Nutrition and health

Objectives:
Peripheral neuropathy (PN) is common in patients with diseases that are in turn associated with deficiency of the B-vitamins, and vitamin treatment has shown mixed results. Therefore, this review article has been conducted.

Does a low vitamin B level increase the risk of peripheral neuropathy?

Study design:
This review article included 46 observational studies and 7 interventional studies.

Results and conclusions:
The investigators found the presence of peripheral neuropathy was significantly associated with lowered B12 levels [1.51, 95% CI = 1.23 to 1.84, n = 34, I2 = 43.3%, p = 0.003].

The investigators found the presence of peripheral neuropathy was significantly associated with elevated methylmalonic acid levels [2.53, 95% CI = 1.39 to 4.60, n = 9, I2 = 63.8%, p = 0.005].

The investigators found the presence of peripheral neuropathy was significantly associated with elevated homocysteine levels [3.48, 95% CI = 2.01 to 6.04, n = 15, I2 = 70.6%, p 0.001].

The investigators found treatment with vitamin B1 was associated with a significant improvement in symptoms of peripheral neuropathy [5.34, 95% CI = 1.87 to 15.19, n = 3, I2 = 64.6%, p = 0.059].

The investigators found B12 treatment (vs. the comparators) showed a non-significant association with symptom improvement [1.36, 95% CI = 0.66 to 2.79, n = 4, I2 = 28.9%].

The investigators found analysis of 7 trials combined showed a non-significant higher odds ratio for improvement under treatment with the B-vitamins [2.58, 95% CI = 0.98 to 6.79, I2 = 80.0%, p 0.001].

The investigators concluded peripheral neuropathy is associated with lowered plasma vitamin B12 and elevated methylmalonic acid and homocysteine levels. Well-designed studies, especially in non-diabetes peripheral neuropathy, are needed.

Original title:
Association between neuropathy and B-vitamins: A systematic review and meta-analysis by Stein J, Geisel J and Obeid R.

Link:
https://pubmed.ncbi.nlm.nih.gov/33619867/

Additional information of El Mondo:
Find here more information/studies about review article/significant, vitamin B1 y B12 and chronic diseases.

Peripheral neuropathy refers to the conditions that result when nerves that carry messages to and from the brain and spinal cord from and to the rest of the body are damaged or diseased.

Increased methylmalonic acid levels are a sensitive indicator of mild vitamin B12 deficiency.
 

Objectives:
Does citrus dietary intake reduce the risk of lung cancer?

Study design:
This review article included 21 observational studies.

Results and conclusions:
The investigators found pooled analyses showed that those with the highest citrus fruit dietary intake compared to the lowest intake had a 9% reduction in lung cancer risk [OR = 0.91, 95% CI = 0.84 to 0.98].

The investigators found a nonlinear association between citrus dietary intake and lung cancer risk in the dose-response analysis [p = 0.0054] and that the risk reached the minimum [OR = 0.91] around 60 g/d.
However, no obvious dose-response association was observed with intakes above 80 g/d.

The investigators concluded that citrus fruit dietary intake is negatively associated with the risk of lung cancer. Besides, there is a nonlinear dose-response relationship between citrus fruit dietary intake and lung cancer risk within a certain range (60-80g per day).

Original title:
Citrus fruit intake and lung cancer risk: A meta-analysis of observational studies by Wang J, Gao J, [...], Qian BY.

Link:
https://pubmed.ncbi.nlm.nih.gov/33529754/

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

Citrus fruits include oranges, lemons, limes and grapefruits.

Objectives:
Does a low-carbohydrate diet (LCD) causally increase adiponectin concentration in adults?

