Nutrition and health

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/

Additional information of El Mondo:
Find more information/studies on dementia and vitamin E right here.

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/

Additional information of El Mondo:
Find more information/studies on fish, milk, meat and elderly right here.

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

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/

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

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/

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

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/

Additional information of El Mondo:
Find more information/studies on meta-analysis/cohort, carotenoids, vitamin E and elderly right here.

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

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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Find more information/studies on protein and elderly right here.

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:
Is there a relationship between the levels of vitamin C, vitamin E and β-carotene in the plasma and Alzheimer's disease risk?

Study design:
This review article included studies with data of levels of vitamin C, vitamin E and β-carotene in the plasma of Alzheimer's disease patients.

Results and conclusions:
The investigators found meta-analysis showed that, compared with the control group, the level of vitamin E in the plasma of Alzheimer's disease patients declined significantly [SMD = -1.49 μmol/L, 95% CI = -2.08 to -0.89 μmol/L, p 0.001].

However, no differences were determined in the levels of the plasma vitamin C and β-carotene between the two groups [vitamin C: SMD = -1.43 μmol/L, 95% CI = -3.05 to 0.19 μmol/L, p = 0.083 and β-carotene: SMD = -0.61 μmol/L, 95% CI = -1.40 to 0.18 μmol/L, p = 0.131].

The investigators concluded increasing vitamin E level in the plasma through vitamin E riched diet is useful to prevent Alzheimer's disease. However, it is not yet believed the beneficial role on Alzheimer's disease to increase vitamin C and β-carotene.

Original title:
Meta-analysis of vitamin C, vitamin E and β-carotene levels in the plasma of Alzheimer's disease patients by Dong R, Yang Q, […], Zhao H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30081996  

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

Objectives:
Although several studies have been conducted on the association of vitamins with glaucoma, it is often noticed that the results are conflicting leaving physicians and patients in doubt about the effect of vitamins on glaucoma. Therefore, this review article has been conducted.

Does dietary vitamin intake reduce risk of the eye disease glaucoma? 

Study design:
This review article included 5 cohort studies with a total of 940 open-angle glaucoma (OAG) cases and 123,697 controls (persons without open-angle glaucoma).

Results and conclusions:
The investigators found a significantly reduced risk of 55% [pooled OR = 0.45, 95% CI = 0.30-0.68, I2 = 0%] for open-angle glaucoma for dietary intake of vitamin A.

The investigators found a significantly reduced risk of 61% [pooled OR = 0.39, 95% CI = 0.23-0.67, I2 = 0%] for open-angle glaucoma for dietary intake of vitamin C.

The investigators found a significantly reduced risk of 61% [pooled OR = 0.39, 95% CI = 0.22-0.70, I2 = 0%] for open-angle glaucoma for dietary intake of green leafy vegetables (a source for vitamin A, C and nitrate).

The investigators concluded dietary intake of vitamin A, C and green leafy vegetables show a beneficial association with the eye disease open-angle glaucoma.

Original title:
The Effect of Vitamins on Glaucoma: A Systematic Review and Meta-Analysis by Ramdas WD, Schouten JSAG and Webers CAB.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872777/

Additional information of El Mondo:
Find more information/studies on vitamin A and C, vegetables and elderly right here.
 

Objectives:
The associations of various dietary or circulating antioxidants with the risk of all-cause mortality in the general population have not been established yet. Therefore, this review article has been conducted.

Do dietary or circulating antioxidants reduced risk of all-cause mortality in the general population?

Study design:
This review article included 41 prospective observational studies with a total of 507,251 participants and 73,965 cases of all-cause mortality.

