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Mediterranean diet and structural neuroimaging biomarkers of Alzheimer's and cerebrovascular disease: A systematic review.
Gregory, S, Pullen, H, Ritchie, CW, Shannon, OM, Stevenson, EJ, Muniz-Terrera, G
Experimental gerontology. 2023;172:112065
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Nearly a million people in the UK have Alzheimer's disease, the most common type of dementia. Mediterranean diet (MedDiet) adherence is associated with healthy brain ageing, a reduced stroke risk, and a lower incidence of dementia. Seven studies were included in this review to evaluate the effects of MedDiet on hippocampal volume and white matter hyperintensity volume, predictors of stroke and dementia. This systematic review did not reveal any associations between MedDiet adherence and hippocampal volume. However, there was a significant negative relationship between MedDiet adherence and white matter hyperintensity volume in two of the studies included. It is necessary to conduct more robust studies to investigate the associations between MedDiet adherence and structural brain imaging findings and understand the mechanisms behind dementia and other cerebrovascular diseases. This study could provide healthcare professionals with valuable information about the effects of increased MedDiet adherence on brain health, including its potential to delay neurodegenerative disease progression.
Expert Review
Conflicts of interest:
None
Take Home Message:
Due to inconclusive results on the associations between MedDiet adherence and AD and cerebrovascular related structural neuroimaging findings, specific recommendations for the MedDiet cannot be made on the basis of this study until further research has been completed.
Evidence Category:
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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:
Changes in hippocampal volume (HV) and white matter intensity volume (WMIV) have been identified as structural neuroimaging biomarkers of neurodegenerative disease such as Alzheimer’s Disease (AD) and Cerebrovascular disease (CVD) respectively. Evidence has shown adherence to the Mediterranean Diet (MedDiet) has been associated with reduced risk for strokes. This review evaluated the MedDiet in relation to HV and WMIV.
Methods:
The review followed PRISMA guidelines and was registered on PROSPERO. Literature searching resulted in seven studies published between 2012 and 2022, which met the inclusion criteria. Six studies analysed cross-sectional data and one analysed longitudinal data. The NIH Quality Assessment Tool for Observational and Cross-Sectional Studies was used to assess risk of bias.
Overall, the studies were rated as low-risk of bias with details of the research question, participant group exposure and outcome variables included. Due to moderate to high heterogeneity in some studies, a meta-analysis was deemed unsuitable and narrative synthesis was conducted to present the results.
Results:
Mean participant age ranged from 53.19 to 80.3 years and volunteers were healthy or had subjective cognitive decline and a few participants had dementia (n=46).
Hippocampal Volume:
Four studies included 20,077 participants and found no significant associations between MedDiet adherence and hippocampal volume. All four studies were cross-sectional from larger cohort studies. To establish causative relationships longitudinal and RCT trials are required.
White Matter Hyperintensity Volumes:
Four studies included 1938 participants. Two studies found a significant negative association between MedDiet and WMHV, demonstrating higher Mediterranean Scores were associated with lower level of WHMV. The other two studies found no significant associations.
Although the review methodology with a piloted search strategy was considered a key strength, the lack of meta-analysis as planned in the a priori protocol, due to minimal eligible studies and high heterogeneity was a limitation as well as the restriction of brain imaging outcomes.
Conclusion:
Overall, these results are inconclusive on the associations between the MedDiet and HV and WMHV, and identify a gap in the knowledge, therefore further research such as RCT’s remains a priority to further understand the impact diet may have on neuroimaging markers of AD and CVD.
Clinical practice applications:
There were no significant associations between MedDiet adherence and HV, which was surprising given the evidence stating adherence to the MedDiet is associated with a lower incidence of dementia and stroke. However all four studies were cross-sectional studies and in order to detect causal associations, longitudinal and RCT’s are needed. Two studies did show a significant association between higher MedDiet adherence and lower WMHV, whereas two studies reported no significant associations.
Caution needs to be taken when recommending the MedDiet specifically for a reduction in HV and WMHV until further research has been undertaken.
Considerations for future research:
Future research should consider:
- larger cohorts and participants from the Mediterranean region where lifelong adherence to the MedDiet is more likely.
- looking at other risk factors to include obesity, lack of activity, poor sleep quality and stress.
- evaluating different socio-economic status, which has been shown to impact dietary behaviour.
- alternative imaging outcomes such as cortical thinning, PET amyloid and tau.
- . gold standard for methodology in particular dietary analysis and scanning and outcome derivation.
