Nutrition and health

Objectives:
Type 1 diabetes mellitus (T1DM) causes the irreversible destruction of pancreatic beta cells. The Bacillus Calmette-Guerin (BCG) vaccine can modulate the immune response and decelerate disease progression. Therefore, this review article has been conducted.

Do patients with type 1 diabetes mellitus benefit from the Bacillus Calmette-Guerin (BCG) vaccine?

Study design:
This review article included 4 RCTs. The sample sizes ranged from 6 to 94, with a total of 198 subjects. The mean age of the examinees ranged from 10.1 to 36.0 years and the follow-up duration ranged from 1 to 8 years.

Results and conclusions:
The investigators found the pooled meta-analysis demonstrated no significant difference in HbA1c levels [MD = -0.12, 95% CI = -0.53 to 0.30, I2 = 56%] or fasting C-peptide levels [MD = -0.15, 95% CI = -0.35 to 0.06, I2 = 0%] in the BCG intervention group as compared with that in the placebo group.
The results remained unchanged after removing each study in the sensitivity analysis.

The investigators concluded there is no robust evidence to support the use of the Bacillus Calmette-Guerin (BCG) vaccine for the treatment of type 1 diabetes mellitus although the HbA1c levels tend to improve. Additional RCTs to assess the long-term effects of the Bacillus Calmette-Guerin (BCG) vaccine on glycemic control are warranted.

Original title:
Therapeutic Effects of BCG Vaccination on Type 1 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Chang YC, Lin CJ, […], Hsu HY.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7139880/

Additional information of El Mondo:
Find more information/studies on vaccination, diabetes mellitus and malnutrition right here.

Objectives:
Does fish consumption reduce risk of coronary heart disease (CHD), stroke and all-cause mortality in patients with type 2 diabetes (T2D)?

Study design:
This review article included 9 prospective cohort studies with 57,394 diabetic patients.

Results and conclusions:
The investigators found for the highest compared with the lowest category of fish consumption, a significantly reduced risk of 14% [relative risk = 0.86, 95% CI = 0.76 to 0.96, I2 = 50%, n = 8] for all-cause mortality in patients with type 2 diabetes.

The investigators found for the highest compared with the lowest category of fish consumption, a significantly reduced risk of 39% [relative risk = 0.61, 95% CI = 0.29 to 0.93, I2 = 68%, n = 3] for coronary heart disease in patients with type 2 diabetes.

The investigators found there was a monotonic inverse association, with a nadir at fish consumption of approximately 2-3 servings/week, in both analyses.

The investigators concluded 2-3 servings/week of fish consumption reduce risk of all-cause mortality and coronary heart disease in patients with type 2 diabetes.

Original title:
Fish consumption and the risk of cardiovascular disease and mortality in patients with type 2 diabetes: a dose-response meta-analysis of prospective cohort studies by Jayedi A, Soltani S, […], Shab-Bidar S.

Link:
https://pubmed.ncbi.nlm.nih.gov/32410513/

Additional information of El Mondo:
Find more information/studies on fish consumption, cardiovascular disease and diabetes right here.
 

Objectives:
Does niacin (vitamin B3) supplementation improve lipid profiles and glycemic control in patients with type 2 diabetes mellitus?

Study design:
This review article included 8 RCTs comprised a total of 2,110 patients with type 2 diabetes mellitus.
Studies published ranged from 1990 to 2016 and 15 to 1,053 patients were included in each individual trial.

The follow-up duration ranged from 8.0 weeks to 12.0 months.

The study quality was assessed using the Jadad scale. 4 studies had 3 scores and the remaining 4 studies had 2 scores.

There was no significant publication bias.

Results and conclusions:
The investigators found patients’ niacin supplementation was associated with lower levels of total cholesterol [WMD = -0.28, 95% CI = -0.44 to -0.12, p =  0.001], triglyceride [WMD = -0.37, 95% CI = -0.52 to -0.21, p   0 .001] and low-density lipoprotein cholesterol (bad cholesterol) [WMD = -0.42, 95% CI = -0.50 to -0.34, p    0.001].

The investigators found, moreover, the level of high-density lipoprotein cholesterol (good cholesterol) was significantly increased when niacin supplementation [WMD = 0.33, 95% CI = 0.21 to 0.44, p 0 .001] was provided.