Results and conclusions:
The investigators found for the highest compared with the lowest category of circulating total carotenes concentrations a significantly reduced risk of 40% [RR = 0.60, 95% CI = 0.46 to 0.74] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating vitamin C concentrations a significantly reduced risk of 39% [RR = 0.61, 95% CI = 0.53 to 0.69] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating selenium concentrations a significantly reduced risk of 38% [RR = 0.62, 95% CI = 0.45 to 0.79] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating β-carotene concentrations a significantly reduced risk of 37% [RR = 0.63, 95% CI = 0.57 to 0.70] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating α-carotene concentrations a significantly reduced risk of 32% [RR = 0.68, 95% CI = 0.58 to 0.78] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating total carotenoids concentrations a significantly reduced risk of 32% [RR = 0.68, 95% CI = 0.56 to 0.80] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating lycopene concentrations a significantly reduced risk of 25% [RR = 0.75, 95% CI = 0.54 to 0.97] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of circulating α-tocopherol concentrations a significantly reduced risk of 16% [RR = 0.84, 95% CI = 0.77 to 0.91] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of total carotenoids a significantly reduced risk of 24% [RR = 0.76, 95% CI = 0.66 to 0.85] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of total antioxidants a significantly reduced risk of 23% [RR = 0.77, 95% CI = 0.73 to 0.81] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of selenium a significantly reduced risk of 21% [RR = 0.79, 95% CI = 0.73 to 0.85] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of α-carotene a significantly reduced risk of 21% [RR = 0.79, 95% CI = 0.63 to 0.94] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of β-carotene a significantly reduced risk of 18% [RR = 0.82, 95% CI = 0.77 to 0.86] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of vitamin C a significantly reduced risk of 12% [RR = 0.88, 95% CI = 0.83 to 0.94] for all-cause mortality.  

The investigators found for the highest compared with the lowest category of dietary intakes of total carotenes a significantly reduced risk of 11% [RR = 0.89, 95% CI = 0.81 to 0.97] for all-cause mortality.  

The investigators found for the highest compared with the lowest category a nonsignificant inverse association between dietary zinc, zeaxanthin, lutein and vitamin E and all-cause mortality risk.

The investigators found in nonlinear dose-response meta-analyses a linear inverse association in the analyses of dietary β-carotene and total antioxidant capacity, as well as in the analyses of circulating α-carotene, β-carotene, selenium, vitamin C and total carotenoids.

The investigators found the association appeared to be U-shaped in the analyses of serum lycopene and dietary vitamin C.

The investigators concluded that a diet with high antioxidant properties reduces the risk of all-cause mortality. These findings confirm current recommendations that promote higher intake of antioxidant-rich foods such as fruit and vegetables.

Original title:
Dietary Antioxidants, Circulating Antioxidant Concentrations, Total Antioxidant Capacity, and Risk of All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Observational Studies by Jayedi A, Rashidy-Pour A, […], Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30239557

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Objectives:
Low carbohydrate diets, which restrict carbohydrate in favour of increased protein or fat intake, or both, are a popular weight-loss strategy. However, the long-term effect of carbohydrate restriction on mortality is controversial and could depend on whether dietary carbohydrate is replaced by plant-based or animal-based fat and protein. Therefore, this review article has been conducted.

Is there a relationship between carbohydrate diet and all-cause mortality?

Study design:
This review article included 8 cohort studies with a total of 432,179 participants, of which 40,181 deaths.

Results and conclusions:
The investigators found in the meta-analysis of 8 cohort studies, low carbohydrate consumption (40 En%) significantly increased all-cause mortality risk with 20% [pooled HR = 1.20, 95% CI = 1.09-1.32].

The investigators found in the meta-analysis of 8 cohort studies, high carbohydrate consumption (>70 En%) significantly increased all-cause mortality risk with 23% [pooled HR = 1.23, 95% CI = 1.11-1.36].

The investigators found, however, results varied by the source of macronutrients: all-cause mortality increased when carbohydrates were exchanged for animal-derived fat or protein [HR = 1.18, 95% CI = 1.08-1.29] and all-cause mortality decreased when the substitutions were plant-based [HR = 0.82, 95% CI = 0.78-0.87].

The investigators found a U-shaped relationship between carbohydrate intake and all-cause mortality, with minimum risk observed with 50-55% of energy from carbohydrate.

The investigators concluded that both high (>70 En%) and low percentages of carbohydrate diets (40 En%) are associated with increased all-cause mortality, with minimal risk observed at 50-55 En% carbohydrate intake. Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork and chicken, are associated with higher all-cause mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter and whole-grain breads, are associated with lower all-cause mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and all-cause mortality.

Original title:
Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis by Seidelmann SB, Claggett B, […], Solomon SD.

Link:
https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30135-X/fulltext

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The most easy way to follow a diet with 50-55 En% carbohydrates is to choose only meals/products with 50-55 En% carbohydrates.
However, the most practical way to follow a diet with 50-55 En% carbohydrates is all meals/products that you eat on a daily basis should contain on average 50-55 En% carbohydrates. Check here which products contain 50-55 En% carbohydrates.
 

