Nutritional advice

Objectives:
Maternal folic acid supplementation is considered mandatory in almost every country in the world to prevent congenital malformations. However, little is known about the association of maternal folic acid intake with the occurrence of childhood cancer. Therefore, this review article has been conducted.

Does maternal folic acid supplementation during pregnancy reduce risk of childhood cancer?

Study design:
This review article included 17 case-control studies.

Results and conclusions:
The investigators found in random-effects model, maternal folic acid supplementation during pregnancy significantly reduced risk of childhood acute lymphoblastic leukaemia with 25% [OR = 0.75, 95% CI = 0.66 to 0.86].
Significantly because OR of 1 was not found in the 95% CI of 0.66 to 0.86. OR of 1 means no risk/association.

The investigators found in random-effects model, there was no significant association between maternal folic acid supplementation during pregnancy and acute myeloid leukaemia [OR = 0.70, 95% CI = 0.46 to 1.06] or childhood brain tumours [OR = 1.02, 95% CI = 0.88 to 1.19].
No significant because OR of 1 was found in the 95% CI of 0.88 to 1.19. OR of 1 means no risk/association.

The investigators concluded maternal folic acid supplementation during pregnancy reduces risk of childhood acute lymphoblastic leukaemia. Thus, healthcare professionals are recommended to provide regular health education and health promotion to the community on the benefits of folic acid supplementation during pregnancy.

Original title:
The Protective Effect of Maternal Folic Acid Supplementation on Childhood Cancer: A Systematic Review and Meta-analysis of Case-control Studies by Wan Ismail WR, Abdul Rahman R, […],Nawi AM.

Link:
https://www.jpmph.org/journal/view.php?doi=10.3961/jpmph.19.020

Additional information of El Mondo:
Find more information/studies on folic acid and pregnancy right here.
 

Objectives:
Does calcium supplement with or without other drugs reduce risk of preeclampsia and gestational hypertension?

Study design:
This review article included 27 RCTs, with 28,492 pregnant women.

Results and conclusions:
The investigators found calcium supplement significantly reduced risk of preeclampsia with 49% [RR = 0.51, 95% CI = 0.40 to 0.64].

The investigators found calcium supplement significantly reduced risk of gestational hypertension with 30% [RR = 0.70, 95% CI = 0.60 to 0.82].

The investigators found sub-analyses revealed high-dose (1.2-2 g/day), moderate-dose (0.6-1.2 g/day) and low-dose (0.6 g/day) of calcium supplement significantly reduced risk of preeclampsia.

The investigators found sub-analyses revealed high-dose (1.2-2 g/day) and moderate-dose (0.6-1.2 g/day) of calcium supplement significantly reduced risk of gestational hypertension.

The investigators concluded high-dose (1.2-2 g/day) and moderate-dose (0.6-1.2 g/day) of calcium supplement reduced both risk of preeclampsia and gestational hypertension. However, further studies with direct comparison of different dose of calcium supplementation are needed to explore the ideal dose of calcium supplementation to prevent preeclampsia and gestational hypertension.

Original title:
The association between calcium supplement and preeclampsia and gestational hypertension: a systematic review and meta-analysis of randomized trials by Sun X, Li H, [...], Zhang X.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30935246

Additional information of El Mondo:
Find more information/studies on calcium and pregnancy right here.

 

Objectives:
Although many studies have shown that low zinc status is associated with diabetes, the putative effects of zinc supplementation on glycemic control are inconclusive. Therefore, this review article (meta-analysis) has been conducted.

Does zinc supplementation reduce risk of diabetes mellitus?

Study design:
This review article included 32 RCTs, involving a total of 1,700 participants in 14 countries.

Results and conclusions:
The investigators found overall, compared with their respective control groups, the subjects in the zinc supplementation group had a statistically significant reduction in concentrations of :
-fasting glucose [WMD = -14.15 mg/dL, 95% CI = -17.36 to -10.93 mg/dL];
-2-h postprandial glucose [WMD = -36.85 mg/dL, 95% CI = -62.05 to -11.65 mg/dL];
-fasting insulin [WMD = -1.82 mU/L, 95% CI = -3.10 to -0.54 mU/L];
-homeostasis model assessment for insulin resistance [WMD = -0.73, 95% CI = -1.22 to -0.24]:
-glycated hemoglobin [WMD = -0.55%, 95% CI = -0.84 to -0.27%] and;
-high-sensitivity C-reactive protein [WMD = -1.31 mg/L, 95% CI = -2.05 to -0.56 mg/L].

The investigators found, moreover, subgroup analyses revealed that the effects of zinc supplementation on fasting glucose were significantly influenced by diabetic status and the formulation of the zinc supplement.

The investigators concluded several key glycemic indicators are significantly reduced by zinc supplementation, particularly the fasting glucose in subjects with diabetes and in subjects who received an inorganic zinc supplement. Together, these findings support the notion that zinc supplementation may have clinical potential as an adjunct therapy for preventing or managing diabetes.

Original title:
Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials by Wang X, Wu W, [...], Wang F.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31161192

Additional information of El Mondo:
Find more information/studies on diabetes and zinc right here.

Objectives:
Dietary proteins, including those obtained from animal and plant sources, have inconsistently been correlated with type 2 diabetes mellitus (T2DM) risk. Therefore, this review article (meta-analysis) has been conducted.

Does dietary protein intake increase risk of type 2 diabetes mellitus?

Study design:
This review article included 21 cohort studies with a total of 487,956 individuals and 38,350 T2DM cases (persons with type 2 diabetes mellitus).

Results and conclusions:
The investigators found high total dietary protein intake was associated with an increased risk of 10% for type 2 diabetes mellitus [RR = 1.10, p = 0.006] whereas moderate total dietary protein intake was not significantly associated with type 2 diabetes mellitus risk [RR = 1.00,  p = 0.917].  
Not significantly because the calculated p-value of 0.917 was larger than the p-value of 0.05.

The investigators found, moreover, an increased risk of 13% [RR = 1.13, p = 0.013] for type 2 diabetes mellitus was observed with high  dietary animal protein intake whereas moderate animal protein intake had little or no effect on type 2 diabetes mellitus risk [RR = 1.06, p = 0.058].

The investigators found, high dietary intake of plant protein did not affect type 2 diabetes mellitus risk [RR = 0.93, p = 0.074], whereas moderate intake was associated with a reduced risk of 6% for type 2 diabetes mellitus [RR = 0.94, p  0.001].

The investigators concluded high dietary total protein and dietary animal protein intakes are associated with an increased risk of type 2 diabetes mellitus, whereas moderate plant protein intake is associated with a decreased risk of type 2 diabetes mellitus.

