Objectives
There is a growing body of evidence linking dietary energy density (DED) with metabolic disorders like obesity, type 2 diabetes (T2D) and metabolic syndrome (MetS). However, according to ...our knowledge, there has been no systematic review and mate‐analysis on T2D and MetS with DED. Therefore, this study aimed to investigate the association between DED with the risk of obesity, T2D and MetS in a systematic review and meta‐analysis of observational studies.
Methods
We searched all published studies according to the defined keywords up to march 2020 in the PubMed/Medline and Scopus databases. We excluded those that did not calculate DED for total intake, no observed association between obesity, T2D, MetS as the primary or one of the outcomes with DED, no reported odds ratio (OR), relative risk (RR) or hazard ratio (HR) estimates with 95% confidence intervals (CIs), studies in children under 2 years old, patients with cancer and pregnant women.
Results
From 2282, after deleting the duplicates and irrelevant studies, we entered 58 articles ( 47 systematic reviews and 11 meta‐analyse). We indicated an increased risk of T2D in relation to DED (OR: 1.25, 95% CI: 1.18‐1.33, P < .001). But studies reviewed were inconsistent. All studies which examined the relationship between DED and MetS showed a positive relationship with an increased significant risk (OR: 1.59, 95% CI: 1.22‐2.07, P < .001). Most articles reported a direct association between DED and obesity but the relationship between DED and risk of obesity was not significant (OR: 1.04, 95% CI: 0.92‐1.17, P = .543).
Conclusion
In this systematic review and meta‐analysis of observational studies, we found that the DED increased the risk of T2D and MetS but was not significant with the risk of obesity.
Clinical trial studies revealed conflicting results on the effect of Ashwagandha extract on anxiety and stress. Therefore, we aimed to evaluate the effect of Ashwagandha supplementation on anxiety as ...well as stress. A systematic search was performed in PubMed/Medline, Scopus, and Google Scholar from inception until December 2021. We included randomized clinical trials (RCTs) that investigate the effect of Ashwagandha extract on anxiety and stress. The overall effect size was pooled by random‐effects model and the standardized mean difference (SMD) and 95% confidence interval (CIs) for outcomes were applied. Overall, 12 eligible papers with a total sample size of 1,002 participants and age range between 25 and 48 years were included in the current systematic review and meta‐analysis. We found that Ashwagandha supplementation significantly reduced anxiety (SMD: −1.55, 95% CI: −2.37, −0.74; p = .005; I2 = 93.8%) and stress level (SMD: −1.75; 95% CI: −2.29, −1.22; p = .005; I2 = 83.1%) compared to the placebo. Additionally, the non‐linear dose–response analysis indicated a favorable effect of Ashwagandha supplementation on anxiety until 12,000 mg/d and stress at dose of 300–600 mg/d. Finally, we identified that the certainty of the evidence was low for both outcomes. The current systematic review and dose–response meta‐analysis of RCTs revealed a beneficial effect in both stress and anxiety following Ashwagandha supplementation. However, further high‐quality studies are needed to firmly establish the clinical efficacy of the plant.
We did this study to clarify the association between carbohydrate intake and the risk of type 2 diabetes (T2D) and potential effect modification by geographical location. PubMed, Scopus and Web of ...Science were searched to find prospective cohort studies of dietary carbohydrate intake and T2D risk. A random-effects dose-response meta-analysis was performed to calculate the summary hazard ratios (HRs) and 95%CIs. The quality of cohort studies and the certainty of evidence was rated using the Newcastle-Ottawa Scale and GRADE tool, respectively. Eighteen prospective cohort studies with 29,229 cases among 607,882 participants were included. Thirteen studies were rated to have high quality, and five as moderate quality. The HR for the highest compared with the lowest category of carbohydrate intake was 1.02 (95%CI: 0.91, 1.15; I
= 67%, GRADE = low certainty). The HRs were 0.93 (95%CI: 0.82, 1.05; I
= 58%, n = 7) and 1.26 (95%CI: 1.11, 1.44; I
= 6%, n = 6) in Western and Asian countries, respectively. Dose-response analysis indicated a J shaped association, with the lowest risk at 50% carbohydrate intake (HR
: 0.95, 95%CI: 0.90, 0.99) and with risk increasing significantly at 70% carbohydrate intake (HR
: 1.18, 95%CI: 1.03, 1.35). There was no association between low carbohydrate diet score and the risk of T2D (HR: 1.14, 95%CI: 0.89, 1.47; I
= 90%, n = 5). Carbohydrate intake within the recommended 45-65% of calorie intake was not associated with an increased risk of T2D. Carbohydrate intake more than 70% calorie intake might be associated with a higher risk.
