Nutrition and health

Objectives:
Does diabetes increase risk of incident dementia and mild cognitive impairment?

Study design:
This review article included 19 prospective longitudinal studies including 6184 subjects with diabetes and 38530 subjects without diabetes. All subjects were without dementia or mild cognitive impairment at baseline (=at the beginning of the study).

There was no publication bias.

Results and conclusions:
The investigators found persons with diabetes had a significant increased risk of 46% for Alzheimer's disease [RR = 1.46, 95% CI = 1.20-1.77]. Significant means that there is an association with a 95% confidence.

The investigators found persons with diabetes had a significant increased risk of 148% for vascular dementia [RR = 2.48, 95% CI = 2.08-2.96].

The investigators found persons with diabetes had a significant increased risk of 51% for any dementia [RR = 1.51, 95% CI = 1.31-1.74]. Significant because RR of 1 was not found in the 95% CI of 1.31 to 1.74. RR of 1 means no risk/association.

The investigators found persons with diabetes had a significant increased risk of 21% for mild cognitive impairment [RR = 1.21, 95% CI = 1.02-1.45].

The investigators concluded diabetes is a risk factor for incident dementia (including Alzheimer's disease, vascular dementia and any dementia) and mild cognitive impairment.

Original title:
Diabetes as a risk factor for dementia and mild cognitive impairment: a meta-analysis of longitudinal studies by Cheng G, Huang G, [...], Wang H.

Link:
http://onlinelibrary.wiley.com/doi/10.1111/j.1445-5994.2012.02758.x/epdf

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

Objectives:
Previous meta-analyses identified an inverse association of coffee consumption with the risk of type 2 diabetes. However, an updated meta-analysis is needed because new studies comparing the trends of association for caffeinated and decaffeinated coffee have since been published. Therefore, this review article has been conducted.

Does coffee intake reduce type 2 diabetes risk in a dose-response manner?

Study design:
This review article included 28 prospective cohort studies with 1109272 study participants and 45335 cases of type 2 diabetes. The follow-up duration ranged from 10 months to 20 years.

Results and conclusions:
The investigators found for compared with no or rare coffee consumption, a significant reduced risk of type 2 diabetes of:
8% [RR = 0.92, 95% CI = 0.90-0.94] for 1 cup/day;
15% [RR= 0.85, 95% CI = 0.82-0.88] for 2 cups/day;
21% [RR = 0.79, 95% CI = 0.75-0.83] for 3 cups/day;
25% [RR = 0.75, 95% CI = 0.71-0.80] for 4 cups/day;
29% [RR = 0.71, 95% CI = 0.65-0.76] for 5 cups/day and;
33% [RR = 0.67, 95% CI = 0.61-0.74] for 6 cups/day.

The investigators found a significant decreased risk of type 2 diabetes of 9% [RR = 0.91, 95% CI = 0.89-0.94] for an increasement of 1 cup/day caffeinated coffee and 6% [RR = 0.94, 95% CI = 0.91-0.98] for an increasement of 1 cup/day decaffeinated coffee [p for difference = 0.17].

The investigators concluded coffee consumption is inversely associated with the risk of type 2 diabetes in a dose-response manner. Both caffeinated and decaffeinated coffee is associated with reduced diabetes risk.

Original title:
Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis by Ding M, Bhupathiraju SN, […], Hu FB.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/24459154

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

Objectives:
The prevalence of obesity and diabetes is increasing among children, adolescents and adults. Although estimates of the efficacy of exercise training on fasting insulin and insulin resistance have been provided for adults, similar estimates have not been provided for youth. Therefore, this review article has been conducted.

Study design:
This review article included 24 trials.

Results and conclusions:
The investigators found a small to moderate effect for exercise training on fasting insulin and improving insulin resistance in youth [Hedges’ d effect size = 0.48, 95% CI = 0.22-0.74, p 0.001 and 0.31, 95% CI = 0.06-0.56, p 0.05, respectively].

The investigators concluded there is evidence to support the use of exercise training in the prevention and treatment of type 2 diabetes in youth.

Original title:
Exercise and Insulin Resistance in Youth: A Meta-Analysis by Fedewa MV, Gist NH, […], Dishman RK.

Link:
http://www.pediatricsdigest.mobi/content/133/1/e163.abstract

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

Objectives:
Reported associations between protein intake from different sources and type 2 diabetes (T2D) have been inconsistent.Therefore, this review article has been conducted.

Study design:
This review article included 11 prospective cohort studies with 505,624 participants and 37,918 type 2 diabetes cases (follow-up range: 5-24 years).

Results and conclusions:
The investigators found for the comparison of the highest with lowest categories of total protein intakes a significant higher risk of 9% for type 2 diabetes [RR = 1.09, 95% CI = 1.06 to 1.13]. Significant means that there is an association with a 95% confidence.

The investigators found for the comparison of the highest with lowest categories of animal protein intakes a significant higher risk of 19% for type 2 diabetes [RR = 1.19, 95% CI = 1.11 to 1.28].