Original title:
Dietary protein intake and subsequent risk of type 2 diabetes: a dose-response meta-analysis of prospective cohort studies by Ye J, Yu Q, [...], Wang Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30929078

Additional information of El Mondo:
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A diet with high protein intake is a diet with a minimum of 35 En% protein (En% = energy percentage). These products from the supermarket contain at least 35 En% protein.
35 En% protein means that the amounts of protein contribute 35% to the total calories (kcal) of the diet.
If the diet contains 2000 kcal, 175 grams of protein contribute 35% to this 2000 kcal.
1 gram of protein gives 4 kcal. Thus, 175 grams of protein provide 700 kcal and 700 kcal is 35% of 2000 kcal.

A diet with moderate protein consumption is a diet with 20-25 En% protein. The easiest way to follow a diet with moderate protein consumption is to choose only products/meals that also contain 20-25 En% protein. These products from the supermarket contain 20-25 En% protein.

 

Objectives:
The role of chromium as a weight loss agent remains questionable and although previous meta-analyses findings have reported small reductions in body weight in individuals with overweight/obesity following chromium supplementation, there have been significant limitations with these findings. Therefore, this review article has been conducted.

Do individuals with overweight/obesity benefit from chromium supplementation?

Study design:
This review article included 21 RCTs with a total of 1,316 participants.

Results and conclusions:
The investigators found pooled analysis showed significant reductions in anthropometric indices associated with body composition for:
-weight loss [WMD = -0.75 kg, 95% CI = -1.04 to -0.45, p  0.001];
-body mass index (BMI) [WMD = -0.40, 95% CI = -0.66 to -0.13, p = 0.003] and;
-body fat percentage [WMD = -0.68%, 95% CI = -1.32 to -0.03, p = 0.04] in individuals with overweight/obesity following chromium supplementation. No changes were detected in controls.

The investigators found subgroup analysis showed significant improvements in weight loss and body fat percentage, particularly for study durations ≤12 weeks and doses ≤400 μg/d chromium.

The investigators concluded ≤400 μg/d chromium supplementation during ≤12 weeks is associated with some improvements in body composition in subjects with obesity/overweight. The effect size was medium and the clinical relevance of chromium as a weight loss aid remains uncertain. Therefore, further investigation from larger and well-designed randomized controlled studies, especially in patients with diabetes, is warranted.

Original title:
A meta-analysis of the effect of chromium supplementation on anthropometric indices of subjects with overweight or obesity by Tsang C, Taghizadeh M, […], Jafarnejad S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31115179

Additional information of El Mondo:
Find more information/studies on chromium and obesity/overweight right here.

Objectives:
The role of gut microbiota in the management of diabetes has been shown. Several current trials are investigating the effect of probiotics and prebiotics, which are widely used to modulate intestinal microbiota, on inflammatory factors and biomarkers of oxidative stress in diabetic patient. However, their findings are controversial. Therefore, this review article (meta-analysis) has been conducted.

Do probiotic and synbiotic supplementation improve biomarkers of inflammation and oxidative stress in diabetic patients?

Study design:
This review article included 16 RCTs (n = 1,060).

Randomized controlled trials (RCTs) reported the effect of probiotics or synbiotics on circulating (serum and plasma) inflammatory marker (hs-CRP) and oxidative stress indicators (malondialdehyde [MDA], glutathione [GSH], nitric oxide [NO] and total antioxidant capacity [TAC]) among patients with diabetes.

The methodological quality varied across these trials.

Results and conclusions:
The investigators found probiotic and synbiotic supplementation significantly decreased hs-CRP level [SMD = -0.38, 95% CI = -0.51 to -0.24, p = 0.000] and the oxidative stress indicator malondialdehyde [SMD = -0.61, 95% CI = -0.89 to -0.32, p = 0.000] in diabetic patients compared to those in subjects receiving placebos.

The investigators found, in addition, probiotic and synbiotic supplementation significantly increased total antioxidant capacity [SMD = 0.31, 95% CI = 0.09 to 0.52, p = 0.006], nitric oxide [SMD = 0.62, 95% CI = 0.25 to 0.99, p = 0.001] and glutathione [SMD = 0.41, 95% CI = 0.26, 0.55, p = 0.000] levels.

The investigators concluded that probiotic and synbiotic supplementation improve biomarkers of inflammation and oxidative stress in diabetic patients. Further studies are needed to develop clinical practice guidelines for the management of inflammation and oxidative stress in these patients.

Original title:
The effect of probiotic and synbiotic supplementation on biomarkers of inflammation and oxidative stress in diabetic patients: A systematic review and meta-analysis of randomized controlled trials by Zheng HJ, Guo J, [...], Wang Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30794924

Additional information of El Mondo:
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Oxidative stress is an imbalance between free radicals and antioxidants in your body. Antioxidants can reduce oxidative stress.
 

Objectives:
Various mechanisms link higher total homocysteine to higher insulin resistance and risk of type 2 diabetes (T2D). Folate supplementation is recognized as a way to lower homocysteine. However, randomized controlled trials (RCTs) show inconsistent results on insulin resistance and type 2 diabetes outcomes. Therefore, this review article (meta-analysis) has been conducted.

Does folate supplementation improve insulin resistance and type 2 diabetes outcomes?

Study design:
This review article included 29 RCTs (22,250 participants) that assessed the effect of placebo-controlled folate supplementation alone or in combination with other B vitamins on fasting glucose, insulin, homeostasis model assessment for insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c) or risk of type 2 diabetes.

The meta-analysis was conducted using both random- and fixed-effects models to calculate weighted mean differences (WMDs) or risk ratios with 95% CIs.
Heterogeneity was low in all meta-analyses.

Results and conclusions:
The investigators found when compared with placebo, folate supplementation significantly lowered fasting insulin [WMD = -13.47 pmol/L, 95% CI = -21.41 to -5.53 pmol/L, p 0.001] and HOMA-IR [WMD = -0.57 units, 95% CI = -0.76 to -0.37 units, p 0.0001], but no overall effects were observed for fasting glucose or HbA1c.

The investigators found subgroup analysis showed no signs of effect modification except for change in homocysteine, with the most pronounced effects in trials with a change of >2.5 µmol/L.
Changes in homocysteine after folate supplementation correlated with changes in fasting glucose [β = 0.07, 95% CI = 0.01 to 0.14, p = 0.025] and HbA1c [β = 0.46, 95% CI = 0.06 to 0.85, p = 0.02].

The investigators found only 2 studies examined folate supplementation on risk of type 2 diabetes and they found no change in RR [pooled RR = 0.91, 95% CI = 0.80 to 1.04, p = 0.16].