Study design:
This review article included 11 RCTs with 534 participants in low-carbohydrate diet group and 513 participants in control group (group without a low-carbohydrate diet).
Proportion of carbohydrate from calorie was from 4 to 34% (4-34 En%).
Time of the follow-up varied between studies and ranged from 6 to 152 weeks.
Meta-regression analysis revealed that age [β = 0.04, p = 0.15], baseline BMI [β= -0.15, p = 0.15], time of follow-up [β = 0.01, p = 0.17], energy percentage of carbohydrates [β = 0.004, p = 0.90], energy percentage of protein [β = -0.12, p = 0.08], energy percentage of fat [β = 0.20, p = 0.61] and baseline adiponectin [β = 0.001, p = 0.97] are not sources of heterogeneity

Results and conclusions:
The investigators found low-carbohydrate diet significantly increased adiponectin concentration [0.02 µg/mL, 95% CI = 0.01 to 0.03, p 0.001].

The investigators found dose-response analysis indicated a nonlinear association between the percentage of carbohydrate and change in adiponectin level from baseline [p = 0.04].

The investigators found in subgroup analysis based on the proportion of carbohydrate from calorie, there was a significant increase in adiponectin concentration in studies that prescribed 30% of calorie from carbohydrates [0.12 µg/mL, 95% CI = 0.07 to 0.18].
In contrast, diets which consisted ≥30% of carbohydrates had no significant effect on adiponectin [0.50 µg/mL, 95% CI = -0.46 to 1.48].

The investigators concluded that a diet with 30% of calorie from carbohydrates (diet with 30 En% carbohydrates) causally increases adiponectin concentration in adults.

Original title:
Effect of low-carbohydrate diet on adiponectin level in adults: a systematic review and dose-response meta-analysis of randomized controlled trials by Shemirani F, Golzarand M, […], Mahmoudi M.

Link:
https://pubmed.ncbi.nlm.nih.gov/33455438/

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Find more information/studies on carbohydrate consumption, diabetes and cardiovascular diseases right here.

The most easy way to follow a diet with maximum 30% of calorie from carbohydrates (diet with 30 En% carbohydrates) is to choose only meals/products with maximum 30 En% carbohydrates. Check here which products contain maximum 30 En% carbohydrates. However, the most practical way to follow a diet with maximum 30 En% carbohydrates is, all meals/products that you eat on a daily basis should on average contain maximum 30 En% carbohydrates.
30 En% carbohydrates means that the total amounts of carbohydrates make up for a 30% of the total kcal of the diet.

Adiponectin is a protein hormone produced and secreted exclusively by adipocytes (fat cells) that regulates the metabolism of lipids and glucose. Adiponectin influences the body's response to insulin. Adiponectin also has antiinflammatory effects on the cells lining the walls of blood vessels.
 

Objectives:
Fish oil has been shown to reduce the risk of metabolic disorders. However, the effects of fish oil intervention on glucose metabolism and insulin sensitivity are still controversial, especially in children. Therefore, this review article has been conducted.

Do fish oil supplements (EPA + DHA) improve insulin sensitivity in children?

Study design:
This review article included 13 RCTs with 567 children in placebo group (group without fish oil supplements) and 565 in fish oil group (intervention group).

No heterogeneity was found for the pooled and subgroup analyses.

Results and conclusions:
The investigators found compared with the placebo group, fish oil intervention had beneficial effects on insulin sensitivity in the pooled analysis [WMD = -0.219, 95% CI = -0.392 to -0.046, p = 0.013].

These beneficial effects were also found in subgroup analyses, when the fish oil intervention period was short-term (≤6 months) low dose (eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) dose 1.5 g/day) and high ratio (eicosapentaenoic acid to docosahexaenoic acid ≥1).

The investigators concluded fish oil supplements, especially 1.5 g/day EPA + DHA during 6 months, improve insulin sensitivity in children.

Original title:
Effect of Fish Oil on Insulin Sensitivity in Children: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials by Hou M, Zhou W, [...], Lv H.

Link:
https://pubmed.ncbi.nlm.nih.gov/33388274/

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Objetivos:
¿Aumenta un nivel bajo de selenio en los tejidos humanos el riesgo de cáncer de mama?

Diseño del estudio:
Este artículo de revisión incluyó 18 estudios de casos y controles con 3,374 mujeres diagnosticadas con cáncer de mama (grupo de casos) y 3,582 controles sanos (mujeres sin cáncer de mama).

