Nutrition and health

Objectives:
Some evidence indicates that carotenoids may reduce the risk of bladder cancer (BC), but the association is unclear. Therefore, this review article has been conducted.

Do carotenoids (β-cryptoxanthin, α-carotene, β-carotene and lutein and zeaxanthin) reduce risk of bladder cancer?

Study design:
This review article included a total of 22 studies (case-control and cohort studies) involving 516,740 adults.

Results and conclusions:
The investigators found for the highest compared with the lowest category of carotenoid dietary intake a non-significantly reduced risk of 12% [RR = 0.88, 95% CI = 0.76 to 1.03] for bladder cancer.
Non-significantly because RR of 1 was found in the 95% CI of 0.76 to 1.03. RR of 1 means no risk/association.

The investigators found for the highest compared with the lowest category of circulating carotenoid concentrations a non-significantly reduced risk of 64% [RR = 0.36, 95% CI = 0.12 to 1.07] for bladder cancer.

The investigators found for the highest compared with the lowest category of circulating lutein and zeaxanthin concentrations a significantly reduced risk of 47% [RR = 0.53, 95% CI = 0.33 to 0.84] for bladder cancer.
Significantly because RR of 1 was not found in the 95% CI of 0.33 to 0.84. RR of 1 means no risk/association.

The investigators found dose-response analysis showed that bladder cancer risk significantly decreased by 42% [RR = 0.58, 95% CI = 0.36 to 0.94] for every 1 mg increase in daily dietary β-cryptoxanthin intake.

The investigators found dose-response analysis showed that bladder cancer risk significantly decreased by 76% [RR = 0.24, 95% CI = 0.08 to 0.67] for every 1 μmol/L increase in circulating concentration of α-carotene.

The investigators found dose-response analysis showed that bladder cancer risk significantly decreased by 27% [RR = 0.73, 95% CI = 0.57 to 0.94] for every 1 μmol/L increase in circulating concentration of β-carotene.

The investigators found dose-response analysis showed that bladder cancer risk significantly decreased by 56% [RR = 0.44, 95% CI = 0.28 to 0.67] for every 1 μmol/L increase in circulating concentrations of lutein and zeaxanthin.

The investigators concluded dietary β-cryptoxanthin intake and circulating concentrations of α-carotene, β-carotene and lutein and zeaxanthin reduce risk of bladder cancer.

Original title:
Carotenoid Intake and Circulating Carotenoids Are Inversely Associated with the Risk of Bladder Cancer: A Dose-Response Meta-analysis by Wu S, Liu Y, […], Ramirez AG.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31800007

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Find more information/studies on carotenoid consumption and cancer right here.

 

Objectives:
Does vitamin K reduce risk of cardiovascular disease (CVD) events and mortality?

Study design:
This review article included 21 articles with 222,592 participants.

Results and conclusions:
The investigators found dietary phylloquinone (vitamin K1) intake significantly reduced risk of total cardiovascular disease with 8% [pooled HR = 0.92, 95% CI = 0.84 to 0.99, I2 = 0%, 4 studies].
Significant means that there is an association with a 95% confidence.

The investigators found dietary menaquinone (vitamin K2) intake significantly reduced risk of total cardiovascular disease with 30% [pooled HR = 0.70, 95% CI = 0.53 to 0.93, I2 = 32.1%, 2 studies].
Significant because HR of 1 was not found in the 95% CI of 0.53 to 0.93. HR of 1 means no risk/association.

The investigators found no significant association between dietary vitamin K and all-cause mortality, cardiovascular disease mortality or stroke.

The investigators found elevated plasma desphospho-uncarboxylated MGP (dp-ucMGP), a marker of vitamin K deficiency, was associated with an increased risk of 84% [HR = 1.84, 95% CI = 1.48 to 2.28, I2 = 16.8%, 5 studies] for all-cause mortality.

The investigators found elevated plasma desphospho-uncarboxylated MGP (dp-ucMGP), a marker of vitamin K deficiency, was associated with an increased risk of 96% [HR = 1.96, 95% CI = 1.47 to 2.61, I2 = 0%, 2 studies] for cardiovascular disease mortality.

The investigators found no significant association between circulating total osteocalcin and all-cause mortality or total cardiovascular disease.

The investigators concluded higher dietary vitamin K consumption reduces risk of cardiovascular disease and higher plasma dp-ucMGP concentration, but not total circulating osteocalcin, increases risk of all-cause and cardiovascular disease mortality. However, causal relations cannot be established because of limited number of available studies and larger prospective studies and randomized clinical trials are needed to validate these findings.  

Original title:
Association of vitamin K with cardiovascular events and all-cause mortality: a systematic review and meta-analysis by Chen HG, Sheng LT, […], Pan A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31119401

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Find more information/studies on vitamin K, significantly/review article and cardiovascular disease right here.

100 grams of fresh parsley provide 548 micrograms (548 mcg) of vitamin K1 or 4.5 days.
 

Objectives:
Is there an association between dietary fat intake and the risk of three major types of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM)?

Study design:
This review article included 3 prospective cohort studies (175,675 participants and 30,915 basal cell carcinoma cases, 4,106 squamous cell carcinoma cases and 1,638 cutaneous malignant melanoma cases) and 9 case-control studies (328 basal cell carcinoma cases, 493 squamous cell carcinoma cases, 1,547 cutaneous malignant melanoma cases and 2,660 controls).

Results and conclusions:
The investigators found pooled results indicated that dietary consumption of total fat and saturated fat were not associated with 3 major types of skin cancer.

The investigators found high consumption of monounsaturated fat was significantly associated with a decreased risk of 10% for basal cell carcinoma [RR = 0.90, 95% CI = 0.85 to 0.96]. 

The investigators found high consumption of polyunsaturated fat was significantly associated with an increased risk of 19% for squamous cell carcinoma [RR = 1.19, 95% CI = 1.06 to 1.33]. 

The investigators concluded high consumption of monounsaturated fat decreases risk of basal cell carcinoma while high consumption of polyunsaturated fat increases risk of squamous cell carcinoma. However, these findings should be confirmed by further evidence from well-designed and large-scale prospective cohort studies.

