Nutrition and health

Objectives:
Does a high antioxidant dietary intake reduce risk of Alzheimer's disease and dementia?

Study design:
This review article included 17 cohort studies with 98,264 participants, of which 7,425 had dementia after 3-23 years of follow-up.

Results and conclusions:
The investigators found a high antioxidant dietary intake significantly reduced the incidence of Alzheimer's disease with 15% [RR = 0.85, 95% CI= 0.79 to 0.92, I2 = 45.5%].
However, this reduced risk was not significant for dementia [RR = 0.84, 95% CI = 0.77 to 1.19, I2 = 54.6%].
Significant because RR of 1 was not found in the 95% CI of 0.79 to 0.92. RR of 1 means no risk/association.

The investigators concluded that a high antioxidant dietary intake reduces Alzheimer's disease.

Original title:
Association of Dietary and Supplement Intake of Antioxidants with Risk of Dementia: A Meta-Analysis of Cohort Studies by Zhao R, Han X, […], You H.

Link:
https://pubmed.ncbi.nlm.nih.gov/36846999/

Additional information of El Mondo:
Find more information/studies on antioxidant and Alzheimer 's disease right here.

Objectives:
The associations between dietary intakes and circulating blood levels of methionine, choline or betaine and breast cancer risk remain currently unclear. Therefore, this review article has been conducted.

Do higher dietary intakes and circulating blood levels of methionine, choline or betaine reduce breast cancer risk?

Study design:
This review article included 8 prospective cohort studies and 10 case-control studies.

Results and conclusions:
The investigators found in case-control studies that higher dietary choline intake significantly reduced breast cancer risk with 62% [OR = 0.38, 95% CI = 0.16 to 0.86].
However, this reduced risk was not significant in prospective cohort studies [HR = 1.01, 95% CI = 0.92 to 1.12].

The investigators concluded that higher choline dietary intake may reduce breast cancer risk. May reduce because this reduced risk is not found in cohort studies.

Original title:
The association between dietary intakes of methionine, choline and betaine and breast cancer risk: A systematic review and meta-analysis by Van Puyvelde H, Dimou N, […], De Bacquer D.

Link:
https://pubmed.ncbi.nlm.nih.gov/36701983/

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

Objectives:
The roles of anti-inflammatory cytokines in the pathogenesis of severe malaria have been widely studied and the role of IL-10 in the pathogenesis of severe malaria remains unclear. Therefore, this review article has been conducted.

Is there a difference in IL-10 levels between patients with severe malaria and those with non-severe malaria?

Study design:
This review article included 19 studies, published between 1994 and 2021.
11 studies (57.9%) were prospective studies, 6 (31.6%) were retrospective studies and 2 (10.5%) were cross-sectional studies.
Of the included studies, 10 (52.6%) were conducted in Africa, 5 (26.3%) were conducted in Asia, 3 (15.8%) were conducted in the United States and 1 (5.26%) was conducted in Europe.
13 studies (68.4%) enrolled patients infected with P. falciparum, 4 (21.1%) enrolled patients with P. vivax, and 2 (10.5%) enrolled patients with both P. falciparum and P. knowlesi.
10 studies (52.6%) enrolled children, 6 (31.6%) enrolled adults and 3 (15.8%) enrolled all age groups.

18 studies (94.7%) were high-quality studies, whereas 1 study (5.26%) was of moderate quality.

Results and conclusions:
The investigators found, overall, the meta-analysis results showed that patients with severe malaria had a higher SMD of the IL-10 levels than those with non-severe malaria [pooled SMD = 0.74, 95% CI = 0.08 to 1.40, p = 0.03, I2 = 97.22%].

The investigators found meta-regression analysis using the study designs, geographic location (continents), Plasmodium spp., age, mean parasitemia and methods for the IL-10’s quantification showed that these covariates did not confound the pooled SMD [p > 0.05].

The investigators found subgroup analysis based on the study design revealed no difference in the SMD of the IL-10 levels between patients with severe and non-severe malaria in cross-sectional studies, prospective studies and retrospective studies.

The investigators found subgroup analysis, based on Plasmodium spp. showed a higher SMD of the IL-10 level in patients with severe P. falciparum malaria than in those with non-severe P. falciparum malaria and a higher SMD of the IL-10 level in patients with severe P. knowlesi malaria than in those with non-severe P. knowlesi malaria.
However, a lower SMD of the IL-10 level was observed in patients with severe P. vivax malaria than in those with non-severe P. vivax malaria.

The investigators found subgroup analysis based on the age groups showed no difference in the SMD of the IL-10 level between patients with severe malaria and those with non-severe malaria among studies that enrolled adults, children and participants of all age groups.   

