Nutrition and health

Objectives:
The results of human studies are inconsistent regarding selenium and depressive disorders. Therefore, this review article has been conducted.

Does high selenium intake (through diet or supplements) reduce risk of depression?

Study design:
This review article included 20 studies (4 RCTs, 9 cross-sectional studies, 4 case-control studies and 3 prospective cohort studies) with a total of 47,164 participants.
The age of participants ranged from 18.0 ± 1.2 to 82 years old.
12 studies included both men and women.
Confounding variables were adjusted in half of included studies.
All included randomized controlled trials (RCTs) had high quality.
There was no publication bias.

Results and conclusions:
The investigators found no significant differences in serum selenium levels between patients with depression and healthy subjects [WMD = 2.12 mg/L, 95% CI = -0.11 to 4.36, I2 = 98.0%, p 0.001].

The investigators found no significant differences between serum levels of selenium and depression scores [r = -0.12, 95% CI = -0.33 to 0.08, I2 = 73.5%, p = 0.010].

The investigators found high selenium supplementation significantly reduced the risk of postpartum depression with 3% [OR = 0.97, 95% CI = 0.95 to 0.99, I2 = 0.0%, p = 0.507].

The investigators found selenium supplementation significantly reduced depressive symptoms [WMD = -0.37, 95% CI = -0.56 to -0.18, I2 = 0.0%, p = 0.959].

The investigators concluded that high selenium supplementation has a protective role against postpartum depression. In addition, supplementation with selenium reduces depressive symptoms. Nevertheless, further studies are needed to draw definitive conclusions.

Original title:
The role of selenium in depression: a systematic review and meta-analysis of human observational and interventional studies by Sajjadi SS, Foshati S, […], Rouhani H.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8776795/

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Objectives:
Inflammation is a major cause of chronic diseases. Several studies have investigated the effects of tomato intake on inflammatory biomarkers; however, the results are equivocal. Therefore, this review article has been conducted.

Does tomato intake have positive impact on inflammatory biomarkers in adults?

Study design:
This review article included 7 RCTs (8 treatment arms) with a total of 465 subjects.

Results and conclusions:
The investigators found that pooled effect size of articles indicated that tomato intake was not significantly effective on CRP [WMD = 0.13 mg/dL, 95% CI = -0.09 to 0.36, p = 0.23, I2 = 83.9%] and IL-6 [Hedges' g = -0.12, 95% CI = -0.36 to 0.13, p = 0.34, I2 = 0.0%] levels compared to the control group.

The investigators found that pooled effect size of articles indicated that tomato intake significantly reduced TNF-α [Hedges' g = -0.45, 95% CI = -0.76 to -0.13, p = 0.005, I2 = 0.0%] levels in adults.

The investigators concluded that tomato intake causally reduces TNF-α levels in adults. However, additional well-designed studies that include more diverse populations and longer duration are warranted.

Original title:
Effect of tomato consumption on inflammatory markers in health and disease status: A systematic review and meta-analysis of clinical trials by Widjaja G, Doewes RI, […], Aravindhan S.

Link:
https://pubmed.ncbi.nlm.nih.gov/35871957/

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Tumor necrosis factor alpha (TNF-α) is an inflammatory cytokine that is elevated in heart failure.

Objectives:
Dementia is a chronic progressive neurodegenerative disease that can lead to disability and death in humans, but there is still no effective prevention and treatment. Due to the neuroprotective effects of vitamin E, a large number of researchers have explored whether vitamin E can reduce the risk of dementia. Some researchers believe that vitamin E can reduce the risk of dementia, while others hold the opposite conclusion. Therefore, this review article has been conducted.

Do high intakes of diet or vitamin E supplements reduce the risk of dementia?

Study design:
This review article included 13 cohort studies (46,968 participants and 6,046 dementia patients after 4-23 years of follow-up) and 2 case-control studies with (3,157 controls and 3,459 patients).
The studies included in this meta-analysis (review article) were published between 1983 and 2022.
The literary NOS quality score ranged from 6 to 8.
There was no publication bias.

Results and conclusions:
The investigators found a high intake of diet or vitamin E supplements significantly decreased the risk of dementia by 21% [OR = 0.79, 95% CI = 0.70 to 0.88, I2 = 35.0%, p = 0.071].
This decreased risk was also significant in cohort studies [OR = 0.79, 95% CI = 0.69 to 0.89], dietary intake of vitamin E [OR = 0.78, 95% CI = 0.65 to 0.95], vitamin E supplement [OR = 0.83, 95% CI = 0.73 to 0.94] and studies with NOS scores >7 [OR = 0.85, 95% CI = 0.75 to 0.97].