Abstract
Previous studies have demonstrated an association between adherence to the Mediterranean diet (MedDiet) and better cognitive performance, lower incidence of dementia and lower Alzheimer's disease biomarker burden. The aim of this systematic review was to evaluate the evidence base for MedDiet associations with hippocampal volume and white matter hyperintensity volume (WMHV). We searched systematically for studies reporting on MedDiet and hippocampal volume or WMHV in MedLine, EMBASE, CINAHL and PsycInfo. Searches were initially carried out on 21st July 2021 with final searches run on 23rd November 2022. Risk of bias was assessed using the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Of an initial 112 papers identified, seven papers were eligible for inclusion in the review reporting on 21,933 participants. Four studies reported on hippocampal volume, with inconclusive or no associations seen with MedDiet adherence. Two studies found a significant association between higher MedDiet adherence and lower WMHV, while two other studies found no significant associations. Overall these results highlight a gap in our knowledge about the associations between the MedDiet and AD and cerebrovascular related structural neuroimaging findings.
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Effectiveness of a minimally processed food-based nutritional counselling intervention on weight gain in overweight pregnant women: a randomized controlled trial.
Sartorelli, DS, Crivellenti, LC, Baroni, NF, de Andrade Miranda, DEG, da Silva Santos, I, Carvalho, MR, de Lima, MC, Carreira, NP, Chaves, AVL, Manochio-Pina, MG, et al
European journal of nutrition. 2023;62(1):443-454
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Excessive gestational weight gain exposes the woman and the child to a higher risk of harmful health outcomes in the short and long term. Dietary patterns based on the substitution of meals made with unprocessed or minimally processed foods for the consumption of ultra-processed items can be partly blamed for the exponential global growth in the incidence of obesity. The main aim of this study was to evaluate the effectiveness of a nutritional intervention based on encouraging the consumption of unprocessed and minimally processed foods rather than ultra-processed products. This study is a two-armed parallel randomised controlled trial conducted among overweight, pregnant women receiving prenatal care in seven primary health units. Participants (n=350) were randomly allocated into the intervention group (IG) or control group (CG). The women allocated into the IG, in addition to the usual prenatal care, were invited to participate in three individualised nutritional counselling sessions conducted by trained nutritionists. Results show that even though there were more women in the IG who had increased their daily intake of minimally processed foods and vegetables at lunch time when compared to the CG, this was not statistically significant. Additionally, there weren’t any differences between the groups in relation to physical activity. Authors conclude that their study was unprecedented in demonstrating that a nutritional counselling intervention based on the NOVA food classification system, together with the practice of physical activity, is effective in preventing excessive gestational weight gain in overweight pregnant women.
Abstract
PURPOSE This study aimed at evaluating the effectiveness of a nutritional counselling intervention based on encouraging the consumption of unprocessed and minimally processed foods, rather than ultra-processed products, and the practice of physical activities to prevent excessive gestational weight gain in overweight pregnant women. METHODS This was a two-armed, parallel, randomized controlled trial conducted in primary health units of a Brazilian municipality from 2018 to 2021. Overweight, adult pregnant women (n = 350) were randomly assigned to control (CG) or intervention groups (IG). The intervention consisted of three individualized nutritional counselling sessions based on encouraging the consumption of unprocessed and minimally processed foods rather than ultra-processed products, following the NOVA food classification system, and the practice of physical activities. The primary outcome was the proportion of women whose weekly gestational weight gain (GWG) exceeded the Institute of Medicine guidelines. Adjusted logistic regression models were employed. RESULTS Complete data on weight gain were available for 121 women of the IG and 139 of the CG. In modified intention-to-treat analysis, there was a lower chance of the IG women having excessive GWG [OR 0.56 (95% CI 0.32, 0.98), p = .04], when compared to the CG. No between-group differences were observed for the other maternal outcomes investigated. CONCLUSION The present study was unprecedented in demonstrating that nutritional counselling based on the NOVA food classification system, together with encouraging the practice of physical activity, is effective in preventing excessive weight gain in overweight pregnant women. TRIAL REGISTRATION Registered on July 30th 2018 at Brazilian Registry of Clinical Trials (RBR-2w9bhc).
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Transform-Us! cluster RCT: 18-month and 30-month effects on children's physical activity, sedentary time and cardiometabolic risk markers.
