Nutrition and health

Objectives:
Due to the high incidence of liver disease and the severity of adverse outcomes, liver disease has become a serious public health problem, bringing a huge disease burden to individuals, families and society. Most studies have shown significant differences in serum carotenoid content and dietary carotenoid intake between liver disease patients and non-liver disease patients, but some studies have reported contrary results.Therefore, this review article has been conducted.

Do higher serum concentrations of carotenoids (such as, α-carotene, β-carotene, lycopene, cryptoxanthin and lutein/zeaxanthin) or higher dietary intakes of carotenoids reduces the risk of liver disease?

Study design:
This review article included 3 RCT studies, 6 cohort studies, 11 case-control studies, 9 cross-sectional studies and 1 RCT-combined cross-sectional study.

The Egger test showed no publication bias.

Results and conclusions:
The investigators found pooled meta-analysis showed that higher serum α-carotene [SMD = -0.58, 95% CI = -0.83 to -0.32, p < 0.001], β-carotene [SMD = -0.81, 95% CI = -1.13 to -0.49, p < 0.001] and lycopene [SMD = -1.06, 95% CI = -1.74 to -0.38, p < 0.001] significantly reduced the risk and severity of liver disease. 

The investigators found, however, no significant difference was observed between serum β-cryptoxanthin [SMD = 0.02, 95% CI = -0.41 to 0.45, p = 0.92] and lutein/zeaxanthin [SMD = 0.62, 95% CI = -1.20 to 2.45, p = 0.502] and the risk and severity of liver disease. 

The investigators found dietary β-carotene intake [SMD = -0.22, 95% CI = -0.31 to -0.13, p < 0.001] significantly reduced the risk of liver disease. 

The investigators found an intake of more than 6 mg of carotenoids on an energy-restricted diet can effectively alleviate the symptoms of NAFLD. 

The investigators concluded that higher serum concentrations of α-carotene, β-carotene and lycopene reduce risk of liver disease. Meanwhile, dietary intake of β-carotene reduces the incidence of liver disease. 

Original title: 
A systematic review of dietary and circulating carotenoids and liver disease by Hu B, Sui J, […], Xia H. 

 

Link:
https://pubmed.ncbi.nlm.nih.gov/39229651/

Additional information of El Mondo:
Find more information/studies on cohort studies/significantly, carotenoids and chronic disease right here. 

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease worldwide.

Objectives:
Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been suggested as a cognitive enhancing agent, though their effect is doubtful. Therefore, this review article has been conducted.

Does supplementation of n-3 PUFA improve cognitive functions of non-demented individuals exclusively of middle age or older? 

Study design:
This review article included 24 RCTs with a total of 9,660 participants.
The length of intervention ranged from 3 to 36 months and the daily dose of n-3 PUFA ranged from 230 to 4000 mg/day. 
6  studies were conducted in countries where the nationwide blood levels of DHA + EPA were notably low, measuring ≤ 4% in erythrocyte equivalents. 

Results and conclusions:
The investigators found that the beneficial effect on executive function demonstrated an upward trend within the initial 12 months of intervention. 
This effect was prominently observed with a daily intake surpassing 500 mg of n-3 PUFA and up to 420 mg of eicosapentaenoic acid (EPA). 

The investigators found a descending curve following 12 months of n-3 PUFA intervention and when the dosage of EPA exceeded 420 mg/d.  

The investigators found, furthermore, these trends exhibit heightened significance in regions where the levels of blood docosahexaenoic acid (DHA) + EPA are not very low.

The investigators concluded supplementation of n-3 PUFA (a daily intake surpassing 500mg n-3 PUFA or up to 420mg of EPA during 12 months) has potential benefits to executive function in non-demented individuals exclusively of middle age or older, particularly in individuals whose dietary DHA + EPA level is not substantially diminished. 

Original title: 
The influence of n-3 polyunsaturated fatty acids on cognitive function in individuals without dementia: a systematic review and dose–response meta-analysis by Suh SW, Lim E, […], Kim KW. 

Link: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10929146/

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

Objectives:
Do dietary choline and betaine increase mortality risk?

Study design:
This review article included 6 cohort studies comprising 482,778 total participants, 57,235 all-cause, 9,351 cardiovascular disease and 4,400 stroke deaths.

Results and conclusions:
The investigators found linear dose-response analysis showed that each 100 mg/day increase in dietary choline intake was significantly associated with 6% increases in risk of all-cause mortality [RR = 1.06, 95% CI = 1.03 to 1.10, I2 = 83.7%, p < 0.001].

The investigators found linear dose-response analysis showed that each 100 mg/day increase in dietary choline intake was significantly associated with 11% increases in risk of cardiovascular diseases mortality [RR = 1.11, 95% CI = 1.06 to 1.16, I2 = 54.3%, p = 0.02].

The investigators found the result of the nonlinear dose-response analysis showed a significant relationship between dietary betaine intake and stroke mortality at the dosages of 50 to 250 mg/day [p non-linearity= 0.0017]. 

The investigators concluded 100 mg/day of choline consumption is associated with a 6% and 11% higher risk of all-cause and cardiovascular disease mortality, respectively. In addition, a positive relationship between betaine dietary intake and stroke mortality at doses of 50 to 250 mg/day is observed. Due to the small number of the included studies and heterogeneity among them more well-designed prospective observational studies considering potential confounding variables are required. 