The investigators found for the comparison of the highest with lowest categories of plant protein intakes a non-significant reduced risk of 5% for type 2 diabetes [RR = 0.95, 95% CI = 0.89 to 1.02]. Non-significant means it cannot be said with a 95% confidence that a daily higher intake of plant protein really reduced risk of type 2 diabetes with 5%.

The investigators found for the comparison of the highest with lowest categories of plant protein intakes a significant reduced risk of 7% for type 2 diabetes among women [RR = 0.93, 95% CI = 0.85 to 1.00].

The investigators found for the comparison of the highest with lowest categories of plant protein intakes a significant reduced risk of 9% for type 2 diabetes among US populations [RR = 0.91, 95% CI = 0.84 to 0.97].

The investigators concluded that a higher intake of total and animal protein are both associated with an increased risk of of type 2 diabetes. However, a higher intake of plant protein decreases risk of type 2 diabetes among women and US populations.

Original title:
Dietary protein intake and risk of type 2 diabetes: results from the Melbourne Collaborative Cohort Study and a meta-analysis of prospective studies by Shang X, Scott D, […], Sanders KM.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/27629053

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

Objectives:
C-reactive protein (CRP) has been proposed as a risk marker and risk factor of cardiovascular disease. There have been a number of clinical reports suggesting that supplementation with L-carnitine can modulate systemic inflammation and lower circulating CRP concentrations, but the results have not been consistent. Therefore, this review article (meta-analysis) has been conducted.

Does supplementation with L-carnitine reduce circulating CRP concentrations?

Study design:
This review article included 6 RCTs comprising 541 cases and 546 controls.
3 studies were conducted in diabetic or prediabetic patients, 2 studies in hemodialysis patients and 1 study in patients with non-alcoholic steatohepatitis.
Duration of L-carnitine supplementation ranged between 8 to 48 weeks.
Dosage of L-carnitine ranged between 1-2 g/day in all the included trials.

Results and conclusions:
The investigators found in random effect analysis a statistically significant pooled effect size [net change = -0.39 mg/L, 95% CI = -0.62 to -0.16, p = 0.001, I2 = 44%, p = 0.11] for the impact of L-carnitine supplementation among 541 cases and 546 controls. This effect size estimate was found to be robust and remained unaffected by the removal of each single study.

The investigators concluded the present meta-analysis support the clinically relevant benefit of L-carnitine supplementation (1-2 g/day) in lowering the circulating levels of CRP. Conducting future, large-scale, randomized clinical trials is warranted in homogenous populations to verify the findings of this meta-analysis.

Original title:
Effect of L-carnitine Supplementation on Circulating C-reactive Protein Levels: A Systematic Review and Meta-Analysis by Sahebkar A.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4922328/

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

Higher circulating levels of CRP increase inflammation.
 

Objectives:
The aim of this review article (meta-analysis) was to assess the clinical efficacy and safety of oral ginger for symptomatic treatment of osteoarthritis (OA).

Study design:
This review article included 5 RCTs with in total 593 patients.

The average age of the patients ranged from 47 years to 66 years and the percentage of women included in the studies ranged from 26% to 80%.
The dose of oral administration of ginger ranged from 500 mg/day to 1000 mg/day.
Trial duration ranged from 3 to 12 weeks.

Results and conclusions:
The investigators found compared to placebo, ginger intake significantly reduced pain [SMD = -0.30, 95% CI = -0.50 to -0.09, p = 0.005, I2 = 27%].

The investigators found compared to placebo, ginger intake showed a statistically significant reduction in disability [SMD = -0.22, 95% CI = -0.39 to -0.04, p = 0.01, I2 = 0%].

The investigators found patients given ginger were more than twice as likely to discontinue (due to adverse events) treatment compared to placebo [RR = 2.33, 95% CI = 1.04 to 5.22, p = 0.04, I2 = 0%].

The investigators concluded that 500-1000 mg/day oral ginger intake is able to reduce pain and disability in osteoarthritis patients.

Original title:
Efficacy and safety of ginger in osteoarthritis patients: a meta-analysis of randomized placebo-controlled trials by Bartels EM, Folmer VN, […], Christensen R.

Link:
http://www.oarsijournal.com/article/S1063-4584(14)01276-X/pdf

Additional information of El Mondo:
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Objectives:
The aim of this review article was to evaluate the diagnostic accuracy of ultrasound in assessing active Crohn’s disease (CD) in adults.

Study design:
This meta-analysis included 15 studies involving 1558 adults with active Crohn’s disease.

Results and conclusions:
The investigators found overall, the pooled sensitivity (0.88) and LR- (0.14) were not heterogeneous, whereas the pooled specificity [0.97, I2 = 72.9%] and LR + [15.10, I2 = 71.8 %] were.

The investigators found the DOR of ultrasound for assessing active CD was 121.70, with significant heterogeneity (I2 = 63.3%).
A symmetrical summary ROC curve was plotted showing that the area under the curve was 0.94, indicating good diagnostic accuracy.