Original title:
Dietary Fat Intake and the Risk of Skin Cancer: A Systematic Review and Meta-Analysis of Observational Studies by Ruan L, Cheng SP and Zhu QX.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31298947

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Objectives:
Is there a causal relationship between grape product supplementation and improved lipid profiles in adults?

Study design:
This review article included 48 RCTs.

Results and conclusions:
The investigators found meta-analysis indicated that consumption of grape products significantly reduced the concentration of total cholesterol [MD = -6.196 mg/dL, 95% CI = -9.203 to -3.189], low-density lipoprotein cholesterol (bad cholesterol) [MD = -4.964 mg/dL, 95% CI = -7.594 to -2.334] and triglyceride [MD = -7.641 mg/dL, 95% CI = -12.120 to -3.162].

The investigators found grape product supplementation changed the HDL and LDL in a non-linear fashion based on the dose of polyphenols.

The investigators concluded that grape products have a favorable role in the achievement of a lipid profile target in adults, particularly total cholesterol, low-density lipoprotein cholesterol (bad cholesterol) and triglyceride levels.

Original title:
Effects of grape products on blood lipids: a systematic review and dose-response meta-analysis of randomized controlled trials by Ghaedi E, Moradi S, [...], Mohammadi H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31517353

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Find more information/studies on fruits, meta-analysis and cholesterol right here.
 

Objectives:
The results of epidemiological studies on the relationship between fruit and vegetable intake and lung cancer risk were inconsistent among participants with different smoking status. Therefore, this review article has been conducted.

Do dietary intakes of fruit and vegetables reduce risk of lung cancer?

Study design:
This review article included a total of 12 prospective cohort studies.
The duration of follow-up ranged from 4 to 12.9 years.
No publication bias was found.

Results and conclusions:
The investigators found for dietary consumption of fruit a significantly reduced risk of 14% [summary RR = 0.86, 95% CI = 0.78 to 0.94, I2 = 0.0%, p = 0.642] for lung cancer among current smokers.

Significant means that there is an association with a 95% confidence.

The investigators found for dietary consumption of fruit a significantly reduced risk of 9% [summary RR = 0.91, 95% CI = 0.84 to 0.99, I2 = 0.0%, p = 0.653] for lung cancer among former smokers.
Significant because RR of 1 was not found in the 95% CI of 0.84 to 0.99. RR of 1 means no risk/association.

The investigators found stratified analysis showed that dietary consumption of fruit significantly reduced risk of lung cancer with 23% [RR = 0.77, 95% CI = 0.62 to 0.96] in current smoking subjects from Europe.

The investigators found in linear dose-response analysis that an increase of 100 grams of fruit intake per day was associated with a 5% reduction [RR = 0.95, 95% CI = 0.93 to 0.97, p for trend 0.001] in current smokers.

The investigators found in linear dose-response analysis that an increase of 100 grams of fruit intake per day was associated with a 5% reduction [RR = 0.95, 95% CI = 0.93 to 0.99, p for trend = 0.001] in former smokers.

The investigators found for dietary consumption of vegetables a significantly reduced risk of 13% [summary RR = 0.87, 95% CI = 0.78 to 0.97, I2 = 25.4%, p = 0.226] for lung cancer among current smokers.

The investigators found in linear dose-response analysis that an increase of 100 grams of vegetable intake per day was associated with a 3% lower risk of lung cancer in current smokers [95% CI = 0.96 to 1.00, p for trend = 0.057]. 

The investigators concluded that fruit consumption, at least 100g per day decreases lung cancer risk among current smokers and former smokers, while vegetables consumption, at least 100g per day decreases lung cancer risk of current smokers. These findings may have considerable public health significance for the prevention of lung cancer through dietary interventions.

Original title:
The Associations of Fruit and Vegetable Intake with Lung Cancer Risk in Participants with Different Smoking Status: A Meta-Analysis of Prospective Cohort Studies by Wang C, Yang T, [...], Li D.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723574/

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Find more information/studies on fruit and vegetables consumption and cancer right here.

 

Objectives:
Findings of epidemiological studies regarding the association between carrot consumption and lung cancer risk remain inconsistent. Therefore, this review article has been conducted.

Do dietary intakes of carrot reduce risk of lung cancer?

Study design:
This review article included a total of 17 case-control studies and 1 prospective cohort study, involving 202,969 individuals and 5,517 patients with lung cancer.

Results and conclusions:
The investigators found in 18 studies a significantly reduced risk of 42% [pooled OR = 0.58, 95% CI = 0.45 to 0.74] for lung cancer by comparing the highest category with the lowest category of carrot consumption.
Exclusion of any single study did not materially alter the pooled OR.

The investigators found based on subgroup analyses for the types of lung cancer a significantly reduced risk of 66% [pooled OR = 0.34, 95% CI = 0.15 to 0.79] for the lung cancer adenocarcinoma by comparing the highest category with the lowest category of carrot consumption.

The investigators found based on subgroup analyses for the types of lung cancer a significantly reduced risk of 39% [OR = 0.61, 95% CI = 0.46 to 0.81] for mixed types of lung cancer by comparing the highest category with the lowest category of carrot consumption.

The investigators concluded that carrot consumption decreases the risk of lung cancer, especially for adenocarcinoma.

Original title:
Is carrot consumption associated with a decreased risk of lung cancer? A meta-analysis of observational studies by Xu H, Jiang H, […], Lu Z.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31552816

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Objectives:
Does green coffee bean extract (GCBE) supplementation reduce blood pressure?

Study design:
This review article included 9 RCTs.

Results and conclusions:
The investigators found a significant reduction in systolic blood pressure (SBP) [WMD = -3.093 mmHg, 95% CI = -3.914 to -2.273, I2 = 0.0%] and diastolic blood pressure (DBP) [WMD = -2.170 mmHg, 95% CI = -2.749 to -1.590, I2 = 46.5%] after green coffee supplementation with low heterogeneity among the studies.

The investigators found in subgroup analysis, a significant reduction in systolic blood pressure and diastolic blood pressure in studies with hypertensive patients, green coffee dosage 400 mg per day and administered for 4 weeks.

The investigators concluded 400 mg coffee bean extract supplementation per day during 4 weeks reduces systolic blood pressure and diastolic blood pressure in hypertensive patients.