Original title: 
Higher dietary choline intake is associated with increased risk of all-cause and cause-specific mortality: A systematic review and dose-response meta-analysis of cohort studies by Sharifi-Zahabi E, Soltani S, […], Shidfar F. 
 

Link:
https://pubmed.ncbi.nlm.nih.gov/39341000/

Additional information of El Mondo:
Find here more information/studies about RCTs/significant, choline, and stroke. 

Betaine-rich foods are

• American Indian/Alaska native foods
• Baked products
• Beef products
• Cereal grains and pasta
• Restaurant foods
• Snacks
• Vegetables and vegetable products

Objectives:
The relationship between beverage consumption and risk of cardiovascular disease has been extensively examined in cross-sectional studies. However, limited studies have investigated beverage consumption as a longer-term habitual behavior, which is important owing to potential cumulative harmful or beneficial cardiovascular effects. Therefore, this review article has been conducted.

What is the relationship between sex-specific long-term consumption of beverages [sugar-sweetened beverages (SSBs) or artificial-sweetened beverages (ASBs), tea, coffee, fruit juices, energy drinks and alcohol] and cardiovascular disease-related mortality? 

Study design:
This review article included 20 prospective cohort studies. The length of follow-up ranged from 5.5 years to 40 years. 
There was no publication bias. 

Results and conclusions:
The investigators found long-term coffee consumption of 2-6 cups per day significantly reduced cardiovascular disease-related mortality with 37% in males [pooled HR = 0.63, 95% CI = 0.46 to 0.87, p = 0.005, I2 = 0%] but not in females [HR = 0.78, 95% CI = 0.60 to 1.02, p = 0.07]. 

The investigators found long-term higher intake of tea was significantly associated with a 19% lower risk of cardiovascular disease-related mortality in all adults [pooled HR = 0.81, 95% CI = 0.72 to 0.92, p ≤ 0.001]. 

The investigators found higher alcohol intake was significantly associated with a 44% higher stroke in males [pooled HR = 1.44, 95% CI = 1.06 to 1.94, p = 0.02] and a 126% higher stroke in females [pooled HR = 2.26, 95% CI = 1.34 to 3.81, p = 0.002]. 

The investigators found higher sugar-sweetened beverage was significantly associated with a 31% higher risk in cardiovascular disease-related mortality [pooled HR = 1.31, 95% CI = 1.16 to 1.46, p ≤ 0.0001]. 
However, no effect was found between artificial-sweetened beverages and cardiovascular disease-related mortality while comparing the highest intake with lowest intake [pooled HR = 1.05, 95% CI = 0.87 to 1.26, p = 0.61, I2 = 61%].
 
The investigators concluded long-term habitual coffee consumption (2-6 cups per day) is beneficial for males and tea consumption is beneficial for all adults. Long-term high alcohol and sugar-sweetened beverage consumption increased risk of cardiovascular disease-related mortality for both males and females. However, it is not possible to draw conclusions on the potential benefit or harm of the long-term consumption of fruit juice and energy drinks on cardiovascular disease-related mortality owing to the limited number of studies available.

Original title: 
Long-Term Consumption of 6 Different Beverages and Cardiovascular Disease-Related Mortality: A Systematic Review and Meta-Analysis of Prospective Cohort Studies by Bhandari B, Zeng L, […], Xu X. 

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10904171/

Additional information of El Mondo:
Find more information/studies on RCT’s/sensitivity analysis, coffee, alcohol and cardiovascular diseases right here. 

Objectives:
Previous studies suggest that dietary vitamin C is inversely associated with gastric cancer (GC), but most of them did not consider intake of fruit and vegetables. Therefore, this review article has been conducted.

Do higher dietary vitamin C intakes reduce gastric cancer risk after adjusting for intake of fruit and vegetables?

Study design:
This review article included 14 case-control studies with in total 5,362 cases (persons with gastric cancer) and 11,497 controls (persons without gastric cancer).

More cases were male (61.88% vs. 54.64%), older than 60 years (63.37% vs. 57.87%) and had low socioeconomic status (57.29% vs. 45.66%) compared with controls. 
In addition, a higher proportion of cases than controls were obese (21.34% vs. 19.06%), current smokers (26.58% vs. 24.14%) and ever drinkers (64.85 vs. 63.29%). 
Similarly, H. pylori seropositivity (63.82% vs. 61.86%) was more common among cases than among controls when considering only participants from the 7 studies with available information. 
A larger proportion of controls reported high intake of fruit and vegetables compared with cases. 
Most cases were of noncardia (57.03%) and intestinal type gastric cancer (33.01%). 
Cases had a lower median intake of vitamin C and fewer of them were in the highest quartiles of intake compared with controls.

Results and conclusions:
The investigators found individuals in the highest quartile of dietary vitamin C intake had a significantly reduced risk of 36% for gastric cancer compared with those in the lowest quartile [OR = 0.64, 95% CI = 0.58 to 0.72]. 

The investigators found, however, when additionally adjusting for BMI and intake of fruit and vegetables, the observed association was attenuated and the OR for the highest versus lowest quartile of dietary vitamin C was 0.85 [95% CI = 0.73 to 0.98].

The investigators found a significant inverse association for noncardia gastric cancer, as well as for both intestinal and diffuse types of the disease. 

The investigators found dose-response analysis showed decreasing ORs of gastric cancer up to 150-200 mg/day of vitamin C [OR = 0.54, 95% CI = 0.41 to 0.71], whereas ORs for higher intakes were close to 1.0. 