The investigators found sensitivity analysis showed that when each study was omitted from the analysis, the meta-analysis results of the IL-10 levels showed outliers [p 0.05 or p > 0.05 in re-run analyses].

The investigators found after the publication bias was adjusted by the trim and fill method, the pooled SMD in the IL-10 levels between severe and non-severe malaria was 0.743 [95% CI = 0.085 to 1.401].

The investigators concluded that patients with severe malaria have a higher mean IL-10 level than those with non-severe malaria. This finding suggests the possibility of using IL-10 as a severity marker for malaria. However, with the heterogeneity of the meta-analysis results, further studies are required to confirm the changes in the IL-10 levels according to the severity of malaria and to investigate whether a combination of other severity parameters with IL-10 levels could be an alternative marker for severe malaria.

Original title:
Relation between Increased IL-10 Levels and Malaria Severity: A Systematic Review and Meta-Analysis by Sornsenee P, Wilairatana P, […], Kotepui M.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9865813/

Additional information of El Mondo:
Find more information/studies on food fortification/malnutrition and malaria right here.

Objectives:
Current findings about the differential effects of various sources of dietary animal protein on the risk of neurodegenerative diseases are contradictory. Therefore, this review article has been conducted.

Is there an association between various sources of dietary animal protein and the risk of Parkinson's disease, Alzheimer's disease, dementia and cognitive impairment?

Study design:
This review article included 33 prospective cohort studies.

Results and conclusions:
The investigators found dietary fish consumption was significantly associated with a reduced risk of 25% for Alzheimer's disease [RR = 0.75, 95% CI = 0.57 to 0.97].

The investigators found dietary fish consumption was significantly associated with a reduced risk of 16% for dementia [RR = 0.84, 95% CI = 0.75 to 0.93].

The investigators found dietary fish consumption was significantly associated with a reduced risk of 15% for cognitive impairment [RR = 0.85, 95% CI = 0.81 to 0.95].

The investigators found compared to the lowest consumption, the highest total dairy products consumption was significantly associated with an increased risk of 49% for Parkinson's disease [RR = 1.49, 95% CI = 1.06 to 2.10].

The investigators found compared to the lowest consumption, the highest milk consumption was significantly associated with an increased risk of 40% for Parkinson's disease [RR = 1.40, 95% CI = 1.13 to 1.73].

The investigators found total dairy products consumption was significantly associated with a reduced risk of 11% for cognitive impairment [RR = 0.89, 95% CI = 0.80 to 0.99].

The investigators found total meat consumption was significantly associated with a reduced risk of 28% for cognitive impairment [RR = 0.72, 95% CI = 0.57 to 0.90].

The investigators found poultry consumption was significantly associated with a reduced risk of 18% for cognitive impairment [RR = 0.82, 95% CI = 0.68 to 0.99].

The investigators found linear dose-response meta-analysis revealed that each 200g/d increase in total dairy dietary intake was significantly associated with an 11% higher risk of Parkinson's disease and a 12% lower risk of cognitive impairment.

The investigators found a strong linear association between fish consumption and reduced risk of dementia.

The investigators concluded dairy consumption, particularly milk is associated with an increased risk of Parkinson's disease, while a higher intake of fish reduces Alzheimer's disease, dementia and cognitive impairment. Future well-controlled, randomized clinical trials are essential to validate the present findings.

Original title:
Association between animal protein sources and risk of neurodegenerative diseases: a systematic review and dose-response meta-analysis by Talebi S, Asoudeh F, […], Mohammadi H.

Link:
https://pubmed.ncbi.nlm.nih.gov/36647769/

Additional information of El Mondo:
Find here more information/studies about RCTs/significant, dairy product, Parkinson's disease and proteins.
 

Objectives:
Is there a causal relationship between drinking green tea and improving risk factors of cardiovascular disease, like cholesterol, fasting blood sugar, blood pressure, HbA1c, HOMA-IR?

Study design:
This review article included 55 RCTs with 63 effect sizes with 2,487 participants in the green tea group and 2,387 in the placebo group (group without green tea).

The participants’ mean age ranged between 18 and 68.7 years and the period of intervention ranged between 2 to 48 weeks.
Some of the studies enrolled only males or females and some of them included both genders.

TC, LDL, HDL, FBS, HbA1c and DBP-related evidence had moderate quality due to the serious inconsistency reasons. Additionally, it was shown that evidence regarding TG, fasting insulin, SBP and CRP had low quality due to serious imprecision and inconsistency reasons. The evidence relating to HOMA-IR was also downgraded to very low quality because of the serious inconsistency, imprecision and publication bias.

