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Dietary polyphenols, metabolic syndrome and cardiometabolic risk factors: An observational study based on the DCH-NG subcohort.
Lanuza, F, Zamora-Ros, R, Bondonno, NP, Meroño, T, Rostgaard-Hansen, AL, Riccardi, G, Tjønneland, A, Landberg, R, Halkjær, J, Andres-Lacueva, C
Nutrition, metabolism, and cardiovascular diseases : NMCD. 2023;33(6):1167-1178
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Metabolic syndrome (MetS) is a cluster of metabolic disorders that increases the risk of developing chronic diseases. Cardiometabolic risk factors include high waist circumference (WC), insulin resistance, hypertension, dysglycaemia, dyslipidaemia, and altered inflammatory markers. The aim of this study was to investigate the associations between intakes of polyphenols (total polyphenols and their main classes) and the prevalence of MetS and cardiometabolic risk factors. This study is an observational sub-cohort study of 676 Danish participants of the MAX study from the Danish Diet, Cancer and Health - Next Generations (DCH-NG) cohort. Results showed that individuals with higher total polyphenol and phenolic acid intakes, were less likely to have MetS. Furthermore, for cardiovascular risk factors, intakes of total polyphenols, flavonoids and phenolic acids were associated with a lower risk of higher systolic blood pressure and lower high-density lipoprotein cholesterol. Authors conclude by suggesting that intervention studies should be undertaken to establish whether a polyphenol-rich diet can improve some cardiometabolic risk factors and can reduce or delay the onset of cardiometabolic diseases in free-living populations.
Abstract
BACKGROUND AND AIMS Polyphenol-rich foods have beneficial properties that may lower cardiometabolic risk. We aimed to prospectively investigate the relationship between intakes of dietary polyphenols, and metabolic syndrome (MetS) and its components, in 676 Danish residents from the MAX study, a subcohort of the Danish Diet, Cancer and Health-Next Generations (DCH-NG) cohort. METHODS AND RESULTS Dietary data were collected using web-based 24-h dietary recalls over one year (at baseline, and at 6 and 12 months). The Phenol-Explorer database was used to estimate dietary polyphenol intake. Clinical variables were also collected at the same time point. Generalized linear mixed models were used to investigate relationships between polyphenol intake and MetS. Participants had a mean age of 43.9y, a mean total polyphenol intake of 1368 mg/day, and 75 (11.6%) had MetS at baseline. Compared to individuals with MetS in Q1 and after adjusting for age, sex, lifestyle and dietary confounders, those in Q4 - for total polyphenols, flavonoids and phenolic acids-had a 50% [OR (95% CI): 0.50 (0.27, 0.91)], 51% [0.49 (0.26, 0.91)] and 45% [0.55 (0.30, 1.00)] lower odds of MetS, respectively. Higher total polyphenols, flavonoids and phenolic acids intakes as continuous variable were associated with lower risk for elevated systolic blood pressure (SBP) and low high-density lipoprotein cholesterol (HDL-c) (p < 0.05). CONCLUSIONS Total polyphenol, flavonoid and phenolic acid intakes were associated with lower odds of MetS. These intakes were also consistently and significantly associated with a lower risk for higher SBP and lower HDL-c concentrations.
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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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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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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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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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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.
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Effects of a low-carbohydrate diet on insulin-resistant dyslipoproteinemia-a randomized controlled feeding trial.
Ebbeling, CB, Knapp, A, Johnson, A, Wong, JMW, Greco, KF, Ma, C, Mora, S, Ludwig, DS
The American journal of clinical nutrition. 2022;115(1):154-162
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Diets high in carbohydrates and particularly processed carbohydrates can increase the risk for developing a dysfunction in the body’s ability to take up sugar from the blood, known as insulin resistance. However how this relates to insulin resistance can contribute to the development of many diseases such as type 2 diabetes, heart disease and stroke, which highlights the importance in preventing this dysfunction. This randomised control trial of 148 individuals aimed to determine the role of low, medium, and high carbohydrate diets with varying saturated fat content on measures for insulin resistance. The results showed that regardless of the fat content, it was the level of carbohydrate that determined the effect on measures of insulin resistance. High saturated fat and low-carbohydrate diets improved insulin resistance and low saturated fat high carbohydrate diets worsened insulin resistance. Improvements were also observed in blood lipids with a high fat low carbohydrate diet. It was concluded that a diet low in carbohydrates, but high in saturated fat improved insulin resistance and blood lipid levels. This study could be used by healthcare professionals to understand that a diet, which replaces fat with carbohydrates may be worsening insulin resistance and that low carbohydrate diets may be of benefit.
