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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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Effects of camelina oil supplementation on lipid profile and glycemic control: a systematic review and dose‒response meta-analysis of randomized clinical trials.
Jalili, C, Talebi, S, Mehrabani, S, Bagheri, R, Wong, A, Amirian, P, Zarpoosh, M, Ghoreishy, SM, Kermani, MAH, Moradi, S
Lipids in health and disease. 2022;21(1):132
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Research indicates that alpha-linolenic acid (ALA) can reduce the risk of cardiovascular disease by improving blood lipids, blood pressure, and haemostatic factors, among others. Camelina oil, considered a good source of ALA compared to other edible oils, is one of the richest dietary sources of omega-3 fatty acids, with a polyunsaturated fatty acid content over 50%. The aim of this study was to determine the effectiveness of camelina oil supplementation (COS) on lipid profiles and glycaemic control in human studies. This study is a systematic review and meta-analysis of seven randomised controlled trials with a total of 428 individuals (202 participants in the COS group and 226 in the control group). Results did not show any affects of COS on lipid profile and glycaemic indices compared with placebo intake. However, subgroup analysis showed that COS for more than 8 weeks and at a dose lower than 30g/d could decrease total cholesterol. Authors conclude that COS may be a beneficial nonpharmacological strategy for the improvement of this lipid marker. However, further studies are required to confirm the findings of this study.
Abstract
BACKGROUND This systematic review and dose-response meta-analysis of published randomized controlled trials (RCTs) was conducted to determine the effectiveness of camelina oil supplementation (COS) on lipid profiles and glycemic indices. METHODS Relevant RCTs were selected by searching the ISI Web of Science, PubMed, and Scopus databases up to July 1, 2022. RTCs with an intervention duration of less than 2 weeks, without a placebo group, and those that used COS in combination with another supplement were excluded. Weighted mean differences and 95% confidence intervals were pooled by applying a random-effects model, while validated methods examined sensitivity analyses, heterogeneity, and publication bias. RESULTS Seven eligible RCTs, including 428 individuals, were selected. The pooled analysis revealed that COS significantly improved total cholesterol in studies lasting more than 8 weeks and utilizing dosages lower than 30 g/d compared to the placebo group. The results of fractional polynomial modeling indicated that there were nonlinear dose-response relations between the dose of COS and absolute mean differences in low-density cholesterol, high-density cholesterol, and total cholesterol, but not triglycerides. It appears that the greatest effect of COS oil occurs at the dosage of 20 g/day. CONCLUSION The present meta-analysis indicates that COS may reduce cardiovascular disease risk by improving lipid profile markers. Based on the results of this study, COS at dosages lower than 30 g/d may be a beneficial nonpharmacological strategy for lipid control. Further RCTs with longer COS durations are warranted to expand on these results.
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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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Association of gestational diabetes mellitus with overall and type specific cardiovascular and cerebrovascular diseases: systematic review and meta-analysis.
Xie, W, Wang, Y, Xiao, S, Qiu, L, Yu, Y, Zhang, Z
BMJ (Clinical research ed.). 2022;378:e070244
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Gestational diabetes mellitus, defined as glucose intolerance with first onset during pregnancy, usually resolves after birth, however, a growing number of long-term observational studies suggest that the impact persists over time. The increased cardiovascular risk in women with gestational diabetes mellitus has been increasingly recognised. The aim of this study was to quantify the risks of overall and type specific cardiovascular and cerebrovascular diseases in women with gestational diabetes mellitus. This study is a systematic review and meta-analysis of fifteen studies. The study included almost nine million women. Results show that participants with a history of gestational diabetes mellitus were at significantly increased risks of cardiovascular and cerebrovascular diseases in general and at variable risks for most common types of cardiovascular and cerebrovascular diseases. Authors conclude that their findings highlight the need for early intervention in women at high risk of gestational diabetes mellitus, and for continuous monitoring of women with a history of gestational diabetes mellitus after pregnancy.