Salmon, J, Arundell, L, Cerin, E, Ridgers, ND, Hesketh, KD, Daly, RM, Dunstan, D, Brown, H, Della Gatta, J, Della Gatta, P, et al
British journal of sports medicine. 2023;57(5):311-319
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Regular physical activity is beneficial to children’s physical, social and mental health. However, most children fail to meet the recommended 60+ min of moderate-intensity to vigorous-intensity physical activity every day. The Transform-Us! school-based and home-based intervention was developed to determine the impact of strategies to promote children’s moderate-to-vigorous physical activity versus reduce sedentary behaviour or a combination of these strategies, on behavioural and health outcomes. The main aim of this study was to determine the efficacy of the independent and combined intervention approaches to promoting physical activity and reducing sedentary behaviour on children’s moderate-to-vigorous physical activity and sedentary time after 18 and 30 months compared with usual practice. This study is a 30-month 2×2 factorial design cluster randomised controlled trial delivered in 20 primary schools with additional home intervention components. After recruitment, schools were then randomly allocated to one of four groups. Results show that Transform-Us! had stronger effects on children’s sedentary behaviour than physical activity in both the physical activity (PA) and sedentary behaviour (SB) interventions, and there were beneficial effects on children’s adiposity for both intervention approaches. However, no clear conclusions could be drawn regarding which intervention (PA or SB) had the strongest or more consistent effects on children’s health outcomes. Authors conclude that, based on their findings, government education departments and schools should consider adopting and implementing whole-of-school programmes to promote children’s physical activity and reduce sitting through active pedagogy and supportive social and physical environments at school and home to benefit children’s sedentary time and some markers of cardiometabolic health.
Abstract
OBJECTIVE To test the efficacy of the Transform-Us! school- and home-based intervention on children's physical activity (PA), sedentary behaviour (SB) and cardiometabolic risk factor profiles. METHODS A 30-month 2×2 factorial design cluster randomised controlled trial delivered in 20 primary schools (148 Year 3 classes) in Melbourne, Australia (2010-2012), that used pedagogical and environmental strategies to reduce and break up SB, promote PA or a combined approach, compared with usual practice. Primary outcomes (accelerometry data; n=348) were assessed at baseline, 18 and 30 months. Secondary outcomes included body mass index (BMI) and waist circumference (WC) (n=564), blood pressure (BP) (n=537) and biomarkers (minimum n=206). Generalised linear mixed models estimated the interactive effects of the PA and SB interventions on the outcomes. If there was no interaction, the main effects were assessed. RESULTS At 18 months, there were intervention effects on children's weekday SB (-27 min, 95% CI: -47.3 to -5.3) for the PA intervention, and on children's average day PA (5.5 min, 95% CI: 0.1 to 10.8) for the SB intervention. At 30 months, there was an intervention effect for children's average day SB (-33.3 min, 95% CI: -50.6 and -16.0) for the SB intervention. Children's BMI (PA and SB groups) and systolic BP (combined group) were lower, and diastolic BP (PA group) was higher. There were positive effects on WC at both time points (SB intervention) and mixed effects on blood parameters. CONCLUSIONS The Transform-Us! PA and SB interventions show promise as a pragmatic approach for reducing children's SB and adiposity indicators; but achieving substantial increases in PA remains challenging. TRIAL REGISTRATION ISRCTN83725066; ACTRN12609000715279.
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Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial.
Mesinovic, J, Rodriguez, AJ, Cervo, MM, Gandham, A, Xu, CLH, Glavas, C, de Courten, B, Zengin, A, Ebeling, PR, Scott, D
European journal of nutrition. 2023;62(2):951-964
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Overweight and obese older adults are at increased risk for vitamin D deficiency, which is associated with poor metabolic and musculoskeletal health, unfavourable body composition, and attenuated responses to exercise. The aim of this study was to determine whether, compared with placebo, vitamin D3 supplementation (4000 IU/day) taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight or obese older adults with vitamin D deficiency. This study is a 24-week parallel-group, double-blind, placebo-controlled pilot randomised controlled trial. Fifty overweight or obese participants were enrolled for the study, and randomised to either 4000 IU/day of oral vitamin D3 or identical placebo. Results demonstrated that 4000 IU/day vitamin D3 supplementation: - did not affect gait speed when taken with or without exercise, - helped achieve optimal serum 25-hydroxyvitamin D levels and decreased waist circumference (compared with placebo) following multi-modal exercise. - taken alone without exercise reduced stair climb times. However, vitamin D3 supplementation did not have any beneficial effects on other biochemical, body composition or physical function parameters when taken alone or during exercise. Authors conclude that future studies should focus on populations with moderate or severe vitamin D deficiency as they are more likely to experience therapeutic benefits from vitamin D supplementation.
Abstract
PURPOSE Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m2) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.5 ± 14.7 nmol/L; treatment: 43.4 ± 18.4 nmol/L; P < 0.001) and reduced stair climb times (placebo: 0.3 ± 1.0 s; treatment: - 0.2 ± 1.0 s; P = 0.046). From 12 to 24 weeks, vitamin D supplementation combined with exercise decreased waist circumference (placebo: 1.3 ± 7.3 cm; treatment: - 3.0 ± 6.1 cm; P = 0.02) and waist-to-hip ratio (placebo: 0.01 ± 0.05; treatment: - 0.03 ± 0.05; P = 0.01) relative to placebo. Vitamin D supplementation, with or without exercise, had no effect on other physical function, body composition or metabolic health outcomes. CONCLUSION Vitamin D supplementation had no effect on most physical function, body composition or metabolic health parameters when taken alone, or during exercise, in overweight or obese older adults with vitamin D deficiency. Vitamin D-related improvements in stair climb times and waist circumference suggest that future trials should explore the effects of vitamin D on muscle power, and its effects on body composition when combined with exercise, in populations with moderate or severe vitamin D deficiency.