The investigators concluded that consumption of 150-200 mg/day of vitamin C reduce gastric cancer risk. However, further well-designed prospective studies, aimed at disentangling the complex relationships between intake of fruit and vegetables, vitamins and other antioxidants and gastric cancer, are warranted to prove causality of the observed relationship between vitamin C and gastric cancer.

Original title: 
Dietary intake of vitamin C and gastric cancer: a pooled analysis within the Stomach cancer Pooling (StoP) Project by Sassano M, Seyyedsalehi  MS, […], Boffetta P. 

 

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11016516/

Additional information of El Mondo:
Find more information/studies on cohort studies/significantly, viamin C and cancer right here. 

Objectives:
While clinical studies indicate that dietary protein may benefit glucose homeostasis in type 2 diabetes (T2D), the impact of dietary protein, including whether the protein is of animal or plant origin, on the risk of type 2 diabetes is uncertain. Therefore, an update of the meta-analysis has been conducted. 

Is there an associations between total, animal and plant protein dietary intakes and the risk of type 2 diabetes?

 

Study design:
This review article included 16 prospective cohort studies, involving 615,125 participants and 52,342 type 2 diabetes cases. Of which 11 studies reported data on intake of both animal and plant protein. 

 

Results and conclusions:
The investigators found dietary intakes of total protein were significantly associated with an increased risk of 14% for type 2 diabetes [pooled effect size = 1.14, 95% CI = 1.04 to 1.24].

The investigators found every increase of 20g dietary intakes of total protein were significantly associated with an increased risk of 3% for type 2 diabetes.

The investigators found dietary intakes of animal protein were significantly associated with an increased risk of 18% for type 2 diabetes [pooled effect size = 1.18, 95% CI = 1.09 to 1.27].

The investigators found every increase of 20g dietary intakes of animal protein were significantly associated with an increased risk of 7% for type 2 diabetes.

The investigators found, in contrast, there was no association between dietary intake of plant protein and type 2 diabetes risk [pooled effect size = 0.98, 95% CI = 0.89 to 1.08].

The investigators found every replacement of 20 grams animal by plant protein was 

significantly associated with a reduced risk of 20% for type 2 diabetes [pooled effect size = 0.80, 95% CI = 0.76 to 0.84].

The investigators concluded that long-term consumption of animal, but not plant, protein is associated with a dose-dependent increase in the risk of type 2 diabetes, with the implication that replacement of animal with plant protein intake may lower the risk of type 2 diabetes.  

Original title: 
Association between total, animal, and plant protein intake and type 2 diabetes risk in adults: A systematic review and dose-response meta-analysis of prospective cohort studies by Ardakani AF, Anjom-Shoae J, […], Horowitz M. 

Link: 
https://pubmed.ncbi.nlm.nih.gov/39032197/

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

 

Objectives:
The association between soy product consumption and cancer risk varies among studies. Therefore, this review article has been conducted.

Do higher soy product consumption reduce cancer risk?

Study design:
This review article included 17 cohort studies and 35 case-control studies with a total of 861,372 participants and 44,932 cases (persons with cancer). 

Regarding quality assessment, the case-control studies achieved an average score of 6.7. The mean score of the cohort study was 7.2, which satisfied the criterion of high quality. 
All analyses adjusted for age and most studies adjusted for smoking status (n = 38), drinking status (n = 29), total energy intake (n = 27), BMI (n = 26) and education level (n = 26). 

Results and conclusions:
The investigators found in pooled analysis of cohort studies and case-control studies that higher consumption of total soy products significantly reduced risk of cancer with 31% [RR = 0.69, 95% CI = 0.60 to 0.80, I2 = 82.7%, p < 0.001]. 
However, this reduced risk was not significant in cohort studies (RR = 0.90, 95% CI = 0.80 to 1.01].

The investigators found higher tofu consumption significantly reduced cancer risk in both men and women.

The investigators found higher consumption of total soy products significantly reduced risk of cancer amond women with 24% [RR = 0.76, 95% CI = 0.65 to 0.89].

The investigators found in subgroup analysis that higher consumption of total soy products was significantly associated with a reduced risk for gastrointestinal cancer [RR = 0.74, 95% CI = 0.61 to 0.89], prostate cancer [RR = 0.47, 95% CI = 0.31 to 0.71], lung cancer [RR = 0.67, 95% CI = 0.52 to 0.86], upper aerodigestive tract cancer [RR = 0.33, 95% CI = 0.22 to 0.49] and multiple myeloma [RR = 0.10, 95% CI = 0.01 to 0.97], but not in bladder or liver cancer.

The investigators found in pooled analysis of cohort studies and case-control studies that higher consumption of tofu significantly reduced risk of cancer with 22% [RR = 0.78, 95% CI = 0.70 to 0.86, I2 = 47.9%, p = 0.004]. 
However, this reduced risk was not significant in cohort studies [RR = 0.89, 95% CI = 0.78 to 1.01, p = 0.186].

The investigators found in pooled analysis of cohort studies and case-control studies that higher consumption of soymilk significantly reduced risk of cancer with 25% [RR = 0.75, 95% CI = 0.60 to 0.86, I2 = 47.9%, p = 0.004]. 
However, this reduced risk was not significant in cohort studies [RR = 1.10, 95% CI = 0.76 to 1.58].