The investigators concluded that folate supplementation lowers fasting insulin and HOMA-IR. However, folate supplementation does not reduce risk of type 2 diabetes.

Original title:
Effect of folate supplementation on insulin sensitivity and type 2 diabetes: a meta-analysis of randomized controlled trials by Lind MV, Lauritzen L, [...], Eriksen JN.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30615110

Additional information of El Mondo:
Find more information/studies on diabetes and folate (also called folic acid) right here.
 

Objectives:
The threshold for population-level optimal red blood cell (RBC) folate concentration among women of reproductive age for the prevention of neural tube defects has been estimated at 906 nmol/L. However, the dose-response relationship between folic acid intake and blood folate concentrations is uncharacterized. Therefore, this review article has been conducted.

Is there dose-response relationship between folic acid intake and blood folate concentrations?

Study design:
This review article included 23 articles for red blood cell folate and by 97 articles for serum/plasma folate.

Results and conclusions:
The investigators found in 17 studies red blood cell (RBC) folate concentration increased 1.78 fold [95% CI = 1.66 to 1.93] from baseline to steady-state at 375-570 µg folic acid/day and it took a median of 36 weeks of folic acid intake [95% CI = 27 to 52] to achieve steady-state red blood cell folate concentrations.

The investigators found for every 100 µg/day folic acid intake, serum/plasma folate concentrations increased 11.6% [95% CI = 8.4 to 14.9] from baseline to steady-state, over a median of 13 weeks [95% CI = 10 to 16].

The investigators concluded that there is a dose-response relationship between folic acid intake and changes in blood folate concentrations. At 375-570 µg folic acid/day, red blood cell folate concentrations increase 1.78 fold from baseline to steady-state, over a median of 36 weeks. For every 100 µg/day folic acid intake, serum/plasma folate concentrations increase 11.6% from baseline to steady-state, over a median of 13 weeks. These results can inform how much additional folic acid intake is needed among populations of women whose red blood cell folate concentrations are below the optimal threshold.

Original title:
Systematic Review and Bayesian Meta-analysis of the Dose-response Relationship between Folic Acid Intake and Changes in Blood Folate Concentrations by Crider KS, Devine O, […], Berry RJ.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356991/

Additional information of El Mondo:
Find here more information/studies about pregnancy and folaat (also called folic acid).
 

Objectives:
Diverse studies have investigated the impact of prenatal exposure to vitamin D levels on brain development. However, evidence in humans has never been systematically reviewed. Therefore, this meta-analysis (systematic review) has been conducted.

Has a high prenatal vitamin D level positive effect on brain development of the born child?

Study design:
This review article included 25 studies.

Results and conclusions:
The investigators found comparing with the lowest category of prenatal 25(OH)D levels (vitamin D level in blood), the highest prenatal 25(OH)D levels had no significant effects on cognition [pooled beta coefficients = 0.95, 95% CI = -0.03 to 1.93, p = 0.05].

The investigators found comparing with the lowest category of prenatal 25(OH)D levels (vitamin D level in blood), the highest prenatal 25(OH)D levels had no significant effects on psychomotor development [pooled beta coefficients = 0.88, 95% CI = -0.18 to 1.93, p = 0.10].

The investigators found comparing with the lowest category of prenatal 25(OH)D levels (vitamin D level in blood), the highest prenatal 25(OH)D levels significantly reduced risk of ADHD of the born child with 28% [pooled relative risk = 0.72, 95% CI = 0.59 to  0.89, p = 0.002].

The investigators found comparing with the lowest category of prenatal 25(OH)D levels (vitamin D level in blood), the highest prenatal 25(OH)D levels significantly reduced risk of autism-related traits of the born child with 58% [pooled odds ratio = 0.42, 95% CI = 0.25 to 0.71, p = 0.001].

The investigators found there was little evidence for protective effects of high prenatal 25(OH)D for language development and behaviour difficulties of the born child.

The investigators concluded this meta-analysis provides supporting evidence that increased prenatal exposure to 25(OH)D levels is associated with reduced risk of ADHD and autism-related traits of the born child later in life. Associations represent a potentially high public health burden given the current prevalence of vitamin D deficiency and insufficiency among childbearing aging and pregnant women.

Original title:
Neurodevelopmental effects of prenatal vitamin D in humans: systematic review and meta-analysis by García-Serna AM and Morales E.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30696940

Additional information of El Mondo:
Find more information/studies on vitamin D and pregnancy right here.

 

Objectives:
Probiotic supplementation in early life may be effective in preventing atopic dermatitis (AD); however, results regarding efficacy have been controversial. Therefore, this meta-analysis (systematic review) has been conducted.

Does probiotic supplementation in early life prevent atopic dermatitis in infants and children?

Study design:
This review article included 28 RCTs.

Results and conclusions:
The investigators found compared with controls, probiotic supplementation of mother was associated with a significantly reduced risk of 31% for atopic dermatitis in infants and children [OR = 0.69, 95% CI = 0.58-0.82, p  0.0001].

The investigators found compared with controls, the use of probiotics of mother during both the prenatal and the postnatal period significantly reduced the incidence of atopic dermatitis in infants and children with 33% [OR = 0.67, 95% CI = 0.54-0.82].
However, analysis of studies of probiotics given prenatally only or postnatally only did not reach statistical significance.

The investigators concluded that probiotic supplementation of mother during both the prenatal and the postnatal period reduces the incidence of atopic dermatitis in infants and children. These findings suggest that starting probiotic treatment during gestation and continuing through the first 6 months of the infant's life may be of benefit in the prevention of atopic dermatitis.

Original title:
Probiotic Supplementation for Prevention of Atopic Dermatitis in Infants and Children: A Systematic Review and Meta-analysis by Li L, Han Z, […], He C.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30465329

Additional information of El Mondo:
Find more information/studies on protbiotics and pregnancy right here.
 

Objectives:
Inositol (ISL) embraces a family of simple carbohydrates with insulin-sensitizing properties, whose most common isoforms are Myo-inositol (MYO) and D-chiro inositol (DCI). Therefore, this meta-analysis (systematic review) has been conducted.

Does inositol supplementation reduce gestational diabetes (GDM)?

Study design:
This review article included 5 RCTs with a total of  965 participants.
The primary outcome was the preventive effect on gestational diabetes, defined as the rate of gestational diabetes in women without a prior diagnosis of gestational diabetes.
Pooled results were expressed as odds ratio (OR) with a 95% confidence interval (95% CI).
No adverse effects were reported for inositol supplementation.

