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Evidence of lifestyle interventions in a pregnant population with chronic hypertension and/or pre-existing diabetes: A systematic review and narrative synthesis.
Goddard, L, Patel, R, Astbury, NM, Tucker, K, McManus, RJ
Pregnancy hypertension. 2023;31:60-72
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Chronic hypertension complicates ≤5 % of pregnancies, and those entering pregnancy with a pre-existing diagnosis of diabetes has a global prevalence of between 0.5 % and 2.6 %. The aim of this study was to collate the evidence around lifestyle interventions during pregnancy for women with chronic hypertension and/or pre-existing diabetes (type 1 and type 2). This study is a systematic review and meta-analysis of nine randomised controlled trials. Results show lack of clarity and data on the effect of lifestyle interventions in pregnant women with chronic hypertension and/or pre-existing diabetes, thereby exposing key gaps in the literature. Authors conclude that there is a shortage of primary interventional studies examining the effect of lifestyle interventions in high-risk pregnant populations who enter pregnancy with chronic conditions.
Abstract
BACKGROUND Pregnant people with chronic hypertension, pre-existing diabetes or both are at high risk of developing cardiovascular disease. Lifestyle interventions play an important role in disease management in non-pregnant populations. AIM: To review the existing evidence of randomised controlled trials (RCTs) that examine lifestyle interventions in pregnant people with chronic hypertension and/or pre-existing diabetes. METHODS A systematic review and narrative synthesis was conducted. Five electronic databases were searched from inception to April 2021 for RCTs evaluating antenatal lifestyle interventions in people with chronic hypertension and/or pre-existing diabetes with outcomes to include weight or blood pressure change. RESULTS Nine randomised controlled trials including 7438 pregnant women were eligible. Eight studies were mixed pregnant populations that included women with chronic hypertension and/or pre-existing diabetes. One study included only pregnant women with pre-existing diabetes. Intervention characteristics and procedures varied and targeted diet, physical activity and/or gestational weight. All studies reported weight and one study reported blood pressure change. Outcome data were frequently unavailable for the subset of women of interest, including subgroup data on important pregnancy and birth complications. Eligibility criteria were often ambiguous and baseline data on chronic hypertension was often omitted. CONCLUSION A lack of primary interventional trials examining the effect of lifestyle interventions on weight and blood pressure outcomes in pregnant populations with chronic hypertension and/or pre-existing diabetes was evident. Lifestyle modification has the potential to alter disease progression. Future trials should address the ambiguity and frequent exclusion of these important populations.
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Low-carbohydrate diets and men's cortisol and testosterone: Systematic review and meta-analysis.
Whittaker, J, Harris, M
Nutrition and health. 2022;28(4):543-554
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Testosterone is the primary male sex hormone, and vital for reproductive development and function. Moreover, low endogenous testosterone is associated with an increased risk of chronic disease, including type 2 diabetes and cardiovascular disease. The aim of this study was to investigate the effects of low- versus high-carbohydrate diets on mens' testosterone and cortisol. This study is a systematic review and meta-analysis of twenty-seven studies with a total of 309 participants. Twelve of these studies were randomised trials whilst the rest were non-randomised. Results show an increase in resting and post-exercise cortisol on short-term low-carbohydrate diets (<3 weeks). In fact, resting cortisol levels return to baseline after <3 weeks on a LC diet, whilst post-exercise cortisol remains elevated. Furthermore, high-protein diets cause a large decrease in resting total testosterone. Authors conclude that further research is required in order to warrant their findings.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Short-term LC-diets diets cause a moderate increase in resting and post-exercise cortisol however this effect is not seen in LC-diets followed for great than 3 weeks
- HP-LC diets caused a statistically significant decrease in resting TT, suggesting caution in relation to endocrine effects of LC diets
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:
A systematic review and network meta-analysis was conducted on the effects of low-carbohydrate (LC) versus high-carbohydrate (HC) diets on men’s testosterone and cortisol.
The review was registered with PROSPERO and reported using PRISMA 2020 checklists.
Methods:
A comprehensive search strategy was used to find intervention studies looking at healthy adult males and LC diets of <35% carbohydrate. Studies were assessed for quality using the Cochrane Risk of Bias tool. Sub-group analyses was conducted for diet duration, protein intake and exercise duration.
Results:
The literature search resulted in 27 studies with a total of 309 healthy adult male participants, age: 27.3 ± 4.7 (to minimise variation in steroid hormone metabolism), body mass: 78.6± 7.1kg and BMI: 24.8 ±1.6. 12 randomised and 15 non-randomised controlled trials were analysed. 21 studies were considered low risk bias, 5 medium and 1 high risk.