Purpose
Previous meta-analyses assessed the association of adherence to the Mediterranean dietary pattern (MedDiet) with the risk of type 2 diabetes (T2D). Since then, new large-scale cohort studies ...have been published. In addition, dose–response relation was not previously investigated and the certainty of evidence was not assessed. We aimed to explore the dose–response relationship between adherence to the MedDiet and the risk of T2D.
Methods
We did a systematic search using PubMed, Scopus, and ISI Web of Science upto April 2021 for prospective cohort studies of the relationship between adherence to the MedDiet and the risk of T2D in the general population. The summary relative risks (RR) and 95%CI were estimated by applying a random-effects model.
Results
Fourteen prospective cohort studies (410,303 participants and 41,466 cases) were included. There was an inverse association for the highest versus lowest category of adherence to the MedDiet (RR: 0.79, 95%CI 0.72, 0.88;
I
2
= 82%,
n
= 14; Risk difference: – 21 per 1000 person, 95%CI – 28, – 12; GRADE = moderate certainty), and for a 2-point increment in the MedDiet adherence score (RR: 0.86, 95%CI 0.82, 0.91;
n
= 13). The RR remained significant after controlling for important confounders and in almost all subgroups, especially subgroups defined by geographical region. We observed an inverse linear association between MedDiet adherence score and T2D incidence.
Conclusion
Adherence to the MedDiet was inversely related to T2D risk in a dose–response manner. Adherence to a Mediterranean-style diet may be a good advice for the primary prevention of T2D.
Registry and registry number
PROSPERO (CRD42021246589).
Summary
Objectives
We aimed to validate dietary assessment methods against the gold standard, doubly labeled water (DLW), for estimating total energy intake (TEI).
Methods
PubMed, Scopus, Web of ...Science, and Google Scholar databases were searched until May 2023. Inclusion criteria encompassed studies involving participants aged 1–18 years, employing dietary assessment methods like food records, dietary histories, food frequency questionnaire (FFQ), or 24‐h recalls estimating TEI alongside DLW to measure total energy expenditure (TEE). Data were pooled using random‐effects meta‐analysis models.
Results
Thirty‐three studies were identified, with sample sizes ranging from 9 to 118 participants. Meta‐analysis of 22 studies identified underestimation of TEI (mean difference MD = −262.9 kcal/day 95% CI: −380.0, −145.8; I2 = 93.55%) for food records compared with TEE estimated by DLW. Other dietary assessment methods, including food recalls (n = 9) (MD = 54.2 kcal/day 95% CI: −19.8, 128.1; I2 = 49.62%), FFQ (n = 7) (MD = 44.5 kcal/day 95% CI: −317.8, 406.8; I2 = 94.94%), and diet history (n = 3) (MD = −130.8 kcal/day 95% CI: −455.8, 194.1; I2 = 77.48%), showed no significant differences in TEI compared with DLW‐estimated TEE. All studies were of high quality.
Conclusion
Food records may underestimate TEI, yet additional research is needed to identify the most accurate methods for assessing children's dietary intake.
Carbohydrate restriction is effective for type 2 diabetes management.
We aimed to evaluate the dose-dependent effect of carbohydrate restriction in patients with type 2 diabetes.
We systematically ...searched PubMed, Scopus, and Web of Science to May 2021 for randomized controlled trials evaluating the effect of a carbohydrate-restricted diet (≤45% total calories) in patients with type 2 diabetes. The primary outcome was glycated hemoglobin (HbA1c). Secondary outcomes included fasting plasma glucose (FPG); body weight; serum total, LDL, and HDL cholesterol; triglyceride (TG); and systolic blood pressure (SBP). We performed random-effects dose-response meta-analyses to estimate mean differences (MDs) for a 10% decrease in carbohydrate intake.
Fifty trials with 4291 patients were identified. At 6 months, compared with a carbohydrate intake between 55%–65% and through a maximum reduction down to 10%, each 10% reduction in carbohydrate intake reduced HbA1c (MD, –0.20%; 95% CI, –0.27% to –0.13%), FPG (MD, –0.34 mmol/L; 95% CI, –0.56 to –0.12 mmol/L), and body weight (MD, –1.44 kg; 95% CI, –1.82 to –1.06 kg). There were also reductions in total cholesterol, LDL cholesterol, TG, and SBP. Levels of HbA1c, FPG, body weight, TG, and SBP decreased linearly with the decrease in carbohydrate intake from 65% to 10%. A U-shaped effect was seen for total cholesterol and LDL cholesterol, with the greatest reduction at 40%. At 12 months, a linear reduction was seen for HbA1c and TG. A U-shaped effect was seen for body weight, with the greatest reduction at 35%.
Carbohydrate restriction can exert a significant and important reduction on levels of cardiometabolic risk factors in patients with type 2 diabetes. Levels of most cardiometabolic outcomes decreased linearly with the decrease in carbohydrate intake. U-shaped effects were seen for total cholesterol and LDL cholesterol at 6 months and for body weight at 12 months.