The investigators found, however, niacin supplementation produced no significant effects on plasma glucose [WMD = 0.18, 95% CI = -0.14 to 0.50, p = 0 .275] and hemoglobin A1c (HbA1c) levels [WMD = 0.39, 95% CI = -0.15 to 0.94, p = 0 .158].

The investigators concluded that niacin (vitamin B3) supplementation improves lipid profiles, including total cholesterol, LDL and HDL cholesterol without affecting the glycemic levels for patients with type 2 diabetes mellitus. Additional large-scale RCTs should be conducted to evaluate the long-term effectiveness of niacin supplementation.

Original title:
Effectiveness of niacin supplementation for patients with type 2 diabetes: A meta-analysis of randomized controlled trials by Xiang D, Zhang Q and Wang YT.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373507/

Additional information of El Mondo:
Find more information/studies on cholesterol, vitamin B3 and diabetes right here.
 

Objectives:
Type 2 diabetes mellitus is a chronic disease that occurs among the general population. The insulin-lowering and homeostasis model assessment of insulin resistance-improving effects of inulin are unconfirmed. Therefore, this review article has been conducted.

Do inulin supplements improve HOMA-IR, fasting plasma glucose and HbA1c in patients with type 2 diabetes mellitus?

Study design:
This review article included 9 RCTs with a total of 661 participants.

The duration of the interventions ranged from 6 weeks to 12 weeks and the dosage of inulin supplementation ranged from 8.4 g to 10 g per day.

Results and conclusions:
The investigators found inulin supplementation significantly improved fasting plasma glucose [SMD = -0.55, 95% CI = -0.73 to -0.36, p = 0.0], HOMA-IR [SMD = -0.81, 95% CI = -1.59 to -0.03, p = 0.042] and HbA1c [SMD = -0.69, 95% CI = -0.92 to -0.46, p = 0.0] in patients with type 2 diabetes mellitus.

The investigators found, further subgroup analyses revealed a significant role of inulin supplementation for treatment durations ≥8 weeks [p = 0.038 for insulin, p = 0.002 for HOMA-IR, p = 0.032 for fasting plasma glucose, p = 0 for HbA1c] in patients with type 2 diabetes mellitus.

The investigators concluded that daily 8.4-10 grams of inulin supplements for at least 8 weeks improve HOMA-IR, fasting plasma glucose and HbA1c in patients with type 2 diabetes mellitus.

Original title:
Efficacy of inulin supplementation in improving insulin control, HbA1c and HOMA-IR in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials by Zhang W, Tang Y, […], Hu H.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7263925/

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

Inulin is a type of fiber that's found in certain plant foods. Chicory root is the main source of inulin in supplement form.

Objectives:
Antioxidant status is considered as important factor in the pathogenesis (the manner of development of a disease) of vitiligo. However, there are controversial findings about serum status of antioxidants in vitiligo patients. Therefore, this review article has been conducted.

Is there a relationship between serum antioxidant level (e.g. vitamin C, E, zinc and selenium) and risk of vitiligo?

Study design:
This review article included 11 studies including 570 vitiligo cases and 580 controls (people without vitiligo).

Serum vitamin A and copper level in vitiligo patients were only evaluated in single studies and not included in meta-analysis.

Results and conclusions:
The investigators found based on fixed effect model, there were no statistical difference between two groups regarding serum vitamin C levels [OR = 1.17, 95% CI = 0.74 to 1.84, p = 0.495] and serum vitamin E levels [OR = 0.61, 95% CI = 0.30 to 1.25, p = 0.180].

The investigators found in sensitivity analysis, higher serum zinc levels significantly decreased risk of vitiligo with 71% [OR = 0.29, 95% CI = 0.15 to 0.54, p 0.001].

The investigators found in sensitivity analysis, higher serum selenium level significantly increased risk of vitiligo with 331% [OR = 4.31, 95% CI = 2.72 to 6.81, p 0.001].

The investigators concluded that higher serum selenium and lower zinc level increase risk of vitiligo. Potential mechanism associated with preventive effects of zinc and the depigmentation effect of selenium should be more elucidated in further studies.

Original title:
Serum Level of Antioxidant Vitamins and Minerals in Patients With Vitiligo, a Systematic Review and Meta-Analysis by Huo J, Liu T, [...], Wang R.

Link:
https://pubmed.ncbi.nlm.nih.gov/32593085/

Additional information of El Mondo:
Find here more information/studies about antioxidants, selenium and zinc.