- Short-term (<3 weeks) LC diets moderately increased resting cortisol (0.41 [0.16, 0.66], p < 0.01) when compared to HC diets.
- Long-term (≥3 weeks) LC diets had no consistent effect on resting cortisol
- LC diets resulted in higher post-exercise cortisol, after long-duration exercise (≥20 min): 0 h (0.78 [0.47, 1.1], p < 0.01), 1 h (0.81 [0.31, 1.31], p < 0.01), and 2 h (0.82 [0.33, 1.3], p < 0.01).
- The overall results for resting total testosterone (TT) showed a significant decrease on LC versus HC diets (SMD = −0.48, p = 0.01. However, subgroup analyses revealed this effect to be limited to high-protein (HP) LC diets, which yielded a very large decrease in TT (SMD = −1.08, p < 0.01; ∼5.23 nmol/L), albeit in a small sample (n = 26).
- Moderate protein (MP) (<35%), low-carbohydrate diets had no consistent effect on resting total testosterone, however high-protein (≥35%), low-carbohydrate diets greatly decreased resting (−1.08 [−1.67, −0.48], p < 0.01) and post-exercise total testosterone (−1.01 [−2, −0.01] p = 0.05).
- There was no overall effect of LC versus HC diets on 0 h post-exercise TT (SMD = −0.03, p = 0.95). However, subgroup analysis showed 0 h post-exercise was non-significantly higher on long-term LC versus HC diets (SMD = 0.44, p = 0.18), and much lower on short-term LC versus HC diets (SMD = −1.01, p = 0.05)
Conclusion:
This systematic review and metanalysis found an increase in resting and post-exercise cortisol on short-term LC diets. Cortisol does return to baseline in the first 3 weeks of a low-carbohydrate (LC) diet. The same response is, however, not seen in post-exercise cortisol, which remains elevated. In addition, the review showed that compared to moderate-protein diets, HP diets were found to cause a large decrease in resting and post-exercise TT (∼5.23 nmol/L).
Clinical practice applications:
The results of this review suggest that exercising whilst following a LC diet can increase cortisol in the short term, but not long-term. This suggests a period of diet adaptation. The effects of long-term LC diets on cardiovascular disease risk is uncertain and healthcare practitioners should monitor client responses and keep up-to-date with new research in this area
Since HP-LC diets were found to significantly decrease resting testosterone it highlights the need to ensure that protein intake does not exceed the urea cycle’s capacity due to potential adverse endocrine effects.
For clients where there is a desire to increase strength, power and hypertrophy, a MP-LC diet could be of benefit, as it showed potential to signal an increased anabolic state post exercise..
NB: Since the review only included a low number of studies and saw within these some heterogeneity that could not be explained, more research is needed before the paper’s findings can be conclusive. The above potential practice applications should therefore be seen as something to be mindful of when working with clients where cortisol and testosterone levels are relevant to their protocol.
Considerations for future research:
Future research should consider:
- Since LC diets have been shown to have a positive effect on health – decreased triglycerides, increased high density lipoprotein cholesterol and weight loss - future studies would benefit from including these markers so any positive and negative impacts can be monitored directly.
- Despite extensive analysis including sensitivity analysis to reduce bias and heterogeneity of the results, the paper highlights a need for further research to ensure consistency in key parameters e.g., exercise duration and intensity, carbohydrate supplements inclusion and period of dietary intervention. Since it was identified that HP-LP diets impact post exercise and resting TT, follow up studies would benefit from consistency in participants diets. This would help to reduce any potential confounding results.
