Nutrition and health

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:
Prostate cancer (PCa) is one of the leading cause cancer among men worldwide. Many epidemiologic studies have reported an association between carbohydrate intake and prostate cancer. However, the evidence from epidemiologic studies is inconsistent. Therefore, this review article has been conducted.

Does carbodydrate intake increase prostate cancer risk?

Study design:
This review article included 21 studies published from 1980 to 2018, including 98,739 participants and 11,573 cases (persons with prostate cancer).

Multivariate-adjusted odds ratios (ORs) were pooled using random-effect models.

Results and conclusions:
The investigators found no association between higher carbohydrate intake and prostate cancer risk [OR =1.11, 95% CI = 0.98-1.26, I2 = 62.7%].
No association because OR of 1 was found in the 95% CI of 0.98 to 1.26. RR of 1 means no risk/association.

The investigators found no association between higher carbohydrate intake and advanced prostate cancer risk [OR = 0.95, 95% CI = 0.78-1.16, I2 = 14.1%].

The investigators found no association between higher carbohydrate intake and non-advanced prostate cancer risk [OR = 1.01, 95% CI = 0.79-1.29, I2 = 64.4%].

The investigators found there was not a significant dose-response association observed for carbohydrate intake with prostate cancer risk and advanced prostate cancer risk.

The investigators concluded that there is no association between carbohydrate intake and prostate cancer risk. Nor is association detected about carbohydrate intake with advanced or non-advanced prostate cancer risk. More studies are needed for a further dose-response meta-analysis.

Original title:
Carbohydrate intake and the risk of prostate cancer by Fan LL, Su HX, […], Nan CJ.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29778541

Additional information of El Mondo:
Find more information/studies on cancer and carbohydrate right here.

Objectives:
Several epidemiological studies have assessed the ability of vitamin B2 to prevent colorectal cancer (CRC), but the results are controversial. Therefore, this review article has been conducted.

Does vitamin B2 intake reduce colorectal cancer risk?

Study design:
This review article included a total of 14 studies reporting vitamin B2 intake and 2 studies reporting blood vitamin B2 concentration, comprising 14,934 cases (persons with colorectal cancer) and 1,593 cases (persons with colorectal cancer), respectively.

Results and conclusions:
The investigators found in pooled analysis a significantly reduced risk of 13% [RR = 0.87, 95% CI = 0.81-0.93] for colorectal cancer for vitamin B2 intake.
Significant means that there is an association with a 95% confidence.

The investigators found in subgroup analysis a significantly reduced risk of 14% [RR = 0.86, 95% CI = 0.78-0.94] for colorectal cancer for vitamin B2 intake from diet and supplements.

The investigators found in subgroup analysis a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.82-0.98] for colorectal cancer for dietary vitamin B2 intake.

The investigators found the dose-response model indicated a non-linear trend and colorectal cancer risk was reduced by 10% when vitamin B2 intake increased to 5 mg/day.

The investigators found that high blood concentrations of vitamin B2 significantly reduced the colorectal cancer risk with 26% [RR = 0.74, 95% CI = 0.59-0.92].

The investigators concluded that both higher vitamin B2 intake (5 mg per dag) and higher blood vitamin B2 concentration reduce colorectal cancer risk. These results suggest the importance of vitamin B2 intake in the prevention of colorectal cancer.

Original title:
Vitamin B2 intake reduces the risk for colorectal cancer: a dose-response analysis by Ben S, Du M, [...], Wang M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29744609

Additional information of El Mondo:
Find more information/studies on vitamin B2 and colorectal cancer right here.

Objectives:
Is there an association between wine consumption and prostate cancer risk?

Study design:
This review article included 6 cohort and 8 case-control studies with a total of 455,413 subjects regarding moderate wine consumption and risk of prostate cancer.

There was no evidence of publication bias.

Results and conclusions:
The investigators found in pooled analysis of cohort studies (438,302 subjects from which 19,238 developed prostate cancer during observation/follow-up) no association between moderate wine consumption and prostate cancer risk [pooled RR = 1.06, 95% CI = 0.96-1.15, p = 0.22, I2 = 0%]. 