The investigators found a high intake of diet or vitamin E supplements significantly decreased the risk of Alzheimer's disease by 22% [OR = 0.78, 95% CI = 0.64 to 0.94, I2 = 36.9%, p = 0.123].
This decreased risk was also significant in cohort studies [OR = 0.77, 95% CI = 0.63 to 0.94].

The investigators found in sensitivity analysis the pooled ORs fluctuated within a certain range after deleting each study, indicating that the results of this meta-analysis were stable.

The investigators concluded high intakes of diet or vitamin E supplements reduce the risk of dementia. Therefore, the elderly can reduce the risk of dementia by appropriately increasing foods rich in vitamin E, but also pay attention to the toxic side effects of vitamin E. Although the results are reliable, they should be further validated by large RCTs.

Original title:
Association of vitamin E intake in diet and supplements with risk of dementia: A meta-analysis by Zhao R, Han X, [...], You H.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9376618/

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Objectives:
Do plant-based diets improve age-related ocular outcomes among adults?

Study design:
This review article included 15 studies (n = 51,695 participants) assessed the impact of fish consumption, 8 studies (n = 28,753 participants) analyzed the effect of red meat intake and 3 studies (n = 7,723 participants) assessed the impact of omission of skim milk, poultry and non-meat animal products and the presence of disease incidence as indicated by age-related macular degeneration or cataract development.

Results and conclusions:
The investigators found in 15 studies (n = 51,695 participants) that regular consumption of fish significantly reduced the risk of age-related eye disease development among adults with 30% [odds ratio = 0.70, 95% CI = 0.62 to 0.79].
Significant means that there is an association with a 95% confidence.

The investigators found in 3 studies (n = 7,723 participants) that regular consumption of skim milk, poultry and non-meat animal products significantly reduced the risk of age-related eye disease development among adults with 30% [odds ratio = 0.70, 95% CI = 0.61 to 0.79].
Significant because odds ratio of 1 was not found in the 95% CI of 1.07 to 1.72. Odds ratio of 1 means no risk/association.

The investigators found in 8 studies (n = 28,753 participants) that regular consumption of red meat significantly increased the risk of age-related eye disease development among adults with 41% [odds ratio = 1.41, 95% CI = 1.07 to 1.86].

The investigators concluded that regular consumption of both fish and skim milk, poultry and non-meat animal products reduce the risk of age-related eye disease development among adults, while regular consumption of red meat increases the risk of age-related eye disease development among adults. Results suggest a need for more initiatives promoting a healthy and balanced diet.

Original title:
Linkage between a plant-based diet and age-related eye diseases: a systematic review and meta-analysis by Cirone C, Cirone KD and Malvankar-Mehta MS.

Link:
https://pubmed.ncbi.nlm.nih.gov/36102832/

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In practice, regular fish consumption corresponds to at least twice (100-150g per time) a week.
 

Objectives:
Do COPD patients benefit from vitamin C supplementation?

Study design:
This review article included 10 RCTs with a total of 487 patients.

Results and conclusions:
The investigators found that vitamin C supplementation (≥400 mg/day) significantly improved the forced expiratory volume in one second as a percentage (FEV1%) of COPD patients [SMD = 1.08, 95% CI = 0.03 to 2.12, p = 0.04].

The investigators found, moreover, vitamin C supplementation (≥400 mg/day) significantly improved the ratio of forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) [WMD = 0.66, 95% CI = 0.26 to 1.06, p = 0.001], vitamin C level in serum [SMD = 0.63, 95% CI = 0.02 to 1.24, p = 0.04] and glutathione (GSH) level in serum [SMD = 2.47, 95% CI = 1.06 to 3.89, p = 0.0006] of COPD patients.

The investigators found no statistically significant difference was observed in body mass index (BMI), fat-free mass index (FFMI), vitamin E level and superoxide dismutase (SOD) level in serum.

The investigators concluded vitamin C supplementation increases the levels of antioxidation in serum (vitamin C and GSH) and improves lung function (FEV1% and FEV1/FVC) of COPD patients, especially when treated with vitamin C supplementation greater than 400 mg/day. However, further prospective studies are needed to explore the role of vitamin C in improving nutritional status.