Abstract
BACKGROUND Carbohydrate restriction shows promise for diabetes, but concerns regarding high saturated fat content of low-carbohydrate diets limit widespread adoption. OBJECTIVES This preplanned ancillary study aimed to determine how diets varying widely in carbohydrate and saturated fat affect cardiovascular disease (CVD) risk factors during weight-loss maintenance. METHODS After 10-14% weight loss on a run-in diet, 164 participants (70% female; BMI = 32.4 ± 4.8 kg/m2) were randomly assigned to 3 weight-loss maintenance diets for 20 wk. The prepared diets contained 20% protein and differed 3-fold in carbohydrate (Carb) and saturated fat as a proportion of energy (Low-Carb: 20% carbohydrate, 21% saturated fat; Moderate-Carb: 40%, 14%; High-Carb: 60%, 7%). Fasting plasma samples were collected prerandomization and at 20 wk. Lipoprotein insulin resistance (LPIR) score was calculated from triglyceride-rich, high-density, and low-density lipoprotein particle (TRL-P, HDL-P, LDL-P) sizes and subfraction concentrations (large/very large TRL-P, large HDL-P, small LDL-P). Other outcomes included lipoprotein(a), triglycerides, HDL cholesterol, LDL cholesterol, adiponectin, and inflammatory markers. Repeated measures ANOVA was used for intention-to-treat analysis. RESULTS Retention was 90%. Mean change in LPIR (scale 0-100) differed by diet in a dose-dependent fashion: Low-Carb (-5.3; 95% CI: -9.2, -1.5), Moderate-Carb (-0.02; 95% CI: -4.1, 4.1), High-Carb (3.6; 95% CI: -0.6, 7.7), P = 0.009. Low-Carb also favorably affected lipoprotein(a) [-14.7% (95% CI: -19.5, -9.5), -2.1 (95% CI: -8.2, 4.3), and 0.2 (95% CI: -6.0, 6.8), respectively; P = 0.0005], triglycerides, HDL cholesterol, large/very large TRL-P, large HDL-P, and adiponectin. LDL cholesterol, LDL-P, and inflammatory markers did not differ by diet. CONCLUSIONS A low-carbohydrate diet, high in saturated fat, improved insulin-resistant dyslipoproteinemia and lipoprotein(a), without adverse effect on LDL cholesterol. Carbohydrate restriction might lower CVD risk independently of body weight, a possibility that warrants study in major multicentered trials powered on hard outcomes. The registry is available through ClinicialTrials.gov: https://clinicaltrials.gov/ct2/show/NCT02068885.
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Time-restricted eating and exercise training improve HbA1c and body composition in women with overweight/obesity: A randomized controlled trial.
Haganes, KL, Silva, CP, Eyjólfsdóttir, SK, Steen, S, Grindberg, M, Lydersen, S, Hawley, JA, Moholdt, T
Cell metabolism. 2022;34(10):1457-1471.e4
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A healthy diet and regular physical activity are primary lifestyle strategies for the prevention and treatment of obesity and its associated conditions. However, poor adherence rates to these strategies limit their effectiveness. Time-restricted eating (TRE) is a popular dietary strategy that emphasises the timing of meals in alignment with diurnal circadian rhythms, permitting ad libitum energy intake during a restricted eating window (8–10 h between the first and last energy intake of the day). The aim of this study was to investigate the isolated and combined effects of TRE and high-intensity interval training (HIIT) on glycaemic control and cardiometabolic health outcomes in women with overweight/obesity. This study is a 7-week randomised controlled trial with four parallel groups: TRE (energy intake limited to a %10-h eating window every day), HIIT (three supervised treadmill exercise sessions per week), a combination (TREHIIT), and a control group (CON, no intervention). Participants (n=131) were randomly assigned to one of the four groups. . Results show that 7 weeks of TRE, HIIT, or a combination failed to improve glycaemic control in reproductive-aged women with overweight/obesity. However, the combination of TRE and HIIT significantly reduced glycated haemoglobin levels compared with CON and induced greater losses in body weight, fat mass, and visceral fat area compared with either intervention alone. Isolated TRE resulted in lower nocturnal glucose concentrations compared with CON. Authors conclude that combining TRE with HIIT can rapidly induce several health benefits and decrease metabolic disease risk in women with overweight/obesity. In fact, the high rates of compliance and adherence shown in their findings, highlight the potential of these diet-exercise (TRE and HIIT) protocols to be implemented in clinical practice for treatment and primary prevention of overweight/ obesity.