The investigators found meta-regression and subgroup analysis showed that the disease location may be a major cause of heterogeneity.

The investigators concluded ultrasound has high diagnostic accuracy in detecting active Crohn’s disease in adults, especially for small bowel Crohn’s disease.

Original title:
Ultrasound as a diagnostic tool in detecting active Crohn’s disease: a meta-analysis of prospective studies by Dong J, Wang H, [...], Li J.

Link:
http://link.springer.com/article/10.1007/s00330-013-2973-0

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

Objectives:
Garlic is a common spicy flavouring agent also used for certain therapeutic purposes. Garlic's effects on blood glucose have been the subject of many clinical and animal studies. However, studies reporting hypoglycemic effects of garlic in humans are conflicting. Therefore, this review article (meta-analysis) has been conducted.

Has garlic supplementation lowering effects on glycemic control measurements such as fasting blood glucose (FBG), postprandial glucose (PPG) and glycated haemoglobin (HbA1c)?

Study design:
This review article included a total of 7 RCTs (parallel design) that involved 9 comparisons with 513 subjects. The trials varied in size from 33 to 180 subjects. The study duration varied from 4 to 24 week (median: 12 week). The trials enrolled male and female subjects, both healthy and with diabetes.

Doses of garlic in the treatment group ranged from 600 to 1500 mg/d.

Results and conclusions:
The investigators found pooled analyses showed that garlic supplementation resulted in a statistically significant lowering in fasting blood glucose [SMD = -1.67, 95% CI = -2.80 to -0.55, p = 0.004].

The investigators could not perform a pooled analyse for postprandial glucose (PPG) control and glycosylated haemoglobin (HbA1c) outcomes, because only 1 study included in the meta-analysis reported PPG variables and only 2 studies reported HbA1c variables.

The investigators concluded that garlic supplementation (600 to 1500 mg/d) during 12 weeks results in a lowering in fasting blood glucose. More trials are needed to investigate the effectiveness of garlic on HbA1c and PPG.

Original title:
Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials by Hou LQ, Liu YH and Zhang YY.

Link:
http://apjcn.nhri.org.tw/server/APJCN/24/4/575.pdf

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

Objectives:
Is there a causal association between low serum vitamin D concentrations, increased body mass index (BMI) and pediatric-onset multiple sclerosis (MS) using genetic risk scores (GRS)?

Study design:
This review article included participants of non-Hispanic white individuals recruited from over 15 sites across the United States (n = 394 cases, 10,875 controls) and Sweden (n = 175 cases, 5,376 controls; total n = 16,820).

Results and conclusions:
The investigators found meta-analysis findings demonstrated that a vitamin D GRS associated with increasing levels of 25(OH)D in serum significantly decreased risk of pediatric-onset MS with 28% [OR =  0.72, 95% CI = 0.55-0.94, p = 0.02] after controlling for sex, genetic ancestry, HLA-DRB1*15:01 and over 100 non-human leukocyte antigen MS risk variants.

The investigators also found that a higher BMI GRS significant increased risk of pediatric-onset MS with 17% [OR = 1.17, 95% CI = 1.05-1.30, p = 0.01] after adjusting for covariates.

The investigators found estimates for each GRS were unchanged when considered together in a multivariable model.

The investigators concluded evidence supporting independent and causal effects of decreased vitamin D levels and increased BMI on susceptibility to pediatric-onset MS.

Original title:
Evidence for a causal relationship between low vitamin D, high BMI, and pediatric-onset MS by Gianfrancesco MA, Stridh P, […], Waubant E.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28356466

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

Objectives:
What is the relationship between intake of 12 major food groups and risk of type 2 diabetes (T2D)?

Study design:
This review article included prospective cohort studies.
The 12 major food groups are whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy, fish, red meat, processed meat and sugar-sweetened beverages (SSB).

The meta-evidence was graded "low" for legumes and nuts; "moderate" for refined grains, vegetables, fruit, eggs, dairy and fish; and "high" for processed meat, red meat, whole grains and sugar-sweetened beverages.

Results and conclusions:
The investigators found 6 out of the 12 food-groups showed a significant relation with risk of type 2 diabetes; 3 of them a decrease of risk with increasing consumption (whole grains, fruits and dairy) and 3 an increase of risk with increasing consumption (red meat, processed meat and sugar-sweetened beverages) in the linear dose-response meta-analysis.

The investigators found evidence of a non-linear relationship between fruits, vegetables, processed meat, whole grains and sugar-sweetened beverages and type 2 diabetes risk.

The investigators found optimal consumption of risk-decreasing foods resulted in a 42% reduction and consumption of risk-increasing foods was associated with a threefold type 2 diabetes risk, compared to non-consumption.

The meta-evidence was graded "low" for legumes and nuts; "moderate" for refined grains, vegetables, fruit, eggs, dairy and fish; and "high" for processed meat, red meat, whole grains, and sugar-sweetened beverages. Among the investigated food groups, selecting specific optimal intakes can lead to a considerable change in risk of type 2 diabetes.