Objectives:
Oxidative stress has been found to be implicated in the development of Alzheimer's disease (AD). Therefore, this review article has been conducted.

Is there an association between selenium level in the brain and Alzheimer’s disease? 

Study design:
This review article included 14 studies with 40 observations on selenium concentrations in Alzheimer’s disease and control brains (persons without Alzheimer’s disease).

The effect size as standardized mean difference (SMD) was generated using review manager 5.3.

The funnel plot with Egger's [p = 0.88] and Begg's tests [p = 0.24] detected no significant publication bias.

Results and conclusions:
The investigators found random-effects meta-analysis indicated a decrease [SMD = - 0.42] in brain tissue selenium levels in patients with Alzheimer’s disease as compared to non-Alzheimer’s disease controls.
The results of sensitivity analysis indicated that no single study/observation had significantly influenced the overall outcome.

The investigators found the subgroup meta-analysis demonstrated that the selenium levels were decreased in the temporal, hippocampal and cortex regions of the brains in patients with Alzheimer’s disease.
The results of sensitivity analysis indicated that no single study/observation had significantly influenced the overall outcome.

The investigators concluded there is consolidated evidence for a significant decrease of selenium status in Alzheimer’s disease brains compared to controls (persons without Alzheimer’s disease). In line with the evidence supporting selenium's antioxidant role and the involvement of oxidative stress in Alzheimer’s disease development, these findings support new therapeutic strategies aimed at brain tissue selenium homeostasis in Alzheimer’s disease.

Original title:
Brain Selenium in Alzheimer's Disease (BRAIN SEAD Study): a Systematic Review and Meta-Analysis by Varikasuvu SR, Prasad VS, [...], Manne M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30171594

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

Objectives:
Total dietary fat intake might influence the risk of fracture; however, conflicting findings have been reported to date. Therefore, this review article has been conducted.

Is there an association between dietary fat intake and risk of fracture?

Study design:
This review article included 6 observational studies.

Results and conclusions:
The investigators found no significant association between total dietary fat intake and risk of fracture [pooled effect size = 1.31, 95% CI = 0.95-1.79, p = 0.09].

The investigators found dietary saturated fat intake significantly increased risk of fracture with 79% [pooled effect size = 1.79, 95% CI = 1.05-3.03, p = 0.03].

The investigators found dietary monounsaturated fatty acids (MUFAs) intake derived from animal sources significantly increased risk of fracture with 129% [pooled effect size = 2.29, 95% CI = 1.50-3.50, p 0.0001].

The investigators concluded that both dietary saturated fat and monounsaturated fatty acids (MUFAs) intake derived from animal sources increase risk of fracture.

Original title:
Dietary fat, saturated fatty acid, and monounsaturated fatty acid intakes and risk of bone fracture: a systematic review and meta-analysis of observational studies by Mozaffari H, Djafarian K, […], Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29947872

Additional information of El Mondo:
Find more information/studies on fat consumption and elderly.

A diet high in saturated fat is a diet that is largely made up of meals/products with more than 10 En% saturated fat. Practically, this means that all meals/products that you eat on a daily basis should on average contain more than 10 En% saturated fat. Check here which products contains more than 10 En% saturated fat.
More than 10 En% saturated fat means that the total amounts of saturated fat make up for more than 10% of the total kcal of the diet.
 

Objectives:
Is there an association between consumption of food groups and the occurrence of age-related macular degeneration (AMD)?

Study design:
This review article included 26 prospective cohort studies with a total of 211,676 subjects and 7,154 cases of age-related macular degeneration.

Results and conclusions:
The investigators found no significant association between age-related macular degeneration and vegetables, fruit, nuts, grains, dairy products or dietary fats such as oils, butter and margarine when comparing the highest vs. the lowest consumption.

The investigators found a significantly reduced risk of 18% for total age-related macular degeneration [RR = 0.82, 95% CI = 0.75-0.90, p  0.05] when comparing the highest vs. the lowest fish consumption.

The investigators found a significantly reduced risk of 16% for early age-related macular degeneration [RR = 0.84, 95% CI = 0.73-0.97, p  0.05] when comparing the highest vs. the lowest fish consumption.