Vitiligo is a long-term condition where pale white patches develop on the skin. It's caused by the lack of melanin, which is the pigment in skin. Vitiligo can affect any area of skin, but it commonly happens on the face, neck and hands and in skin creases.

Objectives:
Does barberry (Berberis vulgaris L.) supplementation improve glycemic markers including fasting blood sugar (FBS) concentrations, insulin levels, homeostatic model assessment for insulin resistance (HOMA-IR) and glycosylated hemoglobin (HbA1c) percentage?

Study design:
This review article included 7 RCTs, comprising 452 participants.

Results and conclusions:
The investigators found the meta-analysis revealed that barberry supplementation significantly reduced insulin levels [Hedges’s = -0.67, 95% CI = -1.31 to -0.03, p = 0.04, I2 = 73.3%].
However, no significant positive effect was observed for fasting blood sugar levels [WMD = -8.06 mg/dL, 95% CI = -20.46 to 4.33, p = 0.23, I2 = 96.1%], HbA1c percentage [WMD = -0.83%, 95% CI = -2.33 to 0.67, p = 0.27, I2 = 88.3%] and HOMA-IR index [WMD = -0.55, 95% CI = -1.60 to 0.50, p = 0.30, I2 = 99.4%].

The investigators concluded barberry supplementation improves insulin levels.

Original title:
The Effect of Barberry (Berberis Vulgaris L.) on Glycemic Indices: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Safari Z, Farrokhzad A, […], Askari G.

Link:
https://www.sciencedirect.com/science/article/abs/pii/S0965229920302235?via%3Dihub

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

Objectives:
A low insulin-like growth factor 1 (IGF-1) level is known to be associated with many disorders. Several studies have shown that soy consumption may influence IGF-1, but the findings remain inconclusive. Therefore, this review article (meta-analysis) has been conducted.

Does soy consumption increase insulin-like growth factor 1 (IGF-1) level?

Study design:
This review article included 8 clinical trials.

Results and conclusions:
The investigators found, overall, a significant increment in plasma IGF-1 was observed following soy intervention [WMD = 13.5 ng/mL, 95% CI = 5.2 to 21.8, I2 = 97%].

The investigators found, subgroup analyses demonstrated a significantly greater increase in IGF-1, when soy was administered at a dosage of ≤40 g/day [WMD = 11.7 ng/mL, 95% CI = 10.9 to 12.6, I2 = 98%] and when the intervention duration was 12 weeks [WMD = 26.6 ng/mL, 95% CI = 9.1 to 44.1, I2 = 0.0%].

The investigators found, in addition, soy intervention resulted in a greater increase in IGF-1 among non-healthy subjects [WMD = 36 ng/mL, 95% CI = 32.7 to 39.4, I2 = 84%] than healthy subjects [WMD = 9.8 ng/mL, 95% CI = 8.9 to 10.7, I2 = 90%].

The investigators concluded ≤40 grams of soy consumption per day during 12 weeks increase the IGF-1 level.

Original title:
The Effect of Soy Intervention on Insulin-Like Growth Factor 1 Levels: A Meta-Analysis of Clinical Trials by Jiawei Zeng J, Feng Y, […], Chen X.

Link:
https://pubmed.ncbi.nlm.nih.gov/32072706/

Additional information of El Mondo:
Find more information/studies on subgroup analysis/significant and soja consumption right here.

Objectives:
Does high magnesium dietary intake reduce risk of type 2 diabetes and stroke?

Study design:
This review article included 53 prospective cohort studies with a total of 1,912,634 participants and 76,678 cases (persons with type 2 diabetes or stroke).

Participants were predominately middle aged at baseline (at the beginning of the studies), with a mean magnesium intake of 370 mg/day for the highest category and 232 mg/day for the lowest category.

The mean duration of all eligible studies was 10.7 years.

Results and conclusions:
The investigators found, when comparing the highest category of magnesium dietary intake (370 mg/day) to the lowest (232 mg/day), a significantly reduced risk of 22% [RR = 0.78, 95% CI = 0.75 to 0.81, p 0.001, I2 = 35.6%, p = 0.021] for type 2 diabetes.

The investigators found, when comparing the highest category of magnesium dietary intake (370 mg/day) to the lowest (232 mg/day), a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.83 to 0.94, p 0.001, I2 = 0%, p = 0.529] for total stroke.