The investigators found in multivariable analysis that moderate red wine consumption was associated with a significantly decreased risk of 12% for prostate cancer [pooled RR = 0.88, 95% CI = 0.78-0.999, p = 0.047, I2 = 0%]. 

The investigators found in multivariable analysis that moderate white wine consumption increased significantly the risk of prostate cancer with 26% [pooled RR = 1.26, 95% CI = 1.10-1.43, p = 0.001, I2 = 34.4%].

The investigators concluded that moderate consumption of white wine increases the risk of prostate cancer, whereas moderate consumption of red wine has a protective role. This hypothesis-generating data should serve as a rationale for uncovering the molecular underpinnings of this differential effect in order to potentially devise prevention strategies in the at-risk population.

Original title:
The impact of moderate wine consumption on the risk of developing prostate cancer by Vartolomei MD, Kimura S, […], Shariat SF.
 
Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909789/

Additional information of El Mondo:
Find more information/studies on alcohol consumption and cancer 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:
Esophageal cancer (EC) is the eighth most common cancer and the sixth most frequent cause of cancer death in the whole world. Many studies have investigated the association between citrus fruit intake and the risk of esophageal cancer, but the results are inconsistent and not analyzed by category. Therefore, this review article has been conducted.

Does citrus fruit intake reduce esophageal cancer risk?

Study design:
This review article included 20 case-control studies and 5 cohort studies.
The studies were published between 1983 and 2015 with a total of 2,456 esophageal squamous cell carcinoma (ESCC) (range 47-395), 1,284 esophageal adenocarcinoma (EAC) (range 67-282) and 1,990 esophageal cancer (EC) (range 53-1,246).

The Newcastle-Ottawa Quality Assessment Scale (NOS) scores of 25 clinical trials range from 5 to 9, with an average of approximately 7. The median score was 6.75 for case-control studies and 8 for cohort studies.

There was no evidence of publication bias. 

Results and conclusions:
The investigators found in 10 case-control studies and 3 cohort studies a significantly reduced risk of 41% [pooled RR = 0.59, 95% CI = 0.47-0.76, I2 = 60.7%, p  = 0 .002] for esophageal squamous cell carcinoma in the citrus fruit consumption group.
Significant because RR of 1 was not found in the 95% CI of 0.47 to 0.76. RR of 1 means no risk/association.

The investigators found in 5 case-control studies and 3 cohort studies a non-significantly reduced risk of 14% [pooled RR = 0.86, 95% CI = 0.74-1.01, I2 = 0.0%, p = 0.598] for esophageal adenocarcinoma in the citrus fruit consumption group.
Non-significantly because RR of 1 was found in the 95% CI of 0.74 to 1.01. RR of 1 means no risk/association.

The investigators found in 20 case-control studies and 5 cohort studies a significantly reduced risk of 35% [pooled RR = 0.65, 95% CI = 0.56-0.75, I2 = 51.1%, p = 0.001] for esophageal cancer in the citrus fruit consumption group.

The investigators found in subgroup analysis significant inverse associations between citrus fruit intake and the risk of esophageal squamous cell carcinoma in cohort studies [OR  =  0.66, 95% CI = 0.49-0.88] and hospital-based cohort studies [OR  =  0.82, 95% CI = 0.33-0.75], but not in population-based cohort studies [OR  =  0.82, 95% CI = 0.62-1.09].

The investigators found in subgroup analysis significant inverse associations between citrus fruit intake and the risk of esophageal squamous cell carcinoma in >7 scores studies [OR =  0.56, 95% CI = 0.43-0.72].

The investigators concluded that citrus fruit intake reduces risk of esophageal cancer, particularly esophageal squamous cell carcinoma. However, further studies are warranted to find which constituents in citrus fruit prevent esophageal cancer and its mechanism.

Original title:
Intakes of citrus fruit and risk of esophageal cancer: A meta-analysis by Zhao W, Liu L and Xu S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5895383/

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

Objectives:
The relationship between vitamin intake and pancreatic cancer (PC) risk is disputed. Therefore, this review article has been conducted.