The investigators found a significantly reduced risk of 21% for late age-related macular degeneration [RR = 0.79, 95% CI = 0.70-0.90, p  0.05], when comparing the highest vs. the lowest fish consumption. 

The investigators found a significantly increased risk of 17% for early age-related macular degeneration [RR = 1.17, 95% CI = 1.02-1.34] when comparing the highest vs. the lowest meat consumption. However, no association was found for late age-related macular degeneration.

The investigators found a significantly increased risk of 20% for early age-related macular degeneration [RR = 1.20, 95% CI = 1.04-1.39] when comparing the highest vs. the lowest alcohol consumption.

The investigators concluded that high fish consumption decreases risk of age-related macular degeneration, while high intake of meat and alcohol increases risk of age-related macular degeneration.

Original title:
Food groups and risk of age-related macular degeneration: a systematic review with meta-analysis by Dinu M, Pagliai G, […], Sofi F.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29978377

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Objectives:
Cardiovascular risk factors are closely linked with dementia risk, but whether heart disease predisposes to dementia is uncertain. Therefore, this review article has been conducted.

Does heart disease increase risk of dementia?

Study design:
This review article included 16 studies (1,309,483 individuals) regarding coronary heart disease and 7 studies (1,958,702 individuals) about heart failure.

Results and conclusions:
The investigators found that a history of coronary heart disease was associated with a 27% increased risk of dementia [pooled relative risk = 1.27, 95% CI = 1.07-1.50, I2 = 80%].

The investigators found that a history of heart failure was associated with a 60% increased dementia risk [pooled relative risk = 1.60, 95% CI = 1.19-2.13, I2 = 59%].

The investigators found among 9 prospective population-based cohort studies, a significantly increased risk of 26% for dementia among patients with coronary heart disease [pooled relative risk = 1.26, 95% CI = 1.06-1.49, I2 = 0%].
Significantly means that there is an association with a 95% confidence.

The investigators found among 4 prospective population-based cohort studies, a significantly increased risk of 80% for dementia among patients with heart failure [pooled relative risk = 1.80, 95% CI = 1.41-2.31, I2 = 0%].
Significantly means it can be said with a 95% confidence that heart failure really increased the risk of getting dementia with 80%. 

The investigators concluded that both coronary heart disease and heart failure are associated with an increased risk of dementia.

Original title:
Coronary heart disease, heart failure, and the risk of dementia: A systematic review and meta-analysis by Wolters FJ, Segufa RA, […], Sedaghat S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29494808

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Objectives:
Inflammatory markers are often elevated in patients with dementia, including Alzheimer's disease (AD). However, it remains unclear whether inflammatory markers are associated with the risk of developing dementia. Therefore, this review article has been conducted.

Do inflammatory markers increase risk of dementia and Alzheimer's disease (AD)?

Study design:
This review article included 13 studies in 6 countries.

Results and conclusions:
The investigators found a significantly increased risk of 37% [HR = 1.37, 95% CI = 1.05-1.78] for all-cause dementia for the highest vs. lowest quantile of C-reactive protein. However, this increased risk was not significant for Alzheimer's disease.

The investigators found a significantly increased risk of 40% [HR = 1.40, 95% CI = 1.13-1.73] for all-cause dementia for the highest vs. lowest quantile of interleukin-6. However, this increased risk was not significant for Alzheimer's disease.

The investigators found a significantly increased risk of 54% [HR = 1.54, 95% CI = 1.14-2.80] for all-cause dementia for the highest vs. lowest quantile of α1-antichymotrypsin. However, this increased risk was not significant for Alzheimer's disease.

The investigators found a significantly increased risk of 40% [HR = 1.40, 95% CI = 1.03-1.90] for all-cause dementia for the highest vs. lowest quantile of lipoprotein-associated phospholipase A2 activity. However, this increased risk was not significant for Alzheimer's disease.

The investigators concluded that several inflammatory markers are associated with an increased risk of all-cause dementia; however, these markers are not specific for Alzheimer's disease. Whether inflammatory markers closely involved in Alzheimer's disease pathology are associated with the risk of Alzheimer's disease remains to be elucidated.