Resultados y conclusiones:
Los investigadores encontraron que el nivel de selenio de grupo de casos (grupo con mujeres diagnosticadas con cáncer de mama) fue significativamente menor que grupo de control (grupo con mujeres sin cáncer de mama) [-0.53 μg/L, 95% IC = -0.72 a -0.34, p 0.001].

Los investigadores encontraron en el análisis de subgrupos que el nivel de selenio sérico de grupo de casos fue significativamente más bajo que grupo de control [-1.14 μg/L, 95% IC = -1.70 a -0.58, p 0.001].

Los investigadores encontraron en el análisis de subgrupos que el nivel de selenio en plasma de grupo de casos fue significativamente más bajo que grupo de control [-0.21 μg/L, 95% IC = -0.37 a -0.04, p 0.014].

Los investigadores encontraron en el análisis de subgrupos que el nivel de selenio de la uña del pie de grupo de casos fue significativamente más bajo que grupo de control [-0.21 μg/L, 95% IC = -0.38 a -0.03, p 0.021].

Los investigadores concluyeron que un nivel bajo de selenio en los tejidos humanos aumenta el riesgo de cáncer de mama, lo que puede mejorar la comprensión de los efectos del selenio en la salud humana.

Título original:
Relationship Between Selenium in Human Tissues and Breast Cancer: a Meta-analysis Based on Case-Control Studies by Zhu X, Pan D, […], Sun G.

Enlace:
https://pubmed.ncbi.nlm.nih.gov/33420696/

Información adicional de El Mondo:
Encontrar aquí más información/estudios sobre el consumon de selenio y el cáncer.

Objectives:
Does a low selenium level in human tissues increase the risk of breast cancer?

Study design:
This review article included 18 case-control studies with 3,374 women diagnosed with breast cancer (case group) and 3,582 healthy controls (women without breast cancer).

Results and conclusions:
The investigators found selenium level of the case group (group with women diagnosed with breast cancer) was significantly lower than the control group (group with women without breast cancer) [-0.53 μg/L, 95% CI = -0.72 to -0.34, p 0.001].

The investigators found in subgroup analysis that serum selenium level of the case group was significantly lower than the control group [-1.14 μg/L, 95% CI = -1.70 to -0.58, p 0.001].

The investigators found in subgroup analysis that plasma selenium level of the case group was significantly lower than the control group [-0.21 μg/L, 95% CI = -0.37 to -0.04, p 0.014].

The investigators found in subgroup analysis that selenium level of toenail of the case group was significantly lower than the control group [-0.21 μg/L, 95% CI = -0.38 to -0.03, p 0.021].

The investigators concluded that a low selenium level in human tissues increases the risk of breast cancer, which may improve the understanding of the effects of selenium on human health.

Original title:
Relationship Between Selenium in Human Tissues and Breast Cancer: a Meta-analysis Based on Case-Control Studies by Zhu X, Pan D, […], Sun G.

Link:
https://pubmed.ncbi.nlm.nih.gov/33420696/

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Objectives:
Does type 1 diabetes mellitus (T1DM) decrease bone mineral density (BMD) in children and adolescents?

Study design:
This review article included 9 cross-sectional studies with a total of 1,522 children and adolescents.

Funnel plot and the Egger test did not reveal significant publication bias.

Results and conclusions:
The investigators found a significant decrease in bone mineral density Z-score in the whole body [pooled WMD = -0.47, 95% CI = -0.92 to -0.02, I2 = 80.2%] and lumbar spine [pooled WMD = -0.41, 95% CI = -0.69 to -0.12, I2 = 80.3%] in children and adolescents with type 1 diabetes mellitus, which was consistent in published studies from Asia and South America, but inconsistent in the North America and Europe.
Sensitivity analyses did not modify these findings.

The investigators found, importantly, the differences in bone mineral density Z-scores were independent of age, level of glucose control (HbA1c) and prepubertal stage.

The investigators concluded type 1 diabetes mellitus (T1DM) decreases bone mineral density (BMD) Z-scores in the whole body and lumbar spine in children and adolescents.