Results and conclusions:
The investigators found inositol supplementation significantly reduced risk of gestational diabetes with 51% [OR = 0.49, p = 0.01]. However, this reduced risk was only significant in patients receiving 2g inositol twice daily.

The investigators found inositol supplementation significantly reduced risk of preterm delivery with 65% [OR = 0.35, 95% CI = 0.17-0.74, p = 0.006]. However, this reduced risk was only significant in patients receiving 2g inositol twice daily.

The investigators concluded double administration of inositol 2g per day reduces gestational diabetes rate and preterm delivery rate. Therefore, inositol supplementation may represent a novel strategy for gestational diabetes prevention.

Original title:
Inositol for the prevention of gestational diabetes: a systematic review and meta-analysis of randomized controlled trials by Vitagliano A, Saccone G, […], Berghella V.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30564926

Additional information of El Mondo:
Find more information/studies on inositol and pregnancy right here.
 

Objectives:
Evidence from randomized controlled trials (RCTs) suggests that viscous dietary fiber may offer beneficial effects on glycemic control and, thus, an improved cardiovascular disease risk profile. Therefore, this review article (meta-analysis) has been conducted.

Does viscous dietary fiber supplementation improve glycemic control in type 2 diabetes?

Study design:
This review article included 28 RCTs of ≥3 weeks in duration that assessed the effects of viscous fiber on markers of glycemic control in type 2 diabetes with a total of 1,394 participants.

Results and conclusions:
The investigators found that viscous fiber at a median dose of ∼13.1 g/day significantly reduced HbA1c in type 2 diabetes [MD = -0.58%, 95% CI = -0.88 to -0.28, p = 0.0002] compared with control and in addition to standard of care.

The investigators found that viscous fiber at a median dose of ∼13.1 g/day significantly reduced fasting blood glucose in type 2 diabetes [MD = -0.82 mmol/L, 95% CI = -1.32 to -0.31, p = 0.001] compared with control and in addition to standard of care. 

The investigators found that viscous fiber at a median dose of ∼13.1 g/day significantly reduced HOMA-insulin resistance in type 2 diabetes [MD = -1.89, 95% CI = -3.45 to -0.33, p = 0.02] compared with control and in addition to standard of care.

The investigators found the certainty of evidence was graded moderate for HbA1c, fasting glucose, fasting insulin and HOMA-IR and low for fructosamine.

The investigators concluded that 13.1 g/day viscous fiber supplements improve conventional markers of glycemic control beyond usual care and should be considered in the management of type 2 diabetes.

Original title:
Should Viscous Fiber Supplements Be Considered in Diabetes Control? Results From a Systematic Review and Meta-analysis of Randomized Controlled Trials by Jovanovski E, Khayyat R, […], Vuksan V.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30617143

Additional information of El Mondo:
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Objectives:
Diabetes prevention is a public health priority. Vitamin D supplementation may help prevent the development of diabetes in persons at increased risk. Therefore, this review article has been conducted.

Does vitamin D supplementation reduce risk of type 2 diabetes?

Study design:
This review article included 28 RCTs with 3,848 participants.

The sample size varied from 23 to 511.
The mean age of participants ranged from 26 years to 71 years.
The duration of follow-up across studies ranged from 2 months to 5 years, with a median follow-up of 22 weeks [interquartile range (IQR): 14 to 48 weeks], a duration long enough to detect changes in measured outcomes.

The average vitamin D supplementation dose of 88 µg/d (3500 IU/d).
All included trials measured the effect of vitamin D supplementation on serum 25(OH)D concentrations.

Results and conclusions:
The investigators found overall, serum 25(OH)D concentrations in the treated arms (vitamin D-supplemented groups) significantly improved by 45.1 nmol/L [95% CI = 41.3 to 48.9, p 0.001, I2 = 97.4%].

The investigators found compared with the control group, vitamin D supplementation significantly reduced HbA1c level by -0.48% [95% CI = -0.79 to -0.18, p = 0.002, I2 = 92.1%].
However, after adjusting the effect size for potential publication bias using the “trim and fill” method, 4 potentially missing studies were imputed in the funnel plot and the effect size increased from -0.48% [95% CI = -0.79 to -0.18] to -0.71% [95% CI = -1.02 to -0.39].

The investigators found compared with the control group, vitamin D supplementation significantly reduced fasting plasma glucose level by -0.46 mmol/L [95% CI = -0.74 to -0.19, p = 0.001, I2 = 92.4%].  
However, after adjusting the effect size for potential publication bias using the “trim and fill” method, 6 potentially missing studies were imputed in the funnel plot and the effect size increased -0.46 mmol/L [95% CI = -0.74 to ­0.19] to -0.72 mmol/L [95% CI =-1.02 to -0.42].

The investigators found compared with the control group, vitamin D supplementation significantly reduced HOMA-IR level by -0.39 [95% CI = -0.68 to -0.11, p = 0.007, I2 = 91.3%].
However, after adjusting the effect size for potential publication bias using the “trim and fill” method, 5 potentially missing studies were imputed in the funnel plot and the effect size increased from -0.39 [95% CI = -0.68 to -0.11] to -0.62 [95% CI = -0.92 to -0.32].

The investigators found in subgroup analysis both HbA1c and HOMA-IR showed a greater reduction over time among overweight/obese individuals compared with prediabetics [HbA1c = -0.98 ± 0.45 vs -0.29 ± 0.14, p = 0.1 and HOMA-IR = -0.62 ± 0.23 vs -0.07 ± 0.16, p = 0.05].

The investigators found in subgroup analysis vitamin D supplementation significantly decreased HbA1c [p = 0.05], fasting plasma glucose level [p = 0.05] and HOMA-IR [p = 0.1] to a greater extent when serum 25(OH)D concentration achieved was above 86 nmol/L.

The investigators found in subgroup analysis vitamin D supplementation for less than 6 months provided a larger effect size on HbA1c in comparison with long durations [-0.75 ± 0.33 vs -0.25 ± 0.11, p = 0.1].

The investigators found in subgroup analysis HbA1c showed greater improvement in populations with a mean age younger than 45 years in comparison with older populations [-1.15 ± 0.6 vs -0.30 ± 0.1, p = 0.05].

The investigators found in subgroup analysis greater reductions were found within HbA1c and fasting plasma glucose levels when baseline (at the beginning of the study) mean serum 25(OH)D concentration was ≥50 nmol/L, whereas the lowering effect was significantly less in the subgroup with baseline mean 25(OH)D 50 nmol/L [HbA1c = -0.79 ± 0.25 vs -0.14 ± 0.13, p = 0.04 and fasting plasma glucose level = -0.69 ± 0.21 vs -0.11 ± 0.10, p = 0.05].