Original title:
Inflammatory markers and the risk of dementia and Alzheimer's disease: A meta-analysis by Darweesh SKL, Wolters FJ, […], Hofman A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29605221

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Objectives:
β-amyloid (Aβ) accumulates abnormally to senile plaque which is the initiator of Alzheimer's disease (AD). As one of the Aβ-degrading enzymes, insulin-degrading enzyme (IDE) remains controversial for its protein level and activity in Alzheimer's brain. Therefore, this review article has been conducted.

Is there an association between insulin-degrading enzyme protein level and risk of Alzheimer's disease (AD)?

Study design:
This review article included 7 studies for IDE protein level (Alzheimer's disease cases = 293 and controls (persons without Alzheimer's disease)  = 126), 3 for mRNA level (Alzheimer's disease cases = 138 and controls = 81) and 3 for enzyme activity (Alzheimer's disease cases = 123 and controls = 75).

Results and conclusions:
The investigators found the insulin-degrading enzyme protein level was significantly lower in Alzheimer's disease patients than in controls [SMD = -0.47, 95% CI = -0.69 to -0.24, p 0.001].
But insulin-degrading enzyme mRNA and enzyme activity had no significant difference [SMD = 0.02, 95% CI = -0.40 to 0.43 and SMD = 0.06, 95% CI = -0.41 to 0.53, respectively].

The investigators found in subgroup analyses (to get more information) that insulin-degrading enzyme protein level was decreased in both cortex and hippocampus of Alzheimer's disease patients [SMD = -0.43, 95% CI = -0.71 to -0.16, p = 0.002 and SMD = -0.53, 95% CI = -0.91 to -0.15, p = 0.006 respectively].
However, insulin-degrading enzyme mRNA was higher in cortex of Alzheimer's disease patients [SMD = 0.71, 95% CI = 0.14 to 1.29, p = 0.01] but not in hippocampus [SMD = -0.26, 95% CI [= -0.58 to 0.06].

The investigators concluded that Alzheimer's disease patients have lower insulin-degrading enzyme protein level. Further relevant studies are still needed to verify whether insulin-degrading enzyme is one of the factors affecting Aβ abnormal accumulation and throw new insights for Alzheimer's disease detection or therapy.

Original title:
Characteristics of Insulin-degrading Enzyme in Alzheimer's Disease: A Meta-analysis by Zhang H, Liu D, […], Zhou H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29357797

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Objectives:
Is there a dose-response association between serum 25(OH)D (vitamin D level in blood) and risk of dementia and Alzheimer's disease (AD)?

Study design:
This review article included 7 prospective cohort studies and 1 retrospective cohort study involving 1,953 cases of dementia and 1,607 cases of Alzheimer's disease among a total of 28,354 participants.

Results and conclusions:
The investigators found no association between vitamin D insufficiency (10-20 ng/mL) and risk of dementia [pooled HR = 1.09, 95% CI = 0.95 to 1.24].
No association because RR of 1 was found in the 95% CI of 0.95 to 1.24. RR of 1 means no risk/association.

The investigators found no association between vitamin D insufficiency (10-20 ng/mL) and risk of Alzheimer's disease [pooled HR = 1.19, 95% CI = 0.96 to 1.41].

The investigators found vitamin D deficiency (10 ng/mL) significantly increased risk of dementia with 33% [pooled HR = 1.33, 95% CI = 1.08 to 1.58].
Significantly means it can be said with a 95% confidence that vitamin D deficiency really increased the risk of getting dementia with 33%. 

The investigators found vitamin D deficiency (10 ng/mL) non-significantly increased risk of Alzheimer's disease with 31% [pooled HR = 1.31, 95% CI = 0.98 to 1.65].

The investigators found lower risk of dementia was observed at serum 25(OH)D of 25 ng/mL, whereas the risk of Alzheimer's disease decreased continuously along with the increase of serum 25(OH)D up to 35 ng/mL.

The investigators concluded that vitamin D (serum 25(OH)D) levels of 25 to 35 ng/mL decrease risk of dementia and Alzheimer's disease. However, there is no conclusive evidence regarding serum 25(OH)D levels of >35 ng/mL.

Original title:
Vitamin D status and risk of dementia and Alzheimer's disease: A meta-analysis of dose-response by Jayedi A, Rashidy-Pour A and Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29447107

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Objectives:
Dairy product consumption may affect the risk of hip fracture, but previous studies have reported inconsistent findings. Therefore, this review article has been conducted.