Abstract
Diet modification and exercise training are primary lifestyle strategies for obesity management, but poor adherence rates limit their effectiveness. Time-restricted eating (TRE) and high-intensity interval training (HIIT) improve cardiometabolic health in at-risk individuals, but whether these two interventions combined induce superior improvements in glycemic control than each individual intervention is not known. In this four-armed randomized controlled trial (ClinicalTrials.gov NCT04019860), we determined the isolated and combined effects of 7 weeks of TRE (≤10-h daily eating window, with ad libitum energy intake) and HIIT (three exercise sessions per week), compared with a non-intervention control group, on glycemic control and secondary cardiometabolic outcomes in 131 women (36.2 ± 6.2 years) with overweight/obesity. There were no statistically significant effects after isolated TRE, HIIT, or a combination (TREHIIT) on glucose area under the curve during an oral glucose tolerance test (the primary outcome) compared with the control group (TRE, -26.3 mmol/L; 95% confidence interval [CI], -82.3 to 29.7, p = 0.36; HIIT, -53.8 mmol/L; 95% CI, -109.2 to 1.6, p = 0.057; TREHIIT, -41.3 mmol/L; 95% CI, -96.4 to 13.8, p = 0.14). However, TREHIIT improved HbA1c and induced superior reductions in total and visceral fat mass compared with TRE and HIIT alone. High participant adherence rates suggest that TRE, HIIT, and a combination thereof may be realistic diet-exercise strategies for improving markers of metabolic health in women at risk of cardiometabolic disease.
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Efficacy and safety of dietary polyphenol supplementation in the treatment of non-alcoholic fatty liver disease: A systematic review and meta-analysis.
Yang, K, Chen, J, Zhang, T, Yuan, X, Ge, A, Wang, S, Xu, H, Zeng, L, Ge, J
Frontiers in immunology. 2022;13:949746
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Non-alcoholic fatty liver disease (NAFLD) is characterised by fat accumulation in the liver that can result in liver damage. NAFLD affects approximately 25% of the global population. There is evidence that dietary polyphenols can improve metabolism and insulin resistance and reduce inflammation and oxidative stress, which are the mechanisms that lead to liver damage in NAFLD. This systematic review and meta-analysis aimed to assess the effectiveness of dietary polyphenols in the treatment of non-alcoholic fatty liver disease (NAFLD). Eight dietary polyphenols, such as curcumin, resveratrol, naringenin, anthocyanin, hesperidin, catechin, silymarin, and genistein, were evaluated for their efficacy and safety. The administration of 80-3,000 mg of Curcumin for an 8-12 week duration is effective and safe for reducing body mass index, aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglycerides (TG), total cholesterol (TC), and insulin resistance (HOMA-IR). Compared with the placebo, Naringenin reduced the percentage of NAFLD grade, TG, TC, and low-density lipoprotein cholesterol and increased high-density lipoprotein cholesterol. Hesperidin may potentially decrease body mass index (BMI), AST, ALT, TG, TC, and HOMA-IR. Catechin is safe, and 500-1000 mg supplementation for 12 weeks may reduce BMI, HOMA-IR, and TG. NAFLD patients who received silymarin showed improvements in ALT and AST, as well as reductions in hepatic fat accumulation and liver stiffness. 94–2100 mg of Silymarin supplementation for 8–48 weeks may reduce liver enzyme levels. Researchers can use the results of this study to understand the clinical utility of different polyphenol supplements in the treatment of NAFLD. Because the current evidence is highly heterogeneous in nature and limited in scope, further robust research is required on various classes of polyphenols and their effectiveness in reducing the severity of NAFLD.