The investigators concluded 88 µg/d vitamin D supplementation during 22 weeks improves glycemic measures and insulin sensitivity and may be useful as part of a preventive strategy for type 2 diabetes, particularly among overweight/obese individuals younger than 45 years.

Original title:
Vitamin D Supplementation, Glycemic Control, and Insulin Resistance in Prediabetics: A Meta-Analysis by Mirhosseini N, Vatanparast H, [...], Kimball SM.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016617/

Additional information of El Mondo:
Find more information/studies on diabetes and vitamin D right here.

HbA1c, FPG, HOMA-IR and plasma glucose after 2-hour oral glucose tolerance test (2HPG) are different parameters associated with (pre)diabetes.

 

Objectives:
Infertility, which affects ∼15% of the world's population, is a global public health issue recognized by the WHO. Therefore, it is of major clinical and public health importance to investigate whether modifiable lifestyle factors,such as stress, drug use, smoking, alcohol intake and diet may influence human fertility. Therefore, this meta-analysis (systematic review) has been conducted.

What is the effect of supplementation of nutrients on sperm quality parameters?

Study design:
This review article included 28 articles (RCTs) for qualitative analysis and 15 for quantitative meta-analysis.

Results and conclusions:
The investigators found total sperm concentrations were significantly increased by:
-selenium [MD = 3.91 × 106 spz/mL, 95% CI = 3.08 to 4.73 spz/mL];
-zinc [MD = 1.48 × 106 spz/mL, 95% CI = 0.69 to 2.27 spz/mL];
-omega 3 fatty acids [MD = 10.98 × 106 spz/mL, 95% CI = 10.25 to 11.72 spz/mL] and
-coenzyme Q10 [MD = 5.93 × 106 spz/mL, 95% CI = 5.36 to 6.51 spz/mL].

The investigators found sperm counts were significantly increased by:
-omega 3 fatty acids [MD = 18.70 × 106 spz/mL, 95% CI = 16.89 to 20.51 spz/mL] and
-coenzyme Q10 [MD = 10.15 × 106 spz/mL, 95% CI = 8.34 to 11.97 spz/mL].

The investigators found sperm total motility was significantly increased by:
-selenium [MD = 3.30%, 95% CI = 2.95% to 3.65%];
-zinc [MD = 7.03%, 95% CI = 6.03% to 8.03%];
-omega 3 fatty acids [MD = 7.55%, 95% CI = 7.09% to 8.01%];
-coenzyme Q10 [MD = 5.30%, 95% CI = 4.98% to 5.62%] and
-carnitines [MD = 7.84%, 95% CI = 6.54% to 9.13%].

The investigators found sperm progressive motility significantly increased by supplementation with carnitines [MD = 7.45%, 95% CI = 6.24% to 8.67%].

The investigators found sperm morphology was significantly enhanced by:
-selenium [MD = 1.87%, 95% CI = 1.50% to 2.24%];
-omega 3 fatty acid [MD = 0.91%, 95% CI = 0.69% to 1.13%];
-coenzyme Q10 [MD = 1.06%, 95% CI = 0.72% to 1.41%] and
-carnitine [MD = 4.91%, 95% CI = 3.68% to 6.15%].

The investigators concluded evidence from RCTs shows that some dietary supplements beneficially modulate sperm quality parameters and affect male fertility. However, results must be cautiously interpreted due to the limited sample size of the meta-analyzed studies and the considerable observed interstudy heterogeneity.

Original title:
The Effect of Nutrients and Dietary Supplements on Sperm Quality Parameters: A Systematic Review and Meta-Analysis of Randomized Clinical Trials by Salas-Huetos A, Rosique-Esteban N, […], Salas-Salvadó J.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30462179

Additional information of El Mondo:
Find more information/studies on mineral, antioxidants and pregnancy right here.

 

Objectives:
The timing of the introduction of egg to an infant's diet is of current interest, as new evidence raises questions regarding the benefit of delaying egg introduction. Therefore, this meta-analysis (systematic review) has been conducted.

Does early introduction of egg into an infant’s diet reduce risk of egg allergy?

Study design:
This review article included 6 RCTs with a total of 3,032 participants.
The RCTs compared early (between 3 and 6 months of age) egg introduction to no early introduction. The primary outcome was the development of egg allergy.

Results and conclusions:
The investigators found compared early (between 3 and 6 months of age) egg introduction to no early introduction, early introduction of egg significantly reduced risk of egg allergy with 40% [RR = 0.60, 95% CI = 0.44-0.82, p = 0.002, I2 = 23%, low to moderate level of evidence].

The investigators found the absolute risk reduction for a population with an incidence of egg allergy was 9.3% or 37 fewer cases [95% CI = 17-52] per 1,000 people.

The investigators found consumption of 4,000 mg/week of egg protein had a greater preventive effect than a higher dose.

The investigators concluded that introduction of egg into an infant’s diet between 3 and 6 months of age reduces risk of egg allergy, particularly for 4,000 mg/week of egg protein. Furthermore, the nature and dose of egg protein exposure may play a role. These findings should be addressed in the context of primary studies.

Original title:
Early Introduction of Egg and the Development of Egg Allergy in Children: A Systematic Review and Meta-Analysis by Al-Saud B and Sigurdardóttir ST.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30184525

Additional information of El Mondo:
Find more information/studies on protein and pregnancy right here.
 

Objectives:
High potato intake has been suggested as a risk factor for the development of type 2 diabetes. Therefore, this review article has been conducted.

Does potato intake increase risk of type 2 diabetes?

Study design:
This review article included 6 prospective cohort studies with a total of 4,545,230 person-year of follow-up and 17,758 diabetes cases.

Results and conclusions:
The investigators found for every increment of 1 serving/day of total potato consumption a significantly increased risk of 20% [HR = 1.20, 95% CI = 1.13 to 1.127, p 0.001, I2 = 27.1%, p for heterogeneity = 0.23] for type 2 diabetes both in men en women.

The investigators found for 2 servings/day of total potato consumption a significantly increased risk of 44% [HR = 1.44, 95% CI = 1.28 to 1.63] for type 2 diabetes both in men en women.

The investigators found for 3 servings/day of total potato consumption a significantly increased risk of 74% [HR = 1.74, 95% CI = 1.45 to 2.09] for type 2 diabetes both in men en women.

The investigators found significant evidence of a non-linear association between total potato consumption and risk of type 2 diabetes [X2 = 17.5, p for linearity 0.001].

The investigators concluded that long-term high consumption of potato (each serving a day increase) is strongly associated with increased risk of type 2 diabetes. These findings suggest that diet-health policy may be of importance in the prevention of diabetes.