The investigators concluded that a higher consumption of whole grains, fruits and dairy products reduces type 2 diabetes risk, while a higher consumption of red meat, processed meat and sugar-sweetened beverages increases type 2 diabetes risk.

Original title:
Food groups and risk of type 2 diabetes mellitus: a systematic review and meta-analysis of prospective studies by Schwingshackl L, Hoffmann G, […], Boeing H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28397016

Additional information of El Mondo:
Find more information/studies on consumption of meat, fruit, dairy products and nuts and type 2 diabetes right here.

Objectives:
Olive oil (OO) as food is composed mainly of fatty acids and bioactive compounds depending from the extraction method. Both had been discussed as health promoting with still open questions. Therefore, this meta-analysis (systematic review) has been conducted.

Does olive oil intake reduce risk of type 2 diabetes?

Study design:
This review article included 4 cohort studies including 15,784 type 2 diabetes cases and 29 intervention trials.

Results and conclusions:
The investigators found the highest olive oil intake category showed a 16% reduced risk of type 2 diabetes [RR = 0.84, 95% CI = 0.77, 0.92) compared with the lowest. The reduced risk was significant.

The investigators found evidence for a nonlinear relationship between olive oil intake and the reduced risk of type 2 diabetes.

The investigators found in patients with type 2 diabetes that olive oil supplementation resulted in a significantly more pronounced reduction in HbA1c [MD = -0.27%, 95% CI = -0.37 to -0.17] and fasting plasma glucose [MD = -0.44 mmol/L, 95% CI = -0.66 to -0.22] as compared with the control groups.

The investigators concluded that the intake of olive oil is beneficial for the prevention and management of type 2 diabetes. This conclusion regards olive oil as food and might not been valid for single components comprising this food.

Original title:
Olive oil in the prevention and management of type 2 diabetes mellitus: a systematic review and meta-analysis of cohort studies and intervention trials by Schwingshackl L, Lampousi AM, […], Boeing H1.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28394365

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

Objectives:
Nutrition therapy is an integral part of self-management education in patients with type 2 diabetes. Carbohydrates with a low glycemic index are recommended, but the ideal amount of carbohydrate in the diet is unclear. Therefore, this meta-analysis (systematic review) has been conducted.

Has carbohydrate restriction (below 45 En% carbohydrate) beneficial effects on glycemic control in type 2 diabetes?

Study design:
This review article included 10 RCTs. In total, 1,376 subjects with type 2 diabetes were included in this analysis. Forty-nine percent were male and the average age was 58 years. The majority were obese; mean BMI ranged from 26 kg/m² in an Asian population to 37 kg/m² in an American population.

The duration of the intervention varied from 3 to 24 months.

The average predefined targets for the assigned carbohydrate restriction were 25 En% (range 14-40 En%). The average reported intake was 30 En% (range 14-45 En%) after 3 or 6 months of intervention and 38 En% (range 27-45 En%) at 1 year (5 trials).

Results and conclusions:
The investigators found following a carbohydrate diet of 30 En% (range 14-45 En%) during 3 to 6 months significantly reduced HbA1c level of patients with type 2 diabetes with 0.34% [95% CI = 0.06 to 0.63] compared with a diet of 45-60 En% carbohydrate (high-carbohydrate diet).
Owing to heterogeneity, however, the quality of the evidence for this is only moderate. However, at 1 year or later, HbA1c level (seven trials included) was similar in the two groups.

The investigators found the greater the carbohydrate restriction, the greater the glucose-lowering effect [R = -0.85, p 0.01].

The investigators found the effect of the 2 types of diet on BMI/body weight, LDL cholesterol, QoL and attrition rate was similar throughout interventions.

The investigators concluded that carbohydrate restriction (below 45 En% carbohydrate) has a greater effect on glycemic control in type 2 diabetes than an high-carbohydrate diet in the short term. The magnitude of the effect was correlated to the carbohydrate intake, the greater the restriction, the greater glucose lowering, a relationship that has not been demonstrated earlier. However, in the long term, the glucose-lowering effect of high-carbohydrate diet (HCD) and low-carbohydrate diets (LCD) was similar.

Original title:
Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes by Snorgaard O, Poulsen GM, [...], Astrup A.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337734/

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

Objectives:
Recent studies have found that the serum zinc levels were associated with the risk of Parkinson's disease (PD), but the results were inconsistent. Therefore, this meta-analysis (review article) has been conducted.

Is there an association between serum zinc levels and Parkinson's disease risk?

Study design:
This review article included 11 articles involving 822 Parkinson's disease patients and 777 healthy controls (subjects without Parkinson's disease).

No publication bias was found.

Results and conclusions:
The investigators found that the serum zinc levels in Parkinson's disease patients were significantly lower than those in health controls [SMD = -0.779, 95% CI = -1.323 to -0.234, p 0.001].

This association was also significant in oriental studies [SMD = -1.601, 95% CI = -2.398 to -0.805, p 0.001].

The investigators concluded that serum zinc levels in Parkinson's disease patients are significantly lower than those in healthy controls.