Original title:
Efficacy of Vitamin C Supplementation on Chronic Obstructive Pulmonary Disease (COPD): A Systematic Review and Meta-Analysis by Lei T, Lu T, […], Liu J.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9473551/

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Objectives:
Although recent studies comparing various dosages and intervals of vitamin D supplementation have been published, it is yet to be elucidated whether there is an appropriate dose or interval to provide benefit regarding fracture risk. Therefore, this review article has been conducted.

What are the putative beneficial effects of vitamin D supplements on fractures and falls according to various dosages and intervals?

Study design:
This review article included 32 RCTs with a total of 104,363 patients, with a median of 3,162 patients per study (range 46 to 36,282).
The median daily dose of cholecalciferol (D3) was 800 IU/day and 8 studies reported 800 IU/day, 15 studies reported 800 to 1,000 IU/day and 9 studies reported >1,000 IU/day.
The median follow-up duration was 24 months (range 9 to 120) and the median age was 72 years (range 53 to 85).

Results and conclusions:
The investigators found vitamin D3 supplementation with daily dose of 800 to 1,000 IU was significantly associated with a lower risk of 13% for osteoporotic fracture [pooled relative risk = 0.87, 95% CI = 0.78 to 0.97, I2 = 23.5%] while studies with 800 or >1,000 IU/day did not.

The investigators found vitamin D3 supplementation with daily dose of 800 to 1,000 IU was significantly associated with a lower risk of 9% for fall [pooled relative risk = 0.91, 95% CI = 0.85 to 0.98, I2 = 70.9%] while studies with 800 or >1,000 IU/day did not.

The investigators found daily administration of vitamin D3 was associated with the reduced risk of falls, while intermittent dose was not.
Also, patients with vitamin D deficiency showed a significant risk reduction of falls after vitamin D3 supplementation.

The investigators concluded that daily vitamin D3 dose of 800 to 1,000 IU (20-25 mcg) during 24 months is the most probable way to reduce the fracture and fall risk among elderly. Further studies designed with various regimens and targeted vitamin D levels are required to elucidate the benefits of vitamin D supplements.

Original title:
Effect of Vitamin D Supplementation on Risk of Fractures and Falls According to Dosage and Interval: A Meta-Analysis by Kong SH, Jang HN, […], Shin CS.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9081312/

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Objectives:
Do rheumatoid arthritis patients benefit from vitamin E supplements?

Study design:
This review article included 9 RCTs with a total of 39,845 patients.

Results and conclusions:
The investigators found that vitamin E supplements were shown to be more effective in individuals with rheumatoid arthritis for sensitive joints [MD = -1.66, 95% CI = -6.32 to -2.99, I2 = 93%, p 0.00001] and swollen joints [MD = -0.46, 95% CI = -1.98 to 1.07, I2 = 56%, p = 0.08].

The investigators concluded vitamin E's ability to restore the intestinal barrier and improve the gastrointestinal tract may be linked to the prevention and treatment of rheumatoid arthritis. Vitamin E supplements used on a regular basis can help individuals with rheumatoid arthritis reduce joint discomfort, edema and stiffness, as well as enhance their overall quality of life.

Original title:
Effect of vitamin E supplementation in rheumatoid arthritis: a systematic review and meta-analysis by Kou H, Qing Z, […], Ma J.

Link:
https://pubmed.ncbi.nlm.nih.gov/35468933/

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Objectives:
In postmenopausal women, vitamin D deficiency (as defined by the circulating level of 25(OH)D being below 20 ng/mL (50 nmol/L)) is a regular occurrence. The effect of vitamin D supplementation on the muscle function of postmenopausal women has been controversial. Therefore, this review article has been conducted.

Does vitamin D supplementation enhance the muscular strength and mobility of postmenopausal women?

Study design:
This review article included 19 RCTs between 2003 and 2021, with 5,398 participants.
The sample size of the RCTs included in multiple countries ranges from 20 to 2,347. Furthermore, the duration of vitamin D supplementation ranged from 3 to 60 months.
Vitamin D3 was applied in 12 of the 19 retrieved trials, whose dosages ranged from 400 IU/day to 300,000 IU (10 tot 7500 mcg vitamin D3) in a single oral dose.
Visual inspection of the funnel plot and Egger’s linear regression test revealed no indication of publication bias in the meta-analysis of vitamin D supplementation on handgrip strength.