Abstract
Background: Dietary polyphenol treatment of non-alcoholic fatty liver disease (NAFLD) is a novel direction, and the existing clinical studies have little effective evidence for its therapeutic effect, and some studies have inconsistent results. The effectiveness of dietary polyphenols in the treatment of NAFLD is still controversial. The aim of this study was to evaluate the therapeutic efficacy of oral dietary polyphenols in patients with NAFLD. Methods: The literature (both Chinese and English) published before 30 April 2022 in PubMed, Cochrane, Medline, CNKI, and other databases on the treatment of NAFLD with dietary polyphenols was searched. Manual screening, quality assessment, and data extraction of search results were conducted strictly according to the inclusion and exclusion criteria. RevMan 5.3 software was used to perform the meta-analysis. Results: The RCTs included in this study involved dietary supplementation with eight polyphenols (curcumin, resveratrol, naringenin, anthocyanin, hesperidin, catechin, silymarin, and genistein) and 2,173 participants. This systematic review and meta-analysis found that 1) curcumin may decrease body mass index (BMI), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Triglycerides (TG) total cholesterol (TC), and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) compared to placebo; and curcumin does not increase the occurrence of adverse events. 2) Although the meta-analysis results of all randomized controlled trials (RCTs) did not reveal significant positive changes, individual RCTs showed meaningful results. 3) Naringenin significantly decreased the percentage of NAFLD grade, TG, TC, and low-density lipoprotein cholesterol (LDL-C) and increased high-density lipoprotein cholesterol (HDL-C) but had no significant effect on AST and ALT, and it is a safe supplementation. 4) Only one team presents a protocol about anthocyanin (from Cornus mas L. fruit extract) in the treatment of NAFLD. 5) Hesperidin may decrease BMI, AST, ALT, TG, TC, HOMA-IR, and so on. 6) Catechin may decrease BMI, HOMA-IR, and TG level, and it was well tolerated by the patients. 7) Silymarin was effective in improving ALT and AST and reducing hepatic fat accumulation and liver stiffness in NAFLD patients. Conclusion: Based on current evidence, curcumin can reduce BMI, TG, TC, liver enzymes, and insulin resistance; catechin can reduce BMI, insulin resistance, and TG effectively; silymarin can reduce liver enzymes. For resveratrol, naringenin, anthocyanin, hesperidin, and catechin, more RCTs are needed to further evaluate their efficacy and safety.
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The effects of the Green-Mediterranean diet on cardiometabolic health are linked to gut microbiome modifications: a randomized controlled trial.
Rinott, E, Meir, AY, Tsaban, G, Zelicha, H, Kaplan, A, Knights, D, Tuohy, K, Scholz, MU, Koren, O, Stampfer, MJ, et al
Genome medicine. 2022;14(1):29
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The Mediterranean (MED) diet, high in nuts, vegetables, and legumes and low in red meat intake, is recommended for the prevention of cardiometabolic diseases. It has been reported that adherence to MED dietary patterns is associated with a distinct gut microbiome profile. The main aim of this study was to investigate the effect of MED-based dietary interventions on the gut microbiome composition and function. This study was focused on the analysis of the DIRECT-PLUS trials’ secondary outcomes, including gut microbiome profile, lipid profile, glycaemic control, inflammatory state, and cardiometabolic risk. All eligible participants were randomised in a 1:1:1 ratio, into one of the three intervention groups: healthy dietary guidelines (HDG), MED, and Green-MED, all combined with physical activity accommodation. Results showed that: - the Green-MED diet [an improved version of the healthy MED diet, with increased consumption of plant-based foods and reduced meat intake] induced a prominent change in the gut microbiome composition, driven by the low-prevalent “non-core” fraction of the gut microbiome. - the MED and Green-MED diets improved cardiometabolic markers. These beneficial changes in levels of cardiometabolic biomarkers were associated with a concurrent shift in the gut microbiome composition. Authors conclude that the Green-MED diet has extensive effects on the composition and function of the host gut microbiome, with the latter partially mediating the beneficial effects of the diet on cardiometabolic health.
Abstract
BACKGROUND Previous studies have linked the Mediterranean diet (MED) with improved cardiometabolic health, showing preliminary evidence for a mediating role of the gut microbiome. We recently suggested the Green-Mediterranean (Green-MED) diet as an improved version of the healthy MED diet, with increased consumption of plant-based foods and reduced meat intake. Here, we investigated the effects of MED interventions on the gut microbiota and cardiometabolic markers, and the interplay between the two, during the initial weight loss phase of the DIRECT-PLUS trial. METHODS In the DIRECT-PLUS study, 294 participants with abdominal obesity/dyslipidemia were prospectively randomized to one of three intervention groups: healthy dietary guidelines (standard science-based nutritional counseling), MED, and Green-MED. Both isocaloric MED and Green-MED groups were supplemented with 28g/day walnuts. The Green-MED group was further provided with daily polyphenol-rich green tea and Mankai aquatic plant (new plant introduced to a western population). Gut microbiota was profiled by 16S rRNA for all stool samples and shotgun sequencing for a select subset of samples. RESULTS Both MED diets induced substantial changes in the community structure of the gut microbiome, with the Green-MED diet leading to more prominent compositional changes, largely driven by the low abundant, "non-core," microorganisms. The Green-MED diet was associated with specific microbial changes, including enrichments in the genus Prevotella and enzymatic functions involved in branched-chain amino acid degradation, and reductions in the genus Bifidobacterium and enzymatic functions responsible for branched-chain amino acid biosynthesis. The MED and Green-MED diets were also associated with stepwise beneficial changes in body weight and cardiometabolic biomarkers, concomitantly with the increased plant intake and reduced meat intake. Furthermore, while the level of adherence to the Green-MED diet and its specific green dietary components was associated with the magnitude of changes in microbiome composition, changes in gut microbial features appeared to mediate the association between adherence to the Green-MED and body weight and cardiometabolic risk reduction. CONCLUSIONS Our findings support a mediating role of the gut microbiome in the beneficial effects of the Green-MED diet enriched with Mankai and green tea on cardiometabolic risk factors. TRIAL REGISTRATION The study was registered on ClinicalTrial.gov ( NCT03020186 ) on January 13, 2017.