Original title:
Association Between Serum Zinc Levels and the Risk of Parkinson's Disease: a Meta-Analysis by Sun H, Liu X, […], Li W.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28160244

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

Objectives:
Randomised controlled trials (RCTs) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation. Therefore, this meta-analysis (systematic review) has been conducted.

Has vitamin C supplementation a favorable effect on circulating biomarkers of glycaemic and insulin regulation?

Study design:
This review article included 22 RCTs with 937 participants.

Results and conclusions:
The investigators found overall, vitamin C supplementation did not modify glucose, HbA1c and insulin concentrations.

The investigators found, however, subgroup analyses showed that vitamin C supplementation significantly reduced glucose concentrations with 0.44 mmol/L [95% CI = -0.81 to -0.07, p =0.01] in patients with type 2 diabetes and in interventions with a duration greater than 30 days [-0.53%, 95% CI = -0.79 to -0.10, p = 0.02].

The investigators found vitamin C administration had greater effects on fasting [-13.63 pmol/L, 95% CI = -22.73 to -4.54, p 0.01] compared to postprandial insulin concentration. However, meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration.

The investigators found the effect size of vitamin C supplementation was associated with baseline BMI and plasma glucose levels and with the duration of the intervention.

The investigators concluded vitamin C supplementation has greater reduction in glucose concentrations in patients with type 2 diabetes, older individuals and with more prolonged supplementation (greater than 30 days). Personalized interventions with vitamin C may represent a feasible future strategy to enhance benefits and efficacy of interventions. Nevertheless, results need to be interpreted cautiously due to limitations in the primary studies.

Original title:
Effects of vitamin C supplementation on glycaemic control: a systematic review and meta-analysis of randomised controlled trials by Ashor AW, Werner AD, […], Siervo M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28294172

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

Objectives:
Does magnesium supplementation reduce risk of cardiovascular disease among diabetic subjects?

Study design:
This review article included RCTs.

Results and conclusions:
The investigators found magnesium supplementation significantly improved fasting plasma glucose with 4.641 mg/dL [WMD = -4.641 mg/dL, 95% CI = -7.602 to -1.680, p = 0.002]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved high-density lipoprotein (HDL or good cholesterol) with 3.197 mg/dL [WMD = 3.197 mg/dL, 95% CI = 1.455 to 4.938, p 0.001]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved low-density lipoprotein (LDL or bad cholesterol) with 10.668 mg/dL [WMD = -10.668 mg/dL, 95% CI = -19.108 to -2.228, p = 0.013]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved plasma triglycerides with 15.323 mg/dL [WMD = -15.323 mg/dL, 95% CI = -28.821 to -1.826, p = 0.026]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators found magnesium supplementation significantly improved systolic blood pressure with 3.056 mmHg [WMD = 3.056 mmHg, 95% CI = -5.509 to -0.603, p = 0.015]. A more beneficial effect of magnesium supplementation was observed in diabetic subjects with hypomagnesaemia.

The investigators concluded magnesium supplementation has a favourable effect on risk factors of cardiovascular diseases. Although future large RCTs are needed for making robust guidelines for clinical practice.

Original title:
Effect of magnesium supplementation on type 2 diabetes associated cardiovascular risk factors: a systematic review and meta-analysis by Verma H and Garg R.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28150351

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Objectives:
The conclusions from epidemiological studies are controversial between apple and pear consumption and type 2 diabetes mellitus (T2DM) risk. Therefore, this meta-analysis (systematic review) has been conducted.

Study design:
This review article included a total of 5 independent prospective cohort studies with 14,120 T2DM incident cases among 228,315 participants.

Results and conclusions:
The investigators found consumption of apples and pears was associated with 18% reduction in type 2 diabetes mellitus risk [multivariate-adjusted relative risk = 0.82, 95% CI = 0.75-0.88, I2 = 0.00%] when comparing the highest versus lowest category.

The investigators found dose-response analysis showed that one serving per week increment of apple and pear consumption was associated with a 3% [95% CI = 0.96-0.98, p for trend 0.001] reduction in type 2 diabetes mellitus risk.

The investigators concluded a higher consumption of apples and pears; at least one serving per week reduces type 2 diabetes mellitus risk.

Original title:
Apple and pear consumption and type 2 diabetes mellitus risk: a meta-analysis of prospective cohort studies by Guo XF, Yang B, […], Li D.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28186516

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

The standard serving size is a 1/2 cup of sliced fruit. A medium pear produces approximately 1 cup of fruit; so an average medium pear equals two fruit servings.
1 small apple = 1 serving.
 

Objectives:
Does niacine supplementation reduce blood lipids levels in patients with type 2 diabetes mellitus?

Study design:
This review article included randomized controlled trials.

The meta-analysis showed the absence of publication bias and any dose-response relations between niacin and effect size.

There was a significant heterogeneity for the impact of niacin on LDL cholesterol and fasting plasma glucose.