The investigators found a 54g per day increment of total soy products significantly reduced cancer risk by 11%, a 61g per day increment of tofu significantly reduced cancer risk by 12%, and a 23g per day increment of soymilk significantly reduced cancer risk by 28%, while none of the other soy products were associated with cancer risk. 

The investigators concluded that daily consumption of 54g total soy products, 61g tofu or 23g soymilk is associated with a lower cancer risk. More prospective cohort studies are still needed to confirm the causal relationship between soy product consumption and cancer risk.

Original title: 
Soy Product Consumption and the Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies by Wang C, Ding K, […], Hong H. 

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11013307/

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

Objectives:
Previous cohort studies have indicated that consumption of total and animal proteins are related to fracture risk; however, results were inconclusive. Therefore, this review article has been conducted.

Does a high dietary intake of protein reduce risk of fractures?

Study design:
This review article included 20 cohort studies with serious to moderate risk of bias involving 780,322 individuals. 

Results and conclusions:
The investigators found a non-statistically significant relation between intake of animal proteins and dairy products and all fracture risk. 

The investigators found, however, a significantly 43% decreased incidence of fracture per 100 g/day total protein dietary intake [RR = 0.57, 95% CI = 0.36 to 0.93]. 

The investigators found, however, a significantly 5% decreased incidence of fracture per 15 g/day fish protein dietary intake [RR = 0.95, 95% CI = 0.91 to 0.99]. 

The investigators found every 100 g/day total and animal protein dietary intake and every 15 g/day fish dietary intake were significantly linked to 48%, 50% and 5% lower hip fracture risk. 

The investigators found greater dietary animal protein intake might reduce risk of hip but not fracture at any site. 

The investigators concluded greater total protein (per 100 g/day) and fish (per 15 g/day) dietary intake may reduce risk of any or hip fracture. May reduce because the cohort studies had serious to moderate risk of bias.

Original title: 
Association between total and animal proteins with risk of fracture: A systematic review and dose-response meta-analysis of cohort studies by Zeraattalab-Motlagh S, Mortazavi AS, […], Mohammadi H.

 

Link: 
https://pubmed.ncbi.nlm.nih.gov/37855886/ 

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

100 grams of protein consumption per day corresponds to a diet with 20 En% protein. A diet with 20 En% protein mainly consists of products with 20 En% protein. Find here which products in the supermarket contain 20 En% protein.

20 En% protein means that the number of grams of protein contributes 20% to the total calorie content of the product in question.

Calculate here whether your daily diet contains 20 En% protein. This tab is only visible after gratis inlog. 

Objectives:
Hypertension (HTN) is regarded as a serious public health issue throughout the world. High blood pressure (BP) may be improved by carotenoid supplementation; however, randomized controlled trials (RCTs) provide conflicting evidence. Therefore, this review article has been conducted.

Do carotenoid supplements reduce blood pressure?

Study design:
This review article included 19 RCTs involving 1,151 participants.
Evidence for all systolic blood pressure, diastolic blood pressure and heart rate values was high quality.

Results and conclusions:
The investigators found carotenoid supplementation significantly reduced the systolic blood pressure (SBP) [WMD = -2.492 mmHg, 95% CI = -4.52 to -0.47, p = 0.016] and diastolic blood pressure (DBP) [MD = -1.60 mmHg, 95% CI = -2.73 to -0.47, p = 0.005]. 

The investigators found greater effects were observed in Asian participants, those aged >50 years, nonhealthy participants and participants with a baseline systolic blood pressure ≥130 mmHg and diastolic blood pressure ≥80 mmHg and at carotenoid dose >10 mg. 

The investigators found dose-response analysis showed that carotenoid supplementation decreased systolic blood pressure and diastolic blood pressure levels at doses of, respectively, 0-25 and 0-20 mg/d. 

The investigators concluded daily 10-25 mg carotenoid supplementation decrease blood pressure, especially in nonhealthy study participants with high blood presurre baseline levels.

Original title: 
Effect of carotenoid supplementation on blood pressure in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trials by Behzadi M, Akbarzadeh M, […], Bideshki MV. 

Link:
https://pubmed.ncbi.nlm.nih.gov/38219250/

Additional information of El Mondo:
Find more information/studies on RCT’s/sensitivity analysis, carotenoids and cardiovascular diseases right here.

Heart patients are advised to choose low fat, low salt and fiber rich products. These products can be found here. 

Patients with a high blood pressure are advised to choose low salt products. These products can be found here. 

Coenzyme Q10 supplements improve endothelial function 

Objectives:
Coenzyme Q10 (CoQ10) has gained attention as a potential therapeutic agent for improving endothelial function. Several randomized clinical trials (RCTs) have investigated CoQ10 supplementation's effect on endothelial function. However, these studies have yielded conflicting results. Therefore, this review article has been conducted.

Do coenzyme  Q10 supplements improve endothelial function?

Study design:
This review article included 12 RCTs comprising 489 subjects.

Results and conclusions:
The investigators found significant increases in Flow Mediated Dilation (FMD) after CoQ10 supplementation [WMD = 1.45, 95% CI = 0.55 to 2.36, p < 0.02], but there was no increase in Vascular cell adhesion protein (VCAM) and Intercellular adhesion molecule (ICAM) following Q10 supplementation. 

The investigators found the sensitivity analysis showed that the effect size was robust in FMD and VCAM. 