Is there a relationship between dietary vitamin intake and pancreatic cancer risk?

Study design:
This review article included 25 observational studies with a total of 1,214,995 individuals, of which 8,000 pancreatic cancer cases.

In the identified studies, 10 were population-based case-control studies, 4 were hospital-based case-control studies, 2 were RCTs, 9 were cohort studies, 11 were prospective studies and 14 were retrospective studies.
The number of participants ranged from 305 to 537,218 and pancreatic cancer cases ranged from 79 to 2,383.
Quality scores of included case-control and cohort studies ranged from 7 to 9 with an average score of about 8.

Results and conclusions:
The investigators found in prospective cohort studies a significantly reduced risk of 10% [multivariable-adjusted RR = 0.90, 95% CI = 0.83-0.98, I2 = 11%] for pancreatic cancer when comparing the highest dietary vitamin intake with the lowest, particularly for 10 μg/d dietary intake of vitamin D [multivariable-adjusted RR = 0.75, 95% BI = 0.60-0.93, I2  =  59%].

The investigators concluded that a high dietary vitamin intake decreases the risk of pancreatic cancer, particularly for 10 μg/d dietary intake of vitamin D.

Original title:
Vitamin intake and pancreatic cancer risk reduction: A meta-analysis of observational studies by Liu Y, Wang X, [...], Liu S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5895396/

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

A review article (a collection of scientific studies on a specific topic) of cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

Objectives:
Breast cancer is the most common cancer in women worldwide. The association between body mass index (BMI) and breast cancer risk has been paid more attention in the past few years, but the findings are still controversial. Therefore, this review article has been conducted.

Is there a relationship between BMI and breast cancer risk among women?

Study design:
This review article included 12 prospective cohort studies comprising 22,728,674 women.

All studies were published from 2004 to 2014, with the mean duration of follow-up varying from 4.29 to 10.8 years.
The sample size of included studies ranged from 15,054 to 1,222,630 women.
The Newcastle-Ottawa scale was applied to assess the quality of the included studies and the results showed all studies were of high quality, with a Newcastle-Ottawa scale score of ≥7.
There was no evidence of publication bias with Egger’s test [p = 0.74] and the funnel plot showed no sign of asymmetry by visual inspection.

Results and conclusions:
The investigators found overall results showed a weak positive association between a 5-unit increase in BMI and breast cancer risk, indicating that a 5 kg/m2 increase in BMI corresponded to a 2% increase in breast cancer risk [SRR = 1.02, 95% CI = 1.01-1.04, p 0.001, I2 = 74.2%, p = 0.00]. The results were statistically robust in sensitivity analyses.

The investigators found in subgroup analysis that higher BMI significantly reduced breast cancer risk with 2% among premenopausal women [SRR = 0.98, 95% CI = 0.96-0.99, p 0.001].

The investigators found there was evidence of a linear association between BMI and breast cancer risk in both premenopausal and postmenopausal women [p nonlinearity = 0.892 and p nonlinearity = 0.630, respectively].

The investigators concluded that every 5 kg/m² increase in BMI corresponds to a 2% increase in breast cancer risk in women. However, higher BMI is a protective factor of breast cancer risk for premenopausal women. Further studies are necessary to verify these findings and elucidate the pathogenic mechanisms.

Original title:
Association between body mass index and breast cancer risk: evidence based on a dose-response meta-analysis by Liu K, Zhang W, [...], Dai Z.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783020/

Additional information of El Mondo:
Find more information/studies on cohort studies/significant and cancer right here.

Objectives:
Lung cancer is the most common cause of cancer death. Fruits and vegetables containing carotenoids and other antioxidants have been hypothesized to decrease lung cancer risk. Therefore, this meta-analysis (systematic review) has been conducted.

Do fruits and vegetables reduce lung cancer risk?

Study design:
This review article included prospective cohort studies up to December 2014.

Results and conclusions:
The investigators found in 18 studies, when comparing the highest fruits and vegetables with the lowest intakes, a significantly reduced risk of 14% for lung cancer [summary RR = 0.86 [95% CI = 0.78-0.94].