The investigators found, when comparing the highest category of magnesium dietary intake (370 mg/day) to the lowest (232 mg/day), a significantly reduced risk of 12% [RR = 0.88, 95% CI = 0.81 to 0.95, p = 0.001, I2 = 16.9%, p = 0.265] for ischaemic stroke.

The investigators found in studies adjusted for cereal fiber dietary intake, a significantly reduced risk of 21% [RR = 0.79, 95% CI = 0.73 to 0.85, p 0.001] for type 2 diabetes.

The investigators found in studies adjusted for calcium dietary intake, a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.80 to 0.99, p = 0.040] for total stroke.

The investigators found in stratified analyses by characteristics of the population and study design, a significantly reduced risk of 9% [RR = 0.91, 95% CI = 0.83 to 0.99] for total stroke among female.

The investigators found in stratified analyses by characteristics of the population and study design, a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.79 to 1.00] for ischaemic stroke among female.

The investigators found in stratified analyses by characteristics of the population and study design, a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.82 to 0.96] for total stroke among individuals with BMI ≥25 kg/m².

The investigators found in stratified analyses by characteristics of the population and study design, a significantly reduced risk of 12% [RR = 0.88, 95% CI = 0.81 to 0.96] for ischaemic stroke among individuals with BMI ≥25 kg/m².

The investigators found in stratified analyses by characteristics of the population and study design, a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.83 to 0.95] for total stroke among studies wtith ≥12-year follow-up.

The investigators found in stratified analyses by characteristics of the population and study design, a significantly reduced risk of 12% [RR = 0.88, 95% CI = 0.81 to 0.95] for ischaemic stroke among studies wtith ≥12-year follow-up.

The investigators found for every 100 mg/day increment of magnesium dietary intake, a significantly reduced risk of 6% [RR = 0.94, 95% CI = 0.93 to 0.95] for type 2 diabetes.

The investigators found for every 100 mg/day increment of magnesium dietary intake, a significantly reduced risk of 2% [RR = 0.98, 95% CI = 0.97 to 0.99] for total stroke.

The investigators found for every 100 mg/day increment of magnesium dietary intake, a significantly reduced risk of 2% [RR = 0.98, 95% CI = 0.97 to 0.99] for ischaemic stroke.

The investigators concluded magnesium dietary intake has a substantial inverse association with type 2 diabetes and (total/ ischaemic) stroke. Furthermore, female, participants with obesity (BMI ≥ 25 kg/m²) and with a longer follow-up period (≥12 years) obtain greater benefit from magnesium intake with a lower risk of total and ischaemic stroke incidence. Overall, these findings support the guidelines to address the role of magnesium dietary intake in early prevention strategies to combat type 2 diabetes and stroke. However, additional RCTs are needed in the future to validate the causality.

Original title:
Association of magnesium intake with type 2 diabetes and total stroke: an updated systematic review and meta-analysis by Zhao B, Zeng L, [...], Zhang W.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7103847/

Additional information of El Mondo:
Find more information/studies magnesium consumption, stroke and diabetes right here.

Objectives:
Is there an association between total meat, red meat, processed meat, poultry and fish intake and risk of type 2 diabetes (T2D)?

Study design:
This review article included 28 prospective cohort studies.

Results and conclusions:
The investigators found when compared with the lowest category, the highest category of total meat intake, significantly increased risk of type 2 diabetes with 33% [summary relative risk = 1.33, 95% CI = 1.16 to 1.52].
Significantly means that there is an association with a 95% confidence.

The investigators found when compared with the lowest category, the highest category of red meat intake, significantly increased risk of type 2 diabetes with 22% [summary relative risk = 1.22, 95% CI = 1.16 to 1.28].
Significantly because summary relative risk of 1 was not found in the 95% CI of 1.16 to 1.28. Summary relative risk of 1 means no risk/association.

The investigators found when compared with the lowest category, the highest category of processed meat intake, significantly increased risk of type 2 diabetes with 25% [summary relative risk = 1.25, 95% CI = 1.13 to 1.37].
Significantly means it can be said with a 95% confidence that the highest category of processed meat intake really increased risk of type 2 diabetes with 25%.