Original title:
Potato consumption and risk of type 2 diabetes: A dose-response meta-analysis of cohort studies by Bidel Z, Teymoori F, […], Nazarzadeh M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30144898

Additional information of El Mondo:
Find more information/studies on diabetes right here.

According to the USDA Dietary Guidelines a serving of potato is 1 cup diced, mashed or baked or 1 medium boiled potato.

 

Objectives:
Low birth weight infant (LBWIs) are prone to mental and behavioural problems. As an important constituent of the brain and retina, long chain polyunsaturated fatty acids are essential for foetal infant mental and visual development. The effect of lactation supplemented with long chain polyunsaturated fatty acids (LCPUFA) on the improvement of intelligence in low birth weight children requires further validation. Therefore, this meta-analysis (systematic review) has been conducted.

Do long chain polyunsaturated fatty acids (LCPUFA or PUFA) supplements improve intelligence in low birth weight children?

Study design:
This review article included 10 studies with a total of 1,793 individuals, of which 908 cases in the intervention group (group with LCPUFA supplements) and 885 controls (group without LCPUFA supplements).

The mean birth weights in 8 studies were less than 1500g and those in 2 studies were more than 1500g. None of the included studies had infants with birth weight less than 750g.

LCPUFA supplements were DHA+AA, DHA+EPA+DPA or DHA+AA+EPA.

There was no evidence of publication bias.

Results and conclusions:
The investigators found that the long chain polyunsaturated fatty acids supplemented group did not have significantly higher mental development index (MDI) scores than the group without supplementation [SMD = 0.07, 95% CI = -0.05 to 0.19, I2 = 23.8%, p = 0.222].
Subgroup analysis showed that the long chain polyunsaturated fatty acids supplementation groups did not have significantly higher mental development index scores than the control groups.

The investigators found that the long chain polyunsaturated fatty acids supplemented group did not have significantly higher psychomotor development index (PDI) scores than the group without supplementation [SMD = -0.01, 95% CI = -0.23 to 0.21, I2 = 60.5%, p = 0.906].
Subgroup analysis showed that the long chain polyunsaturated fatty acids supplementation groups did not have significantly higher psychomotor development index scores than the control groups.

The investigators found that the long chain polyunsaturated fatty acids supplemented group did not have significantly higher full scale intelligence quotient (FSIQ) scores than the group without supplementation [SMD = 0.00, 95% CI = -0.14 to 0.14, I2 = 0.00%, p = 0.991].

The investigators found that the long chain polyunsaturated fatty acids supplemented group did not have significantly higher verbal intelligence quotient (VIQ) scores than the group without supplementation [SMD = 0.01, 95% CI = -0.15 to 0.12, I2 = 42.2%, p = 0.844].

The investigators found that the long chain polyunsaturated fatty acids supplemented group did not have significantly higher performance intelligence quotient (PIQ) scores than the group without supplementation [SMD = -0.01, 95% CI = -0.15 to 0.13, I2 = 0.00, p = 0.877].

The investigators concluded that long chain polyunsaturated fatty acids (LCPUFA or PUFA) supplements do not improve intelligence in low birth weight children. Therefore, whether long-chain polyunsaturated fatty acids supplements are beneficial for LBWIs has not been shown conclusively.

Original title:
The effect of long chain polyunsaturated fatty acid supplementation on intelligence in low birth weight infant during lactation: A meta-analysis by Song Y, Liu Y, […], Li D.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5892917/

Additional information of El Mondo:
Find more information/studies on long chain polyunsaturated fatty acids and pregnancy right here.

 

Objectives:
Several studies have been published about the effect of garlic on lipid profile and blood glucose in diabetic patients. Which, the results mostly contradict with each other. Therefore, this review article has been conducted.

Does garlic improve lipid profile and blood glucose in diabetic patients?

Study design:
This review article included 33 articles with a total of 1,273 individuals, with a mean of 39 samples per study.

Results and conclusions:
The investigators found the concentration of serum total cholesterol significantly decreased wih 16.87 mg/dL [95% CI = -21.01 to -12.73, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum LDL cholesterol (bad cholesterol) significantly decreased with 9.65 mg/dL [95% CI = -15.07 to -4.23, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum triglycerides significantly decreased with 12.44 mg/dL [95% CI = -18.19 to -6.69, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum HDL cholesterol (good cholesterol) significantly increased with 3.19 mg/dL [95% CI = 1.85 to 4.53, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum fasting blood sugar significantly decreased with 10.90 mg/dL [95% CI = -16.40 to -5.40, p = 0.001] in the garlic group when compared with the placebo group.

The investigators found the concentration of serum HbA1c significantly decreased with 0.60 mg/dL [95% CI = -0.98 to -0.22, p = 0.001] in the garlic group when compared with the placebo group.

The investigators concluded that garlic improves lipid profile as well as glucose parameters and can be therapeutically effective in patients suffering from cardiovascular diseases and diabetes.

Original title:
The effect of garlic on lipid profile and glucose parameters in diabetic patients: A systematic review and meta-analysis by Shabani E, Sayemiri K and Mohammadpour M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30049636

Additional information of El Mondo:
Find more information/studies on diabetes, cholesterol, meta-analyses/heterogeneity and garlic right here.

 

Objectives:
Despite the World Health Organization recommendation of exclusive breastfeeding (EBF) for the first six months of life, the rate remains low both in developed and developing countries. In Ethiopia, findings regarding the prevalence of exclusive breastfeeding have been highly variable. Antenatal care and institutional delivery are the most important factors contributing to the practice of exclusive breastfeeding. However, their effect has not been investigated in Ethiopia. Therefore, this review article has been conducted.

Do antenatal care and institutional delivery increase exclusive breastfeeding?

Study design:
This review article included 32 studies (published between 2007 to 2017) with a total of 23,543 breastfeeding women. 29 (71.8%) of the studies are cross-sectional study design. The sample size of the studies ranged from 119 to 5, 227.

Results and conclusions:
The investigators found the result of 32 included studies indicated that the pooled prevalence of exclusive breastfeeding in Ethiopia was 59.3% [95% CI = 53.8 to 64.8%].

The investigators found subgroup analysis indicated that the highest prevalence was observed in Afar region (65.6%), followed by SNNP (63.8%) and then by Oromia (61.8%).

The investigators found mothers who attended antenatal visits were 2.1 times more likely to practice exclusive breastfeeding compared to their counterparts [OR = 2.1, 95% CI = 1.5 to 2.8).

The investigators found, moreover, mothers who gave birth at a health institution were 2.2 times more likely to practice exclusive breastfeeding compared to mothers who gave birth at home [OR = 2.2, 95% CI = 1.3 to 3.5].