Summary
Background
Understanding the association between water consumption and mortality is important for guiding consumers and prioritizing dietary guidelines to reduce the risk. Therefore, in the ...current study, we conducted a systematic review and dose−response meta‐analysis of prospective cohort studies to summarise the association between total water and drinking intake and risk of mortality from all causes and CVD.
Method
A comprehensive search was performed on PubMed/Medline, Scopus, and ISI Web of Science up to February 2020. The random‐effects model was used to calculate the pooled effect size (ES) and 95% confidence interval.
Result
Seven prospective cohort studies were included in the systematic review and meta‐analysis. During the follow‐up period of 6 to 19.1 years, 14 754 deaths (7611 from cardiovascular disease) occurred among 116 816 participants. No significant association was found between drinking water intake and all‐cause mortality (ES: 0.82; 95% CI: 0.63‐1.08, I2 = 77.3%, P = .16). Total water intake was not associated with all‐cause mortality (ES: 0.94; 95% CI: 0.82‐1.08, I2 = 66.5%, P = .41). However, a significant inverse association was seen between total water intake and risk of CVD mortality (ES: 0.86; 95% CI: 0.78‐0.95, I2 = 0%, P = .002). Linear dose−response meta‐analysis revealed a significant inverse association between total water intake and all‐cause mortality by an additional one cup per day (pooled ES: 0.98; 95% CI: 0.97‐0.99, P = .001). Furthermore, each additional cup of total water intake per day was associated with a 3% lower risk of death from CVD (pooled ES: 0.97; 95% CI: 0.96‐0.98, P < .001).
Conclusion
High consumption of total water is associated with a lower risk of CVD mortality. However, total water intake was not associated with risk of all‐cause mortality.
Background
Data about the relation between dietary insulin load (DIL) and dietary insulin index (DII) with metabolic syndrome (MetS) and obesity are scarce. Therefore, the present study aimed to ...examine the association of the insulinemic potential of the diet with MetS and obesity amongst Iranian adults.
Methods
This cross‐sectional study was conducted amongst 850 adults aged 20‐59 years. Dietary data were collected using a 168‐item food frequency questionnaire. DIL was calculated using a standard formula and DII was obtained by dividing DIL by the total energy intake of each participant. The guidelines of the International Diabetes Federation were used to define MetS. General obesity was considered as body mass index ≥ 30 kg/m2, and abdominal obesity as waist circumference ≥ 94 cm for men and ≥ 80 cm for women.
Results
Mean DIL and DII values were 101 684 ± 54 802 and 49.4 ± 33.4, respectively. The mean age of participants was 44.9 ± 10.7 years and 36.8%, 28.5% and 48.8% of participants were suffering from MetS, general and abdominal obesity, respectively. In contrast with DIL (P = .73), participants in the last quartile of DII (P = .62) had lower odds of MetS than the first quartile. There were non‐significant inverse associations between DIL (P = .91, P = .85) and DII (P = .59, P = .53) with odds of general and abdominal obesity before and after the adjustment of confounders, respectively.
Conclusions
We did not observe any significant association of DIL and DII with the risk of MetS and obesity amongst the Iranian population. Further prospective studies are needed to confirm the findings of this study.
Summary
Background & aims
Observational studies examining the relationship between metabolic syndrome and the risk of chronic kidney disease (CKD) have reported inconclusive results. This ...meta‐analysis was performed to resolve these controversies.
Methods
The MEDLINE, EMBASE, and PubMed databases were systematically searched from their inception until March 2016 to identify all relevant studies. Risk estimates and their corresponding 95% confidence intervals (CIs) for the associations of MetS and its components with CKD risk were extracted and pooled using a random‐effects model.
Results
A total of 66 studies, including 18 prospective cohorts and 48 cross‐sectional studies, with 699 065 CKD patients and 11 109 003 participants were included in the meta‐analysis. When all definitions were pooled, the presence of MetS was associated with a significant 50% increase of CKD risk (OR = 1.50, 95% CI = 1.43‐1.56), with evidence of moderate heterogeneity (I2 = 72.3%, P < .001). The risk of CKD associated with MetS was higher in studies using the American Heart Association/National Heart, Lung, and Blood Institute criteria (OR = 1.68, 95% CI = 1.25‐2.10) compared with those using the Adult Treatment Panel III (OR = 1.49, 95% CI = 1.42‐1.56) and the International Diabetes Federation (OR = 1.32, 95% CI = 1.22‐1.41) definitions. This relationship was independent of diabetes status. Moreover, all individual components of the MetS were significantly associated with CKD, and their coexistence resulted in an escalating dose‐response relationship. The sensitivity and subgroup analyses established the stability of the findings.
Conclusions
This meta‐analysis strongly suggests that the metabolic syndrome and its components are independently associated with the increased risk of CKD.
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