manage T2DM and slow or prevent its complications.
- The study authors state that the vitamin and mineral supplements under review had a statistically significant improvement, however they did not reach the study threshold for clinical significance. Therefore they advise caution in utilising micronutrient supplements in the management of glucose and lipid metabolism for T2DM.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Objectives
The aim of this systematic review was to evaluate the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM).
Methodology
This systematic review is registered with PROSPERO and adhered to PRISMA-2020 guidelines for network meta-analysis
The Cochrane Collaboration’s risk-of-bias tool was used to assess eligible randomised trials
8 prespecified markers identified and assessed in this study : 1) HbA1c (%), 2) fasting blood glucose (mmol/L), 3) total cholesterol (mmol/L), 4) triglycerides (mmol/L), 5) fasting insulin (μIU/mL), 6) HOMA-IR, 7) LDL-c (mmol/L), and 8) HDL-c (mmol/L).
Results
- 170 RCT trials of 14223 participants with T2DM treated with vitamin supplements, mineral supplements, or placebo/no treatment were included
- Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively)
- Vitamin K supplements ranked best in reducing glycated haemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence
- Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%)
- Niacin supplements ranked best in triglyceride reductions and increasing high-density lipo-protein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively)
- Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%).
Conclusion
- Micronutrient supplements, such as chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be efficacious in managing T2DM
- It should be noted that the evidence certainty for all was low.
Clinical practice applications:
- Chromium plays an important role in carbohydrate and lipid metabolism and was the most effective micronutrient for decreasing fasting blood glucose, HbA1c, fasting insulin, and HOMA-IR reductions. More pronounced effects were seen for chromium than vitamin E, vitamin C, niacin, selenium, and magnesium supplements
- Vitamin K was the top-ranked micronutrient in reducing HbA1c and fasting insulin levels. The mechanism through which Vitamin K affects glucose metabolism is proposed as activation of the AMP-activated protein kinase/sirtuin 1, that in turn increases phosphocreatine 3-kinase and glucose transporter 2 to decrease insulin resistance and fasting glucose.
- Vanadium was the top-ranked micronutrient in total cholesterol (TC) reductions, where supplementation dosage should be carefully considered, as vanadium compounds can be moderately or highly toxic. Vanadium supplementation is only recommended in cases of vanadium deficiency or diabetes, hyperlipidemia, and hypertension, where the intake of vanadium from food should be enhanced in preference to supplementation
- Niacin was ranked as the most effective in triglyceride (TG) reductions and increasing HDL cholesterol levels. The dose of niacin could not be determined
- Vitamin E was the top-ranked micronutrient in low-density lipo- protein (LDL) cholesterol reductions.
Considerations for future research:
- Considering the clinical importance of these findings, new research is needed to get better insight into the efficacy of micronutrient supplements in managing T2DM
- Selenium homeostasis, selenoprotein, insulin signaling/secretion, and carbohydrate/lipid metabolism are linked in multiple and complex ways but the authors could not explain why chromium supplementation would lower blood glucose more effectively than selenium supplementation, and suggest more research is needed to clarify this
- While vitamin K status could be an emerging treatment target in T2DM prevention and management, it remains to be determined whether vitamin K supplementation has an advantage over other nutrients in terms of hypoglycemic effect, and further research is necessary
- The beneficial effect of vitamin E and niacin supplements regarding lipid metabolism warrant investigation through more rigorous comparative studies.
Abstract
Medical nutrition treatment can manage diabetes and slow or prevent its complications. The comparative effects of micronutrient supplements, however, have not yet been well established. We aimed at evaluating the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM) to inform clinical practice. Electronic and hand searches for randomized controlled trials (RCTs) were performed until June 1, 2022. We selected RCTs enrolling patients with T2DM who were treated with vitamin supplements, mineral supplements, or placebo/no treatment. Data were pooled via frequentist random-effects network meta-analyses. A total of 170 eligible trials and 14223 participants were included. Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively). Vitamin K supplements ranked best in reducing glycated hemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence. Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%). Niacin supplements ranked best in triglyceride reductions and increasing high-density lipoprotein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively). Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%). Our analyses indicated that micronutrient supplements, especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more efficacious in managing T2DM than other micronutrients. Considering the clinical importance of these findings, new research is needed to get better insight into this issue.
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9.
Distribution of energy intake across the day and weight loss: A systematic review and meta-analysis.