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Hypnotherapy, Intermittent Fasting, and Exercise Group Programs in Atopic Dermatitis: A Randomized Controlled Explorative Clinical Trial During the COVID-19 Pandemic.
Rotter, G, Teut, M, Schleicher, R, Dell'Oro, M, Ortiz, M, Binting, S, Tissen-Diabaté, T, Roll, S, Michalsen, A, Staab, D, et al
Journal of integrative and complementary medicine. 2023;29(2):99-110
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Relaxation techniques, diet, and exercise can diminish atopic dermatitis (AD) symptoms. Patients with AD worry about the side-effects of the medical treatment for AD thus the majority try to engage in potentially healthy lifestyle behaviours. The aim of this study was to exploratively investigate the effectiveness of hypnotherapy, fasting with diet adjustments, and exercise in adult AD patients This study is a four-armed, randomised controlled, single-centre, open explorative clinical trial. Patients were randomly assigned to one of the four groups: i) hypnotherapy group program (HTP), ii) intermittent fasting with diet adjustment group program (IFDP), iii) an exercise group program or the control group. The study was strongly impacted by confinements and research restrictions due to the coronavirus 2019 pandemic. However, results showed potential beneficial changes to baseline in perceived itching intensity, disease severity, and disease-specific quality of life for HTP and IFDP. Authors conclude that further high-quality clinical trials should be performed investigating the effectiveness and safety of hypnotherapy, fasting with diet adjustments, as well as exercise.
Abstract
Background: Patients with atopic dermatitis (AD) frequently use healthy lifestyle behaviors, although their benefits are unclear. This study's aim was to investigate the effectiveness of hypnotherapy, fasting with diet adjustments, and exercise in AD patients. Methods: In a four-armed randomized controlled monocenter open explorative clinical trial, adult patients with mild-to-moderate severe AD underwent, over 16 weeks, a five-session hypnotherapy group program (HTP), a five-session intermittent fasting with diet adjustment group program (IFDP), a five-session exercise group program (EP), or no study intervention (control) as add-on to topical corticosteroid use if required. Endpoints included subjectively perceived itching on a visual analogue scale (VAS, 0-100 mm); disease severity by SCORing Atopic Dermatitis (SCORAD); and adverse events (AEs). Endpoints were analyzed descriptively in the Full Analysis Set (FAS). Due to the coronavirus disease 2019 (COVID-19) pandemic, relevant changes to the study protocol included online in addition to "in-presence" group interventions, closing the study arm EP and premature trial termination before randomization of 120 intended patients. Results: During the COVID-19 pandemic, study recruitment was poor. The FAS included 20 patients (17 female) with 35.0 ± 12.1 (mean ± standard deviation [SD]) years of age. At baseline, mean ± SD for HTP (n = 6), IFDP (n = 4), EP (n = 1), and control (n = 9) were VAS itching 63.2 ± 18.0, 65.0 ± 13.9, 43.0 mm, 62.1 ± 17.3; SCORAD 43.0 ± 13.6, 47.0 ± 21.0, 60.3, 39.1 ± 15.6. After 16 weeks, endpoints were VAS itching 26.0 ± 16.4, 31.7 ± 9.9, 23.0 mm, 39.3 ± 27.0; SCORAD 24.1 ± 12.2, 29.1 ± 19.1, 49.1, 25.5 ± 14.4. No serious AEs related to the interventions were observed. Conclusion: Despite very small groups, study results indicated potential beneficial changes to baseline in perceived itching intensity, disease severity, and disease-specific quality of life for HTP and IFDP. Therefore, further clinical trials should be performed investigating the effectiveness and safety of all interventions. Clinical Trial Registration: January 31, 2020 German Clinical Trials Register (DRKS): DRKS00020557, Universal Trial Number (UTN): U1111-1247-1512.
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Effects of Morning Vs. Evening exercise on appetite, energy intake, performance and metabolism, in lean males and females.