The investigators found in 25 studies, when comparing the highest vegetables with the lowest intakes, a significantly reduced risk of 8% for lung cancer [summary RR = 0.92 [95% CI = 0.87-0.97].

The investigators found in 29 studies, when comparing the highest fruits with the lowest intakes, a significantly reduced risk of 18% for lung cancer [summary RR = 0.82, 95% CI = 0.76-0.89].

The investigators found the association with fruit and vegetable intake was marginally significant in current smokers and inverse but not significant in former or never smokers.

The investigators found in 4 studies for each 100 g/day increase of fruits and vegetables, a significantly reduced risk of 4% for lung cancer [RR = 0.96, 95% CI = 0.94-0.98, I2 = 64%, n (cases) = 9,609].

The investigators found in 20 studies for each 100 g/day increase of vegetables, a significantly reduced risk of 6% for lung cancer [RR = 0.94, 95% CI = 0.89-0.98, I2 = 48%, n (cases) = 12,563].

The investigators found in 23 studies for each 100 g/day increase of fruits, a significantly reduced risk of 8% for lung cancer [RR = 0.92, 95% CI = 0.89-0.95, I2 = 57%, n (cases) = 14,506].

The investigators found the results were consistent among the different types of fruits and vegetables. However, the strength of the association differed across locations.

The investigators found evidence of a non-linear relationship [p 0.01] between fruit and vegetable intake and lung cancer risk showing that no further benefit is obtained when increasing consumption above ∼400g per day.

The investigators concluded fruits and/or vegetables intakes reduce risk of lung cancer with no further benefit when increasing consumption of fruits and vegetables above ∼400g per day.

Original title:
Fruits, vegetables and lung cancer risk: a systematic review and meta-analysis by Vieira AR, Abar L, […], Norat T.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/26371287

Additional information of El Mondo:
Find more information/studies on fruits and vegetables consumption and cancer right here.

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:
Multiple epidemiologic studies have evaluated the relationship between dietary cholesterol and lung cancer risk, but the association is controversial and inconclusive. Therefore, this review article has been conducted.

Does consumption of dietary cholesterol increase risk of lung cancer?

Study design:
This review article included 10 case-control studies (6,894 lung cancer cases and 29,736 controls/persons with no lung cancer) and 6 cohort studies (1,769 lung cancer cases among 241,920 participants).

The Newcastle-Ottawa Scale scores for the included studies ranged from 6 to 9 and all studies were deemed to be of high quality (≥6).

There was no evidence of publication bias observed. Case-control studies: Egger’s test, p = 0.737, Begg’s test, p = 0.213 and cohort studies: Egger’s test, p = 0.459, Begg’s test, p = 1.000.

Results and conclusions:
The investigators found in case-control studies that a high dietary cholesterol intake significantly increased lung cancer risk with 70% [OR = 1.70, 95% CI = 1.43-2.03, I2 = 42.3%, p = 0.067]. No significant change in the result was found in the sensitivity analysis.

The investigators found in cohort studies no association between a high dietary cholesterol intake and lung cancer risk [RR = 1.08, 95% CI = 0.94-1.25, I2 = 0.0%, p = 0.833]. No significant change in the result was found in the sensitivity analysis.

The investigators found in 6 case-control studies that a high dietary total fat intake significantly increased lung cancer risk with 64% [OR = 1.64, 95% BI = 1.16-2.33, I2 = 68.7%, p = 0.004]. No significant change in the result was found in the sensitivity analysis.

The investigators concluded that a high dietary cholesterol intake might increase lung cancer risk. Might increase because the increased risk was not significant in cohort studies. Therefore, carefully designed and well-conducted cohort studies are needed to identify the association between dietary cholesterol and lung cancer risk.

Original title:
Dietary Cholesterol Intake and Risk of Lung Cancer: A Meta-Analysis by Lin X, Liu L, […], Lian X.

Link:
http://www.mdpi.com/2072-6643/10/2/185/htm

Additional information of El Mondo:
Find more information/studies on cohort studies/significant, cholesterol consumption and cancer right here.