The investigators found in meta-regression, changes in FMD percent were significantly associated with the dose of supplementation [slope = 0.01, 95% CI = 0.004 to 0.03, p = 0.006].

The investigators concluded coenzyme Q10 supplementation has a positive effect on Flow Mediated Dilation (FMD) in a dose-dependent manner.  

Original title: 
Effect of Coenzyme Q10 Supplementation on Vascular Endothelial Function: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Daei S, Ildarabadi A, […], Mohamadi-Sartang M. 

Link:
https://pubmed.ncbi.nlm.nih.gov/38630421/

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Find more information/studies on RCT’s/sensitivity analysis, coenzyme Q10 and cardiovascular diseases right here. 

Endothelial function can be assessed non-invasively using the flow-mediated dilation (FMD) technique. Flow-mediated dilation (FMD) refers to dilation (widening) of an artery when blood flow increases in that artery.

Heart patients are recommended to choose high-fiber, low-fat and low-salt products.

High-fiber, low-fat and low-salt products are products with minimum 1.5 grams of fiber per 100 kcal, maximum 30 En% fat and maximum 0.2 grams salt per 100 kcal. 
Find here which products are suitable for heart patients.

Calculate here whether your daily diet meets the requirements for heart patients.

Calculate here whether your diet for the past six months meets the requirements for heart patients.

Objectives:
Carotenoids appear to have anticancer effects. Prospective evidence for the relation between serum carotenoids and breast cancer is controversial. Therefore, this review article has been conducted.

Do higher carotenoids levels (likes, α-carotene, β-carotene, β-cryptoxanthin, lycopene, zeaxanthin and lutein) reduce breast cancer risk among women?

Study design:
This review article included 17 nested case-control studies and 1 cohort study, published between 1984 and 2016 with a total of 20,188 participants. 
Median follow-up ranged from 8 months to 21 years during which 7,608 breast cancer cases were reported. 
All studies assessed circulating carotenoids using high-performance liquid chromatography. The majority of studies carried out on circulating carotenoids and the risk of breast cancer were adjusted for the following variables: BMI (n = 9), dietary variables (n = 8), age (n = 9), alcohol (n = 6), age at menarche (n = 6) and age at first birth (n = 8). 
According to the quality assessment, except for 2 studies, other publications had high quality. 

There was no publication bias. 

Results and conclusions:
The investigators found that the highest levels of total carotenoids compared to the lowest were significantly related to a 24% lower risk of breast cancer [relative risk (RR) = 0.76, 95% CI = 0.62 to 0.93, I2 = 45.6%, p = 0.075]. 
According to the sensitivity analysis, no study affected the overall RR. 

The investigators found according to linear dose-response analysis, the risk of breast cancer decreased by 2% for every 10 μg/dL of total carotenoids [RR = 0.98, 95% CI = 0.97 to 0.99]. A steady drop in the risk of breast cancer was observed for total carotenoid concentrations <1200 μg/dL followed by a plateau. The level of evidence was graded as low.

The investigators found that the highest levels of α-carotene compared to the lowest were significantly related to a 23% lower risk of breast cancer [relative risk (RR) = 0.77, 95% CI = 0.68 to 0.87, I2 = 0.0%, p = 0.48]. 
According to the sensitivity analysis, no study affected the overall RR. 

The investigators found according to linear dose-response analysis, the risk of breast cancer decreased by 22% for every 10 μg/dL of α-carotene [RR = 0.78, 95% CI = 0.66 to 0.93]. 
No evidence for nonlinear association was found. The level of evidence was graded as low. 

The investigators found that the highest levels of β-carotene compared to the lowest were significantly related to a 20% lower risk of breast cancer [relative risk (RR) = 0.80, 95% CI = 0.65 to 0.98, I2 = 56.5%, p = 0.004]. 
According to the sensitivity analysis, no study affected the overall RR. 

The investigators found according to linear dose-response analysis, the risk of breast cancer decreased by 4% for every 10 μg/dL of β-carotene [RR = 0.96, 95% CI = 0.93 to 0.99]. No evidence for nonlinear association was found. The level of evidence was graded as low. 

The investigators found that the highest levels of β-cryptoxanthin compared to the lowest were significantly related to a 15% lower risk of breast cancer [relative risk (RR) = 0.85, 95% CI = 0.74 to 0.96, I2 = 0.0%, p = 0.80]. 
According to the sensitivity analysis, no study affected the overall RR. 

The investigators found according to linear dose-response analysis, the risk of breast cancer decreased by 10% for every 10 μg/dL of β-cryptoxanthin [RR = 0.90, 95% CI = 0.82 to 0.99]. 

The investigators found that the highest levels of lycopene compared to the lowest were significantly related to a 14% lower risk of breast cancer [relative risk (RR) = 0.86, 95% CI = 0.76 to 0.98, I2 = 0.0%, p = 0.46]. 
According to the sensitivity analysis, no study affected the overall RR. 

The investigators found that the highest levels of lutein compared to the lowest were significantly related to a 30% lower risk of breast cancer [relative risk (RR) = 0.70, 95% CI = 0.52 to 0.93, I2 = 17.1%, p = 0.30]. 
According to the sensitivity analysis, no study affected the overall RR. 

The investigators concluded that higher levels of carotenoids, α-carotene, β-carotene, β-cryptoxanthin, lycopene and lutein are related to a decreased risk of breast cancer. Additionally, each 10 μg/dL of total carotenoids, α-carotene, β-carotene and β-cryptoxanthin reduce breast cancer risk with 2%, 22%, 4% and 10%, respectively. 