Original title:
The effect of green coffee extract supplementation on blood pressure: A systematic review and meta-analysis of randomized controlled trials by Han B, Nazary-Vannani A, […], Kord-Varkaneh H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31429515

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Find more information/studies on coffee and reducing blood pressure right here.
 

Objectives:
Observational studies have reported controversial evidence of the association between dietary fat intake and ovarian cancer. Therefore, this review article has been conducted.
Does dietary fat intake increase risk of ovarian cancer among women?

Study design:
This review article included 21 observational studies involved approximately 900,000 women.

Results and conclusions:
The investigators found a significant nonlinear association between dietary total fat intake with the risk of ovarian cancer, with a relatively steep slope at dietary total fat intake higher than 30 g/day [p non-linearity 0.01].

The investigators found, moreover, the risk of ovarian cancer was increased in non-linear form for both saturated and monounsaturated fat from 25 g/day [p non-linearity 0.05].

The investigators found in linear meta-analysis a 2% greater risk of ovarian cancer per 10 g/day increase in total dietary fat intake.

The investigators found in linear meta-analysis a 2% greater risk of ovarian cancer per 0.5 g/day increase in dietary trans fat intake.

The investigators found in linear meta-analysis a 1% greater risk of ovarian cancer per 2.5 g/day increase in dietary monounsaturated fat intake.
However, this association for monounsaturated fat was marginally significant [p = 0.052].

The investigators found in linear meta-analysis a 1% greater risk of ovarian cancer per 50 mg/day increase in dietary cholesterol intake.

The investigators concluded that dietary total, trans, saturated and partially monounsaturated fat as well as cholesterol intake increase risk of ovarian cancer among women.

Original title:
Dietary Fat Intake and Risk of Ovarian Cancer: A Systematic Review and Dose-Response Meta-Analysis of Observational Studies by Sadeghi A, Shab-Bidar S, […], Djafarian K.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31058552

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Find more information/studies on fat consumption and cancer right here.
 

Objectives:
Do dietary intakes or circulating concentration of major dietary antioxidants, like vitamin C, E and beta-carotene reduce risk of total cardiovascular mortality?

Study design:
This review article included a total of 15 prospective cohort studies and 3 prospective evaluations within interventional studies with 320,548 participants and 16,974 deaths from total cardiovascular mortality.

Results and conclusions:
The investigators found compared to the lowest category, the highest category of dietary vitamin C intake significantly reduced risk of total cardiovascular mortality with 21% [relative risk = 0.79, 95% CI = 0.68 to 0.89, I2 = 46%, n = 10].

The investigators found compared to the lowest category, the highest category of circulating concentration of vitamin C significantly reduced risk of total cardiovascular mortality with 40% [relative risk = 0.60, 95% CI = 0.42 to 0.78, I2 = 65%, n = 6].

The investigators found compared to the lowest category, the highest category of circulating concentration of vitamin E (α-tocopherol) significantly reduced risk of total cardiovascular mortality with 18% [relative risk = 0.82, 95% CI = 0.76 to 0.88, I2 = 0%, n = 5].

The investigators found compared to the lowest category, the highest category of circulating concentration of β-carotene significantly reduced risk of total cardiovascular mortality with 32% [relative risks = 0.68, 95% CI = 0.52 to 0.83, I2 = 50%, n = 6].

The investigators found dose-response meta-analyses demonstrated that the circulating biomarkers of antioxidants were more strongly associated with risk of total cardiovascular mortality than dietary intakes.

The investigators concluded that higher dietary vitamin C intakes and higher circulating concentrations of vitamin C, vitamin E and β-carotene are associated with a lower risk of total cardiovascular mortality.

Original title:
Dietary and circulating vitamin C, vitamin E, β-carotene and risk of total cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective observational studies by Jayedi A, Rashidy-Pour A, […], Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30630552

Additional information of El Mondo:
Find more information/studies on antioxidants, vitamin C, E, β-carotene and cardiovascular diseases right here.

Circulating concentration of vitamin C in blood can be increased by eating foods that are high in vitamin C and/or taking vitamin C supplements.

Objectives:
Dietary polyphenols, including flavonoids, have been the focus of major recent attentions due to their wide content in a variety of foods commonly consumed and the findings from numerous studies showing evidence of an association with positive outcomes on human health. Therefore, this review article has been conducted.

Does dietary intake of flavonoids (e.g., anthocyanins, isoflavones, flavones, flavonols, flavanones, flavan-3-ols) reduce hypertension?

Study design:
This review article included 15 cross-sectional investigations and 7 prospective cohort studies (1 study reported on 3 prospective cohort studies).
5 prospective cohort studies, comprising 200,256 individuals and 45,732 cases of hypertension were included in the quantitative analysis.

All studies included covariates that may have significantly influenced the endpoint outcome (hypertension), such as age, sex (when not analyzed separately), BMI, education, physical activity and smoking status. However, not all studies adjusted for key dietary factors that might influence risk of hypertension, such as sodium and potassium intake.

There was no publication bias.

Results and conclusions:
The investigators found analysis by extreme quantiles of intake of flavonoid showed a non-significant association with decreased risk of hypertension [risk ratio = 0.96, 95% CI = 0.89 to 1.03, I2 = 74%, p = 0.01].
Non-significant because RR of 1 was found in the 95% CI of 0.89 to 1.03. RR of 1 means no risk/association.

The investigators found taking into consideration individual flavonoid subclasses, dietary intake of anthocyanins was associated with 8% reduction in risk of hypertension, when comparing highest vs. lowest exposure [risk ratio = 0.92, 95% CI = 0.88 to 0.97].
Significant because RR of 1 was not found in the 95% CI of 0.88 to 0.97. RR of 1 means no risk/association.

The investigators concluded dietary intakes of anthocyanins reduce risk of hypertension. However, further studies are needed to elucidate the retrieved association between polyphenol consumption and decreased risk of hypertension and to clarify whether individual subclasses, rather than the total content of polyphenols, may exert beneficial effects on blood pressure.

Original title:
Dietary Polyphenol Intake, Blood Pressure, and Hypertension: A Systematic Review and Meta-Analysis of Observational Studies by Godos J, Vitale M, […], Grosso G.

Link:
https://www.mdpi.com/2076-3921/8/6/152/htm

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Find more information/studies on flavonoids and cardiovascular diseases right here.