Original title:
Association between type 1 diabetes mellitus and reduced bone mineral density in children: a meta-analysis by Zhu Q, J Xu J, […], Shi J.

Link:
https://pubmed.ncbi.nlm.nih.gov/33404757/  

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Objectives:
Although several epidemiological studies have investigated associations between poultry and fish consumption and pancreatic cancer (PC) risk, these findings have been inconsistent. Therefore, this review article has been conducted.

Do high dietary poultry or fish intakes increase risk of pancreatic cancer?

Study design:
This review article included 25 studies (cohort studies and case-control studies).

Results and conclusions:
The investigators found for the highest vs. lowest poultry intake category a significantly increased risk of 14% for pancreatic cancer [pooled RR = 1.14, 95% CI = 1.02 to 1.26] in cohort studies.
Significant because RR of 1 was not found in the 95% CI of 1.02 to 1.26. RR of 1 means no risk/association.

The investigators found there was no association between fish intake and pancreatic cancer risk [RR = 1.00, 95% CI = 0.93 to 1.07].
No association because RR of 1 was found in the 95% CI of 0.93 to 1.07. RR of 1 means no risk/association.

The investigators concluded that large amount of poultry intake increases pancreatic cancer risk, while fish intake is unlikely to be linked to pancreatic cancer risk. These findings require further investigation, particularly between poultry and pancreatic cancer.

Original title:
Poultry and Fish Intake and Pancreatic Cancer Risk: A Systematic Review and Meta-Analysis by Gao Y, Ma Y, […], Wang X.

Link:
https://pubmed.ncbi.nlm.nih.gov/33432844/

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Objectives:
Does dietary acrylamide intake increase risk of breast, endometrial and ovarian cancer?

Study design:
This review article included 14 prospective cohort studies.

Results and conclusions:
The investigators found no significant association between dietary acrylamide intake and the risk of breast [RR = 0.95, 95% CI = 0.90 to 1.01], endometrial [RR = 1.03, 95% CI = 0.89 to 1.19] and ovarian cancers [RR = 1.02, 95% CI = 0.84 to 1.24].
In addition, no significant association between dietary acrylamide intake and the risk of breast, endometrial and ovarian cancers in different subgroup analyses by smoking status, menopausal status, BMI status and different types of breast cancer.

The investigators concluded there is no significant association between dietary acrylamide intake and the risk of breast, endometrial and ovarian cancers.

Original title:
Dietary acrylamide intake and risk of women's cancers: a systematic review and meta-analysis of prospective cohort studies by Benisi-Kohansal S, Salari-Moghaddam A, […], Esmaillzadeh A.

Link:
https://pubmed.ncbi.nlm.nih.gov/33413725/

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Find more information/studies on breast cancer right here.

Acrylamide is a chemical that naturally forms in starchy food products during high-temperature cooking processes, such as frying, roasting and baking. Acrylamide in food forms from sugars and an amino acid that are naturally present in food.
 

Objetivos:
¿Reduce el consumo de frutas y verduras el riesgo de cáncer del conducto biliar?

Diseño del estudio:
Este artículo de revisión incluyó 14 estudios.

No hubo sesgo de publicación entre los estudios [p Begg = 0.53, p Egger = 0.84 para hortalizas y p Begg = 0.95, p Egger = 0.64 para frutas].

Resultados y conclusiones:
Los investigadores encontraron para el consumo más alto en comparación con más bajo, un riesgo significativamente reducido del 52% para el cáncer del conducto biliar [RR resumido = 0.48, 95% IC = 0.22 a 0.74, I2 = 86.8%, p 0.001, n = 10] para el consumo de verduras.

Los investigadores encontraron para el consumo más alto en comparación con más bajo, un riesgo significativamente reducido del 53% para el cáncer del conducto biliar [RR resumido = 0.47, 95% IC = 0.32 a 0.61, I2 = 63.3%, p = 0.001, n = 13] para el consumo de fruta.

Los investigadores encontraron por cada incremento de 100 gramos/día de consumo de verduras, un riesgo significativamente reducido del 69% para el cáncer del conducto biliar [RR = 0.31, 95% IC = 0.20 a 0.47, I2 = 63.3, n = 8].