Abstract
Background: Low-carbohydrate diets may have endocrine effects, although individual studies are conflicting. Therefore, a review was conducted on the effects of low- versus high-carbohydrate diets on men's testosterone and cortisol. Methods: The review was registered on PROSPERO (CRD42021255957). The inclusion criteria were: intervention study, healthy adult males, and low-carbohydrate diet: ≤35% carbohydrate. Eight databases were searched from conception to May 2021. Cochrane's risk of bias tool was used for quality assessment. Random-effects, meta-analyses using standardized mean differences and 95% confidence intervals, were performed with Review Manager. Subgroup analyses were conducted for diet duration, protein intake, and exercise duration. Results: Twenty-seven studies were included, with a total of 309 participants. Short-term (<3 weeks), low- versus high-carbohydrate diets moderately increased resting cortisol (0.41 [0.16, 0.66], p < 0.01). Whereas, long-term (≥3 weeks), low-carbohydrate diets had no consistent effect on resting cortisol. Low- versus high-carbohydrate diets resulted in much higher post-exercise cortisol, after long-duration exercise (≥20 min): 0 h (0.78 [0.47, 1.1], p < 0.01), 1 h (0.81 [0.31, 1.31], p < 0.01), and 2 h (0.82 [0.33, 1.3], p < 0.01). Moderate-protein (<35%), low-carbohydrate diets had no consistent effect on resting total testosterone, however high-protein (≥35%), low-carbohydrate diets greatly decreased resting (-1.08 [-1.67, -0.48], p < 0.01) and post-exercise total testosterone (-1.01 [-2, -0.01] p = 0.05). Conclusions: Resting and post-exercise cortisol increase during the first 3 weeks of a low-carbohydrate diet. Afterwards, resting cortisol appears to return to baseline, whilst post-exercise cortisol remains elevated. High-protein diets cause a large decrease in resting total testosterone (∼5.23 nmol/L).
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Food Timing, Circadian Rhythm and Chrononutrition: A Systematic Review of Time-Restricted Eating's Effects on Human Health.
Adafer, R, Messaadi, W, Meddahi, M, Patey, A, Haderbache, A, Bayen, S, Messaadi, N
Nutrients. 2020;12(12)
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Time restricted eating (TRE) is a type of intermittent fasting that limits food intake to a window lasting between 4 and 12 hours each day. Animal studies have found that TRE has beneficial effects on chronic diseases such as obesity, diabetes, and heart disease, and there are early indications of benefits to human health too. This systematic review examined previous studies exploring the effects of TRE on human health. The study authors analysed data from 22 clinical trials. The eating window in the trials varied from 4 to 12 hours, with the most common pattern being an 8-hour eating window, followed by a 16-hour fasting period. The overall adherence to TRE was 80%, with a 20% unintentional reduction in energy intake. TRE resulted in an average weight loss of 3% as well as a reduction in fat mass. This fat loss was also observed without any energy restriction. Interestingly, TRE produced metabolic benefits such as improvements in blood sugar and blood pressure even when there was no weight loss. This suggests that the beneficial effects of TRE are due to the realignment of eating with the circadian clock. More rigorous studies are needed, however, to confirm those effects, understand their mechanisms and assess their applicability to human health.
Abstract
INTRODUCTION Recent observations have shown that lengthening the daily eating period may contribute to the onset of chronic diseases. Time-restricted eating (TRE) is a diet that especially limits this daily food window. It could represent a dietary approach that is likely to improve health markers. The aim of this study was to review how time-restricted eating affects human health. METHOD Five general databases and six nutrition journals were screened to identify all studies published between January 2014 and September 2020 evaluating the effects of TRE on human populations. RESULTS Among 494 articles collected, 23 were finally included for analysis. The overall adherence rate to TRE was 80%, with a 20% unintentional reduction in caloric intake. TRE induced an average weight loss of 3% and a loss of fat mass. This fat loss was also observed without any caloric restriction. Interestingly, TRE produced beneficial metabolic effects independently of weight loss, suggesting an intrinsic effect based on the realignment of feeding and the circadian clock. CONCLUSIONS TRE is a simple and well-tolerated diet that generates many beneficial health effects based on chrononutrition principles. More rigorous studies are needed, however, to confirm those effects, to understand their mechanisms and to assess their applicability to human health.
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Assessment and Treatment of the Anorexia of Aging: A Systematic Review.
Cox, NJ, Ibrahim, K, Sayer, AA, Robinson, SM, Roberts, HC
Nutrients. 2019;11(1)
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The loss of appetite experienced by older people has been largely attributed to the aging process and is often termed the ‘anorexia of aging’. The aims of the study were (1) to describe current interventions for anorexia of aging and their reported effectiveness in the older population, and (2) to identify the methods of the appetite assessment used. The study is a systemic review with 18 studies meeting inclusion criteria (17 journal articles and 1 conference abstract), which were carried out in different settings including hospital, rehabilitation, care homes, and own home. From these studies, 9 different types of intervention for anorexia of aging were identified. Results indicate that five of the nine different types of interventions exhibited some favourable effects on appetite (flavour enhancement, oral nutritional supplement, an amino acid precursor [compounds that give amino acids after some reactions], fortified food, and megestrol acetate [type of hormone treatment] medication) when compared to controls or from baseline. Appetite was assessed in a number of different ways, predominantly using Likert or visual analogue scale methods. Authors conclude that flavour enhancement and supplementation particularly in the form of fortified food could be potential avenues of interest, together with a more rigorous assessment of the impact of lifestyle measures.