Results and conclusions:
The investigators found niacin supplementation significantly increased HDL cholesterol with 0.27 mmol/L [95% CI = 0.24 to 0.30, p 0.001] in patients with type 2 diabetes mellitus.

The investigators found niacin supplementation significantly reduced LDL cholesterol with 0.250 mmol/L [95% CI = -0.47 to -0.03, p 0.05] in patients with type 2 diabetes mellitus.

The investigators found niacin supplementation significantly reduced triglycerides with 0.39 mmol/L [95% CI = -0.43 to -0.34, p 0.001] in patients with type 2 diabetes mellitus.

The investigators found niacin supplementation significantly increased fasting plasma glucose with 0.085 mmol/L [95% CI = 0.029 to 0.141, p 0.05] compared with controls in patients with long term treatment.

The investigators concluded niacin alone or in combination improves lipid abnormalities in patients with type 2 diabetes mellitus, but requires monitoring of glucose in long term treatment.

Original title:
Effect of niacin on lipids and glucose in patients with type 2 diabetes: A meta-analysis of randomized, controlled clinical trials by Ding Y, Li Y and Wen A.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/25306426

Additional information of El Mondo:
Find more information on niacin (vitamin B3) and diabetes.

Objectives:
Observational studies suggest an association between dietary fiber intake and risk of type 2 diabetes, but the results are inconclusive. Therefore, this review article (meta-analysis) has been conducted.

Does dietary fiber intake reduce risk of type 2 diabetes?

Study design:
This review article included 17 prospective cohort studies of dietary fiber intake and risk of type 2 diabetes involving 19,033 cases and 488,293 participants.

Results and conclusions:
The investigators found total dietary fiber intake significantly reduced risk of type 2 diabetes with 19% [combined RR = 0.81, 95% CI = 0.73-0.90].

The investigators found dietary cereal fiber intake significantly reduced risk of type 2 diabetes with 23% [combined RR = 0.77, 95% CI = 0.69-0.85].

The investigators found dietary fruit fiber intake significantly reduced risk of type 2 diabetes with 6% [combined RR = 0.94, 95% CI = 0.88-0.99].

The investigators found dietary insoluble fiber intake significantly reduced risk of type 2 diabetes with 25% [combined RR = 0.75, 95% CI = 0.63-0.89].

The investigators found a nonlinear relationship of total dietary fiber intake with risk of type 2 diabetes [p for nonlinearity 0.01].

The investigators found dietary fiber intake of 15g per day non-significantly reduced risk of type 2 diabetes with 2% [combined RR = 0.98, 95% CI = 0.90-1.06].

The investigators found dietary fiber intake of 20g per day non-significantly reduced risk of type 2 diabetes with 3% [combined RR = 0.97, 95% CI = 0.87-1.07].

The investigators found dietary fiber intake of 25g per day significantly reduced risk of type 2 diabetes with 11% [combined RR = 0.89, 95% CI = 0.80-0.99].

The investigators found dietary fiber intake of 30g per day significantly reduced risk of type 2 diabetes with 24% [combined RR = 0.76, 95% CI = 0.65-0.88].

The investigators found dietary fiber intake of 35g per day significantly reduced risk of type 2 diabetes with 34% [combined RR = 0.66, 95% CI = 0.53-0.82].

The investigators found that the risk of type 2 diabetes decreased by 6% [combined RR = 0.94, 95% CI = 0.93-0.96] for 2 g/day increment in cereal fiber intake.

The investigators concluded that the intakes of dietary fiber, at least 25g total dietary fiber intake per day reduce risk of type 2 diabetes.

Original title:
Dietary fiber intake and risk of type 2 diabetes: a dose–response analysis of prospective studies by Yao B, Fang H, […], Zhao Y.

Link:
http://link.springer.com/article/10.1007/s10654-013-9876-x

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Objectives:
Is there an association between folate level and the risk of schizophrenia?

Study design:
This review article included 16 high quality studies with a total of 1,183 (52.1%) cases and 1,089 (47.9%) controls.

There was no publication bias based on Egger’s and Begg’s tests [p = 0.48 and 0.30, respectively].

Results and conclusions:
The investigators found folate level in schizophrenia patients was significantly lower than that in healthy controls [SMD = -0.65, 95% CI = -0.86 to -0.45, p 0.00001].

The investigators found in subgroup analysis a decreased folate level in both Asian and European patients (SMD = -0.86, p 0.00001 and SMD = -0.44, p 0.00001, respectively], while there were no significant differences in patients from other areas [p > 0.05].

The investigators found sensitivity analysis confirmed that these results were stable and reliable.

The investigators concluded decreased folate level is a risk factor for schizophrenia, especially in Asian and European patients. More epidemiological and biochemistry studies are required to describe how folate or folate supplementation play roles in the progress of schizophrenia.

Original title:
Folate Deficiency Increased the Risk of Schizophrenia: a Meta-Analysis by Ding Y, Ju M, […], He L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28124599

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The folate level of the human body can be increased by dietary folate intake and/or taking folate supplements.