Objectives:
Preventing cardiovascular disease (CVD) is the top priority in public health. Hyperlipidemia and hypertension are key contributors to cardiovascular disease which can be easily modified with dietary and lifestyle interventions. Therefore, this review article has been conducted.

Does cashew consumption reduce blood lipids levels (i.e., triglyceride, total cholesterol, HDL cholesterol (good cholesterol) and LDL cholesterol (bad cholesterol) and blood pressure?

Study design:
This review article included 5 RCTs with 246 participants receiving cashew nut (intervention group) and 235 receiving placebo (placebo group).

There was no publication bias.

Results and conclusions:
The investigators found overall analysis showed a statistically significant reducing effect of cashew nut consumption on triglyceride levels [WMD = -14.39, 95% CI = -27.30 to -1.49, I2 = 82%].
Significant means that there is an association with a 95% confidence.

The investigators found overall analysis showed a statistically significant reducing effect of cashew nut consumption on systolic blood pressure [WMD = -1 mm/Hg, 95% CI = -5.12 to -3.01, I2 = 0%].

The investigators found overall analysis showed a statistically significant reducing effect of cashew nut consumption on diastolic blood pressure [WMD = -4.06 mm/Hg, 95% CI = -1.65 to -0.35, I2 = 0%].

The investigators found, however, no statistically significant changes of other cardiovascular risk markers including total cholesterol [WMD = -1.89, 95% CI = -9.17 to 5.39, p = 0.61], LDL cholesterol [WMD = -5.49, 95% CI = -16.76 to 5.78, p = 0.34] and HDL cholesterol [WMD = -0.67, 95% CI = -2.54 to 1.19, p = 0.48] were observed after cashew nut consumption.
No statistically significant because the calculated p-values of e.g. 0.61 or 0.34 were larger than the p-value of 0.05.

The investigators concluded that cashew consumption improves triglyceride levels as well as systolic and diastolic blood pressure with no significant effects on other cardiometabolic factors (i.e., total cholesterol, HDL cholesterol (good cholesterol) and LDL cholesterol (bad cholesterol)). Further studies are warranted with different calories and dietary compositions.

Original title:
The Effect of Cashew Nut on Cardiovascular Risk Factors and Blood Pressure: A Systematic Review and Meta-analysis (P06-117-19) by Mahboobi S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6573847/

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Objectives:
Iron has been shown to promote breast carcinogenesis in animal models through generation of oxidative stress and interaction with estrogen. Heme iron, which is found exclusively in animal-sourced foods, is suggested to have a more detrimental effect. Epidemiological evidence of the association between iron and breast cancer risk remains inconclusive and has not been comprehensively summarized. Therefore, this review article has been conducted.

Does dietary iron consumption increase breast cancer risk?

Study design:
This review article included 15 case-control studies and 12 prospective cohort studies.

Of the 17 studies assessing iron intake, 7 were cohort studies with study size ranging from 4,646 to 193,742 participants, follow-up ranging from 5.5 to 20 years and number of breast cancer cases ranging from 188 to 9,305. The remaining 10 studies were case-control studies, of which 4 were hospital-based, 3 were population-based and 3 were nested within existing cohorts, with case numbers ranging from 220 to 3,452.

Of the 11 studies assessing body iron status, 5 were cohort studies with study size ranging from 1,795 to 164,355 participants, follow-up ranging from 7.1 to 17.6 years and number of cases ranging from 80 to 3,238. The remaining 6 studies used a nested case-control or case-cohort design, with follow-up (where reported) ranging from 4 to 15.7 years and case numbers ranging from 107 to 795.

Overall, NOS scores ranged from 4 to 9 (mean = 7.0).

No publication bias was found.

Results and conclusions:
The investigators found compared to lowest category, highest dietary heme iron intake significantly increased risk of breast cancer with 12% [pooled RR = 1.12, 95% CI = 1.04-1.22, I2 = 39%, p heterogeneity = 0.15].

The investigators found each 1 mg/day increase in dietary heme iron intake, was associated with a statistically significant 8% increase in breast cancer risk [pooled RR = 1.08, 95% CI = 1.002–1.17].

The investigators found compared to lowest levels, highest serum iron levels significantly increased risk of breast cancer with 22% [pooled RR = 1.22, 95% CI = 1.01-1.47, I2 = 61%, p heterogeneity = 0.04].

The investigators found serum iron levels exhibited a J-shaped dose-response relationship with breast cancer risk, with strong evidence of a nonlinear effect [p nonlinearity  0.001].

Specifically, a steady increase in risk was noted for serum iron levels above ~ 100 μg/dL, with the association becoming statistically significant at just beyond ~ 125 μg/dL.

The investigators concluded that higher dietary heme iron intake and higher serum iron levels increase breast cancer risk. Further research is needed to better elucidate the association between iron intake/status and risk of breast cancer.

Original title:
Iron intake, body iron status, and risk of breast cancer: a systematic review and meta-analysis by Chang VC, Cotterchio M and Khoo E.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6555759/

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Objectives:
Is there an association between poultry and egg consumption and brain cancer risk?

Study design:
This review article included a total of 10 articles (6 articles for poultry consumption and 5 articles for egg consumption).

Results and conclusions:
The investigators found no association between poultry consumption and reduced risk of brain cancer [summarized relative risk = 0.901, 95% CI = 0.703-1.154, I2 = 60.7%, p = 0.018].
No association because RR of 1 was found in the 95% CI of 0.703 to 1.154. RR of 1 means no risk/association.

The investigators found in 4 studies no association between poultry consumption and reduced risk of brain cancer glioma [summarized relative risk = 0.873, 95% CI = 0.737-1.034, I2 = 0.0%, p = 0.838].

The investigators found no association between egg consumption and reduced risk of brain cancer [summarized relative risk = 0.998, 95% CI = 0.552-1.805, I2 = 82.6%, p = 0.001].

The investigators found no association between egg consumption and increased risk of brain cancer glioma [summarized relative risk = 1.472, 95% CI = 0.935-2.316].

The investigators concluded that poultry and egg consumption are not associated with the risk of brain cancer. Due to the limited quality of evidence currently available, more studies related to poultry and egg consumption for brain cancer is necessary.