The investigators concluded exclusive breastfeeding in Ethiopia is significantly lower than the global recommendations. Mothers who attended antenatal visits and who gave birth at health institutions have better exclusive breastfeeding practices. Based on these findings, it is strongly recommended that the utilization of antenatal care and institutional delivery should be improved through health extension workers.

Original title:
Exclusive breastfeeding practice in Ethiopia and its association with antenatal care and institutional delivery: a systematic review and meta-analysis by Alebel A, Tesma C, […], Kibret GD.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6048887/

Additional information of El Mondo:
Find more information/studies on food fortification/malnutrition and breastfeeding right here.

Objectives:
Whether a vegetarian diet is appropriate for pregnancy remains unclear. Therefore, this review article has been conducted.

What is the association between vegetarian diet during pregnancy and various maternal-fetal outcomes?

Study design:
This review article included 19 observational studies.

Results and conclusions:
The investigators found in pooled analysis no association between vegetarian pregnancy and low birth weight (LBW) [RR = 1.27, 95% CI = 0.98-1.65, p = 0.07, I2 = 0%].

The investigators found, however, in subgroup analysis that Asian (India/Nepal) vegetarian mothers exhibited a significantly increased risk of 33% to deliver a baby with low birth weight [RR = 1.33, 95% CI = 1.01-1.76, p = 0.04, I2 = 0%]. But, the WMD of neonatal birth weight in 5 studies suggested no difference between vegetarians and omnivores.

Given the high heterogeneity of the included studies, lack of high-quality evidence and limited studies included for each category, the investigators failed to reach conclusive results regarding the risks of hypospadias, intrauterine growth retardation, maternal anemia and gestational diabetes mellitus.

The investigators concluded that Asian vegetarian mothers have an increased risk to deliver babies with low birth weight than those of omnivores. Large-scale prospective studies focusing on pre- and/or early gestational nutrition will help clarify the correlation between vegetarian diet and various pregnancy outcomes.

Original title:
Is a vegetarian diet safe to follow during pregnancy? A systematic review and meta-analysis of observational studies by Tan C, Zhao Y and Wang S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29621406

Additional information of El Mondo:
Find more information/studies on veganism and pregnancy right here.

 

Objectives:
The purpose of this review article is to review previously published meta-analyses on the effectiveness of dietary fiber on type 2 diabetes.

Study design:
This umbrella review article included 16 meta-analyses.

Results and conclusions:
The investigators found in the meta-analyses when comparing highest versus lowest dietary fiber intake, a statistically significant reduced risk of 15 to 19% [RR = 0.81-0.85] for type 2 diabetes. However, statistically significant heterogeneity was observed in all of these meta-analyses.

The investigators found in the meta-analyses when comparing highest versus lowest dietary cereal fibers, a statistically significant reduced risk of 13 to 33% [RR = 0.67-0.87] for type 2 diabetes. However, statistically significant heterogeneity was observed in all of these meta-analyses.

The investigators found in the meta-analyses of supplementation studies using β-glucan or psyllium fibers on type 2 diabetic participants, statistically significant reductions were identified in both fasting blood glucose concentrations and glycosylated hemoglobin percentages.

The investigators concluded that those consuming the highest amounts of dietary fiber, especially cereal fiber, may benefit from a reduction in the incidence of developing type 2 diabetes. May benefit because statistically significant heterogeneity was observed in all of these meta-analyses.
There also appears to be a small reduction in fasting blood glucose concentration, as well as a small reduction in glycosylated hemoglobin percentage for individuals with type 2 diabetes who add β-glucan or psyllium to their daily dietary intake.

Original title:
Dietary Fiber Intake and Type 2 Diabetes Mellitus: An Umbrella Review of Meta-analyses by McRae MP.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29628808

Additional information of El Mondo:
Find more information/studies on diabetes, meta-analyses/heterogeneity and dietary fiber right here.

 

Objectives:
The association between dietary protein intake and type 2 diabetes risk has been inconsistent in the previous epidemiological studies. Therefore, this review article (meta-analysis) has been conducted.

Is there an association between dietary protein intake and type 2 diabetes risk?

Study design:
This review article included 10 prospective cohort studies with a total of 34,221 type 2 diabetes cases.
No publication bias was detected.

Results and conclusions:
The investigators found after adjustment of potential confounders, a 5% of energy (5 En%) increment from dietary total protein intake was related to a significantly 9% [95 CI = 1.04-1.13, I2 = 42.0%] higher risk of type 2 diabetes. The results were robust in sensitivity analysis.

The investigators found after adjustment of potential confounders, a 5% of energy (5 En%) increment from dietary animal protein intake was related to a significantly 12% [95 CI = 1.08-1.17, I2 = 14.0%] higher risk of type 2 diabetes. The results were robust in sensitivity analysis.

The investigators found after adjustment of potential confounders, a significant U-shaped curve was observed for plant protein intake with the most risk reduction at about 6% of energy from plant protein intake [p nonlinearity = 0.001]. The results were robust in sensitivity analysis.

The investigators concluded that the consumption of protein, particularly animal protein increases risk of type 2 diabetes.

Original title:
Dietary protein intake and risk of type 2 diabetes: a dose-response meta-analysis of prospective studies by Zhao LG, Zhang QL, [...], Xiang YB.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29858629

Additional information of El Mondo:
Find more information/studies on diabetes and protein right here.

 

Objectives:
The association between coffee consumption and the level of C-reactive protein (CRP) has been evaluated in several epidemiological studies with conflicting results. Therefore, this meta-analysis (systematic review) has been conducted.

Does coffee consumption reduce level of C-reactive protein in humans?

Study design:
This review article included a total of 9 cross-sectional studies.

Results and conclusions:
The investigators found according to the combined standard mean difference (SMD) between the highest and the lowest coffee intake category, coffee consumption was associated with a significantly lower level of serum CRP level [SMD = -0.34, 95% CI = -0.62 to -0.06, p = 0.016].

The investigators found subgroup analysis for CRP marker showed that coffee consumption was associated with a significantly lower level of serum high-sensitivity CRP (hsCRP) [SMD = -0.51, 95% CI = -0.88 to -0.14, p = 0.007], but not standard CRP [SMD = 0.02, 95% CI = -0.28 to 0.32, p = 0.913].

The investigators concluded that coffee consumption is associated with a lower level of serum CRP, particularly serum high-sensitivity CRP. However, more well-designed prospective cohort studies are needed to elaborate the concerned issues further.