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A randomized controlled trial for response of microbiome network to exercise and diet intervention in patients with nonalcoholic fatty liver disease.
Cheng, R, Wang, L, Le, S, Yang, Y, Zhao, C, Zhang, X, Yang, X, Xu, T, Xu, L, Wiklund, P, et al
Nature communications. 2022;13(1):2555
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Non-alcoholic fatty liver disease (NAFLD) is a common chronic disease that is associated with the development of type 2 diabetes (T2D). A commonality between the two diseases is the body’s inefficiency to uptake sugar from the blood, known as insulin resistance. Dysbiosis of the gut microbiota has been shown to be involved in NAFLD and T2D. Exercise and dietary modifications have been shown to increase gut microbiota diversity altering the composition, however the extent of this change is poorly understood. This randomised control trial of 115 individuals with NAFLD and insulin resistance aimed to determine the effects of aerobic exercise and a diet comprising of 37-40% carbohydrate, 35-37% fat, and 25-27% protein on gut microbiota diversity, liver fat content and sugar metabolism. The results showed that generally diet and exercise increased gut microbiota diversity and ensured maintenance of gut microbiota associated with healthy outcomes. Liver fat content was decreased the most with diet and exercise and by nearly 50% but not all subjects responded the same with responders and non-responders identified. It was concluded that there is a necessity for personalisation of diet and exercise programmes for the treatment of NAFLD. This study could be used by healthcare professionals to understand that gut microbiota diversity may be improved by diet and exercise, however not everyone may be similarly affected. Until more is understood about the gut microbiota, it may be necessary to try different diet and exercise regimes, which are optimal for each individual.
Abstract
Exercise and diet are treatments for nonalcoholic fatty liver disease (NAFLD) and prediabetes, however, how exercise and diet interventions impact gut microbiota in patients is incompletely understood. We previously reported a 8.6-month, four-arm (Aerobic exercise, n = 29; Diet, n = 28; Aerobic exercise + Diet, n = 29; No intervention, n = 29) randomized, singe blinded (for researchers), and controlled intervention in patients with NAFLD and prediabetes to assess the effect of interventions on the primary outcomes of liver fat content and glucose metabolism. Here we report the third primary outcome of the trial-gut microbiota composition-in participants who completed the trial (22 in Aerobic exercise, 22 in Diet, 23 in Aerobic exercise + Diet, 18 in No Intervention). We show that combined aerobic exercise and diet intervention are associated with diversified and stabilized keystone taxa, while exercise and diet interventions alone increase network connectivity and robustness between taxa. No adverse effects were observed with the interventions. In addition, in exploratory ad-hoc analyses we find that not all subjects responded to the intervention in a similar manner, when using differentially altered gut microbe amplicon sequence variants abundance to classify the responders and low/non-responders. A personalized gut microbial network at baseline could predict the individual responses in liver fat to exercise intervention. Our findings suggest an avenue for developing personalized intervention strategies for treatment of NAFLD based on host-gut microbiome ecosystem interactions, however, future studies with large sample size are needed to validate these discoveries. The Trial Registration Number is ISRCTN 42622771.
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Comparison of dietary and physical activity behaviors in women with and without polycystic ovary syndrome: a systematic review and meta-analysis of 39 471 women.