Original title:
A meta-analysis of the association between poultry and egg consumption and the risk of brain cancer by Luo H, Sun P, [...], Guo Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30782302

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Find more information/studies on poultry and egg consumption, review article/significantly and cancer right here.

Objectives:
Does coenzyme Q10 (CoQ10) supplementation improve biomarkers of inflammation and oxidative stress among patients with coronary artery disease (CAD)?

Study design:
This review article included 13 RCTs.

Given the presence of heterogeneity, random-effects model or fixed-effect model were used to pool standardized mean differences (SMDs) as summary effect sizes.

Results and conclusions:
The investigators found pooled findings for biomarkers of inflammation and oxidative stress demonstrated that coenzyme Q10 supplementation significantly increased superoxide dismutase (SOD) [SMD = 2.63, 95% CI = 1.17 to 4.09, p  0.001, I2 = 94.5%] and catalase (CAT) levels [SMD = 1.00, 95% CI = 0.57 to 1.43, p  0.001, I2 = 24.5%] among patients with coronary artery disease.

The investigators found pooled findings for biomarkers of inflammation and oxidative stress demonstrated that coenzyme Q10 supplementation significantly reduced malondialdehyde (MDA) [SMD = -4.29, 95% CI = -6.72 to -1.86, p = 0.001, I2 = 97.6%] and diene levels [SMD = -2.40, 95% CI = -3.11 to -1.68, p  0.001, I2 = 72.6%] among patients with coronary artery disease.

The investigators found among patients with coronary artery disease no significant effect of coenzyme Q10 supplementation on:
-C-reactive protein (CRP) [SMD = -0.62, 95% CI = -1.31 to 0.08, p = 0.08, I2 = 87.9%];
-tumor necrosis factor alpha (TNF-α) [SMD = 0.22, 95% CI = -1.07 to 1.51, p = 0.73, I2 = 89.7%];
-interleukin-6 (IL-6) [SMD = -1.63, 95% CI = -3.43 to 0.17, p = 0.07, I2 = 95.2%] and;
-glutathione peroxidase (GPx) levels [SMD = 0.14, 95% CI = -0.77 to 1.04, p = 0.76, I2 = 78.7%].
No significant because the calculated p-values were larger than the p-value of 0.05.

The investigators concluded coenzyme Q10 supplementation increases superoxide dismutase and catalase and decreases malondialdehyde and diene levels, but has no affect on C-reactive protein, tumor necrosis factor alpha, interleukin-6 and glutathione peroxidase levels among patients with coronary artery disease.

Original title:
The effects of coenzyme Q10 supplementation on biomarkers of inflammation and oxidative stress in among coronary artery disease: a systematic review and meta-analysis of randomized controlled trials by Jorat MV, Tabrizi R, […], Asemi Z.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30758695

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Malondialdehyde and diene are biomarkers of oxidative stress. Oxidative stress can arise when human cells cannot adequately destroy the excess of free radicals formed.

Free radicals can be rendered harmless by antioxidants such as vitamins C and E and by antioxidative enzymes such as superoxide dismutase and catalase.

Objectives:
Previous studies had demonstrated some associations between coffee and tea consumption and brain cancer risk resulted in an inconsistent relationship. Therefore, this review article has been conducted.

Does coffee or tea consumption reduce brain cancer risk?

Study design:
This review article included 8 cohort studies and 3 case-control studies, involving 2,583 cases (persons with brain cancer) among 1,684,262 participants.

Based on Egger’s test and funnel plot, there existed no publication bias.

Results and conclusions:
The investigators found highest category of coffee consumption significantly reduced risk of brain cancer with 21.5% [RR = 0.785, 95% CI = 0.580-0.984, I2 = 65.6%, p for heterogeneity = 0.001], when compared with the lowest category.

The investigators found in supgroup analysis highest category of coffee consumption significantly reduced risk of glioma with 24% [RR = 0.760, 95% CI = 0.548-0.972], when compared with the lowest category.

The investigators found in cohort studies highest category of coffee consumption significantly reduced risk of brain cancer with 14.2% [RR = 0.858, 95% CI = 0.700-0.992], when compared with the lowest category. However, this reduced risk was not significant in case-control studies.

The investigators found highest category of coffee consumption significantly reduced risk of brain cancer with 88.3% in Asian populations [RR = 0.217, 95% CI = 0.042-0.896], when compared with the lowest category. However, this reduced risk was not significant in other populations.

The investigators found sensitivity analysis showed pooled RR of coffee consumption ranged from 0.738 [95% CI = 0.542-0.961) to 0.905 [95% CI = 0.754-1.088].

The investigators found highest category of tea consumption significantly reduced risk of brain cancer with 20.2% in American populations [RR = 0.798, 95% CI = 0.646-0.986], when compared with the lowest category.

The investigators found sensitivity analysis showed pooled RR of tea consumption ranged from 0.863 [95% CI = 0.699-1.067] to 0.947 [95% CI = 0.763-1.176].

The investigators found highest category of coffee plus tea consumption significantly reduced risk of brain cancer with 31.6% [RR = 0.684, 95% CI = 0.481-0.975], when compared with the lowest category.

The investigators concluded higher consumption of coffee reduces risk of brain cancer in Asian populations and higher consumption of tea reduces risk of brain cancer in American population. However, future studies with detailed information about sex, lifestyle and some other related factors are warranted to further explore the association between coffee or tea consumption and risk of brain cancer.

Original title:
Association between tea and coffee consumption and brain cancer risk: an updated meta-analysis by Song Y, Wang Z, [....], Guo J.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6419842/

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Objectives:
Does kiwifruit improve metabolic health in participants with cardiovascular risk factors, including hypercholesterolemia, hypertension, diabetes type 2 and smokers?

Study design:
This review article included 5 RCTs involving 489 participants.