Young, IE, Poobalan, A, Steinbeck, K, O'Connor, HT, Parker, HM
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2023;24(3):e13537
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Obesity increases an individual's risk of metabolic disease, such as diabetes and cardiovascular disease, musculoskeletal disorders such as osteoarthritis, and some cancers. “Chrononutrition” relates to the timing of meals and distribution of total energy intake across the day. Evidence is building chrononutrition as a potential target in both weight loss and metabolic disease interventions. The aim of this study was to examine the impact of earlier versus later distribution of total daily energy intake on weight loss, and to evaluate the potential for utilizing altered energy distribution as a tool in weight loss interventions. This study is a systematic review and meta-analysis of nine clinical studies. Total number of participants was 485 (earlier distributed total energy intakes: n = 244, later distributed total energy intakes; n = 241). Results show that energy intakes with a focus on earlier distribution resulted in significantly greater weight loss when compared with similarly energy-restricted diets with individuals consuming a larger proportion of their total energy intake later in the day and into the evening. Authors conclude that earlier energy intakes may be a promising tool to be used in conjunction with other weight loss strategies such as energy restriction to enhance weight loss. However, further research is required to elucidate the additional positive impacts that earlier distributed total energy intakes may have on weight and metabolic health.
Expert Review
Conflicts of interest:
None
Take Home Message:
Implementing a dietary strategy where a higher proportion of energy is consumed earlier in the day may offer additional benefits to an energy restricted diet for weight loss, blood glucose, improve markers of insulin resistance, increase satiety and improve hunger management. Based on the findings, earlier distribution of energy intake may serve as an effective component of a weight loss protocol.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Background
Chrononutrition refers to the timing and distribution of total daily energy intake across the day. It has been proposed that consuming a greater proportion of total daily energy intake earlier in the day as opposed to the evening may be beneficial for weight loss and metabolic health.
Aims
This systematic review and meta-analysis aimed to assess the impact of earlier versus later distribution of total daily energy intake on weight loss.
Results
A total of 9 randomised controlled trials involving 485 participants were included in this analysis. The study durations ranged from 5-16 weeks. All of the studies included in this analysis applied energy-restricted diets to both intervention arms. The mean percentages of energy intake in 8 of the 9 studies per meal were:
- Earlier distributed intakes: breakfast: 34% ± 16%, lunch: 38% ± 7%, dinner: 20% ± 6%.
- Later distributed intakes: breakfast: 19% ± 6%, lunch: 30% ± 10%, dinner; 40% ± 11%.
One of the studies advised percentage of energy intakes as either:
- Earlier: 70% for breakfast, morning tea and lunch and 30% for afternoon tea and dinner
- Late: 55% for breakfast, morning tea and lunch and 45% for afternoon tea and dinner.
The earlier distributed energy intake groups demonstrated significantly greater weight loss when compared with later distributed energy intake groups ( Mean Difference (MD) −1.23 kg; 95% CI −2.40, −0.06, p = 0.04;
I2 = 98%).
The earlier energy intake groups also displayed lower fasting and bedtime glucose levels (fasting: −0.83 vs. −0.27 mmol/L, p = 0.001; before sleep: −1.70 vs. −0.28 mmol/L, p = 0.009).
A random-effects model demonstrated that the earlier intake groups displayed greater reductions in LDL (MD: −0.11 mmol/L; 95% CI −0.14, −0.07, p < 0.01), fasting glucose (MD: 0.15 mmol/L, 95% CI −0.23, −0.06, p < 0.001) and HOMA-IR (MD: −0.38; 95% CI −0.64, −0.11, p = 0.005).
One study reported that earlier distribution energy intake also led to a greater reduction in medications following the intervention for type 2 diabetics (31% vs. 0%, P=0.002).
Two of the studies assessed both appetite and hunger and identified that earlier distribution of energy led to improvements in their urge to eat, preoccupation with food and cravings for sweets and fats.
Clinical practice applications:
Earlier distribution of energy intake may be beneficial for:
- Weight loss
- Improve fasting insulin, HOMA-IR, fasting glucose and HbA1c
- Reducing LDL
- Improving satiety and hunger management
- Supporting the reduction of medications for individuals with type 2 diabetes
- Improving regularity of sleep and waking times
Considerations for future research:
As the included studies only ranged from 5-16 weeks, longer duration studies would be useful to identify the effect of earlier distribution of energy intake on body weight, metabolic health and appetite over a longer period of time. There was a high degree of heterogeneity between the studies and a lack of uniformity in the distributions of energy intake across the day. Further studies with more uniformity of energy distribution would be needed to identify the optimal distribution of energy across the day to improve body weight and metabolic health.