A high dietary cholesterol intake is an intake of more than 200-300 mg cholesterol per day.

The result of a review article is only reliable when the result is also significant in cohort studies (thus not only significant in case-control studies).
 

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.

Objectives:
Does the consumption of various types of tomato products reduce prostate cancer risk and is there a potential dose-response relationship?

Study design:
This review article included 30 studies, which summarized data from 24,222 cases (subjects with prostate cancer) among 260,461 participants.

Results and conclusions:
The investigators found that higher total tomato consumption was associated with a reduced risk of 19% for prostate cancer [RR = 0.81, 95% CI = 0.71 to 0.92, p = 0.001].

The investigators found in subgroup analysis that higher tomato foods consumption was associated with a reduced risk of 16% for prostate cancer [RR = 0.84, 95% CI = 0.72 to 0.98, p = 0.030].

The investigators found in subgroup analysis that higher cooked tomatoes and sauces consumption was associated with a reduced risk of 16% for prostate cancer [RR = 0.84, 95% CI = 0.73 to 0.98, p = 0.029]. 

The investigators found in subgroup analysis, however, no association between higher raw tomatoes consumption and prostate cancer risk [RR = 0.96, 95% CI = 0.84 to 1.09, p = 0.487].

The investigators found there was a significant dose-response association for total tomato consumption [p = 0.040], cooked tomatoes and sauces [p  0.001] and raw tomatoes [p = 0.037], but there was not a significant association with tomato foods [p-linear = 0.511, p-nonlinear = 0.289].

The investigators concluded that increased tomato consumption, particularly cooked tomatoes and sauces reduces prostate cancer risk. Furthermore, there are dose-response relationships for total tomato consumption and for cooked tomatoes and sauces. Further studies are required to determine the underlying mechanisms of these associations.

Original title:
Processed and raw tomato consumption and risk of prostate cancer: a systematic review and dose-response meta-analysis by Rowles JL, Ranard KM, […], Erdman JW Jr.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29317772

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

Objectives:
Fish oil supplementation has been shown to be associated with a lower risk of metabolic syndrome and benefit a wide range of chronic diseases, such as cardiovascular disease, type 2 diabetes and several types of cancers. However, the evidence of fish oil supplementation on glucose metabolism and insulin sensitivity is still controversial. Therefore, this review article (meta-analysis) has been conducted.

Does fish oil supplementation improve insulin sensitivity in humans?

Study design:
This review article included a total of 17 RCTs with 672 participants. One of the 17 studies was crossover design and others were parallel design.
The doses of active ingredients of fish oil (n-3 fatty acids) ranged from 1 g/d to 4 g/d. Duration of the interventions was ranged from 4 weeks to 24 weeks.
There was no suggestion of small study effect based on visual inspection of the funnel plot. Results of the Egger’s (p = 0.78) and Begg’s (p = 0.43) tests showed that there was no potential publication bias.

Results and conclusions:
The investigators found pooled analysis showed that fish oil supplementation had no effects on insulin sensitivity overall [SMD = 0.17, 95% CI = -0.15 to 0.48, p = 0.292, I2 = 58.1%, p = 0.001].

The investigators found subgroup analysis showed that fish oil supplementation significantly improved insulin sensitivity among people who were experiencing at least one symptom of metabolic disorders [SMD = 0.53, 95% CI = 0.17 to 0.88, p 0.001].

The investigators found subgroup analysis showed a positive effect of fish oil on insulin sensitivity among the short-term intervention group (12 weeks) rather than the long-term intervention group [SMD = 0.31, 95% CI = 0.01-0.61, p = 0.04].

The investigators found subgroup analysis showed that fish oil had no effects on insulin sensitivity among the healthy people or people with T2DM.

The investigators found there were no significant differences between subgroups of methods of insulin sensitivity and doses of omega-3 polyunsaturated fatty acids (n-3 PUFA) of fish oil supplementation.

The investigators found in sensitivity analysis that summary results did not differ significantly when omitting studies one at a time.

The investigators concluded that fish oil supplementation during 12 weeks improves insulin sensitivity among people who were experiencing at least one symptom of metabolic disorders.