Results and conclusions:
The investigators found no significant effect of kiwifruit on:
-systolic blood pressure (SBP) [MD = -1.72 mmHg, 95% CI = -4.27 to 0.84];
-diastolic blood pressure (DBP) [MD = -2.35 mmHg, 95% CI = -5.10 to 0.41];
-total cholesterol (TC) [MD = -0.14 mmol/L, 95% CI = -0.71 to 0.43];
-triglyceride (TG) [MD = -0.23 mmol/L, 95% CI = -0.66 to 0.20];
-low-density lipoprotein cholesterol (bad cholesterol or LDL) [MD = -0.41 mmol/L, 95% CI = -0.99 to 0.18];
-high-density lipoprotein cholesterol (good cholesterol or HDL) [MD = 0.15 mmol/L, 95% CI = -0.18 to 0.48];
-fasting plasma glucose (FPG) [MD = -0.08 mmol/L, 95% CI = -0.37 to 0.21];
-homeostasis model assessment of insulin resistance (HOMA-IR) [MD = -0.29, 95% CI = -0.61 to 0.02] and;
-body weight (BW) [MD = 1.08 kg, 95% CI = -4.22 to 2.05].

The investigators found subgroup analysis limiting to studies of whole kiwifruit and duration of intervention of at least 8 weeks again revealed no such effect of kiwifruit on total cholesterol, triglyceride, LDL cholesterol and HDL cholesterol.

The investigators concluded kiwifruit has no effect on metabolic health, as measured by systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, LDL cholesterol and HDL cholesterol, fasting plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR) and body weight in participants with cardiovascular risk factors including hypercholesterolemia, hypertension, diabetes type 2 and smokers. Due to limited evidence and high heterogeneity of the study results, the potential of kiwifruit as a nonpharmaceutical alternative for metabolic health should be further evaluated in well-defined, well-controlled trials with larger sample size and standardized preparation.

Original title:
Effect of kiwifruit on metabolic health in patients with cardiovascular risk factors: a systematic review and meta-analysis by Suksomboon N, Poolsup N and Lin W.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350646/

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Objectives:
Results from earlier publications on the association of coffee and caffeine and risk of ovarian cancer are inconsistent. Therefore, this review article has been conducted.

Is there an association between coffee and caffeine consumption and risk of ovarian cancer among women?

Study design:
This review article included 22 case-control studies with a total of 40,140 participants, of which 8,568 patients with ovarian cancer. The participants were ≥ 17 years.

Results and conclusions:
The investigators found combining 21 effect sizes from 18 studies, no significant association was observed between total coffee consumption and risk of ovarian cancer [OR = 1.09, 95% CI = 0.94 to 1.26].

The investigators found no significant association between total caffeine intake and ovarian cancer risk [OR = 0.89, 95% CI = 0.55 to 1.45].

The investigators found, in addition, caffeinated coffee intake was not significantly associated with ovarian cancer risk [OR = 1.05, 95% CI = 0.87 to 1.28].

The investigators found, however, combining effect sizes from 5 studies, an inverse significant association between decaffeinated coffee intake and risk of ovarian cancer [OR = 0.72, 95% CI = 0.58 to 0.90].

The investigators concluded decaffeinated coffee consumption could reduce risk of ovarian cancer among women. Could reduce because this review article only included case-control studies and no cohort studies.

Original title:
Coffee and caffeine intake and risk of ovarian cancer: a systematic review and meta-analysis by Shafiei F, Salari-Moghaddam A , […], Esmaillzadeh A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30833443

Additional information of El Mondo:
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Objectives:
Several epidemiological studies have investigated the association between dietary fat intake and cardiovascular disease. However, dietary recommendations based on systematic review and meta-analysis might be more credible. Therefore, this review article has been conducted.

Does dietary fat intake increase cardiovascular disease risk?

Study design:
This review article included 56 cohort studies.
Egger test showed no evidence of significant publication bias.

Results and conclusions:
The investigators found highest versus lowest levels of total dietary fat were not associated with cardiovascular disease risk [RR = 0.97, 95% CI = 0.93-1.01, I2 = 54.0%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found highest versus lowest levels of dietary trans fatty acids intake were associated with a 14% increase of the risk of cardiovascular disease [RR = 1.14, 95% CI = 1.08-1.21, I2 = 26.1%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.

The investigators found dose-response analysis showed the risk of cardiovascular disease significantly increased with 16% [RR = 1.16, 95% CI = 1.07-1.25, p-linearity = 0.033] for an increment of 2% energy/day (2 En%/day) of dietary trans fatty acids intake.

The investigators found highest versus lowest levels of dietary saturated fatty acids intake were not associated with the risk of cardiovascular disease [RR = 0.97, 95% CI = 0.93-1.02, I2 = 56.8%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found highest versus lowest levels of dietary monounsaturated fatty acids intake were not associated with the risk of cardiovascular disease [RR = 0.97, 95% CI = 0.93-1.01, I2 = 50.3%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found highest versus lowest levels of dietary polyunsaturated fatty acids intake were not associated with the risk of cardiovascular disease [RR = 0.97, 95% CI = 0.93-1.004, I2 = 55.8%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found in studies that has been followed up more than 10 years, that dietary polyunsaturated fatty acids intake significantly reduced cardiovascular disease risk with 5% [RR = 0.95, 95% CI = 0.91-0.99, I2 = 62.4%].

The investigators concluded there is a cardio-protective effect of dietary polyunsaturated fatty acids intake in studies that has been followed up more than 10 years. While, an increment of 2% energy/day (2 En%/day) of dietary trans fatty acids intake increases risk of cardiovascular disease.

Original title:
Dietary total fat, fatty acids intake, and risk of cardiovascular disease: a dose-response meta-analysis of cohort studies by Zhu Y, Bo Y and Liu Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6451787/

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Objectives:
Do omega-3 fatty acids in fish consumption reduce risk of breast cancer in Asian patients?

Study design:
This review article included 4 cohort studies and 7 case-control studies with a total of 130,365 Asian patients.

There was not any study with significant publication bias included.

Results and conclusions:
The investigators found omega-3 fatty acids in fish consumption significantly reduced risk of  breast cancer in Asian patients with 20% [OR = 0.80, 95% CI = 0.73-0.87, p 0.00001].
Significant because OR of 1 was not found in the 95% CI of 0.73 to 0.87. OR of 1 means no risk/association.

The investigators concluded omega-3 fatty acids in fish consumption reduce breast cancer risk in Asian patients.

Original title:
Protective Effect of Omega-3 Fatty Acids in Fish Consumption Against Breast Cancer in Asian Patients: A Meta-Analysis by Nindrea RD, Aryandono T, […], Dwiprahasto I.