Abstract
Consuming a greater proportion of total energy intake earlier in the day rather than in the evening is proposed to positively influence weight loss and health, potentially due to greater synchronization of human body circadian rhythms. This systematic review provides an update on existing evidence regarding earlier distributed eating patterns in weight loss interventions. Using a robust search strategy in five electronic databases, nine randomized controlled trials investigating the impact of energy intake distribution on weight loss were identified. Following critical appraisal, a random-effects meta-analyses found that, in the context of an energy-reduced diet, distributing energy intake with a focus on earlier intake resulted in significantly greater weight loss (-1.23 kg; 95% CI 2.40, -0.06, p = 0.04). Improvements in HOMA-IR, fasting glucose, and LDL cholesterol were also seen. The current study provides a timely update on the evidence linking distribution of total daily energy intake and health, showing that a focus on earlier intakes can result in greater short-term weight loss compared with later intakes. Future studies are needed to elucidate the impact that earlier intakes may have on weight management and metabolic health.
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10.
The Effect of Regular Consumption of Reformulated Breads on Glycemic Control: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.
Schadow, AM, Revheim, I, Spielau, U, Dierkes, J, Schwingshackl, L, Frank, J, Hodgson, JM, Moreira-Rosário, A, Seal, CJ, Buyken, AE, et al
Advances in nutrition (Bethesda, Md.). 2023;14(1):30-43
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The metabolic effect of bread depends on several qualitative aspects ranging from the type of grain, the amount of carbohydrates, levels of other nutrients, as well as the chemical structure and processing. The aim of this study was to assess the certainty of the evidence and to investigate the overall effect of regular consumption of reformulated breads on glycaemic control in the following groups: a) healthy adults; b) those at risk of developing cardiometabolic disease (e.g., having hypertension, hyperglycaemia, hypercholesterolemia and/or overweight/obesity); and c) those with manifest type 2 diabetes mellitus (T2DM). This study is a systematic review and meta-analysis of 22 studies and 23 distinct study populations. All studies were randomised controlled trials, 12 of which had a crossover design and 10 had a parallel design. In total, 1037 participants were included. These provided 669 and 595 data points for intervention and control comparisons, respectively. Results show a beneficial effect of reformulated bread variants on fasting blood glucose concentrations. This benefit may be more pronounced among people with manifest T2DM (low certainty of evidence). Authors conclude that bread quality is relevant for metabolic health among adults and that future studies should address its relevance among people at risk of T2DM.
Expert Review
Conflicts of interest:
None
Take Home Message:
This study’s findings suggest the effect of reformulated breads high in dietary fibre, whole grains, and/or functional ingredients may be more beneficial than regular breads on fasting blood glucose concentrations in adults, primarily among those with T2DM. Reformulated breads however, did not lower fasting insulin concentrations, HOMA-IR and HbA1C when compared to regular bread.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Overview
This study evaluated the effect of regular consumption of “reformulated breads” on glycemic control among healthy adults, adults at cardiometabolic risk or with manifest T2DM in 22 RCTs with 1037 participants. Compared with “regular” or comparator bread, consumption of reformulated intervention breads yielded lower fasting blood glucose concentrations only among people with T2DM (low certainty of evidence), yet no differences in fasting insulin, HOMA-IR, HbA1c, or postprandial glucose response were identified.
[*’reformulated bread’ as defined by the World Health Organisation of altering the processing or composition of a food to improve its nutritional profile, and contained whole-grains and dietary fibre]
Results
Sub group analysis revealed that the effect of reformulated breads high in dietary fibre, whole grains, and/or functional ingredients on lowering fasting blood glucose was confined to participants with T2DM, with no significant effect among participants without T2DM (0.68 mmol/L; 95% CI: 1.11, 0.36; I2 1⁄4 57% and 0.04 mmol/L; 95% CI: 0.13, 0.05; I2 1⁄4 25%, respectively; P < 0.001).