Los investigadores concluyeron que el consumo de frutas y verduras reduce el riesgo de cáncer del conducto biliar. Se necesitan más estudios prospectivos bien diseñados para confirmar estos hallazgos.

Título original:
Vegetable, Fruit Consumption and Risk of Biliary Cancer: Evidence from a Meta-Analysis by Huai J and Xiaohua Ye X.

Enlace:
https://pubmed.ncbi.nlm.nih.gov/32731775/

Información adicional de El Mondo:
Encontrar aquí más información/estudios sobre significativamente/estudios de cohorte, el consumo de frutas y verduras y el cáncer.

Objectives:
Data on the association of nut intake with risk of cancer and its mortality are conflicting. Although previous meta-analyses summarized available findings in this regard, some limitations may distort their findings. Moreover, none of these meta-analyses examined the dose-response associations of total nut intake with the risk of specific cancers as well as associations between specific types of nuts and cancer mortality. Therefore, this review article (meta-analysis) has been conducted.

Do higher nut dietary intakes reduce risk of cancer incidence and mortality?

Study design:
This review article included in total 43 articles (observational studies) on cancer risk and 9 articles (observational studies) on cancer mortality.

Results and conclusions:
The investigators found when comparing the highest with lowest intakes of total nuts, the highest intakes of total nuts (tree nuts and peanuts), significantly reduced risk of cancer with 16% [summary effect size = 0.86, 95% CI = 0.81 to 0.92, p 0.001, I2 = 58.1%, p 0.01].

The investigators found when comparing the highest with lowest intakes of tree nuts, the highest intakes of tree nuts significantly reduced risk of cancer with 13% [pooled effect size = 0.87, 95% CI = 0.78 to 0.96, p 0.01, I2 = 15.8%, p = 0.28].

The investigators found based on the dose-response analysis, a 5-g/d increase in total nut intake was associated with 3%, 6% and 25% lower risks of overall, pancreatic and colon cancers, respectively.  

The investigators found in terms of cancer mortality, 13%, 18% and 8% risk reductions with higher intakes of total nuts, tree nuts and peanuts, respectively.

The investigators found, in addition, a 5-g/d increase in total nut intake was associated with a 4% lower risk of cancer mortality.

The investigators concluded there is a protective association between total nut and tree nut intake and the risk of cancer and its mortality.

Original title:
Association of Total Nut, Tree Nut, Peanut, and Peanut Butter Consumption with Cancer Incidence and Mortality: A Comprehensive Systematic Review and Dose-Response Meta-Analysis of Observational Studies by Naghshi S, Sadeghian M, […], Sadeghi O.

Link:
https://pubmed.ncbi.nlm.nih.gov/33307550/

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Tree nuts in this review article are walnuts, pistachios, macadamia nuts, pecans, cashews, almonds, hazelnuts and Brazil nuts.

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

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

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

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

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

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

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

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Find more information/studies on vaccination, diabetes mellitus and malnutrition right here.

Objectives:
Epidemiological studies showing the correlation between folate (folic acid) and the breast cancer risk have revealed inconsistent results. Therefore, this review article (meta-analysis) has been conducted.

Do higher folate dietary intakes or plasma folate levels reduce risk of breast cancer?

Study design:
This review article included 39 studies on folate dietary intake (19 were prospective cohort studies, which included 37,917 cases (persons with breast cancer) and 20 were case-control studies, which included 13,074 cases and 17,497 controls (persons without breast cancer)) and 12 studies on plasma folate level (10 were case-control studies, consisting of 7,850 cases and 8,898 controls and 2 cohort studies, consisting of 815 incident cases).

Results and conclusions:
The investigators found when compared to the lowest folate dietary intake, the highest folate dietary intake significantly reduced risk of breast cancer with 15% [combined OR = 0.85, 95% CI = 0.79 to 0.92, I2 = 75.2%, p 0.001].
This reduced risk was not significant for cohort studies [OR = 0.97, 95% CI = 0.91 to 1.03, I2 = 53.3%, p = 0.316].