Link:
http://journal.waocp.org/?sid=Entrez:PubMed&id=pmid:30803190&key=2019.20.2.327

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Fish containing omega-3 fatty acids are salmon, mackerel, herring, lake trout, bluefin tuna, sturgeon, sablefish, anchovy, albacore tuna, whitefish, arctic char, sardines, bluefish, mullet, halibut, striped bass, mahi mahi, pollock, rockfish, rainbow trout, shark, catfish, carp, cod, flounder, grouper, haddock, ocean perch, red snapper, swordfish, pike, sole and tilapia.

Objectives:
Several studies have been conducted on the effects of peanut consumption on cardiovascular diseases (CVD) risk factors. However, the findings are conflicting and appear inconsistent. Therefore, this review article has been conducted.

Does peanut consumption reduce cardiovascular disease risk?

Study design:
This review article included 13 RCTs.

Results and conclusions:
The investigators found peanuts consumption had no significant effect on:
-weight [WMD = -0.11 kg, p = 0.773];
-waist circumference [WMD = -1.41 cm, p = 0.139];
-body mass index [WMD = -0.14 kg/m², p = 0.428];

-systolic and diastolic blood pressure [WMD = -0.09 mmHg, p = 0.939 and WMD = 0.60 mmHg, p = 0.652, respectively];
-low-density lipoprotein (LDL or bad) cholesterol [WMD = -3.31 mg/dL, p = 0.472];
-triglyceride [WMD = -7.59 mg/dL, p = 0.180];
-total cholesterol [WMD = 3.15 mg/dL, p = 0.171];
-fasting blood sugar [WMD = 0.57 mg/dL, p = 0.604] and;
-serum insulin [WMD = -0.40, p = 0.582].

The investigators found peanuts consumption had a positive significant effect on high-density lipoprotein (HDL or good) cholesterol [WMD = 2.72 mg/dL, p = 0.001].
Significant because the calculated p-value of 0.001 was smaller than the p-value of 0.05.

The investigators found peanut consumption had a positive significant effect on HDL cholesterol, especially at the type of peanut oil, high-oleic peanut and peanut sprout and in healthy subjects and for consumption more than 12 weeks, while had no significant effect on other cardiovascular diseases risk factors.

The investigators concluded both high-oleic peanut and peanut sprout consumption during at least 12 weeks increases HDL cholesterol (good cholesterol) in healthy subjects.

Original title:
Peanut and cardiovascular disease risk factors: A systematic review and meta-analysis by Jafari Azad B, Daneshzad E and Azadbakht L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30638042

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Objectives:
Although the relationship between dietary intake and serum levels of trans fatty acids and risk of breast cancer has been investigated extensively, findings are inconsistent. Therefore, this review article has been conducted.

Do dietary intake and serum levels of trans fatty acids increase risk of breast cancer?

Study design:
This review article included 6 cohort studies and 1 nested case-control study on total dietary trans fat intake and 1 cohort study and 4 nested case-control studies on serum trans fatty acids.

Participants were apparently healthy aged 26 years or older.

Results and conclusions:
The investigators found no significant relationship between dietary intake of total trans fatty acids and risk of breast cancer [pooled effect size = 1.02, 95% CI = 0.95-1.10, p = 0.403].

The investigators found in 3 effect sizes from 2 cohort studies and 1 nested case-control study, no significant relation between dietary intake of conjugated linoleic acid (CLA) and risk of breast cancer [pooled effect size = 1.05, 95% CI = 0.95-1.17, p = 0.513].

The investigators found based on 5 effect sizes, each additional 1 g/day dietary intake of total trans fats was not significantly associated with risk of breast cancer [RR = 1.00, 95% CI = 0.99-1.01].

The investigators found high serum levels of trans fats were associated with an increased risk of 37% of breast cancer among postmenopausal women [pooled effect size = 1.37, 95% CI = 1.04-1.81, p = 0.02].

The investigators concluded dietary intake of trans fatty acids (also called trans fats) is not associated with risk of breast cancer. However, a significant positive association is seen between serum trans fats and risk of breast cancer in postmenopausal women.

Original title:
Dietary intake and serum levels of trans fatty acids and risk of breast cancer: A systematic review and dose-response meta-analysis of prospective studies by Anjom-Shoae J, Sadeghi O, […], Esmaillzadeh A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30954361

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Find more information/studies on trans fatty acids consumption, review article/significantly and breastcancer right here.

Objectives:
Epidemiological studies focusing on the association between folate and breast cancer risk reported inconsistent findings. Therefore, this review article has been conducted.

Does dietary folate intake reduce breast cancer risk?

Study design:
This review article included a total of 23 prospective cohort studies involving 41,516 cases (=women with breast cancer) among 1,171,048 individuals.

Results and conclusions:
The investigators found dietary folate intake significantly reduced risk of oestrogen-receptor-negative breast cancer with 12% [pooled risk ratio = 0.88, 95% CI = 0.78-1.00].

The investigators found dietary folate intake significantly reduced risk of oestrogen-receptor-negative/progesterone-receptor-negative breast cancer with 18% [pooled risk ratio = 0.82, 95% CI = 0.68-0.97].

The investigators found an increment of dietary folate intake of 100 μg per day was associated with a deceased risk of oestrogen-receptor-negative breast cancer with 6% [RR = 0.94, 95% CI = 0.88-0.99].

The investigators found an increment of dietary folate intake of 100 μg per day was associated with a deceased risk of oestrogen-receptor-negative/progesterone-receptor-negative breast cancer with 10% [RR = 0.90, 95% CI = 0.85-0.97].

The investigators found high dietary folate intake significantly reduced breast cancer risk in premenopausal women with 6% [RR = 0.94, 95% CI = 0.88-1.00].

The investigators found high dietary folate intake significantly reduced breast cancer risk in women with moderate or high levels of alcohol consumption with 18% [RR = 0.82, 95% CI = 0.72-0.94].

The investigators concluded that at least 100 μg per day dietary folate intake, reduce both oestrogen-receptor-negative and oestrogen-receptor-negative/progesterone-receptor-negative breast cancer, particularly among premenopausal women and women with moderate or high levels of alcohol consumption.

Original title:
Folate intake and the risk of breast cancer: an up-to-date meta-analysis of prospective studies by Zeng J, Wang K, [...], Chang H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30647438

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Objectives:
Low fruit and vegetable intakes are recognized risk factors for noncommunicable diseases. Therefore, this review article has been conducted.