Results and conclusions:
The investigators found green tea supplementation significantly reduced total cholesterol levels (TC) [WMD = -7.62, 95% CI = -10.51 to -4.73, p ≤ 0.001, I2 = 90.9%].
This significantly reduced effect was also found if females or both males and females were included, the dosage of supplementation was less than 1,000 mg/d, the baseline BMI was between 25-29.9 kg/m² and the baseline value of TC was more than 200 mg/dL.

The investigators found green tea supplementation significantly reduced LDL cholesterol levels (LDL-C) [WMD = -5.80, 95% CI = -8.30 to -3.30, p ≤ 0.001, I2 = 90.5%].
This significantly reduced effect was also found if males or both males and females were included, the baseline BMI was between 25-29.9 kg/m² and participants were not affected by T2DM.

The investigators found green tea supplementation significantly reduced fasting blood sugar levels (FBS) [WMD = -1.67, 95% CI = -2.58 to -0.75, p ≤ 0.001, I2 = 72.2%].

This significantly reduced effect was also found when the baseline BMI of participants was between 25-29.9 kg/m², female or both male and female were included, the duration of intervention was more than 12 weeks, the dosage of supplementation was less than 1,000 mg/d and baseline values of FBS were less than 100 mg/dL.

The investigators found green tea supplementation significantly reduced HbA1c levels [WMD = -0.15, 95% CI = -0.26 to -0.04, p = 0.008, I2 = 71.3%].
This significantly reduced effect was also found if the duration of intervention was ≤ 12 weeks, the dosage of supplementation was ≥ 1,000 mg/d, baseline values of HbA1c were less than 6.5%, male or both genders were involved and the baseline value of BMI was ≥ 30 kg/m².

The investigators found green tea supplementation significantly reduced diastolic blood pressure (DBP) [WMD = -0.87, 95% CI = -1.45 to -0.29, p = 0.003, I2 = 92.4%].
This significantly reduced effect was also found if the duration of intervention was ≤ 12 weeks, the dosage of supplementation was less than 1,000 mg/d, baseline values of DBP were more than 80 mmHg and the baseline value of BMI was ≥ 30 kg/m².

The investigators found green tea supplementation significantly increased HDL cholesterol levels (HDL-C) [WMD = 1.85, 95% CI = 0.87 to 2.84, p = 0.010, I2 = 94.4%].
This significantly increased effect was also found if females were included, the baseline BMI was lower more than 30 kg/m², there was no past medical history of T2DM, the duration of intervention was more than 12 weeks, the dosage of supplementation was less than 1,000 mg/d and baseline values of HDL were more than 50 mg/dL.

The investigators found sensitivity analysis showed no significant difference in results with removing one single study for all considered cardiovascular risk factors including lipid profiles, glycemic indices, SBP and DBP and CRP.

The investigators concluded drinking ≤1,000 mg/d green tea may causally improve risk factors of cardiovascular disease. May improve because the RCTs are of low quality.

Original title:
The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis by Zamani M, Kelishadi MR, […], Asbaghi O.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9871939/

Additional information of El Mondo:
Find more information/studies on green tea, lowering blood pressure and cardiovascular diseases right here.

Objectives:
Is there a causal relationship between drinking green tea and lowering blood pressure in healthy individuals?

Study design:
This review article included 9 RCTs with 345 healty individuals in the intervention group (group with green tea) and 335 healthy individuals in the control group (group without green tea).

The mean age of the individuals in the intervention group was 35.89 ± 8.52, while the mean age of the control group was 36.48 ± 7.68.
All studies clearly described allocation randomization, none had incomplete outcome data, and all used appropriate statistical analysis.
The completion rate of the consumption of green tea ranged from 85-100%.
No publication bias was observed in the studies.

Results and conclusions:
The investigators found combined results of the studies showed that green tea was effective in lowering systolic blood pressure in healthy individuals [MD = -2.99, 95% CI = -3.77 to -2.22, p 0.00001, I2 = 0%].

The investigators found combined results of the studies showed that green tea was effective in lowering diastolic blood pressure in healthy individuals [MD= -0.95, 95% CI = -1.62 to -0.27, p = 0.006, I2 = 0%]. 

The investigators concluded in healthy individuals, green tea supplementation reduces systolic blood pressure by 2.99 mmHg and diastolic blood pressure by 0.95 mmHg.

Original title:
Effect of Green Tea on Blood Pressure in Healthy Individuals: A Meta-Analysis by Ayaz EY, Dincer B and Mesci B.

Link:
https://pubmed.ncbi.nlm.nih.gov/36689359/

Additional information of El Mondo:
Find more information/studies on green tea, lowering blood pressure and cardiovascular diseases right here.