The investigators found for every 100-μg/day increase in folate dieatary intake, a significantly reduced risk of 2% for breast cancer [combined OR = 0.98, 95% CI = 0.97 to 0.99, I2 = 72.8%, p = 0.002].
This reduced risk was also significantly in cohort studies [summary OR = 0.99, 95% CI = 0.98 to 1.00]. 
Significant means that there is an association with a 95% confidence.

The investigators found stratification by menopausal status showed that a higher folate dietary intake significantly reduced risk of breast cancer in premenopausal women with 20% [OR = 0.80, 95% CI = 0.66 to 0.97, p = 0.022] but not in postmenopausal women [OR = 0.94, 95% CI = 0.83 to 1.06, p = 0.320].
Significant because OR of 1 was not found in the 95% CI of 0.66 to 0.97. OR of 1 means no risk.

The investigators found the highest versus lowest plasma folate levels had no correlation with the risk of breast cancer [combined OR = 0.98, 95% CI = 0.82 to 1.17, I2 = 63.0%, p = 0.822].

The investigators concluded there is a negative correlation between folate dieatary intake, at least 100-μg/day and the risk of breast cancer. However, plasma folate levels have no correlation with the risk of breast cancer. Therefore, whether folate dietary intake has practical clinical significance requires further study and the use of additional folate supplements should be carefully considered.

Original title:
Association of folate intake and plasma folate level with the risk of breast cancer: a dose-response meta-analysis of observational studies by Ren X, Xu P, [...], Dai Z.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7695428/

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The plasma folate level can be increased by taking folate-rich foods and/or folate supplements.

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

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

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

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

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

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

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

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

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Find more information/studies on fish consumption, cardiovascular disease and diabetes right here.
 

Objectives:
The association between vitamin C intake and breast cancer is unclear. Therefore, this review article (meta-analysis) has been conducted.

Does a higher vitamin C intake reduce risk of breast cancer incidence, mortality and recurrence?

Study design:
This review article included 24 cohort studies and 30 case-control studies.

Results and conclusions:
The investigators found pooled results suggested that the highest versus lowest vitamin C intake was significantly associated with a 14% lower risk of breast cancer incidence [relative risk = 0.86, 95% = 0.81 to 0.92, I2 = 78.7%, p 0.00].
Sensitivity analysis indicated that the overall results remained consistent even after excluding studies individually.

The investigators found the use of random-effects model indicated that a 100-mg/day increment in vitamin C intake had no significant effect on breast cancer risk.

The investigators found stratification by study design showed a 26% lower risk of breast cancer incidence for vitamin C intake in case-control studies [RR = 0.74, 95% CI = 0.65 to 0.84, p 0.001]. However, a non-significant inverse association was found in cohort studies [RR = 0.96, 95% CI = 0.89 to 1.04, p = 0.295].

The investigators found when the studies were stratified by the source of vitamin C, a 11% lower risk of breast cancer incidence with dietary intake [RR = 0.89, 95% CI = 0.82 to 0.96, p = 0.004] but not with supplements [RR = 1.02, 95% CI = 0.94 to 1.10, p = 0.678].

The investigators found that the highest versus lowest vitamin C intake was significantly associated with a 22% lower risk of breast cancer mortality [HR = 0.78, 95% CI = 0.69 to 0.88, I2 = 2.6%].

The investigators found that the highest versus lowest vitamin C intake was significantly associated with a 19% lower risk of breast cancer recurrence [HR = 0.81, 95% CI = 0.67 to 0.99, p = 0.043, I2 = 0.0%].

The investigators concluded that higher vitamin C dietary intake is significantly associated with a reduced risk of breast cancer incidence, mortality and recurrence.

Original title:
Association of vitamin C intake with breast cancer risk and mortality: a meta-analysis of observational studies by Zhang D, Xu P, [...], Dai Z.

Link:
https://www.aging-us.com/article/103769/text

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Objectives:
Heated debates have been on-going about tea consumption and the incidence of cancer, especially in head and neck cancer types. Therefore, this review article (meta-analysis) has been conducted.