Do fruit or vegetables intakes reduce noncommunicable diseases, likes cancer, coronary heart disease and all-cause mortality?

Study design:
This review article included 64 reports investigating 98 risk-disease pairs. 56 pairs from 39 reports were assessed as statistically significant, involving 29 burden of diseases.

Results and conclusions:
The investigators found in linear dose analysis for each 100 g/day increase in fruit intakes a significantly reduced risk of 44% [RR = 0.56, 95% CI = 0.42 to 0.74] for esophageal cancer.
Significant means that there is an association with a 95% confidence.

The investigators found in linear dose analysis for each 100 g/day increase in fruit intakes a significantly reduced risk of 28% [RR = 0.72, 95% CI = 0.59 to 0.87] for mouth, pharynx and larynx cancer.

The investigators found in nonlinear dose analysis for the first 100 g/day increase in fruit intakes a significantly reduced risk of 14% [RR = 0.86, 95% CI = 0.84 to 0.88] for stroke.

The investigators found in nonlinear dose analysis for the first 100 g/day increase in fruit intakes a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.88 to 0.90] for all-cause mortality.

The investigators found in linear dose analysis for each 100 g/day increase in vegetable intakes a significantly reduced risk of 12% [RR = 0.88, 95% CI = 0.80 to 0.95] for renal cell cancer.

The investigators found in linear dose analysis for each 100 g/day increase in vegetable intakes a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.84 to 0.95] for non-Hodgkin lymphoma.

The investigators found in nonlinear dose analysis for the first 100 g/day increase in vegetable intakes a significantly reduced risk of 14% [RR = 0.86, 95% CI = 0.84 to 0.89] for coronary heart disease.

The investigators found in nonlinear dose analysis for the first 100 g/day increase in vegetable intakes a significantly reduced risk of 13% [RR = 0.87, 95% CI = 0.84 to 0.90] for all-cause mortality.

The investigators found in nonlinear dose analysis clear increases in protective associations were observed with the first 200 g/day of fruit or vegetable intakes, whereas little further increase or even decrease in protective associations were reported beyond 300 g/day intakes.

The investigators found canned fruit intakes were positively associated with all-cause and cardiovascular disease mortality.

The investigators found pickled vegetable intakes were positively associated with stomach cancer.

The investigators concluded that 100-300 g/day of fruit or vegetables intakes reduce certain cancers, coronary heart disease and all-cause mortality. These findings support existing recommendations for fruit and vegetable intakes. Current comparative risk assessments might significantly underestimate the protective associations of fruit and vegetable intakes.

Original title:
The Associations of Fruit and Vegetable Intakes with Burden of Diseases: A Systematic Review of Meta-Analyses by Yip CSC, Chan W and Fielding R.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30639206

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Objectives:
Findings from observational studies on the associations between vitamin E intake and stroke risk remain controversial and the dose-response relationship between vitamin E intake and risk of stroke remains to be determined. Therefore, this review article has been conducted.

Does dietary vitamin E intake reduce risk of stroke?

Study design:
This review article included 9 prospective cohort studies involving 3,284 cases of stroke among 220,371 participants.

Results and conclusions:
The investigators found high dietary vitamin E intake significantly reduced risk of overall stroke with 17% [RR = 0.83, 95% CI = 0.73 to 0.94].
Omission of any single study (=sensitivity analysis) did not alter the summary result.

The investigators found high dietary vitamin E intake significantly reduced risk of overall stroke with 16% [RR = 0.84, 95% CI = 0.72 to 0.91] among individuals who were followed-up for 10 years.

The investigators found a non-linear association between dietary vitamin E intake and stroke risk [p = 0.0249].

The investigators concluded that a higher dietary vitamin E intake is associated with a lower stroke risk.

Original title:
Vitamin E intake and risk of stroke: a meta-analysis by Cheng P, Wang L, [...], Zhu J.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30401005

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Objectives:
Epidemiological studies regarding the association between dietary fiber intake and ovarian cancer risk are still inconsistent. Therefore, this review article has been conducted.

Does dietary fiber intake reduce ovarian cancer risk?

Study design:
This review article included 10 case-control studies and 3 cohort studies, with a total of 5,777 ovarian cancer cases and 142,189 participants.

All the included studies provided RRs that were adjusted for energy intake and most provided RRs that were adjusted for age, oral contraceptive use, menopausal status and parity.
All the original studies measured dietary intakes using a food-frequency questionnaire. NOS scores ranged from 6 to 8 and 7 studies were considered high quality.

Funnel plot shapes demonstrated a symmetrical distribution and no evidence of publication bias was detected by the Egger’s regression test [p = 0.73].

Results and conclusions:
The investigators found for the highest vs. the lowest category of dietary fiber intake a significantly reduced risk of 22% [pooled multivariable RR = 0.78, 95% CI = 0.70 to 0.88, I2 = 4.20%, p = 0.40] for ovarian cancer.

The investigators found a significantly reduced risk of 12% [summarized RR = 0.88, 95% CI = 0.82 to 0.93, I2 = 7.3%, p = 0.38] for ovarian cancer per 10 g/day increase of dietary fiber intake.

The investigators found there was no evidence for a nonlinear association between dietary fiber intake and ovarian cancer risk [p for nonlinearity = 0.83].

The investigators found in subgroup analysis a significantly reduced risk of 23% [pooled RR = 0.77, 95% CI = 0.66 to 0.90] for ovarian cancer in case-control studies. However, the reduced risk was not significant in cohort studies [pooled RR = 0.84, 95% CI = 0.65 to 1.10].

The investigators found sensitivity analysis showed that none of the studies influenced the combined results substantially, with a range from 0.77 [95% CI = 0.68 to 0.87] to 0.81 [95% CI = 0.71 to 0.91].

The investigators concluded that 10g dietary fiber intake per day may reduce the risk of ovarian cancer with 12%. May reduce because the reduced risk was not significant in cohort studies.

Original title:
Dietary fiber intake and reduced risk of ovarian cancer: a meta-analysis by Zheng B, Shen H, […], Qin Y.

Link:
https://nutritionj.biomedcentral.com/articles/10.1186/s12937-018-0407-1

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