Abstract
(1) Background: Appetite loss in older people, the 'Anorexia of Aging' (AA), is common, associated with under-nutrition, sarcopenia, and frailty and yet receives little attention. This review had two aims: describe interventions for AA and their effectiveness, and identify the methods of appetite assessment. (2) Methods: Study inclusion: participants aged ≥65, intervention for AA, and appetite assessment, any design, and comparator. Exclusion: studies on specific health cohorts. Searches in four databases with hand searching of references and citing works. Two researchers independently assessed eligibility and quality. (3) Results: Authors screened 8729 titles, 46 full texts. Eighteen articles were included describing nine intervention types: education (n = 1), exercise (n = 1), flavor enhancement (n = 2), increased meal variety (n = 1), mealtime assistance (n = 1), fortified food (n = 1), oral nutritional supplement (ONS) (n = 8), amino acids (n = 1), and medication (n = 2). Three studies evaluated combinations: education + exercise, ONS + exercise, and ONS + medication. Five intervention types exhibited favorable effects on appetite but in single datasets or not replicated. Appetite was assessed predominantly by Likert (n = 9), or visual analogue scales (n = 7). (4) Conclusions: A variety of interventions and methods of appetite assessments were used. There was a lack of clarity about whether AA or undernutrition was the intervention target. AA is important for future research but needs standardized assessment so that effectiveness of a range of interventions can be fully explored.
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Nutritional Interventions to Improve Clinical Outcomes in Ovarian Cancer: A Systematic Review of Randomized Controlled Trials.
Rinninella, E, Fagotti, A, Cintoni, M, Raoul, P, Scaletta, G, Quagliozzi, L, Miggiano, GAD, Scambia, G, Gasbarrini, A, Mele, MC
Nutrients. 2019;11(6)
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Ovarian cancer is one of the most common cancers worldwide and it has the highest mortality rate of all gynaecologic cancers. The aim of the study was to examine the impact of several types of nutrition interventions on clinical outcomes in ovarian cancer patients. The study is a systemic review of fourteen randomised controlled trials (RCTs) focusing on nutritional interventions during chemotherapy or during the perioperative period. The majority of RCTs reported improved clinical outcomes after nutritional interventions. Most RCTs show a reduction in length of hospital stay and ameliorated intestinal recovery after surgery. Authors conclude that it is important to find nutritional interventions in order to improve patient’s survival since the ovarian mortality rate is one of the highest among malignancies.
Abstract
Among all gynaecological neoplasms, ovarian cancer has the highest rate of disease-related malnutrition, representing an important risk factor of postoperative mortality and morbidity. Hence, the importance of finding effective nutritional interventions is crucial to improve ovarian cancer patient's well-being and survival. This systematic review of randomized controlled trials (RCTs) aims at assessing the effects of nutritional interventions on clinical outcomes such as overall survival, progression-free survival, length of hospital stay (LOS), complications following surgery and/or chemotherapy in ovarian cancer patients. Three electronic bibliographic databases (MEDLINE, Web of Science, and Cochrane Central Register of Controlled Trials) were used to conduct a systematic literature search based on fixed inclusion and exclusion criteria, until December 2018. A total of 14 studies were identified. Several early postoperative feeding interventions studies (n = 8) were retrieved mainly demonstrating a reduction in LOS and an ameliorated intestinal recovery after surgery. Moreover, innovative nutritional approaches such as chewing gum intervention (n = 1), coffee consumption (n = 1), ketogenic diet intervention (n = 2) or fruit and vegetable juice concentrate supplementation diet (n = 1) and short-term fasting (n = 1) have been shown as valid and well-tolerated nutritional strategies improving clinical outcomes. However, despite an acceptable number of prospective trials, there is still a lack of homogeneous and robust endpoints. In particular, there is an urgent need of RCTs evaluating overall survival and progression-free survival during ovarian oncology treatments. Further high-quality studies are warranted, especially prospective studies and large RCTs, with more homogeneous types of intervention and clinical outcomes, including a more specific sampling of ovarian cancer women, to identify appropriate and effective nutritional strategies for this cancer, which is at high risk of malnutrition.
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Comparison of the Effectiveness of Lifestyle Modification with Other Treatments on the Incidence of Type 2 Diabetes in People at High Risk: A Network Meta-Analysis.