Results and conclusions:
The investigators found meta-analysis of 9 RCTs (1,997 participants supplemented with vitamin D and 2,232 participants as the control group (vitamin D in low dosage or placebo)), showed that vitamin D supplementation significantly improved handgrip strength in postmenopausal women [WMD = 0.876 kg, 95% CI = 0.180 to 1.571, p = 0.014, I2 = 68.5%, p = 0.001].
Moreover, according to subgroup analysis, vitamin D supplementation substantially raised handgrip strength when compared to baseline blood vitamin D levels >75 nmol/L (30 ng/ml) [WMD = 0.478 kg, 95% CI = 0.963 to 1.918, p = 0.003], without calcium [WMD = 1.931 kg, 95% CI = 0.166 to 3.697, p = 0.032] and subject to an age of more than 60 [WMD = 1.116 kg, 95% CI = 0.433 to 1.799, p = 0.001].

The investigators concluded that 400 IU/day to 300,000 IU vitamin D supplementation during 3 to 60 months improves handgrip strength in postmenopausal women over 60 years of age who are without calcium supplementation or whose baseline vitamin D is >75 nmol/L (30 ng/mL). These findings show that future trials should focus on determining the ideal dosage and duration and taking into account the several factors that may impair muscle performance, such as exercise, calcium consumption, frailty, a history of falls or fractures and baseline vitamin D status and the relationship between muscle function and/or strength with muscle composition.

Original title:
Vitamin D Supplementation Improves Handgrip Strength in Postmenopausal Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials by Zhang JL, Poon CCW, […], Zhang Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9199366/

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Objectives:
Data from studies support a beneficial effect of carotenoids and vitamins on an age-related macular degeneration (AMD) risk. However, studies on the relations between blood levels of these nutrients and AMD are limited and provided conflicting results. Therefore, this review article has been conducted.

Does a higher concentration of carotenoids (lutein/zeaxanthin, β-carotene, β-cryptoxanthin, lycopene) and vitamins in blood reduce age-related macular degeneration risk?

Study design:
This review article included 9 studies (1 cohort, 4 case-control and 4 cross-sectional studies) involving 15,674 participants and 2,077 AMD cases (persons with age-related macular degeneration).  
There was no evidence of publication bias.

Results and conclusions:
The investigators found in the meta-analysis that high blood lutein/zeaxanthin level significantly reduced risk of age-related macular degeneration with 47% [OR = 0.53, 95% CI = 0.40 to 0.72, p 0.001, I2 = 43.3%, p = 0.079], compared to those with low level.
Results stratified by factors yielded similar results to the main analysis.

The investigators found in the meta-analysis that high blood β-carotene level significantly reduced risk of age-related macular degeneration with 52% [OR = 0.48, 95% CI = 0.28 to 0.84, p = 0.01, I2 = 71.7%, p = 0.003], compared to those with low level.
A subgroup analysis by geographic region showed that the significant inverse association between blood β-carotene levels and risk of age-related macular degeneration was only found among the Asians.

The investigators found in the meta-analysis that high blood β-cryptoxanthin level significantly reduced risk of age-related macular degeneration with 52% [OR = 0.48, 95% CI = 0.23 to 1.00, p = 0.04, I2 = 83.5%, p 0.001], compared to those with low level.
In stratified analyses, no significant difference was observed for any subgroups.

The investigators found in the meta-analysis that high blood lycopene level significantly reduced risk of age-related macular degeneration with 30% [OR = 0.70, 95% CI = 0.54 to 0.90, p = 0.006, I2 = 0.0%, p = 0.67], compared to those with low level.

The investigators found in the meta-analysis that high blood α-tocopherol (vitamin E) level significantly reduced risk of age-related macular degeneration with 50% [OR = 0.50, 95% CI = 0.31 to 0.81, p = 0.005, I2 = 34.4%, p = 0.19], compared to those with low level.

The investigators found sensitivity analyses, that excluded one study at a time, did not change the statistical significance or the direction of the present findings, corroborating the robustness of the results.

The investigators concluded that there is a protective effect of higher concentration of carotenoids (lutein/zeaxanthin, β-carotene, β-cryptoxanthin, lycopene) and vitamin E in blood against age-related macular degeneration risk, which provides further evidence of the associations between carotenoid and vitamin status and the risk of age-related eye problems. Further randomized clinical trials are necessary for Asians to confirm such associations and to provide the most reliable direct information to base public health recommendations for age-related eye disease prevention by nutritional supplementation with carotenoids and vitamins.