The investigators found no association between highest category of poultry intake and risk of type 2 diabetes [summary relative risk = 1.00, 95% CI = 0.93 to 1.07].
No association because summary relative risk of 1 was found in the 95% CI of 0.93 to 1.07. Summary relative risk of 1 means no risk/association.

The investigators found no association between highest category of fish intake and risk of type 2 diabetes [summary relative risk = 1.01, 95% CI = 0.93 to 1.10].

The investigators found in the dose-response analysis, each additional 100g/day of total and red meat and 50g/day of processed meat, were found to be associated with a 36% [95% CI = 1.23 to 1.49], 31% [95% CI = 1.19 to 1.45] and 46% [95% CI = 1.26 to 1.69] increased risk of type 2 diabetes, respectively.

The investigators found, in addition, there was evidence of a non-linear dose-response association between processed meat and type 2 diabetes [p = 0.004], with the risk increasing by 30% with increasing intakes up to 30g/day.

The investigators concluded 100g/day of total meat, 100g/day red meat and 50g/day of processed meat, increase risk of type 2 diabetes.

Original title:
Meat and fish intake and type 2 diabetes: dose-response meta-analysis of prospective cohort studies by Yang X, Li Y, […], Li L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32302686

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

Objectives:
Is there a causal relationship between psyllium (a dietary fiber) consumption and improvements of risk factors of diabetes?

Study design:
This review article included 9 RCTs with 395 participants.

Results and conclusions:
The investigators found psyllium consumption significantly reduced triglycerides levels with 19.18 mg/dL [WMD = -19.18 mg/dL, 95% CI = -31.76 to -6.60, I2 = 98%].

The investigators found psyllium consumption significantly reduced low-density lipoprotein cholesterol levels with 8.96 mg/dL [WMD = -8.96 mg/dL, 95% CI = -13.39 to -4.52, I2 = 97%].

The investigators found psyllium consumption significantly reduced fasting blood sugar levels with 8.96 mg/dL [WMD = -31.71 mg/dL, 95% CI = -50.04 to -13.38, I2 = 97%].

The investigators found psyllium consumption significantly reduced hemoglobin A1c levels with 0.91% [WMD = -0.91%, 95% CI = -1.31 to -0.51, I2 = 99%].

The investigators found no significant change in high-density lipoprotein, body mass index, cholesterol and weight following psyllium consumption.

The investigators concluded there is a significant reduction in triglycerides, low-density lipoprotein cholesterol (bad cholesterol), fasting blood sugar and hemoglobin A1c levels following psyllium consumption among diabetic patients.

Original title:
The effect of psyllium consumption on weight, body mass index, lipid profile, and glucose metabolism in diabetic patients: A systematic review and dose-response meta-analysis of randomized controlled trials by Xiao Z, Chen H, [...], Wei Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31919936

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

Psyllium is a form of fiber made from the husks of the Plantago ovata plant’s seeds. The psyllium husk is a naturally occurring source of soluble fiber.
Psyllium is commonly found in cereals, dietary supplements and is also added to some foods including baked products such as breads, cereal bars and rice/grain cakes.
 

Objectives:
Previous findings on the associations of legume and soy intake with the risk of type 2 diabetes are conflicting. Therefore, this review article (meta-analysis) has been conducted.

Does legume or soy dietary intake reduce risk of type 2 diabetes?

Study design:
This review article included 15 unique cohort studies with a total of 565,810 individuals and 32,093 incident cases (persons with type 2 diabetes).

Overall quality of evidence was rated as moderate for total legumes and low for total soy and soy subtypes.

Results and conclusions:
The investigators found no association between total legumes dietary intake and risk of type 2 diabetes [summary RR = 0.95, 95% CI = 0.79 to 1.14, I2 = 84.8%].
No association because RR of 1 was found in the 95% CI of 0.79 to 1.14. RR of 1 means no risk/association.

The investigators found no association between total soy dietary intake and risk of type 2 diabetes [summary RR = 0.83, 95% CI = 0.68 to 1.01, I2 = 90.8%].

The investigators found no association between soy milk dietary intake and risk of type 2 diabetes [summary RR = 0.89, 95% CI = 0.71 to 1.11, I2 = 91.7%].

The investigators found tofu dietary intake significantly reduced risk of type 2 diabetes with 8% [summary RR = 0.92, 95% CI = 0.84 to 0.99].
Significantly because RR of 1 was not found in the 95% CI of 0.84 to 0.99. RR of 1 means no risk/association.