Mode, WJA, Slater, T, Pinkney, MG, Hough, J, James, RM, Varley, I, James, LJ, Clayton, DJ
Appetite. 2023;182:106422
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Long-term weight management is notoriously difficult, with many people experiencing progressive weight gain throughout adult life. The aim of this study was to assess the acute effects of morning and evening cycling exercise on appetite, post-exercise ad-libitum energy intake, substrate metabolism, voluntary performance, and subjective responses to exercise, in young, healthy males and females. Sixteen healthy participants (eight males and eight females) were recruited to the study. Each participant completed two preliminary trials, followed by two experimental trials which involved exercising at 10:30 or 18:30. Results show that: - post-exercise energy intake was greater after acute cycling exercise performed in the evening compared to the morning, despite no post-exercise differences in subjective appetite. - there wasn’t any difference in exercise performance between morning and evening exercise. - exercise timing did not affect performance during a 15-min all-out performance test. Authors conclude that their findings demonstrate a disconnect between subjective appetite and ad-libitum energy intake but provide some evidence that exercise can offset circadian-related appetite profiles.
Abstract
Exercise is an important component of a weight management strategy. However, little is known about whether circadian variations in physiological and behavioural processes can influence the appetite and energy balance responses to exercise performed at different times of the day. This study compared the effects of morning and evening exercise on appetite, post-exercise energy intake, and voluntary performance. In randomised, counterbalanced order, 16 healthy males and females (n = 8 each) completed two trials, performing morning exercise at 10:30 (AMEx) or evening exercise at 18:30 (PMEx). Exercise consisted of 30 min steady-state cycling (60% V˙ O2peak), and a 15-min performance test. A standardised meal (543 ± 86 kcal) was consumed 2-h before exercise and ad-libitum energy intake was assessed 15 min after exercise, with subjective appetite measured throughout. Absolute ad-libitum energy intake was 152 ± 126 kcal greater during PMEx (P < 0.001), but there was no differences in subjective appetite between trials immediately pre-exercise, or immediately before the post-exercise meal (P ≥ 0.060). Resting energy expenditure (P < 0.01) and carbohydrate oxidation (P < 0.05) were greater during AMEx, but there were no differences in substrate oxidation or energy expenditure during exercise (P ≥ 0.155). Exercise performance was not different between trials (P = 0.628). In conclusion, acute morning and evening exercise prompt similar appetite responses, but post-exercise ad-libitum energy intake is greater following evening exercise. These findings demonstrate discordant responses between subjective appetite and ad-libitum energy intake but suggest that exercise might offset circadian variations in appetite. Longer-term studies are required to determine how exercise timing affects adherence and weight management outcomes to exercise interventions. TRIAL REGISTRATION NCT04742530, February 8, 2021.
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Inflammation moderates the effects of lifestyle modification on neurocognition among individuals with resistant hypertension.
Avorgbedor, F, Blumenthal, JA, Hinderliter, A, Ingle, K, Lin, PH, Craighead, L, Tyson, C, Kraus, W, Sherwood, A, Smith, PJ
Journal of clinical hypertension (Greenwich, Conn.). 2023;25(1):106-110
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Hypertension is one of the primary causes of cardiovascular disease, stroke, Alzheimer’s Disease, and Alzheimer’s Disease and related dementias (AD/ADRD). Among individuals with hypertension, those with resistant hypertension (RH) appear to have the greatest risk of cerebrovascular disease and associated cognitive impairment. The aim of this study was to investigate the potential influence of individual differences in pre-treatment inflammatory profiles on changes in cognition following lifestyle modification among RH participants in the TRIUMPH clinical trial. This study is a report based on the TRIUMPH study which was a randomised clinical trial. One hundred forty patients with RH were randomised with 2:1 allocation to either a 4-month Centre-based Lifestyle intervention or Standardized Education and Physician Advice. Results show that basal levels of elevated peripheral inflammation may represent an intermediate phenotype of risk for cognitive decline. In fact, individuals with higher levels of c-reactive protein at baseline demonstrated greater improvements in Executive Function/Learning following participation in an intensive lifestyle intervention. Authors conclude that their findings may help inform targeted treatments to reduce ADRD among middle-aged and older adults with cardiovascular disease risk factors.
Abstract
Individuals with resistant hypertension (RH) have the greatest risk of cerebrovascular disease and cognitive impairment among individuals with hypertension. Elevated levels of pro-inflammatory cytokines may represent a critical yet unexamined factor influencing the impact of healthy lifestyle changes on cognitive function. We explored the influence of inflammation on changes in cognition following lifestyle modification among individuals with RH participating in the TRIUMPH clinical trial. One hundred forty participants with RH completed a battery of neurocognitive tests along with the inflammatory marker C-reactive protein (hsCRP) and were subsequently randomized to an intensive 4-month lifestyle modification intervention or to education and physician advice control. Results indicated that the effects of lifestyle modification on Executive Function and Learning were moderated by pre-intervention hsCRP levels (P = .049), with treatment efficacy increasing across levels of baseline inflammation levels (low: d = 0.12; mild: d = 0.43; moderate: d = 0.81). We conclude that inflammatory profiles may help identify individuals more likely to improve executive functioning resulting from lifestyle modification.