Subgroup analyses by continent revealed a more pronounced effect on fasting blood glucose concentrations in studies conducted in Asia and the Middle East compared with studies conducted in Europe, North America, and Oceania (MD: 0.84 mmol/L; 95% CI: 1.35, 0.33; I2 1⁄4 52% and MD: 0.04 mmol/L; 95% CI: 0.10, 0.03; I2 1⁄4 0%, respectively; P < 0.001)
Additional subgroup analyses found that the type of control bread, but not the type of intervention bread, affected the pooled effect estimate of fasting blood glucose concentration (P 1⁄4 0.03), with the largest difference reported in studies not describing the control bread used.
Limitations
Publication bias was considered negligible for the studies included in this meta-analysis, and the risk of bias assessment revealed that most of the studies had some concerns of risk of bias. One author is a member of the International Carbohydrate Quality Consortium and another is a member of the GRADE working group.
Strengths
This systematic review and meta-analysis include the focus on high-quality intervention studies (i.e., RCTs using either crossover or parallel design) and the inclusion of longer-term studies (>2 wk) to address the effectiveness of regular bread replacement for glycemic control in everyday life.
Clinical practice applications:
- This data suggests that bread quality is relevant for metabolic health among adults at risk of T2DM. In particular, reformulated breads were found to have a more beneficial impact than regular breads on fasting blood glucose concentrations in adults with TsDM. However, consumption of the reformulated bread (enriched with dietary fiber, whole grains, or functional ingredients) did not lower fasting insulin concentrations compared with the control breads (MD: 1.59 pmol/L; 95% CI: 5.78, 2.59; moderate certainty of evidence)
- Consumption of the reformulated bread did not lower HOMA-IR compared with the control breads (MD: 0.09; 95% CI: 0.35, 0.22; moderate certainty of evidence)
- Consumption of the reformulated bread did not lower HbA1c concentrations compared with the control bread (0.14; 95% CI: 0.39, 0.10; P 1⁄4 0.195; very low certainty of evidence).
Considerations for future research:
- Longer intervention periods may be required to determine the beneficial effects on the HbA1c concentrations and to elicit changes in markers of insulin resistance
- Future studies should use the 2022 WHO standardised HbA1c diagnostic reference criterion for diabetes mellitus
- Improvements in specific outcomes may also be linked to defined groups within populations such as persons with manifest T2DM.
- The type of reformulation of the bread may be an important factor but differ considerably around the world
Abstract
Bread is a major source of grain-derived carbohydrates worldwide. High intakes of refined grains, low in dietary fiber and high in glycemic index, are linked with increased risk for type 2 diabetes mellitus (T2DM) and other chronic diseases. Hence, improvements in the composition of bread could influence population health. This systematic review evaluated the effect of regular consumption of reformulated breads on glycemic control among healthy adults, adults at cardiometabolic risk or with manifest T2DM. A literature search was performed using MEDLINE, Embase, Web of Science and the Cochrane Central Register of Controlled Trials. Eligible studies employed a bread intervention (≥2 wk) in adults (healthy, at cardiometabolic risk or manifest T2DM) and reported glycemic outcomes (fasting blood glucose, fasting insulin, HOMA-IR, HbA1c, and postprandial glucose responses). Data were pooled using generic inverse variance with random-effects model and presented as mean difference (MD) or standardized MD between treatments with 95% CIs. Twenty-two studies met the inclusion criteria (n = 1037 participants). Compared with "regular" or comparator bread, consumption of reformulated intervention breads yielded lower fasting blood glucose concentrations (MD: -0.21 mmol/L; 95% CI: -0.38, -0.03; I2 = 88%, moderate certainty of evidence), yet no differences in fasting insulin (MD: -1.59 pmol/L; 95% CI: -5.78, 2.59; I2 = 38%, moderate certainty of evidence), HOMA-IR (MD: -0.09; 95% CI: -0.35, 0.23; I2 = 60%, moderate certainty of evidence), HbA1c (MD: -0.14; 95% CI: -0.39, 0.10; I2 = 56%, very low certainty of evidence), or postprandial glucose response (SMD: -0.46; 95% CI: -1.28, 0.36; I2 = 74%, low certainty of evidence). Subgroup analyses revealed a beneficial effect for fasting blood glucose only among people with T2DM (low certainty of evidence). Our findings suggest a beneficial effect of reformulated breads high in dietary fiber, whole grains, and/or functional ingredients on fasting blood glucose concentrations in adults, primarily among those with T2DM. This trial was registered at PROSPERO as CRD42020205458.