The investigators found soy protein dietary intake significantly reduced risk of type 2 diabetes with 16% [summary RR = 0.84, 95% CI = 0.75 to 0.95].

The investigators found soy isoflavones dietary intake significantly reduced risk of type 2 diabetes with 12% [summary RR = 0.88, 95% CI = 0.81 to 0.96].

The investigators found in dose-response analysis, significant linear inverse associations for tofu, soy protein and soy isoflavones [all p 0.05].

The investigators concluded dietary intakes of tofu, soy protein and soy isoflavones reduce incident type 2 diabetes. These findings support recommendations to increase intakes of certain soy products for the prevention of type 2 diabetes. However, the overall quality of evidence was low and more high-quality evidence from prospective studies is needed.

Original title:
Legume and soy intake and risk of type 2 diabetes: a systematic review and meta-analysis of prospective cohort studies by Tang J, Wan Y, […], Feng F.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31915830

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

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:
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:
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:
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.

Objectives:
Observationally, homocysteine is associated with higher risk of diabetes. Folate, which reduces homocysteine, is promising for the prevention and treatment of diabetes. Previous meta-analysis (review) of 3 trials suggested folate might lower hemoglobin A1c (HbA1c). Therefore, this review article (meta-analysis) has been conducted.

Have folic acid supplementation positive effects on insulin resistance and glycemic control, like HbA1c level and fasting glucose level?

Study design:
This review article included 18 RCTs with in total of 21,081 people with/without diabetes.

Results and conclusions:
The investigators found that folic acid (folate) supplementation significantly reduced fasting glucose level with 0.15 mmol/L [95% CI = -0.29 to -0.01]. Significant means that there is an association with a 95% confidence.

The investigators found that folic acid (folate) supplementation significantly reduced homeostatic model assessment-insulin resistance (HOMA-IR) with 0.83 [95% CI = -1.31 to -0.34].

The investigators found that folic acid (folate) supplementation significantly reduced fasting insulin level with 1.94 μIU/mL [95% CI = -3.28 to -0.61].

The investigators found that folic acid (folate) supplementation had no clear effect on diabetes or HbA1c level.

The investigators concluded that folic acid (folate) supplementation reduces both fasting glucose level, fasting insulin level and homeostatic model assessment-insulin resistance (HOMA-IR) but it has no effect on diabetes or HbA1c level.

Original title:
The effects of folate supplementation on glucose metabolism and risk of type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials by Zhao JV, Schooling CM and Zhao JX.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29501221

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

Patients with diabetes often have both an increased fasting glucose level, HOMA-IR value and fasting insulin level.

Objectives:
The increasing prevalence of diabetes in the United Kingdom and worldwide calls for new approaches to its management and diets with low glycaemic index have been proposed as a useful means for managing glucose response. However, there are conflicting reports and differences in the results of studies in terms of their effectiveness. Furthermore, the impact of low-glycaemic index diets (low GI-diets) and their long-term use in patients with type 2 diabetes remains unclear. Therefore, this review article (meta-analysis) has been conducted.

Do patients with type 2 diabetes mellitus benefit from low-GI diets?

Study design:
This review article included 6 RCTs.

Results and conclusions:
The investigators found in 2 RCTs that low-glycaemic index (low-GI) diet resulted in a significant improvement in glycated haemoglobin (HbA1c) [0.05]:
low-GI diet Δ = -0.5% [95% CI = -0.61% to -0.39%] vs. high-cereal fibre diet Δ = -0.18% [95% CI = -0.29% to -0.07%] and;
low-GI legume diet Δ = -0.5% [95% = -0.6% to -0.4%] vs. high-wheat fibre diet Δ = -0.3% [95% Cl = -0.4 to -0.2%].

The investigators found in 4 RCTs significant improvements in fasting blood glucose in low-GI diets compared to higher-GI diets or control:
low-GI diet = [150.8 ± 8.7] vs. higher-GI diet = [157.8 ± 10.4 mg/dL, mean ± SD, p = 0.43];
low-GI diet = [127.7] vs. high-cereal fibre diet = [136.8 mg/dL, p = 0.02];
low-GI diet = [6.5 (5.6-8.4)] vs. standard diabetic diet = [6.7 (6.1-7.5 mmol/L), median and interquartile range p > 0.05] and;
low-GI diet = [7.3 ± 0.3] vs. conventional carbohydrate exchange diet = [7.7 ± 0.4 mmol/L, mean ± SEM (Standard Error of Mean), p 0.05].