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The Influence of n-3PUFA Supplementation on Muscle Strength, Mass, and Function: A Systematic Review and Meta-Analysis.
Santo André, HC, Esteves, GP, Barreto, GHC, Longhini, F, Dolan, E, Benatti, FB
Advances in nutrition (Bethesda, Md.). 2023;14(1):115-127
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Omega 3 polyunsaturated fatty acids (n-3PUFA) are long-chain polyunsaturated fatty acids essential to human health. They play a role in cell membrane integrity, immune and inflammation regulation, cognition and neuromuscular function. As the human body cannot make these fatty acids, they need to be obtained through diet or supplementation. Regarding skeletal muscle, recent research showed that n-3PUFAs may increase the uptake of amino acids by increasing the membrane fluidity in the muscle, and by activating pathways that inhibit protein breakdown. This led to the hypothesis that n-3PUFAs may enhance muscle mass gain and strength. This systematic review sought to gather all available evidence about the impact of n-3PUFA supplementation on muscle mass, strength, and function in healthy young and older adults. The review included 14 studies with a total of 1443 participants. The authors found that n-3PUFA supplementation had no significant effect on muscle mass or muscle function in healthy young and older adults, however, a very small but significant positive effect was noted regarding muscle strength. In the discussion section, the authors explain the challenges of their review and how these findings integrate with the current understanding and other research findings. They concluded more research is needed to get a better insight into the effects of n-3PUFA on muscle function and the variants.
Abstract
The effects of omega 3 polyunsaturated fatty acids (n-3PUFA) supplementation on skeletal muscle are currently unclear. The purpose of this systematic review was to synthesize all available evidence regarding the influence of n-3PUFA supplementation on muscle mass, strength, and function in healthy young and older adults. Four databases were searched (Medline, Embase, Cochrane CENTRAL, and SportDiscus). Predefined eligibility criteria were determined according to Population, Intervention, Comparator, Outcomes, and Study Design. Only peer-reviewed studies were included. The Cochrane RoB2 Tool and the NutriGrade approach were used to access risk of bias and certainty in evidence. Effect sizes were calculated using pre-post scores and analyzed using a three-level, random-effects meta-analysis. When sufficient studies were available, subanalyses were performed in the muscle mass, strength, and function outcomes according to participant's age (<60 or ≥60 years), supplementation dosage (<2 or ≥2 g/day), and training intervention ("resistance training" vs. "none or other"). Overall, 14 individual studies were included, total 1443 participants (913 females; 520 males) and 52 outcomes measures. Studies had high overall risk of bias and consideration of all NutriGrade elements resulted in a certainty assessment of moderate meta-evidence for all outcomes. n-3PUFA supplementation had no significant effect on muscle mass (standard mean difference [SMD] = 0.07 [95% CI: -0.02, 0.17], P = 0.11) and muscle function (SMD = 0.03 [95% CI: -0.09, 0.15], P = 0.58), but it showed a very small albeit significant positive effect on muscle strength (SMD = 0.12 [95% CI: 0.006, 0.24], P = 0.04) in participants when compared with placebo. Subgroup analyses showed that age, supplementation dose, or cosupplementation alongside resistance training did not influence these responses. In conclusion, our analyses indicated that n-3PUFA supplementation may lead to very small increases in muscle strength but did not impact muscle mass and function in healthy young and older adults. To our knowledge, this is the first review and meta-analysis investigating whether n-3PUFA supplementation can lead to increases in muscle strength, mass, and function in healthy adults. Registered protocol: doi.org/10.17605/OSF.IO/2FWQT.
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Impact of probiotics on muscle mass, muscle strength and lean mass: a systematic review and meta-analysis of randomized controlled trials.
Prokopidis, K, Giannos, P, Kirwan, R, Ispoglou, T, Galli, F, Witard, OC, Triantafyllidis, KK, Kechagias, KS, Morwani-Mangnani, J, Ticinesi, A, et al
Journal of cachexia, sarcopenia and muscle. 2023;14(1):30-44
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Sarcopenia is a progressive skeletal muscle disorder involving accelerated loss of muscle mass, strength and function. It generally occurs in older age groups but can also be seen in younger people. Multiple factors contribute to the development of the condition. Besides nutritional management strategies, probiotics have recently caught the interest of researchers. As probiotics promote metabolic building activity, aid digestion and absorption and reduce muscle breakdown by favourably managing inflammation, they present great potential for the management of sarcopenia. This systematic review and meta-analysis explored the impact of probiotic supplementation on muscle mass, total lean mass and muscle strength in human adults. The review included 24 studies, with probiotics mainly from the Bifidobacteria or Lactobacilli family. The analysis concluded that probiotic supplementation improved muscle mass in comparison to placebos. It also significantly increased overall muscle strength in 6 randomized controlled trials, which was most obvious in age groups of 50 and above. However, no changes were seen concerning total lean mass. It appeared that longer studies, of >12 weeks or more, showed better outcomes in this review. Furthermore, Bifidobacteria species seemed to exhibit more favourable effects, and the authors also noted the beneficial results were more significant in Asian populations. Further research is needed to understand more about the underlying mechanism, best probiotics strains and the specifics of different demographic groups. This article yields a concise overview of sarcopenia, the nutritional aspects of the disease and how probiotics may be beneficial in disease management, strengthened with data from the review.