Original title:
The Associations of Plasma Carotenoids and Vitamins With Risk of Age-Related Macular Degeneration: Results From a Matched Case-Control Study in China and Meta-Analysis by Jiang H, Fan  Y, […], Ma L.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8873933/

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High blood levels of beta-carotene can be obtained by consuming beta-carotene-rich foods and/or taking beta-carotene supplements.
 

Objectives:
What is the association of total protein, animal protein and animal protein sources with risk of kidney stones in the general population?

Study design:
This review article included 14 prospective cohort studies.
According to NutriGrade scoring system, the credibility of evidence for most of the exposures was rated as low.
Some kind of publication bias was found in the association of animal protein intake and risk of kidney stones, according to Egger's and Begg's tests.
Sensitivity analysis of processed meat as well as dairy consumption with risk of kidney stones showed one study changed the overall estimate.

Results and conclusions:
The investigators found that higher dietary intake of non-dairy animal protein significantly increased risk of kidney stones with 11% [RR = 1.11, 95% CI = 1.03 to 1.20, I2 = 0%, n = 4].
Significant means that there is an association with a 95% confidence.

The investigators found that higher dietary intake of total meat and meat products significantly increased risk of kidney stones with 22% [RR = 1.22, 95% CI = 1.09 to 1.38, I2 = 13%, n = 3].
Significant because RR of 1 was not found in the 95% CI of 1.09 to 1.38. RR of 1 means no risk/association.

The investigators found that higher dietary intake of processed meat significantly increased risk of kidney stones with 22% [RR = 1.22, 95% CI = 1.10 to 1.51, I2 = 0%, n = 2]. 

The investigators found that higher intake of dairy protein significantly decreased risk of kidney stones with 9% [RR = 0.91, 95% CI = 0.84 to 0.99, I2 = 0%, n = 4].

The investigators found, moreover, each 100 gram increment of red meat dietary intake was significantly associated with an increased risk of 39% for kidney stones [RR = 1.39, 95% CI = 1.13 to 1.71].

The investigators concluded that higher dietary intake of meat and meat products may increase the risk of kidney stones in the general population, while higher dietary intake of dairy proteins may decrease the risk of kidney stones in the general population. May because the credibility of evidence for most of the exposures was rated as low and there was publication bias. Therefore, further observational studies are needed to confirm present results.

Original title:
Associations of Total Protein or Animal Protein Intake and Animal Protein Sources with Risk of Kidney Stones: A Systematic Review and Dose-Response Meta-Analysis by Asoudeh F, Talebi S, […], Mohammadi H.

Link:
https://pubmed.ncbi.nlm.nih.gov/35179185/

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When the credibility of evidence of the studies in the review article is low and there is publication bias, the results will not be very reliable.
 

Objectives:
While there is growing research interest in the effects of nutrition and exercise on delaying sarcopenia, the results are inconclusive and there is scarce information on regional patterns. Therefore, this review article has been conducted.

Do protein supplements combined with exercise improve extremity strength in healthy older adults with sarcopenia?

Study design:
This review article included 14 RCTs, involving a total of 888 healthy older adults (>60 years).

4 studies in Asian countries provided data on lower-extremity strength, involving 280 participants (138 in protein supplements + exercise group and 142 in exercise group).
Lower-extremity strength was assessed using knee extension (n = 3) or leg extension (n = 1).
The intervention period of all studies was 12 weeks.
The dosage of protein ranged from 3 g/d to 40 g/d.

Results and conclusions:
The investigators found in 4 studies in Asian countries a significant increase in the lower-extremity strength in the protein supplementation + exercise group compared to the exercise group, with a SMD of 0.24 [95% CI = 0.00 to 0.47, p = 0.048, I2 = 0.0%, p = 0.513].

The investigators concluded that protein supplements (3 g/d to 40 g/d during 12 weeks) combined with exercise (knee extension and leg extension) exerts superior benefit on lower-extremity strength in healthy older adults with sarcopenia in Asian countries, when compared to exercise alone or with a placebo. However, no additional benefits from protein supplementation are observed on upper-extremity strength, muscle mass and physical performance regardless of the regions. More well-designed RCTs with information on baseline and total protein intake for longer follow-up periods are warranted to evaluate the effectiveness of protein supplementation and exercise on the prevention and management of sarcopenia in healthy older adults.

Original title:
Effects of protein supplementation and exercise on delaying sarcopenia in healthy older individuals in Asian and non-Asian countries: A systematic review and meta-analysis by Li L, He Y, […], Liu X.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8808080/

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Upper extremity is part of the body that includes the arm, wrist and hand.