Original title: 
The Association between Circulating Carotenoids and Risk of Breast Cancer: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies by Dehnavi MK, Ebrahimpour-Koujan S, […], Azadbakht L.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10694674/ 

Additional information of El Mondo:
Find more information/studies on cohort studies/significantly, carotenoids and breast cancer right here. 

Objectives:
Systematic reviews of case-control studies evaluating the relationship between dietary salt intake and gastric cancer showed a positive association, however a quantitative analysis of longitudinal cohort studies is lacking. Therefore, this review article has been conducted.

Does a high salt intake increase gastric cancer risk?

Study design:
This review article contained 10 cohort studies with 268,718 participants, of which 1,474 gastric cancer events and a follow-up of 6-15 years.

Meta-regression analyses did not detect specific sources of heterogeneity.

There was no evidence of publication bias.

Results and conclusions:
The investigators found for high vs low salt intake a significantly increased risk of 68% for gastric cancer [RR = 1.68, 95% CI = 1.17 to 2.41, p = 0.005].

The investigators found for moderate vs low salt intake a significant increased risk of 41% for gastric cancer [RR = 1.41, 95% CI = 1.03 to 1.93, p = 0.032].

The investigators found the association was stronger in the Japanese population and higher consumption of selected salt-rich foods was also associated with greater risk.

The investigators concluded high salt intake is directly associated with an increased risk of gastric cancer in prospective population studies, with progressively increasing risk across consumption levels.

Original title:
Habitual salt intake and risk of gastric cancer: A meta-analysis of prospective studies by D’Elia L, Rossi G, […], Strazzullo P.

Link:
http://www.clinicalnutritionjournal.com/article/S0261-5614%2812%2900005-2/abstract

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

According to WHO, a high salt intake is a salt intake of more than 5 grams salt per day.

A diet with more than 5 grams salt per day is a diet with mainly products/meals with more than 0.25 grams salt per 100 kcal. Check here which products contain maximum 5 grams salt per 100 kcal.
Use the 7-points nutritional profile app to see whether your daily diet contains maximum 5 grams salt per 100 kcal.
 

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

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Objectives:
Is there a relationship between serum 25(OH)D (vitamin D blood level) and mortality risk in the general population?

Study design:
This review article included 14 prospective cohort studies that involved 5562 deaths out of 62548 individuals.
In the parametric model, which is based on 11 studies and 59231 individuals, the lowest quantile as the reference category has been used.

Evidence of heterogeneity for the RR was apparent when highest were compared with lowest categories [p = 0.008, I2 = 58%].

There was no evidence of publication bias.

Results and conclusions:
The investigators found for “highest compared with lowest” categories of 25(OH)D, a significant reduced risk of 29% for mortality [RR = 0.71, 95% CI = 0.50-0.91].

The investigators found in the parametric model, the estimated summary RRs of mortality were 0.86 [95% CI = 0.82-0.91], 0.77 [95% CI = 0.70-0.84] and 0.69 [95% CI = 0.60-0.78] for individuals with an increase of 12.5, 25 and 50 nmol 25(OH)D serum values/L, respectively, from a median reference category of ∼27.5 nmol/L.
However, no significant decrease in mortality was found above ∼87.5 nmol/L.

The investigators concluded there is a nonlinear decrease in mortality risk as circulating 25(OH)D increases, with optimal concentrations ∼75-87.5 nmol/L. Because many adults do not achieve these 25(OH)D values, large prospective randomized trials are urgently needed to investigate whether vitamin D supplementation is able to reduce mortality risk in the general population.

Original title:
Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies by Zittermann A, Iodice S, [...], Gandini S.

Link:
http://ajcn.nutrition.org/content/95/1/91.full

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Objectives:
Low glycaemic index (GI) diets are beneficial in the management of hyperglycemia. Cardiovascular diseases are the major cause of mortality in diabetes therefore it is important to understand the effects of GI on blood lipids. Therefore, this review article has been conducted.

Does a low GI diet lower the cholesterol levels?

Study design:
This review article included 28 RCTs comparing low with high GI diets over at least 4 weeks. These 28 RCTs contained 1272 participants with studies ranged from 6 to 155 participants, one was powered on blood lipids and 3 had adequate allocation concealment.

Results and conclusions:
The investigators found that compared to high GI diet low GI diet significantly reduced total cholesterol by 0.13 mmol/L [95% CI = -0.22 to -0.04, p = 0.004, 27 trials, 1441 participants]. Significantly means, it can be said with 95% confidence that low GI diet really lowered the total cholesterol levels with 0.13 mmol/L.

The investigators found that compared to high GI diet low GI diet significantly reduced LDL-cholesterol by 0.16 mmol/L [95% CI = -0.24 to -0.08, p 0.0001, 23 studies, 1281 participants]. Significantly, because the p-value was less than 0.05.

The investigators found subgroup analyses suggested that reductions in LDL-cholesterol were greatest in studies of shortest duration and greatest magnitude of GI reduction. Furthermore, lipid improvements appeared greatest and most reliable when the low GI intervention was accompanied by an increase in dietary fiber.

The investigators found sensitivity analyses, removing studies without adequate allocation concealment, lost statistical significance but retained suggested mean falls of 0.10 mmol/L in both.