Abstract
OBJECTIVE To quantify the risk of overall and type specific cardiovascular and cerebrovascular diseases as well as venous thromboembolism in women with a history of gestational diabetes mellitus. DESIGN Systematic review and meta-analyses. DATA SOURCES PubMed, Embase, and the Cochrane Library from inception to 1 November 2021 and updated on 26 May 2022. REVIEW METHODS Observational studies reporting the association between gestational diabetes mellitus and incident cardiovascular and cerebrovascular diseases were eligible. Data, pooled by random effects models, are presented as risk ratios (95% confidence intervals). Certainty of evidence was appraised by the Grading of Recommendations, Assessment, Development, and Evaluations. RESULTS 15 studies rated as moderate or serious risk of bias were included. Of 513 324 women with gestational diabetes mellitus, 9507 had cardiovascular and cerebrovascular disease. Of more than eight million control women without gestational diabetes, 78 895 had cardiovascular and cerebrovascular disease. Compared with women without gestational diabetes mellitus, women with a history of gestational diabetes mellitus showed a 45% increased risk of overall cardiovascular and cerebrovascular diseases (risk ratio 1.45, 95% confidence interval 1.36 to 1.53), 72% for cardiovascular diseases (1.72, 1.40 to 2.11), and 40% for cerebrovascular diseases (1.40, 1.29 to 1.51). Women with gestational diabetes mellitus showed increased risks of incident coronary artery diseases (1.40, 1.18 to 1.65), myocardial infarction (1.74, 1.37 to 2.20), heart failure (1.62, 1.29 to 2.05), angina pectoris (2.27, 1.79 to 2.87), cardiovascular procedures (1.87, 1.34 to 2.62), stroke (1.45, 1.29 to 1.63), and ischaemic stroke (1.49, 1.29 to 1.71). The risk of venous thromboembolism was observed to increase by 28% in women with previous gestational diabetes mellitus (1.28, 1.13 to 1.46). Subgroup analyses of cardiovascular and cerebrovascular disease outcomes stratified by study characteristics and adjustments showed significant differences by region (P=0.078), study design (P=0.02), source of data (P=0.005), and study quality (P=0.04), adjustment for smoking (P=0.03), body mass index (P=0.01), and socioeconomic status (P=0.006), and comorbidities (P=0.05). The risk of cardiovascular and cerebrovascular diseases was, however, attenuated but remained significant when restricted to women who did not develop subsequent overt diabetes (all gestational diabetes mellitus: 1.45, 1.33 to 1.59, gestational diabetes mellitus without subsequent diabetes: 1.09, 1.06 to 1.13). Certainty of evidence was judged as low or very low quality. CONCLUSIONS Gestational diabetes mellitus is associated with increased risks of overall and type specific cardiovascular and cerebrovascular diseases that cannot be solely attributed to conventional cardiovascular risk factors or subsequent diabetes.
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The Dose-Response Associations of Sugar-Sweetened Beverage Intake with the Risk of Stroke, Depression, Cancer, and Cause-Specific Mortality: A Systematic Review and Meta-Analysis of Prospective Studies.
Wang, Y, Zhao, R, Wang, B, Zhao, C, Zhu, B, Tian, X
Nutrients. 2022;14(4)
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The consumption of sugar-sweetened beverages is high in today's society, which may lead to weight gain, inflammation, and a number of obesity-associated diseases. The objective of this systematic review and meta-analysis was to investigate the associations and causal links between the consumption of sugar-sweetened beverages and cancer, stroke, depression, and cause-specific mortality. Consumption of sugar-sweetened beverages significantly increased the risk of cancer, strokes, depression, and cause-specific mortality when compared with the consumption of low or no-sugar-sweetened beverages. As little as a 250ml increment of sugar-sweetened beverages was associated with an increase in risk. Consumption of sugar-sweetened beverages increases the risk of ischemic stroke by 10%, CVD-caused mortality by 13%, and cancer-caused mortality by 6.0% compared to those who consume less or no sugar-sweetened beverages. These findings can be used by healthcare professionals to understand the clinical significance of intervention strategies that reduce the consumption of sugar-sweetened beverages. It is imperative to conduct additional robust studies as there is an insufficient amount of evidence at present to establish a causal connection between the consumption of sugary beverages and the risk of depression, stroke, cancer, and cause-specific mortality.
Abstract
The associations between sugar-sweetened beverage (SSB) consumption and the risk of stroke, depression, cancer, and cause-specific mortality have not been determined, and the quantitative aspects of this link remain unclear. This meta-analysis therefore conducted a systematic review and dose-response analysis to determine their causal links. The database searches were conducted in PubMed, Cochrane library, Embase, Web of Science up to 10 November 2021. The intervention effects were evaluated by relative risk (RR) with 95% confidences (CI). Thirty-two articles met the inclusion criteria. Higher levels of SSB consumption significantly increased the risk of stroke (RR 1.12, 95% CI 1.03-1.23), depression (1.25, 1.11-1.41), cancer (1.10, 1.03-1.17), and all-cause mortality (1.08, 1.05-1.11) compared with none or lower SSB intake. The associations were dose-dependent, with per 250 mL increment of SSB intake daily increasing the risk of stroke, depression, cancer, and all-cause mortality by RR 1.09 (1.03-1.15), 1.08 (1.06-1.10), 1.17 (1.04-1.32), and 1.07 (1.03-1.11), respectively. The link was curved for depression and cancer risk (pnon-linear < 0.05). Subgroup analysis suggested that higher SSB intake increased ischemic stroke by 10%, CVD-caused mortality by 13%, and cancer-caused mortality by 6.0% than none or lower SSB consumption. It is suggested that SSB accounts for a leading risk factor of stroke, depression, cancer, and mortality, and that the risk rises in parallel with the increment of SSB intake (and is affected by participant characteristics).