Does habitual tea consumption reduce risk of nasopharyngeal cancer?

Study design:
This review article included 6 articles.

Results and conclusions:
The investigators found that habitual tea consumption significantly reduced risk of nasopharyngeal cancer with 13.5% [OR = 0.865, 95% CI = 0.806 to 0.929].

The investigators concluded that habitual tea consumption is associated with prevention of nasopharyngeal cancer development. Additional studies are needed to further understand the molecular role of bioactive compound and potential health benefit of tea consumption in nasopharyngeal cancer prevention.

Original title:
The Association between Tea Consumption and Nasopharyngeal Cancer: A Systematic Review and Meta-Analysis by Okekpa SI, Basria R, […], Musa MY.

Link:
https://pubmed.ncbi.nlm.nih.gov/32856842/

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Objectives:
The number of cancer survivors is growing rapidly worldwide, especially long-term survivors. Although a healthy diet with a high vegetable and fruit consumption is a key factor in primary cancer prevention, there is a lack of specific dietary recommendations for cancer survivors, except in the case of breast cancer [World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) report]. Therefore, this review article (meta-analysis) has been conducted.

Does the general recommendation to consume ≥5 servings of vegetables and fruit per day (400 g/d) meet the needs of cancer survivors?

Study design:
This review article included 28 cohort studies.

Results and conclusions:
The investigators found a high vegetable intake before diagnosis significantly reduced overall mortality in survivors of head and neck cancer with 25% [HR = 0.75, 95% CI = 0.65 to 0.87].  

The investigators found a high vegetable intake before diagnosis significantly reduced overall mortality in survivors of ovarian cancer with 22% [HR = 0.78, 95% CI = 0.66 to 0.91].  

The investigators found a high fruit intake before diagnosis significantly reduced overall mortality in survivors of ovarian cancer with 18% [HR = 0.82, 95% CI = 0.70 to 0.96].  

The investigators found the evidence was insufficient for survivors of other cancers, although these associations generally tended to be protective. Therefore, more studies are needed to clarify the association between vegetable and fruit consumption and the prognosis of these different types of cancer.

The investigators concluded the general recommendation to consume ≥5 servings of vegetables and fruit per day (400 g/d) could underestimate the needs of cancer survivors, particularly those with ovarian tumors, in which the recommendation could increase to 600 g/d (i.e., 300 g/d of vegetables and 300 g/d of fruit).

Original title:
Vegetable and Fruit Consumption and Prognosis Among Cancer Survivors: A Systematic Review and Meta-Analysis of Cohort Studies by Hurtado-Barroso S, Trius-Soler M, […], Zamora-Ros R.

Link:
https://pubmed.ncbi.nlm.nih.gov/32717747/

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

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

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

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

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

There was no significant publication bias.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Objectives:
It is unclear how dietary intake influences the ovarian cancer. Therefore, this review article (meta-analysis) has been conducted.

Is there a relationship between dietary intake of different nutrients/food groups and ovarian cancer risk?

Study design:
This review article included 97 cohort studies.

Results and conclusions:
The investigators found no significant association between dietary intake and risk of ovarian cancer.

The investigators found in subgroup analyses that dietary intake of green leafy vegetables significantly reduced risk of ovarian cancer with 9% [RR = 0.91, 95% CI = 0.85 to 0.98].

The investigators found in subgroup analyses that dietary intake of allium vegetables significantly reduced risk of ovarian cancer with 21% [RR = 0.79, 95% CI = 0.64 to 0.96].

The investigators found in subgroup analyses that dietary intake of fiber significantly reduced risk of ovarian cancer with 11% [RR = 0.89, 95% CI = 0.81 to 0.98].

The investigators found in subgroup analyses that dietary intake of flavonoids significantly reduced risk of ovarian cancer with 17% [RR = 0.83, 95% CI = 0.78 to 0.89].

The investigators found in subgroup analyses that dietary intake of green tea significantly reduced risk of ovarian cancer with 39% [RR = 0.61, 95% CI = 0.49 to 0.76].