Original title:
Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis by Gao H, Geng T, [...], Zhao Q.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5496233/

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

 

Objectives:
What is the relationship between dietary intake of 12 major food groups, including whole grains, refined grains, vegetables, fruit, nuts, legumes, eggs, dairy, fish, red meat, processed meat and sugar-sweetened beverages and colorectal cancer (CRC) risk?

Study design:
This review article included cohort studies.

Results and conclusions:
The investigators found in the linear dose-response meta-analysis, that every 30 g/d whole grains significantly reduced risk of colorectal cancer with 5% [RR = 0.95, 95% CI = 0.93 to 0.97, n = 9 cohort studies].

The investigators found in the linear dose-response meta-analysis, that every 100 g/d vegetables significantly reduced risk of colorectal cancer with 3% [RR = 0.97, 95% CI = 0.96 to 0.98, n = 15 cohort studies].

The investigators found in the linear dose-response meta-analysis, that every 100 g/d fruit significantly reduced risk of colorectal cancer with 3% [RR = 0.97, 95% CI = 0.95 to 0.99, n = 16 cohort studies]. 

The investigators found in the linear dose-response meta-analysis, that every 200 g/d dairy products significantly reduced risk of colorectal cancer with 7% [RR = 0.93, 95% CI = 0.91 to 0.94, n = 15 cohort studies]. 

The investigators found in the linear dose-response meta-analysis, that every 100 g/d red meat significantly increased risk of colorectal cancer with 12% [RR = 1.12, 95% CI = 1.06 to 1.19, n = 21 cohort studies].

The investigators found in the linear dose-response meta-analysis, that every 50 g/d processed meat significantly increased risk of colorectal cancer with 17% [RR = 1.17, 95% CI = 1.10 to 1.23, n = 16 cohort studies].

The investigators found some evidence for a nonlinear relationship between dietary intake of vegetables, fruit and dairy products and risk of colorectal cancer.

The investigators concluded that daily dietary intake of 30g whole grains, 100g vegetables,100g fruit and 200g dairy products reduce risk of colorectal cancer, while daily dietary intake of 100g red meat and 50g processed meat increase risk of colorectal cancer.

Original title:
Food groups and risk of colorectal cancer by Schwingshackl L, Schwedhelm C, [...], Schlesinger S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29210053

Additional information of El Mondo:
Find more information/studies on different food groups and colorectal cancer right here.

Objectives:
Carnitine deficiency has been implicated as a potential pathway for cancer-related fatigue that could be treated with carnitine supplementation. Therefore, this review article (meta-analysis) has been conducted.

Does carnitine supplementation reduce cancer-related fatigue?

Study design:
This review article included 3 RCTs involving a total of 659 participants.

There were not enough studies to conduct sensitivity analyses to isolate potential sources of heterogeneity and test the robustness of findings.

Results and conclusions:
The investigators found in 3 RCTs involving a total of 659 participants that carnitine supplementation did not significantly reduce cancer-related fatigue [SMD = 0.06 points, 95% CI = -0.09 to 0.21, p = 0.45, I2 = 0%].
Clinical heterogeneity was evident from these studies in regards to the dose (2-4 g of carnitine per day), patient demographics (40-100% females included) and carnitine status.

The investigators concluded there is no evidence to support the use of carnitine supplementation (2-4 g of carnitine per day) for cancer-related fatigue.

Original title:
Efficacy and Effectiveness of Carnitine Supplementation for Cancer-Related Fatigue: A Systematic Literature Review and Meta-Analysis by Marx W, Teleni L, [...], Isenring E.

Link:
http://www.mdpi.com/2072-6643/9/11/1224/htm

Additional information of El Mondo:
Find more information/studies on carnitine, randomized controlled trials/cohort studies/subgroup analysis and cancer right here.

Objectives:
Previous studies regarding the relationship between carrot intake and risk of urothelial cancer have reported conflicting results. Therefore, this review article (meta-analysis) has been conducted.

Does a high consumption of carrot reduce urothelial cancer risk?

Study design:
This review article included a total of 6 epidemiological studies (4 case-control and 2 cohort studies) with 1,523 urothelial cancer cases.