Objectives:
The association between serum folate and vitamin B12 levels and the risk of diabetic peripheral neuropathy (DPN) remains unclear. Therefore, this review article (meta-analysis) has been conducted.

Do reduced serum levels of folate and vitamin B12 increase peripheral neuropathy risk among patients with type 2 diabetes?

Study design:
This review article included 16 studies of serum folate levels (1190 patients with diabetic peripheral neuropathy and 1501 patients without diabetic peripheral neuropathy) and 18 studies of serum vitamin B12 levels (1239 patients with diabetic peripheral neuropathy and 1562 patients without diabetic peripheral neuropathy) in patients with type 2 diabetes mellitus (T2DM).

Results and conclusions:
The investigators found reduced serum levels of folate in patients with type 2 diabetes and diabetic peripheral neuropathy compared with patients with type 2 diabetes but without diabetic peripheral neuropathy [WMD = -1.64, 95% CI = -2.46 to -0.81].
A subgroup analysis confirmed this association in the Chinese population, but not in the Caucasian and mixed populations.

The investigators found reduced serum levels of vitamin B12 in patients with type 2 diabetes and diabetic peripheral neuropathy compared with patients with type 2 diabetes but without diabetic peripheral neuropathy [WMD = -70.86, 95% CI = -101.55 to -40.17].
A subgroup analysis confirmed this association in the Chinese population, but not in the Caucasian and mixed populations.

The investigators concluded reduced serum levels of folate and vitamin B12 increase peripheral neuropathy risk among patients with type 2 diabetes. These findings support the need for further controlled studies in defined patient populations and the importance of monitoring serum folate and vitamin B12 levels in patients with type 2 diabetes.

Original title:
Serum folate, vitamin B12 levels and diabetic peripheral neuropathy in type 2 diabetes: A meta-analysis by Wang D, Zhai JX and Liu DW.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28081987

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Diabetic peripheral neuropathy is a long-term complication of diabetes. Exposure to high blood glucose levels over an extended period of time causes damage to the peripheral nerves; the nerves that go to the arms, hands, legs and feet. It is one of many complications associated with diabetes, with nearly 60 percent of diabetics having some form of nerve damage.

Objectives:
Is there an association between individual micronutrients and blood pressure in patients with type 2 diabetes?

Study design:
This review article included 11 RCTs (13 interventions, 723 patients with type 2 diabetes and ages ranging from 50.7 to 66.8 years and 54% of them were males. The duration of diabetes varied from 4.6 to 8.6 years) with 3 to 52 weeks of follow-up were classified according to the type of micronutrient intervention: sodium (n = 1), vitamin C (n = 2), vitamin D (n = 7) and magnesium (n = 1).
Only a meta-analysis of vitamin C and D was able to perform with the available data.

Results and conclusions:
The investigators found vitamin C significantly reduced diastolic blood pressure of patients with type 2 diabetes with 2.88mmHg [WMD = -2.88 mmHg, 95% CI = -5.31 to -0.46, p = 0.020].
However, vitamin C not significantly reduced systolic blood pressure [WMD = -3.93mmHg, 95% CI = -14.78 to 6.92, p = 0.478].
Significant means that there is an association with a 95% confidence.

The investigators found vitamin D significantly reduced diastolic blood pressure of patients with type 2 diabetes with 2.44mmHg [WMD = -2.44 mmHg, 95% CI = -3.49 to -1.39, p  0.001].

The investigators found vitamin D significantly reduced systolic blood pressure of patients with type 2 diabetes with 4.56mmHg [WMD = -4.56 mmHg, 95% CI = -7.65 to -1.47, p = 0.004].

The investigators concluded vitamin D and possibly vitamin C have beneficial effects on blood pressure in patients with type 2 diabetes. Therefore, these interventions might represent a novel approach to the treatment of hypertension in patients with type 2 diabetes.

Original title:
Effects of individual micronutrients on blood pressure in patients with type 2 diabetes: a systematic review and meta-analysis of randomized clinical trials by de Paula TP, Kramer CK, [...], Azevedo MJ.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5233957/

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Objectives:
Has coenzyme Q10 supplementation lowering effects on inflammatory mediator C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α)?

Study design:
This review article included 17 RCTs.

Results and conclusions:
The investigators found coenzyme Q10 supplementation significantly reduced the levels of circulating CRP with 0.35 mg/L [95% CI = -0.64 to -0.05, p = 0.022].
The results of meta-regression showed that the changes of CRP were independent of baseline CRP, treatment duration, dosage and patients characteristics.

The investigators found coenzyme Q10 supplementation significantly reduced the levels of circulating IL-6 with 1.61 pg/mL [95% CI = -2.64 to -0.58, p = 0.002].
In the meta-regression analyses, a higher baseline IL-6 level was significantly associated with greater effects of coenzyme Q10 on IL-6 levels [p for interaction = 0.006].

The investigators found coenzyme Q10 supplementation significantly reduced the levels of circulating TNF-α with 0.49 pg/mL [95% CI = -0.93 to -0.06, p = 0.027].