Expert Review
Conflicts of interest:
None
Take Home Message:
- This was a well-conducted meta-analysis based on its methodological approach that demonstrated that Lactobacillus and Bifidobacterium probiotic supplementation may contribute to improved muscle mass in younger adults and improved muscle strength in older adults.
- Bifidobacterium probiotic supplementation was associated with enhanced muscle mass in younger adults, a potential focus for those considering probiotic supplements.
- The duration of probiotic therapy matters, with longer-term (12 weeks or more) supplementation showing improvements in muscle mass and strength..
Evidence Category:
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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 systematic review and meta-analysis evaluated the effect of probiotics on muscle mass, total lean mass and muscle strength in both young and older adults.
Methods
- The search encompassed PubMed, Scopus, Web of Science, and Cochrane Library databases, from inception up to June 2022; studies included spanned a period from 2013 to June 2022.
- The study adhered to Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines and included the Risk-of-Bias tool to assess study quality.
- The study focused on changes in muscle mass, total lean mass, and muscle strength.
- Inclusion criteria: randomised controlled trials (RCTs) with adult participants (>18 years); interventions involving any probiotics, and a control group receiving either no treatment or a placebo.
Results
- 24 RCTs were included (709 participants), with studies conducted in Europe, USA, and Asia. Intervention durations: ranged from 3 weeks to 12 months.
- Participants included overweight, untrained healthy and resistance-trained individuals, and those with specific conditions like metabolic syndrome and frailty.
- Body composition assessments were conducted using bioelectrical impedance (BIA) and/or dual-energy X-ray absorptiometry (DXA).
- Probiotic strains employed in the included studies varied, with Lactobacillus the most common, followed by Bifidobacterium; some combined both. 5 of 24 studies also used additional strains.
- Dosages: ranged from 2 × 10^9 to 11.2 × 10^10 colony-forming units (CFU).
- 4 out of 24 studies used fermented food products like cheese and noodles as sources of probiotics.
- 22 RCTs measured muscle mass and total lean mass; 6 RCTs measured global muscle strength.
- Probiotic supplementation (≥12 weeks) moderately increased muscle mass, with a standardised mean difference (SMD) of 0.42. This significant effect (95% CI: 0.10–0.74, P=0.009) was observed only in younger Asian adults (<50 years) after Bifidobacterium supplementation, based on a meta-analysis of 10 studies.
- Probiotic supplementation (≥12 weeks) significantly increased global muscle strength in older adults (>50 years; SMD: 0.69, 95% CI: 0.33–1.06, P = 0.0002).
- Probiotic supplementation showed no significant impact on lean mass (SMD: -0.03, 95% CI: 0.19 – 0.13, P = 0.69).
Conclusion
Probiotic supplementation, especially Lactobacillus and Bifidobacterium may have a positive impact on muscle mass and global strength
Clinical practice applications:
- Consumption of probiotics, mainly Lactobacillus and Bifidobacterium may contribute to improved muscle strength in older individuals (>50y).
- Consumption of Bifidobacterium strains was associated with improved muscle mass in younger individuals (<50y) in Asian countries, in a low number of studies (k=2).
- Bifidobacterium breve B-3 was associated with an improvement in muscle mass in older overweight individuals, although a causal relationship was not established.
- Probiotics may enhance muscle mass or strength by enhancing protein digestion and amino acid absorption for muscle synthesis and function.
- Considering an individual’s goals, a practitioner could consider probiotic supplementation as a complementary intervention when aiming to enhance muscle mass or strength .
Considerations for future research:
- Future research could focus on pinpointing which specific probiotic strains are most effective for muscle strength or muscle mass to tailor more precise interventions.
- Most studies did not exceed 12 weeks, highlighting the need for long-term research on probiotics sustained muscle impact.
- Future research could investigate the effects of probiotics across diverse demographic groups including different ages, sexes, and ethnic backgrounds to understand the impact in different populations.
- Delving deeper into the mechanisms by which probiotics influence muscle health could lead to targeted probiotic therapies that address specific physiological pathways.