The investigators found no effects on HDL-cholesterol [MD = -0.03 mmol/L, 95% CI = -0.06 to 0.00, I2 = 0%], or triglycerides [MD was 0.01 mmol/L, 95% CI = -0.06 to 0.08, I2 = 0%].

The researchers concluded that low GI diets reduce total and LDL-cholesterol (bad cholesterol) but had no effect on HDL-cholesterol (good cholesterol) or triglycerides.

Original title:
Low glycemic index diets and blood lipids: A systematic review and meta-analysis of randomized controlled trials by Goff LM, Cowland DE, [...], Frost GS.

Link:
http://www.sciencedirect.com/science/article/pii/S0939475312001524

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High LDL-cholesterol levels and high triglyceride levels increase the risk of getting cardiovascular diseases whereas high HDL-cholesterol levels decrease the risk of getting cardiovascular diseases.

A low GI diet is a diet with a GI value of 55 or lower.

Objectives:
Does soy isoflavone reduce the frequency and severity of hot flashes?

Study design:
This review article included 19 trials (13 included hot flash frequency, of which 10 for severity and 3 for composite scores).
17 trials were selected for meta-analyses to clarify the effect of soybean isoflavones on hot flash frequency (13 trials) and severity (9 trials).

Results and conclusions:
The investigators found intake of soy isoflavones (median = 54 mg aglycone equivalents) for 6 weeks to 12 months significantly reduced the frequency (combined fixed-effect and random effects model) of hot flashes by 20.6% [95% CI = -28.38 to -12.86, p 0.00001] compared with placebo [p heterogeneity = 0.0003, I2 = 67% for random effects model].

The investigators also found isoflavones significantly reduced hot flash severity by 26.2% [95% CI = -42.23 to -10.15, p = 0.001] compared with placebo [p heterogeneity 0.00001, I2 = 86% for random effects model].

The investigators found isoflavone supplements providing more than 18.8 mg of genistein (the median for all studies) were more than twice as potent at reducing hot flash frequency than lower genistein supplements.

The investigators concluded soy isoflavone supplements (54 mg per day for 6 weeks to 12 months), derived by extraction or chemical synthesis, are significantly more effective than placebo in reducing the frequency and severity of hot flashes. Additional studies are needed to further address the complex array of factors that may affect efficacy, such as dose, isoflavone form, baseline hot flash frequency and treatment duration.

Original title:
Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials by Taku K, Melby MK, […], Messina M.

Link:
http://journals.lww.com/menopausejournal/Abstract/2012/07000/Extracted_or_synthesized_soybean_isoflavones.11.aspx

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Objectives:
In view of the vital role of oxidative stress in the pathogenesis of Alzheimer's disease (AD), the potential of antioxidant supplements to prevent AD have gained much interest, while there are conflicting results on this topic in recent years. Therefore, this review article has been conducted.

Does dietary intake of vitamin C and E and β-carotene decrease risk of Alzheimer's disease?

Study design:
This review article included 7 articles (dietary intake, but no supplements).

Results and conclusions:
The investigators found a significant decreased risk for Alzheimer disease of 24% [pooled relative risk = 0.76 95% CI = 0.67-0.84] for dietary intake of vitamin E and of 17% [pooled relative risk = 0.83, 95% CI = 0.72-0.94] for dietary intake of vitamin C.

However, the investigators found a non-significant decreased risk of 12% [pooled relative risk = 0.88, 95% CI = 0.73-1.03] for dietary intake of β-carotene.

The investigators concluded dietary intakes of vitamin C and E lower the risk of Alzheimer's disease, with vitamin E exhibiting the most pronounced protective effects. The findings will be of significance to the prevention and interventional treatment of Alzheimer's disease.

Original title:
Dietary intakes of vitamin E, vitamin C, and β-carotene and risk of Alzheimer's disease: a meta-analysis by Li FJ, Shen L and Ji HF.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/22543848

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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

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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

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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

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Objectives:
Does allium vegetable consumption reduce gastric cancer risk?

Study design:
This review article included 22 case-control and 4 cohort studies with more than 10,000 cases.

Results and conclusions:
The investigators found in 10 case-control and 4 cohort studies for the highest versus lowest allium vegetables intake category a significant reduced risk of 22% for gastric cancer [OR = 0.78, 95% CI = 0.67-0.91].

The investigators found in 12 case-control studies for the highest versus lowest garlic intake category a significant reduced risk of 40% for gastric cancer [OR = 0.60, 95% CI = 0.47-0.76].

The investigators found in 13 case-control studies for the highest versus lowest onion intake category a significant reduced risk of 45% for gastric cancer [OR = 0.55, 95% CI = 0.41-0.73].

The investigators found in 4 cohort studies for the highest versus lowest allium vegetables intake category a non-significant increased risk of 2% for gastric cancer [RR = 1.02, 95% CI = 0.88-1.18]. Non-significant means no association with 95% confidence.

The investigators concluded high allium vegetable consumption, like garlic and onion is likely to reduce gastric cancer risk. Likely because this evidence is derived mainly from case-control studies. Therefore, further data from large cohorts are desirable for conclusive confirmation.

Original title:
Allium vegetable intake and gastric cancer: a case-control study and meta-analysis by Turati F, Pelucchi C, […], Galeone C.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/25215621

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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:
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Objectives:
Emerging randomized controlled trials (RCTs) investigating the effect of green tea or green tea extract (GTE) supplementation on blood pressure (BP) among overweight and obese adults reported inconsistent findings. Therefore, this review article has been conducted.