There was no significant publication bias by Begg's test (p = 0.348) or Egger's test (p = 0.130).

Results and conclusions:
The investigators found overall analysis indicated a significantly reduced risk of 37% for urothelial cancer for high intake of carrot [OR = 0.63, 95% CI = 0.44-0.90, I2 = 79.6%, p 0.001].

The investigators found in the subgroup analysis by study design, a significantly reduced risk of 55% for urothelial cancer in case-control studies [OR = 0.45, 95% CI = 0.25-0.81]. However, this reduced risk was not significant in cohort studies [OR = 0.91, 95% CI = 0.67-1.24].
Not significant because OR of 1 was found in the 95% CI of 0.67 to 1.24. OR of 1 means no risk/association.

The investigators found, when separately analyzed by carrot type, a significantly reduced risk of 31% for cooked carrot [OR = 0.69, 95% CI 0.51-0.94], but the reduced risk was not significant for raw carrot [OR = 0.84, 95% CI = 0.37-1.93].

The investigators found in the stratified analysis by geographical region, a non-significantly reduced risk of 38% [OR = 0.62, 95% CI = 0.37-1.06], a non-significantly reduced risk of 30% [OR = 0.70, 95% CI = 0.29-1.67] and a non-significantly reduced risk of 47% [OR = 0.53, 95% CI = 0.22-1.26] for Europe, Asia and USA, respectively.

The investigators also found a non-significantly reduced risk of 44% [OR = 0.56, 95% CI = 0.27-1.17] and a non-significantly reduced risk of 27% [OR = 0.73, 95% CI = 0.12-4.60] for male and female, respectively.

The investigators concluded that a high intake of carrot might be associated with a low incidence of urothelial cancer. Might be associated because the reduced risk was not significant in cohort studies. Considering the limited included studies and huge heterogeneity, further large well-designed prospective cohort studies are warranted to confirm these findings.

Original title:
Carrot intake and incidence of urothelial cancer: a systematic review and meta-analysis by Luo X, Lu H, [...], Wang S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5652827/

Additional information of El Mondo:
Find more information/studies on carrot consumption, randomized controlled trials/cohort studies/subgroup analysis and cancer right here.

Objectives:
Surgical resection remains the primary treatment for gastrointestinal (GI) malignancy including early-stage cancer. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to have beneficial clinical and immune-modulating effects in the prognosis of gastrointestinal cancer patients undergoing surgery. Therefore, this review article (meta-analysis) has been conducted.

What is the impact of n-3 PUFA supplementation on postoperative inflammation status and immune function of gastrointestinal cancer patients?

Study design:
This review article included a total of 9 RCTs with 623 participants.

The homogeneous test detected no statistical heterogeneity between studies.

There was no evidence of publication bias following assessment by funnel plot, Egger’s test [p > 0.05] and Begg’s test [p > 0.05].

Results and conclusions:
The investigators found the n-3 PUFAs regime significantly resulted in lower levels of C-reactive protein [p 0.05], interleukin-6 [p 0.01] and higher levels of albumin, CD3+ T cells, CD4+ T cells and CD4+/CD8+ ratio [p 0.05] compared with the isocaloric nutrition regime.

The investigators found, however, no significant difference in the level of tumor necrosis factor-α between the n-3 PUFAs regime and the isocaloric nutrition regime [p = 0.17].

The investigators found that the level of CD8 + T cells significantly decreased compared with the isocaloric nutrition regime [p 0.0001].

The investigators concluded that n-3 PUFAs are effective in improving the nutritional status and immune function of gastrointestinal cancer patients undergoing surgery as they effectively enhance immunity and attenuate the inflammatory response. Although further larger trials are needed, these fatty acids should be widely used in the clinic.

Original title:
Effects of omega-3 fatty acids on patients undergoing surgery for gastrointestinal malignancy: a systematic review and meta-analysis by Yu J, Liu L, [...], Yang F.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5391568/

Additional information of El Mondo:
Find more information/studies on n-3 PUFA consumption and cancer right here.
 