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Breakfast Skipping, Body Composition, and Cardiometabolic Risk: A Systematic Review and Meta-Analysis of Randomized Trials.
Bonnet, JP, Cardel, MI, Cellini, J, Hu, FB, Guasch-Ferré, M
Obesity (Silver Spring, Md.). 2020;28(6):1098-1109
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Breakfast has been considered the most important meal of the day. However, despite the fairly consistent association of breakfast consumption with decreased body weight, randomized controlled trials (RCTs) have shown equivocal results. The aim of this study was to conduct a systematic review and meta-analysis of RCTs evaluating the effect of skipping breakfast on body composition and cardiometabolic risk factors over a period of at least 4 weeks. This study is a systematic review and meta-analysis of RCTs. A total of 425 participants were included in the meta-analysis. Participant range of age was 18 to 65 years old, with a mean age of 35 years. This study demonstrates that breakfast skipping compared with breakfast consumption over the short-term (4 to 16 weeks) results in weight loss without significant changes in other body composition parameters. Furthermore, breakfast skipping, as compared with breakfast consumption, led to significant increases in low-density lipoprotein cholesterol. Authors conclude that although breakfast skipping had a modest impact on weight loss in the short term, its long-term impact on body composition and cardiometabolic health requires further study.
Abstract
OBJECTIVE The objective of this study was to evaluate the effect of skipping breakfast on body composition and cardiometabolic risk factors. METHODS This study conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating breakfast skipping compared with breakfast consumption. Inclusion criteria included age ≥ 18, intervention duration ≥ 4 weeks, ≥ 7 participants per group, and ≥ 1 body composition measure. Random-effects meta-analyses of the effect of breakfast skipping on body composition and cardiometabolic risk factors were performed. RESULTS Seven RCTs (n = 425 participants) with an average duration of 8.6 weeks were included. Compared with breakfast consumption, breakfast skipping significantly reduced body weight (weighted mean difference [WMD] = -0.54 kg [95% CI: -1.05 to -0.03], P = 0.04, I2 = 21.4%). Percent body fat was reported in 5 studies and was not significantly different between breakfast skippers and consumers. Three studies reported on low-density lipoprotein cholesterol (LDL), which was increased in breakfast skippers as compared with breakfast consumers (WMD = 9.24 mg/dL [95% CI: 2.18 to 16.30], P = 0.01). Breakfast skipping did not lead to significant differences in blood pressure, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, C-reactive protein, insulin, fasting glucose, leptin, homeostatic model assessment of insulin resistance, or ghrelin. CONCLUSIONS Breakfast skipping may have a modest impact on weight loss and may increase LDL in the short term. Further studies are needed to provide additional insight into the effects of breakfast skipping.
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Vitamin D metabolites across the menstrual cycle: a systematic review.
Subramanian, A, Gernand, AD
BMC women's health. 2019;19(1):19
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Vitamin D deficiency is highly prevalent in women compared to men particularly at reproductive age. The Institute of Medicine defines vitamin D deficiency as having concentrations of 25-hydroxyvitamin D [25(OH)D] < 30 nmol/l and vitamin D insufficiency as 25(OH)D < 50 nmol/l. Furthermore, 25(OH)D is further metabolised in the kidneys to 1,25 dihydroxyvitamin D [1,25(OH)2D], the biologically active form of vitamin D. The aim of this study was to conduct a systematic review of studies that assessed concentrations of 25(OH)D and/or 1,25(OH)2D longitudinally to assess if these vitamin D biomarkers change across the normal menstrual cycle. This study is a systematic review of ten longitudinal studies. Results show conflicting data between studies. For example, 1,25(OH)2D concentrations increased across the menstrual cycle in a few studies but did not change in others. 25(OH)D concentrations changed across the cycle in one study but not others. This was due to the fact that only a few studies have examined vitamin D metabolites across the menstrual cycle, thus, there is limited to insufficient data to be able to understand potential changes or lack thereof. Authors conclude that future studies are needed to better understand 25(OH)D and 1,25(OH)2D in menstruating women. These studies should particularly focus on examining both metabolites (at minimum) at least two points across the menstrual cycle using the robust lab methods.