Lower extremity refers to the part of the body from the hip to the toes.

Sarcopenia is a type of muscle loss (muscle atrophy) that occurs with aging and/or immobility. Sarcopenia can affect people in their 30s and beyond.
 

Objectives:
There is currently a lack of high-quality research on the best dietary recommendations for patients with early glaucoma or at high risk for glaucoma. Therefore, this review article has been conducted.

Does a high dietary vitamin intake reduce risk of glaucoma?

Study design:
This review article included 8 cohort studies, with a total of 262,189 patients.

There was no publication bias.

Results and conclusions:
The investigators found that high-dose dietary intake of vitamins A was significantly associated with a 27% low risk of glaucoma [OR = 0.63, 95% CI = 0.53 to 0.76 , p 001, I2 = 49%].

The investigators found that high-dose dietary intake of vitamins B (a combination of B1, B2, B3, B6 and B12) was significantly associated with a 29% low risk of glaucoma [OR = 0.71, 95% CI = 0.64 to 0.80, p 0.001, I2 = 29%].

The investigators found no association between high-dose dietary intake of vitamins C, D or E and lower risk of glaucoma.

The investigators concluded that high-dose dietary intake of vitamins A and B, but not vitamins C, D or E, is associated with a low prevalence of glaucoma. Overall, middle-aged and elderly people or patients with early glaucoma should consume vitamin-rich foods rich or take additional vitamin supplements.

Original title:
Vitamin intake and glaucoma risk: A systematic review and meta-analysis by Han FF and Fu XX.             

Link:
https://www.sciencedirect.com/science/article/pii/S0181551222000419?via%3Dihub

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Objectives:
Does a higher intake of dietary antioxidants (like vitamin C and E, β-carotene, zinc, anthocyanins, lutein) reduce risk of Parkinson's disease (PD)?

Study design:
This review article included 6 prospective cohort studies and 2 nested case-control studies (448,737 participants with 4,654 persons with Parkinson's disease) and 6 case-control studies (1,948 persons without Parkinson's disease and 1, 273 persons with Parkinson's disease).

Results and conclusions:
The investigators found comparded to the lowest dietary vitamine E intake, that the highest dietary vitamine E intake significantly reduced risk of Parkinson's disease with 16% [pooled RR = 0.84, 95% CI = 0.71 to 0.99, n = 7 cohort studies].
Significantly means that there is an association with a 95% confidence.

The investigators found compared to the lowest dietary anthocyanins intake, that the highest dietary anthocyanins intake significantly reduced risk of Parkinson's disease with 24% [pooled RR = 0.76, 95% CI = 0.61 to 0.96, n = 2 cohort studies].
Significantly because pooled RR of 1 was not found in the 95% CI of 0.61 to 0.96. RR of 1 means no risk/association.

The investigators found compared to the lowest dietary lutein intake, that the highest dietary lutein intake significantly increased risk of Parkinson's disease with 86% [pooled RR = 1.86, 95% CI = 1.20 to 2.88, n = 3 case-control studies].

The investigators found in dose-response meta-analyses that every increment of dietary vitamin C intake with 50 mg/d significantly reduced risk of Parkinson's disease with 6% [RR = 0.94, 95% CI = 0.88 to 0.99, n = 6].

The investigators found in dose-response meta-analyses that every increment of dietary vitamin E intake with 5 mg/d significantly reduced risk of Parkinson's disease with 16% [RR = 0.84, 95% CI = 0.70 to 0.99, n = 7].

The investigators found in dose-response meta-analyses that every increment of dietary β-carotene intake with 2 mg/d significantly reduced risk of Parkinson's disease with 6% [RR = 0.94, 95% CI = 0.89 to 0.99, n = 6].

The investigators found in dose-response meta-analyses that every increment of dietary zinc intake with 1 mg/d significantly reduced risk of Parkinson's disease with 35% [RR = 0.65, 95% CI = 0.49 to 0.86, n = 1].

The investigators concluded that higher intake of antioxidant-rich foods reduces risk of Parkinson's disease. Future, well-designed prospective studies are needed to validate the present findings.

Original title:
Dietary Antioxidants and Risk of Parkinson's Disease: A Systematic Review and Dose-response Meta-analysis of Observational Studies by Talebi S, Ghoreishy SM, […], Mohammadi H.

Link:
https://pubmed.ncbi.nlm.nih.gov/35030236/

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