Yamaoka, K, Nemoto, A, Tango, T
Nutrients. 2019;11(6)
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The prevalence of diabetes has been increasing worldwide. The accompanying increase in the prevalence of diabetes-related complications and the occurrence of diabetes are likely to have a substantial impact on healthcare costs. The aim of the study was to compare the effectiveness of lifestyle modifications to other treatments for patients at high risk of type 2 diabetes. The study design is a systemic review of published literature and a network meta-analysis of data from each selected study. Forty-seven interventions were used for the analyses. The results of the meta-analysis highlight the efficacy of lifestyle modification in preventing the onset of type 2 diabetes in high-risk patients in comparison with standard treatment or placebo as well as other treatments. The proportion of patients with onset of type 2 diabetes in the intervention (lifestyle modification) group was approximately twice as low as compared to the control (standard intervention) group. Authors conclude that lifestyle modification is the superior treatment intervention among 12 treatments for the prevention of type 2 diabetes in high-risk individuals.
Abstract
BACKGROUND Many clinical trials have been conducted to verify the effects of interventions for prevention of type 2 diabetes (T2D) using different treatments and outcomes. The aim of this study was to compare the effectiveness of lifestyle modifications (LM) with other treatments in persons at high risk of T2D by a network meta-analysis (NMA). METHODS Searches were performed of PUBMED up to January 2018 to identify randomized controlled trials. The odds ratio (OR) with onset of T2D at 1 year in the intervention group (LM, dietary, exercise, or medication) versus a control group (standard treatments or placebo) were the effect sizes. Frequentist and Bayesian NMAs were conducted. RESULTS Forty-seven interventions and 12 treatments (20,113 participants) were used for the analyses. The OR in the LM was approximately 0.46 (95% CI: 0.33 to 0.61) times lower compared to the standard intervention by the Bayesian approach. The effects of LM compared to other treatments by indirect comparisons were not significant. CONCLUSIONS This meta-analysis further strengthened the evidence that LM reduces the onset of T2D compared to standard and placebo interventions and appears to be at least as effective as nine other treatments in preventing T2D.
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Effects of Popular Diets without Specific Calorie Targets on Weight Loss Outcomes: Systematic Review of Findings from Clinical Trials.
Anton, SD, Hida, A, Heekin, K, Sowalsky, K, Karabetian, C, Mutchie, H, Leeuwenburgh, C, Manini, TM, Barnett, TE
Nutrients. 2017;9(8)
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Calorie-restricted diets have not been highly successful in reducing obesity levels. This has led to an increased interest in alternative dietary approaches to achieve sustained weight loss. The purpose of this systematic review was to analyse the most popular diets of 2016 for short- and long-term weight loss outcomes based on findings from clinical trials that do not include calorie restriction or increased physical activity levels. Of all existing literature, only 16 articles met the inclusion criteria covering 7 popular diets, indicating the lack of clinical trials and high-quality evidence. The Atkins diet is the most well-researched popular diet and demonstrates substantial long-term weight loss. The Paleolithic diet has also been found to produce sustained weight loss according to the one study included on this diet. Based to these findings, the authors conclude that of the popular diets, those with a low carbohydrate component seem to be effective, though the safety of these diets has not been critically examined. Further evidence is needed to provide a more comprehensive evaluation of the efficacy of each of these popular diets.
Abstract
The present review examined the evidence base for current popular diets, as listed in the 2016 U.S. News & World Report, on short-term (≤six months) and long-term (≥one year) weight loss outcomes in overweight and obese adults. For the present review, all diets in the 2016 U.S. News & World Report Rankings for "Best Weight-Loss Diets", which did not involve specific calorie targets, meal replacements, supplementation with commercial products, and/or were not categorized as "low-calorie" diets were examined. Of the 38 popular diets listed in the U.S. News & World Report, 20 met our pre-defined criteria. Literature searches were conducted through PubMed, Cochrane Library, and Web of Science using preset key terms to identify all relevant clinical trials for these 20 diets. A total of 16 articles were identified which reported findings of clinical trials for seven of these 20 diets: (1) Atkins; (2) Dietary Approaches to Stop Hypertension (DASH); (3) Glycemic-Index; (4) Mediterranean; (5) Ornish; (6) Paleolithic; and (7) Zone. Of the diets evaluated, the Atkins Diet showed the most evidence in producing clinically meaningful short-term (≤six months) and long-term (≥one-year) weight loss. Other popular diets may be equally or even more effective at producing weight loss, but this is unknown at the present time since there is a paucity of studies on these diets.