Abstract
BACKGROUND Accurate estimation of vitamin D status is important for health research and can impact prevention and treatment of deficiency in women of reproductive age. We aimed to assess if blood concentrations of 25-hydroxyvitamin D [25(OH)D] or 1,25-dihydroxyvitamin D [1,25(OH)2D] change across the menstrual cycle. METHODS We conducted a systematic search in PubMed, Web of Science, CAB and BIOSIS of literature published until December 2018 which reported concentrations of vitamin D metabolites at two or more identified points among women with regular menstrual cycles. RESULTS Ten longitudinal studies met the inclusion criteria; nine studies measured 1,25(OH)2D and five studies measured 25(OH)D. Study size ranged from 5 to 47 subjects, with an age range of 18-47 years. One study found a decrease in concentration of 25(OH)D in the periovulatory and luteal phase. Four studies found no changes in concentrations of 25(OH)D. Two studies found a rise in 1,25(OH)2D within the follicular phase, including a 128% increase from day 1 to 15 and a 56% increase from day 0 to 12. Two studies found rises in 1,25(OH)2D concentrations from the follicular to luteal phase of 13 and 26%. Five studies did not find any changes in concentrations of 1,25(OH)2D. CONCLUSIONS No conclusion can be drawn on the pattern of 1,25(OH)2D concentrations across the normal menstrual cycle due to inconsistencies in study findings. Evidence is currently insufficient to assess 25(OH)D concentrations across the cycle. Future studies should aim to measure 1,25(OH)2D and 25(OH)D longitudinally, to understand relationships with other hormones and the potential impact on estimates of vitamin D deficiency.
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Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease, and cancer: systematic review and meta-analysis.
Ma, C, Avenell, A, Bolland, M, Hudson, J, Stewart, F, Robertson, C, Sharma, P, Fraser, C, MacLennan, G
BMJ (Clinical research ed.). 2017;359:j4849
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Obesity is known to increase the risk of many diseases including cardiovascular disease, various cancers and type 2 diabetes. Interestingly, there is evidence suggesting weight loss in obese adults may be harmful, particularly in older people with cardiovascular disease. The aim of this systematic review was to assess the effect of weight loss interventions for adults with obesity on mortality, cardiovascular disease, cancer and body weight. Based on the 30,000 participants identified, current evidence shows that weight loss interventions significantly decrease all cause mortality. There was also evidence to suggest weight loss is associated with developing new cardiovascular events, though fewer trials reported these outcomes so uncertainty remains around these results. Based on the current literature and this review, the authors conclude weight-reducing diets may reduce all cause mortality in adults with obesity and support public health measures to prevent weight gain and facilitate weight loss.
Abstract
Objective To assess whether weight loss interventions for adults with obesity affect all cause, cardiovascular, and cancer mortality, cardiovascular disease, cancer, and body weight.Design Systematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios, and mean differences. Heterogeneity investigated using Cochran's Q and I2 statistics. Quality of evidence assessed by GRADE criteria.Data sources Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials' registry for data not evident in databases. Authors were contacted for unpublished data.Eligibility criteria for selecting studies RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥1 year.Results 54 RCTs with 30 206 participants were identified. All but one trial evaluated low fat, weight reducing diets. For the primary outcome, high quality evidence showed that weight loss interventions decrease all cause mortality (34 trials, 685 events; risk ratio 0.82, 95% confidence interval 0.71 to 0.95), with six fewer deaths per 1000 participants (95% confidence interval two to 10). For other primary outcomes moderate quality evidence showed an effect on cardiovascular mortality (eight trials, 134 events; risk ratio 0.93, 95% confidence interval 0.67 to 1.31), and very low quality evidence showed an effect on cancer mortality (eight trials, 34 events; risk ratio 0.58, 95% confidence interval 0.30 to 1.11). Twenty four trials (15 176 participants) reported high quality evidence on participants developing new cardiovascular events (1043 events; risk ratio 0.93, 95% confidence interval 0.83 to 1.04). Nineteen trials (6330 participants) provided very low quality evidence on participants developing new cancers (103 events; risk ratio 0.92, 95% confidence interval 0.63 to 1.36).Conclusions Weight reducing diets, usually low in fat and saturated fat, with or without exercise advice or programmes, may reduce premature all cause mortality in adults with obesity.Systematic review registration PROSPERO CRD42016033217.