Objectives:
The aim of this review article (meta-analysis) is to compare empirically derived dietary patterns in relation to cancer risk.

Study design:
This review article included observational studies, which evaluated the association with cancer risk between a posteriori derived dietary patterns.

Results and conclusions:
The investigators found a significantly 64% increased risk of cancer for the adoption of high-meat compared to plant-based dietary patterns [RR = 1.64, 95% CI = 1.02-2.63].

The investigators found a significantly 12% lower risk of cancer for individuals adopting a plant-based dietary pattern over a mixed one [RR = 0.88, 95% BI = 0.82-0.95].

The investigators concluded that plant-based dietary patterns decrease cancer risk; meanwhile meat-based dietary patterns increase cancer risk.

Original title:
Differences in the association between empirically derived dietary patterns and cancer: a meta-analysis by Bella F, Godos J, […], Sciacca S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/27894200

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

Objectives:
The potential glucose-lowering effects of pomegranate have been reported in animal and observational studies, but intervention studies in humans have generated mixed results. Therefore, this review article (meta-analysis) has been conducted.

What are the effects of pomegranate supplementation on measures of glucose control, insulin levels and insulin sensitivity in humans?

Study design:
This review article included 16 RCTs with 538 subjects. 14 trials adopted parallel study designs and the 2 remaining trials used crossover designs.
The total number of subjects included in each study ranged from 14 to 74 subjects.
The mean age of participants in each trial ranged from 30 to 70 years, with differing age ranges in most studies.
11 studies used pomegranate juice as a supplement (the dosage ranged from 120 to 500 ml/day).
2 studies used pomegranate seed oil as treatments (the dosage ranged from 400 to 2000 mg/day).
3 studies utilized pomegranate extract as the intervention (the dosage ranged from 710 to 1420 mg/day).  
The duration of the pomegranate intervention varied from 1 to 12 weeks (median: 5.5 weeks).

Overall, significant heterogeneity was detected for FBI and HOMA-IR, but subgroup analysis could not identify factors significantly influencing these parameters.
No significant publication bias was found.

Results and conclusions:
The investigators found that pomegranate did not significantly affect the measures of:
-FBG (fasting blood glucose) [WMD = -0.6 mg/dL, 95% CI = -2.79 to 1.58, p = 0.59, I2 = 0%];
-FBI (fasting blood insulin) [WMD = 0.29 μIU/mL, 95% CI = -1.16 to 1.75, p = 0.70, I2 = 60.4%];
-HOMA-IR (homeostatic model assessment of insulin resistance) [WMD = -0.04, 95% CI = -0.53 to 0.46, p = 0.88, I2 = 59.8%] or;
-HbA1c (glycated haemoglobin) [WMD = -0.11%, 95% CI = -0.39 to 0.18, p = 0.46, I2 = 0%].
These results were robust in sensitivity analysis.

The investigators found meta-regression analysis showed that the factor (dose of pomegranate juice supplementation) was not associated with the treatment effects on FBG level [coefficient = -0.006, 95% CI = -0.023 to 0.011, p = 0.46].

The investigators found no significant difference in the FBG-lowering effect between trials that were conducted in subjects with cardiovascular disease risk [WMD = 0.30 mg/dL, 95% CI = -2.36 to 2.97, p = 0.82] and those that were conducted in healthy individuals [WMD = -2.53 mg/dL, 95% CI = -6.36 to 1.30, p = 0.19].

The investigators found no statistically significant differences in the pooled effects of pomegranate on FBG in the subgroups stratified by study designs, intervention durations, types of intervention, baseline BMI and baseline FBG levels (FBG levels at the beginning of the studie).

The investigators concluded pomegranate supplements have no favourable effect on improvements in glucose and insulin metabolism. The current evidence suggests that daily pomegranate supplementation is not recommended as a potential therapeutic strategy in glycemic management. Further large-scale RCTs with longer duration are required to confirm these results.

Original title:
Lack of efficacy of pomegranate supplementation for glucose management, insulin levels and sensitivity: evidence from a systematic review and meta-analysis by Huang H, Liao D, […], Zhu Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5629805/

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