The investigators concluded that the low-GI diet is more effective in controlling glycated haemoglobin (HbA1c) and fasting blood glucose compared with a higher-GI diet or control in patients with type 2 diabetes. It will useful to evaluate the long-term effectiveness of low-glycaemic index diet in patients with type 2 diabetes.

Original title:
The Effect of Dietary Glycaemic Index on Glycaemia in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Ojo O, Ojo OO, [...], Wang XH.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872791/

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

A low-GI diet is a diet with a lot of products/meals with a low GI.
Products/meals with a low GI are products/meals with a GI-number of 55 or less.
In daily life, products/meals with a low GI contain at least 1.5 grams fiber per 100 kcal. These products and meals contain at least 1.5 grams fiber per 100 kcal.
 

Objectives:
Type 2 diabetes mellitus (T2DM) is one of the most important public health issues. Vitamin K supplementation might have favorable effect on risk factors of T2DM. Therefore, this review article (meta-analysis) has been conducted.

Have vitamin K supplementation favorable effects on risk factors of type 2 diabetes mellitus?

Study design:
This review article included 5 RCTs with in total of 533 participants.

There was no evidence of publication bias.

Results and conclusions:
The investigators found overall, meta-analysis did not show any beneficial effect of vitamin K supplementation on both:
-fasting blood sugar levels [-0.91 mg/dL, 95% CI = -2.57 to 0.76, p = 0.28];
-fasting insulin levels [-0.35 μIU/mL, 95% CI = -1.70 to 1.00, p = 0.61];
-HOMA-IR [-0.06, 95% CI = -0.32 to -0.19, p = 0.63] and
-2-h oral glucose tolerance test [-4.00 mg/dL, 95% CI = -20.00 to 11.99, p = 0.62].

The investigators found sensitivity analysis showed that overall estimates were not affected by elimination of any study.

The investigators concluded that vitamin K supplementation has no significant effect on glycemic control in healthy subjects. However, further studies should be performed on diabetic and pre-diabetic patients to determine the effect of vitamin K supplementation on impaired glycemic control.

Original title:
Effect of Vitamin K Supplementation on Glycemic Control: A Systematic Review and Meta-Analysis of Clinical Trials by Shahdadian F, Mohammadi H and Rouhani M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29523009

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

Objectives:
The actual effects of L-carnitine administration on leptin serum level is inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Does L-carnitine supplementation reduce leptin serum level?

Study design:
This review article included 7 RCTs with 325 cases (group with L-carnitine administration) and 330 controls (group without L-carnitine administration).

Subgroup analysis to find the sources of heterogeneity showed that L-carnitine dosage [ 2 g: I2 = 00.0%, p = 0.408] and study population [diabetes: I2 = 46.7%, p = 0.153 and non-diabetes: I2 = 15.1%, p = 0.317] were the potential sources of heterogeneity.

Results and conclusions:
The investigators found that L-carnitine supplementation had no significant effect on serum leptin concentrations [WMD = -0.565 ng/mL, 95% CI = -2.417 to 1.287, p = 0.550, I2 = 84.3%, p  0.0001].

The investigators found in subgroup analysis that  ≥ 2 mg L-carnitine supplementation significantly reduced serum leptin concentrations [WMD = -2.742 ng/mL, 95% CI = -3.039 to -2.444, p  0.001].

The investigators found in subgroup analysis that L-carnitine supplementation significantly reduced serum leptin concentrations in diabetic patients [WMD = -2.946 ng/mL, 95% CI = -3.254 to -2.638, p  0.001].

The investigators found in subgroup analysis that L-carnitine supplementation during 12 weeks significantly reduced serum leptin concentrations [WMD = -2.772 ng/mL, 95% CI = -3.073 to -2.471, p  0.001].

The investigators concluded that at least 3 mg L-carnitine per day in the course of 12 weeks reduce serum leptin concentrations, especially in diabetic patients.

Original title:
The effect of L-carnitine supplementation on serum leptin concentrations: a systematic review and meta-analysis of randomized controlled trials by Nazary-Vannani A, Ghaedi E, […], Varkaneh HK.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29453657

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

L-carnitine is a non-essential amino acid, which is also found in foods.