Does tea consumption decrease blood pressure among overweight and obese adults?

Study design:
This review article included 14 RCTs with 971 participants (47% women).

Results and conclusions:
The investigators found green tea or green tea extract supplementation compared with placebo, significantly reduced systolic blood pressure with 1.42 mmHg [95% CI = -2.47 to -0.36, p  =  0.008, I2  =  52%, p for heterogeneity =  0.01 ] among overweight and obese adults.

The investigators found green tea or green tea extract supplementation compared with placebo, significantly reduced diastolic blood pressure with 1.25 mmHg [95% CI = -2.32 to -0.19, p = 0.02, I2 = 74%, p for heterogeneity   0.001] among overweight and obese adults.

The investigators found the quality of evidence across studies was low. Similar results were found in subgroup and sensitivity analyses.

The investigators concluded among overweight and obese adults, green tea or green tea extract supplementation is found to cause a small but significant reduction in blood pressure. However, more high-quality RCTs with large sample sizes are needed to further confirm the efficacy on blood pressure and make strong recommendations for green tea or green tea extract supplementation among the overweight and obese adults.

Original title:
Effect of green tea supplementation on blood pressure among overweight and obese adults: a systematic review and meta-analysis by Li G, Zhang Y, […], Holbrook A.

Link:
http://journals.lww.com/jhypertension/Abstract/2015/02000/Effect_of_green_tea_supplementation_on_blood.6.aspx

Additional information of El Mondo:
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Objectives:
An increased intake of magnesium might lower blood pressure (BP), yet evidence from clinical trials is inconsistent, perhaps as a result of small sample size or heterogeneity in study design. Therefore, this review article (meta-analysis) has been conducted.

Are there dose-dependent effects of magnesium supplementation on blood pressure?

Study design:
This review article included 20 RCTs included 14 of hypertensive and 6 of normotensive persons totaling 1220 participants.
The doses of magnesium ranged from 10 to 40 mmol/day (median: 15.4 mmol/day or 370 mg per day).

Results and conclusions:
The investigators found magnesium supplementation resulted in only a small overall non-significant reduction in blood pressure. The pooled net estimates of blood pressure change were -0.6 mmHg [95% CI = -2.2 to 1.0] for systolic blood pressure and -0.8 mmHg [95% CI = -1.9 to 0.4] for diastolic blood pressure.

However, the investigators found an apparent dose-dependent effect of magnesium, with significant reductions of 4.3 mmHg systolic blood pressure [95% CI = 6.3 to 2.2, p 0.001) and non-significant reductions of 2.3 mmHg diastolic blood pressure [95% CI = 4.9 to 0.0, p = 0.09) for each 10 mmol/day (240 mg/day) increase in magnesium dose.

The investigators concluded there is a dose-dependent blood pressure reductions, especially systolic blood pressure from magnesium supplementation. However, adequately powered trials with sufficiently high doses of magnesium supplements need to be performed to confirm this relationship.

Original title:
The effect of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials by Jeea SH, Miller ER, [...], Klagb MJ.

Link:
http://www.sciencedirect.com/science/article/pii/S0895706102029643

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Objectives:
There are conflicting reports on the correlation between manganese (Mn) levels and breast cancer. Therefore, this review article (meta-analysis) has been conducted.

Does manganese deficiency increase risk of breast cancer?

Study design:
This review article included 11 case-control studies involving 1302 subjects.

There was no evidence of publication bias. Sensitivity analysis showed that excluding any one study from the pooled analysis did not vary the results substantially.

Results and conclusions:
The investigators found the random-effects meta-analysis results indicated that subjects with breast cancer had lower manganese levels in serum and hair than healthy controls [SMD = -1.51, 95% CI = -2.47 to -0.56, I2 = 97.8%, p 0.001].

The investigators found in subgroup analysis that subjects with breast cancer had lower manganese levels than healthy controls in China [SMD = -1.32, 95% CI = -2.33 to -0.32] and Korea [SMD = -4.08, 95% CI = -4.63 to -3.54], but not in Turkey [SMD = -0.96, 95% CI = -3.19 to 1.27].

The investigators found in subgroup analysis that the differences of manganese levels between patients with breast cancer and healthy controls were similar in different sample specimens:
serum [SMD = -1.24, 95% CI = -2.31 to -0.16];
hair [SMD = -1.99, 95% CI = -3.91 to -0.06] and;
different types of manganese measurement:

ICP-AAS [SMD = -1.14, 95% CI = -2.24 to -0.04];
GFAAS [SMD = -1.94, 95% CI = -2.38 to -1.49];
ICP-AES [SMD = -3.77, 95% CI = -4.70 to -2.85]. These findings can well explain that  the between-study variability was the main source of heterogeneity.

The investigators concluded there is an association between deficient manganese concentration and breast cancer. However, the subgroup analysis found that there was contradiction regarding races and geography, like China and Turkey. Thus this finding needs further confirmation by trans-regional multicenter, long-term observation in a cohort design to obtain better understanding of causal relationships between manganese levels and breast cancer, through measuring manganese at baseline to investigate whether the highest manganese category versus lowest was associated with breast cancer risk.

Original title:
The association between deficient manganese levels and breast cancer: a meta-analysis by Shen F, Cai WS, [...],Xu B.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443096/

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