The investigators found in subgroup analyses that dietary intake of tota fat significantly increased risk of ovarian cancer with 10% [RR = 1.10, 95% CI = 1.02 to 1.18].

The investigators found in subgroup analyses that dietary intake of saturated fat significantly increased risk of ovarian cancer with 11% [RR = 1.11, 95% CI = 1.01 to 1.22].

The investigators found in subgroup analyses that dietary intake of saturated fatty acid significantly increased risk of ovarian cancer with 19% [RR = 1.19, 95% CI = 1.04 to 1.36].

The investigators found in subgroup analyses that dietary intake of cholesterol significantly increased risk of ovarian cancer with 13% [RR = 1.13, 95% CI = 1.04 to 1.22].

The investigators found in subgroup analyses that dietary intake of retinol (vitamin A) significantly increased risk of ovarian cancer with 14% [RR = 1.14, 95% CI = 1.00 to 1.30].

The investigators found, in addition, acrylamide, nitrate, water disinfectants and polychlorinated biphenyls were significantly associated with an increased risk of ovarian cancer.

The investigators concluded that dietary intakes of green leafy vegetables, allium vegetables, fiber, flavonoids and green tea reduce ovarian cancer.

Original title:
Association between dietary intake and risk of ovarian cancer: a systematic review and meta-analysis by Khodavandi A, Alizadeh F and Razis AFA.

Link:
https://pubmed.ncbi.nlm.nih.gov/32661683/

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Do dietary carotenoid (β-cryptoxanthin, α-carotene, β-carotene and lutein and zeaxanthin) intakes or circulating carotenoid concentrations reduce bladder cancer risk in men and women?

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

Results and conclusions:
The investigators found no association for the highest compared with the lowest category of carotenoid dietary intake and reduced risk of bladder cancer [RR = 0.88, 95% CI = 0.76 to 1.03].
No association 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 no association for the highest compared with the lowest category of circulating carotenoid concentrations and reduced risk of bladder cancer [RR = 0.36, 95% CI = 0.12 to 1.07].

The investigators found for the highest compared with the lowest category of circulating lutein and zeaxanthin concentrations a significantly reduced risk of 47% for bladder cancer [RR = 0.53, 95% CI = 0.33 to 0.84].
Significant 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://pubmed.ncbi.nlm.nih.gov/31800007/

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

Objectives:
A growing number of epidemiological studies have suggested a possible association between long-chain omega-3 polyunsaturated fatty acid (PUFA) intake and the risk of cancers, but the results have been inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Does dietary intake of omega-3 PUFAs reduce digestive system cancers?

Study design:
This review article included 8 case-control studies and 17 cohort studies, involving 1,247,271 participants and 23,173 patients with digestive system cancers.

Visual inspection of funnel plots and the Begg's and Egger's tests revealed no evidence of publication bias.

Results and conclusions:
The investigators found the risk of digestive system cancers significantly decreased by 17% in individuals who consumed omega-3 PUFAs [RR = 0.83, 95% CI = 0.76 to 0.91].

The investigators found the risk estimates of digestive system cancers varied by cancer sites, study location, study design, type of omega-3 PUFAs and other confounders (smoking, alcohol consumption, body mass index and physical activity).

The investigators concluded omega-3 PUFA is a healthy dietary component for the prevention of digestive system cancers. Cancer incidence decreases with increasing omega-3 PUFAs intake for most digestive system cancer sites. The relation between omega-3 PUFAs and digestive system cancers RR is similar among different populations.

Original title:
Omega-3 PUFA Intake and the Risk of Digestive System Cancers: A Meta-Analysis of Observational Studies by Jian J, Zhang and Zhao L.

Link:
https://pubmed.ncbi.nlm.nih.gov/32384489/

Additional information of El Mondo:
Find more information/studies on omega-3 PUFAs and cancer right here.

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

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

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

The investigators concluded barberry supplementation improves insulin levels.

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

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

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

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

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

Study design:
This review article included 8 clinical trials.

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

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

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

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

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

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

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