- Finally, future research could explore how probiotics can be combined with other interventions, such as exercise or nutritional modifications, to synergistically improve muscle health and function.
Abstract
Probiotics have shown potential to counteract sarcopenia, although the extent to which they can influence domains of sarcopenia such as muscle mass and strength in humans is unclear. The aim of this systematic review and meta-analysis was to explore the impact of probiotic supplementation on muscle mass, total lean mass and muscle strength in human adults. A literature search of randomized controlled trials (RCTs) was conducted through PubMed, Scopus, Web of Science and Cochrane Library from inception until June 2022. Eligible RCTs compared the effect of probiotic supplementation versus placebo on muscle and total lean mass and global muscle strength (composite score of all muscle strength outcomes) in adults (>18 years). To evaluate the differences between groups, a meta-analysis was conducted using the random effects inverse-variance model by utilizing standardized mean differences. Twenty-four studies were included in the systematic review and meta-analysis exploring the effects of probiotics on muscle mass, total lean mass and global muscle strength. Our main analysis (k = 10) revealed that muscle mass was improved following probiotics compared with placebo (SMD: 0.42, 95% CI: 0.10-0.74, I2 = 57%, P = 0.009), although no changes were revealed in relation to total lean mass (k = 12; SMD: -0.03, 95% CI: -0.19 - 0.13, I2 = 0%, P = 0.69). Interestingly, a significant increase in global muscle strength was also observed among six RCTs (SMD: 0.69, 95% CI: 0.33-1.06, I2 = 64%, P = 0.0002). Probiotic supplementation enhances both muscle mass and global muscle strength; however, no beneficial effects were observed in total lean mass. Investigating the physiological mechanisms underpinning different ageing groups and elucidating appropriate probiotic strains for optimal gains in muscle mass and strength are warranted.
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Can dementia risk be reduced by following the American Heart Association's Life's Simple 7? A systematic review and dose-response meta-analysis.
Wu, J, Xiong, Y, Xia, X, Orsini, N, Qiu, C, Kivipelto, M, Rizzuto, D, Wang, R
Ageing research reviews. 2023;83:101788
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Plain language summary
The American Heart Association (AHA) has defined ideal levels of seven modifiable cardiovascular health (CVH) factors, known as Life's Simple 7, that consist of smoking, physical activity, diet, body mass index, fasting blood glucose, total cholesterol, and blood pressure. Maintaining ideal levels of these factors has been recommended as a prevention strategy against not only cardiovascular diseases but also neurodegenerative disorders, e.g., cognitive decline and dementia. However, studies exploring the beneficial effects of the AHA’s CVH metrics on cognitive outcomes, especially among older populations, have been uncertain, and solid evidence is lacking in this field. This systematic review and meta-analysis aimed to quantify the relationship between the AHA’s CVH metrics and cognitive outcomes. 14 longitudinal studies were included in the meta-analysis. The results showed a considerable effect of a favourable total CVH score on reduced risk of incident dementia in adults aged 70 years or older. When looking at the individual factors, dementia risk can be reduced significantly if older adults achieved the recommended level of physical activity, blood glucose, or total cholesterol. The association with smoking appeared to be borderline, and there was no association between diet, body mass index hazard ratio or blood pressure and dementia risk. The authors concluded that their findings provide evidence that maintaining a favourable level of CVH score, either in mid- or late- life, would substantially reduce the risk of dementia among older adults. Preserving cardiovascular health by quitting smoking, engaging in physical exercise, controlling blood glucose and total cholesterol might be especially effective for forestalling cognitive decline and dementia.
Abstract
This study aimed to quantify the relationships between the American Heart Association (AHA) Cardiovascular Health (CVH) metrics, namely AHA Life's Simple 7, and cognitive outcomes. We searched PubMed and Embase (January 1, 2010-August 24, 2022) and finally included 14 longitudinal studies (311654 participants with 8006 incident dementia cases). Random-effects meta-analysis and one-stage linear mixed-effects models were performed. Increased CVH score seemed to associate with decreased risk of incident dementia in a linear manner, but this relationship varied by the measurement age of CVH metrics. That is, midlife CVH tended to have a linear association with late-life dementia risk, whereas a J-shaped association was observed between the late-life CVH score and dementia. In addition, late-life dementia risk was reduced significantly if individuals maintained an ideal level of AHA's CVH guidelines of physical activity, fasting plasma glucose, total cholesterol, and smoking. However, our meta-analysis did not show a significant association between CVH score and global cognitive decline rate. Following AHA's CVH guidelines and maintaining CVH at an optimal level would substantially reduce the late-life dementia risk. More research is required to explore the link between a favorable CVH score and cognitive trajectories among cognitively asymptomatic older populations.