Original title:
Is coffee consumption associated with a lower level of serum C-reactive protein? A meta-analysis of observational studies by Zhang Y and Zhang DZ.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29405789

Additional information of El Mondo:
Find more information/studies on coffee and chronic disease right here.

 

Objectives:
Epidemiological studies exploring the role of flavonoids intake in preventing type 2 diabetes mellitus (T2DM) showed inconsistent results. Therefore, this review article (meta-analysis) has been conducted.

Does flavonoids intake decrease risk of developing type 2 diabetes?

Study design:
This review article included 10 independent cohorts published between 2002 and 2017 with a total of 312,015 participants, of which 19,953 type 2 diabetes cases were identified during the follow-up periods from 4 to 28 years.
All participants were free of type 2 diabetes at baseline (at the beginning of the study), with age ranging from 28 to 75 years.
Dietary flavonoids intake was evaluated using food-frequency questionnaire and type 2 diabetes was frequently ascertained through medical records.
In the original studies, the median intake level of total flavonoids was 8.9 to 501.8 mg/day for the lowest categories and 33.2 to 1452.3 mg/day for the highest categories.
The most commonly adjusted variables included age, sex, total energy intake, body mass index, smoking, alcohol consumption and physical activity.
All included studies had a NOS score of ≥7, with an average score of 7.9, indicating the presence of high methodological quality.

There was no indication of publication bias from visual inspection of the funnel plot, which was further confirmed by Egger test [p = 0.253].

Results and conclusions:
The investigators found when compared with the lowest intake, the highest intake of total flavonoids was associated with a significantly 9% decreased risk of type 2 diabetes [RR = 0.91, 95% CI = 0.86-0.96, I2  =  21%, p =  0.257].
In stratified analyses, the pooled RR for total flavonoids intake was not modified by sample size, sex, follow-up duration and study location.
Leave-one-out sensitivity analysis showed that no individual study had a significant influence on the final result.

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of anthocyanidins significantly decreased risk of type 2 diabetes with 11% [RR = 0.89, 95% CI = 0.82-0.95].

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of flavan-3-ols significantly decreased risk of type 2 diabetes with 14% [RR = 0.86, 95% CI = 0.78-0.95].

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of flavonols significantly decreased risk of type 2 diabetes with 14% [RR = 0.86, 95% CI = 0.80-0.94].

The investigators found in subgroup analyses when compared with the lowest intake, the highest intake of isoflavones significantly decreased risk of type 2 diabetes with 9% [RR = 0.91, 95% CI = 0.84-0.98].

The investigators found in 9 cohort studies a curvilinear relationship between total flavonoids intake and type 2 diabetes risk [p for nonlinearity = 0.042] with a significant risk reduction at an intake of ≥550 mg/day.

The investigators found when assuming a linear association, the risk of type 2 diabetes was reduced by 5% [RR = 0.95, 95% CI = 0.93-0.97] for each 300-mg/day increment in total flavonoids intake.

The investigators concluded that intakes of total flavonoids, particularly ≥550 mg/day, anthocyanidins, flavan-3-ols, flavonols and isoflavones are associated with significantly decreased risks of type 2 diabetes in the highest versus lowest analyses. Additionally, the dose-response analysis suggest a curvilinear relationship of total flavonoids intake with type 2 diabetes risk; when assuming a linear manner, the risk of type 2 diabetes is reduced by 5% for an increment of 300 mg/day in total flavonoids intake.

Original title:
Flavonoids intake and risk of type 2 diabetes mellitus: A meta-analysis of prospective cohort studies by Xu H, Luo J, [...], Wen Q.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959406/

Additional information of El Mondo:
Find more information/studies on diabetes and flavonoids right here.

Objectives:
There is an increasing trend in the consumption of poor-quality diets worldwide, contributing to the increase of non-communicable diseases. Diet directly influences physiological composition and subsequently physical health. Studies have shown that dietary macronutrient and energy content can influence the proportion of intramuscular fat (IMF), which mediates various metabolic and endocrine dysfunction. Therefore, this review article has been conducted.

Do different types of dietary macronutrient intake increase the proportion of intramuscular fat?

Study design:
This review article included 13 trials (RCTs, quasi-RCTs, controlled trials, randomized controlled crossover trials or controlled crossover trials).

High-fat diets were diets with a proportion of fat between 38 and 85 En%. Participants in high-fat diets were all young to middle aged adults with ages varying between 18 and 50 years.

Participants in starvation diets (a decrease of 25% calorie from weight maintenance energy requirements) and hypocaloric diets (890 calories per day, until 15% weight reduction) followed the diet for 8 days with a 3-week washout period in between.

Cohen’s criteria were used to determine the effect size of SMDs, where a SMD between 0.2 and 0.5 is small, a SMD between 0.5 and 0.8 is moderate and a SMD above 0.8 is large. SMDs below 0.2 were considered unsubstantial.

Results and conclusions:
The investigators found in 6 studies with in a total of 134 participants receiving a high-fat intervention and 135 people receiving a control intervention, that high-fat diets (38 and 85 En% fat) significantly increased the proportion of intramuscular fat [SMD = 1.24, 95% CI = 0.43-2.05, p  = 0.003, I2 = 87%].  
Sensitivity analysis (excluding studies with a quality value 20, smallest sample size 8 and those that do not specify participant characteristics) showed a significantly SMD of 1.26 [95% CI = 0.23-2.28, p = 0.02]. 

The investigators found diets with an increased proportion of carbohydrates decreased the proportion of intramuscular fat.
However, increasing caloric intake with carbohydrates compared to a standardized diet (55 En% carbohydrates, 30 En% fat and 15 En% protein) increased the proportion of intramuscular fat.

The investigators found starvation diets (a decrease of 25% calorie from weight maintenance energy requirements) increased intramuscular fat stores and hypocaloric diets (890 calories per day, until 15% weight reduction) did not result in any intramuscular fat proportion changes.

The investigators concluded that high-fat diets (38 y 85 En%), excessive caloric intake in the form of carbohydrates and short-term starvation diets are associated with increases in the proportion of intramuscular fat. However, further studies are needed to assess the effects of macronutrient combinations on intramuscular fat and the influence of diet-induced intramuscular fat alterations on health outcomes. In addition, intramuscular fat poses a possibly effective clinical marker of health.

Original title:
The Effects of Diet on the Proportion of Intramuscular Fat in Human Muscle: A Systematic Review and Meta-analysis by Ahmed S, Singh D, [...], Kumbhare D.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826234/

Additional information of El Mondo:
Find more information/studies on fat and carbohydrates consumption and diabetes right here.

Higher intramuscular fat levels are positively associated with insulin resistance and an increased risk of developing type 2 diabetes.