Kazemi, M, Kim, JY, Wan, C, Xiong, JD, Michalak, J, Xavier, IB, Ganga, K, Tay, CT, Grieger, JA, Parry, SA, et al
Human reproduction update. 2022;28(6):910-955
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Polycystic ovary syndrome (PCOS) is a heritable, prevalent and complex endocrine disorder. Besides reproductive manifestations of increased risk of infertility and pregnancy complications, women with PCOS often exhibit cardio-metabolic aberrations and are at risk for developing metabolic syndrome, type 2 diabetes and sleep disturbance. The aim of this study was to test the hypothesis that reproductive-aged women with PCOS would exhibit worse dietary and physical activity (PA) behaviours versus their counterparts without PCOS. This study was a systematic review and meta-analysis of 54 studies (61 publications). The studies included a total of 39,471 participants and 116 experimental arms (n = 8736 PCOS [59 arms]). Results showed that women with PCOS exhibit an overall adverse lifestyle behaviour, specifically poorer dietary intakes (lower diet quality, higher cholesterol, lower magnesium, tendency for lower zinc), and lower total PA compared to those without PCOS, despite lower alcohol intakes. Furthermore, compared to women without PCOS, the women with PCOS consumed worse or similar consumption of core food groups (grains, fruits, vegetables, proteins, seeds, nuts, dairy). Authors conclude that providing education on lifestyle modification is crucial for women with PCOS to improve their short- and long-term reproductive, metabolic, and psychological health.
Abstract
BACKGROUND Lifestyle (dietary and/or physical activity [PA]) modification is recommended as first-line therapy to manage polycystic ovary syndrome (PCOS). Current recommendations are based on healthy lifestyle practices for the general public since evidence for unique lifestyle approaches in PCOS is limited and low quality. OBJECTIVE AND RATIONALE We aimed to synthesize evidence on dietary and PA behaviors between women with PCOS and those without PCOS. Primary outcomes were overall diet quality, total energy intake and total PA, and secondary outcomes included macronutrients, micronutrients, food groups, foods, glycemic indices, sedentary time and sitting levels. We conducted this work to identify any unique lifestyle behaviors in women with PCOS that could underlie the propensity of weight gain and obesity in PCOS and be targeted for precision nutrition and PA interventions. These findings could be used to inform future practice recommendations and research that more effectively address complications (weight gain, obesity, diabetes, infertility, cardiovascular disease and mental health) in this high-risk population. SEARCH METHODS Databases of MEDLINE, Web of Science, Scopus and CINAHL were searched until 15 February 2022 to identify observational studies documenting dietary and PA behaviors between women with PCOS and without PCOS (Controls). Studies on children, adolescents (<18 years), pregnant or menopausal-aged women (>50 years) were excluded. Data were pooled by random-effects models and expressed as (standardized) mean differences (MD) and 95% CIs. The risk of bias was assessed by the Newcastle-Ottawa scale (NOS). OUTCOMES Fifty-four studies (N = 39 471 participants; [n = 8736 PCOS; 30 735 Controls]) were eligible (96%; [52/54] NOS scores ≥ 7). Women with PCOS had higher cholesterol (MD: 12.78, 95% CI: 1.48 to 24.08 mg/day; P = 0.03; I2 = 19%), lower magnesium (MD: -21.46, 95% CI: -41.03 to -1.91 mg/day; P = 0.03; I2 = 76%), and a tendency for lower zinc (MD: -1.08, 95% CI: -2.19 to -0.03 mg/day; P = 0.05; I2 = 96%) intake, despite lower alcohol consumption (MD: -0.95, 95% CI: -1.67 to 0.22 g/day; P = 0.02; I2 = 0%) versus Controls. Also, women with PCOS had lower total PA (standardized mean difference: -0.38, 95% CI: -0.72 to 0.03; P = 0.03; I2 = 98%). Conversely, energy, macronutrients (carbohydrate, fat, protein, fiber), micronutrients (folic acid, iron, calcium, sodium), glycemic index and glycemic load were similar (all: P ≥ 0.06). Most eligible studies reported lower total adherence to healthy eating patterns or poorer consumption of major food groups (grains, fruits, vegetables, proteins, seeds, nuts, dairy) in women with PCOS, as described narratively since variable study methodology did not permit meta-analyses. WIDER IMPLICATIONS Collective evidence supports that women with PCOS have a lower overall diet quality, poorer dietary intakes (higher cholesterol, lower magnesium and zinc) and lower total PA, despite lower alcohol consumption versus those without PCOS. Considerable heterogeneity among studies reinforces the need for research to address any relative contributions of other factors (e.g. genetic, metabolic or sociodemographic) to the observed differences. These clarifications may contribute to future evidence-based guideline recommendations on monitoring and managing PCOS in the era of precision lifestyle medicine.