The investigators concluded coenzyme Q10 supplementation has lowering effects on CRP, IL-6 and TNF-α. However, these results should be interpreted with caution because of evidence of heterogeneity between studies and limited number of studies.

Original title:
Effects of coenzyme Q10 supplementation on inflammatory markers: A systematic review and meta-analysis of randomized controlled trials by Fan L, Feng Y, […], Chen LH.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28179205

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Objectives:
The associations between dietary zinc and iron intake and risk of depression remain controversial. Therefore, this meta-analysis (systematic review) has been conducted.

Do dietary zink and iron intake decrease risk of depression?

Study design:
This review article included a total of 9 studies for dietary zinc intake and 3 studies for dietary iron intake. 

Results and conclusions:
The investigators found for the highest versus lowest dietary zinc a significant reduced risk of 33% [pooled RR = 0.67, 95% CI = 0.58-0.76] for depression.

The investigators found for the highest versus lowest dietary iron a significant reduced risk of 43% [pooled RR = 0.57, 95% CI = 0.34-0.95] for depression.

The investigators found in subgroup analysis by study design, the inverse association between dietary zinc intake and risk of depression remained significant in cohort studies and cross-sectional studies.

The investigators found the pooled RRs (95% CIs) for depression did not substantially change in the influence analysis and subgroup analysis by adjustment for body mass index (BMI).

The investigators concluded dietary zinc intake reduces risk of depression.

Original title:
Dietary zinc and iron intake and risk of depression: A meta-analysis by Li Z, Li B, [...], Zhang D.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28189077

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Objectives:
Arthritis patients often take fish oil supplements to alleviate symptoms, but limited evidence exists regarding their efficacy. Therefore, this meta-analysis (systematic review) has been conducted.

Do taking marine oil supplements alleviate pain in arthritis patients?

Study design:
This review article included 42 randomized trials; 30 trials reported complete data on pain.

The trials used treatment durations from 2 weeks to 18 months, with doses of EPA from 0.013 to 4.050 g/day and doses of DHA from 0.010 to 2.700 g/day.
Most trials used marine oil from whole fish, but some used cod liver oil, mussel extracts, seal oil and krill oil.

The trials included 2751 patients with a mean age of 53.8 years (range of mean age of 10-68 years) and the mean disease duration was 9.7 years (range 2.3-19.0 years).

Results and conclusions:
The investigators found a favorable effect [SMD = -0.24, 95% CI = -0.42 to -0.07, I2 = 63%] for using marine oil supplements.

The investigators found in 22 trials a significant effect in patients with rheumatoid arthritis [SMD = -0.21, 95% CI = -0.42 to -0.004] for using marine oil supplements.

The investigators also found in 3 trials a significant effect for other or mixed diagnoses [SMD = -0.63, 95% CI = -1.20 to -0.06] for using marine oil supplements, but no significant effect was found in osteoarthritis patients [5 trials: SMD = -0.17, 95% CI = -0.57 to 0.24].

The investigators found a significant, beneficial effect on pain for marine oil with an EPA/DHA ratio >1.5.

The investigators found a significant positive association between SMD and total dose of EPA and DHA [slope β, 0.13 (g/day), 95% CI = 0.04 to 0.22, p = 0.006], indicating less effect at higher dose, but there was no duration-response relationship [p = 0.568].

The investigators concluded using marine oil supplements (with an EPA/DHA ratio >1.5) alleviates pain in rheumatoid arthritis patients.

Original title:
Marine Oil Supplements for Arthritis Pain: A Systematic Review and Meta-Analysis of Randomized Trials by Senftleber NK, Nielsen SM, […], Christensen R.

Link:
http://www.mdpi.com/2072-6643/9/1/42/htm

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Objectives:
The role of vitamin D status in the etiology of allergic diseases is uncertain. Therefore, this meta-analysis (systematic review) has been conducted.

Study design:
This review article included a total of 21 observational studies.

Results and conclusions:
The investigators found children with serum 25(OH)D ≥75 nmol/L had significantly reduced odds of aeroallergen sensitization, but neither vitamin D intake during pregnancy nor vitamin D supplementation in infancy were associated with risk of allergic rhinitis.

The investigators found compared to those with serum 25(OH)D 50 nmol/L, individuals with serum 25(OH)D ≥75 nmol/L had a significant decreased risk of 29% [OR = 0.71, 95% CI = 0.56-0.89, p = 0.04] for allergic rhinitis.
However, this association was mainly observed in adult men; prevalence of allergic rhinitis (AR) was lower in men with serum 25(OH)D ≥75 nmol/L compared to men with serum 25(OH)D 50 nmol/L, while this association was not observed in women.

The investigators concluded serum 25(OH)D ≥75 nmol/L reduced odds of aeroallergen sensitization in children and risk of allergic rhinitis in men.

Original title:
Vitamin D status, aeroallergen sensitization, and allergic rhinitis: A systematic review and meta-analysis by Aryan Z, Rezaei N and Camargo CA Jr.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28102718

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