Does consumption of dairy products reduce risk of hip fracture?

Study design:
This review article included 10 cohort studies (with a total of 8,613 hip fracture events and 363,557 participants. The length of follow-up ranged from 3 to 22 years) and 8 case-control studies (3,815 hip fracture cases and 6,415 controls/subjects without hip fracture).

Results and conclusions:
The investigators found in cohort studies no association between a high milk consumption and hip fracture risk [pooled RR = 0.91, 95% CI = 0.74-1.12, I2 = 75.0%, p  0.01].
There were no significant changes to the results after using the trim-and-fill method when including 4 missing articles [adjusted random effects summary RR = 1.06, 95% CI = 0.91-1.23].

The investigators found, however, case-control studies indicated that participants in the highest categories of milk consumption had a 29% reduction in the risk of hip fracture [OR = 0.71, 95% CI = 0.55-0.91, I2 = 54%, p = 0.04].
There were no significant changes to the results after using the trim-and-fill method when including 1 missing article [adjusted random effects summary OR = 0.74, 95% CI = 0.57-0.97].

The investigators found in cohort studies no association between a high total dairy consumption and hip fracture risk [pooled RR = 1.02, 95% CI = 0.93-1.12]. No association because RR of 1 was found in the 95% CI of 0.93 to 1.12. RR of 1 means no risk/association.

The investigators found cohort studies indicated that participants in the highest categories of yoghurt consumption had a 25% reduction in the risk of hip fracture [RR = 0.75, 95% CI = 0.66-0.86].
 

The investigators found cohort studies indicated that participants in the highest categories of cheese consumption had a 32% reduction in the risk of hip fracture [RR = 0.68, 95% CI = 0.61-0.77].

The investigators found the summary RR for an increased milk consumption of 200 g/day was 1.00 [95% CI = 0.94-1.07, I2 = 87%, p heterogeneity  0.01] among cohort studies.

The investigators found in cohort studies there was a nonlinear positive association between milk consumption and hip fracture risk [p nonlinearity  0.01], with a rapid increase in risk when milk consumption increased from 0 to 600 g/d. However, there was no further increase in risk with milk consumption between 600 and 1200 g/d.

The investigators found in case-control studies there was a nonlinear association between milk consumption and hip fracture risk [p nonlinearity = 0.28], with a reduction in risk with milk consumption of 200-600 g/d. However, the confidence intervals were wide for all outcomes.

The investigators concluded that a high consumption of yogurt and cheese is associated with a lower risk of hip fracture in cohort studies.

Original title:
Dairy product consumption and risk of hip fracture: a systematic review and meta-analysis by Bian S, Hu J, [...], Ma J.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5778815/

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Objectives:
Does exercise training delay the decline in cognitive function among individuals who are at risk of/or have Alzheimer's disease?  

Study design:
This review article included 19 controlled studies with 23 interventions including 1,145 subjects with a mean age of 77.0 ± 7.5.
The studies included an exercise-only intervention and a nondiet, nonexercise control group and reported pre- and post-intervention cognitive function measurements.

Most subjects were at risk of Alzheimer's disease because they had mild cognitive impairment (64%) or a parent diagnosed with Alzheimer's disease (1%) and 35% presented with Alzheimer's disease.

Exercise interventions were performed 3.4 ± 1.4 days per week at moderate intensity (3.7 ± 0.6 metabolic equivalents) for 45.2 ± 17.0 minutes per session for 18.6 ± 10.0 weeks and consisted primarily of aerobic exercise (65%).

Results and conclusions:
The investigators found overall, there was a modest favourable effect of exercise on cognitive function [d+ = 0.47, 95% CI = 0.26 to 0.68].

The investigators found within-group analyses revealed that exercise improved cognitive function [d+w = 0.20, 95% CI = 0.11 to 0.28], whereas cognitive function declined in the control group [d+w = -0.18, 95% CI = -0.36 to 0.00].

The investigators found within-group analyses revealed that aerobic exercise had a moderate favourable effect on cognitive function [d+w = 0.65, 95% CI = 0.35 to 0.95), but other exercise types did not [d+w = 0.19, 95% CI = -0.06 to 0.43].

The investigators concluded that exercise training (3.4 days per week at moderate intensity for 45.2 minutes per session during 18.6 weeks) delays the decline in cognitive function that occurs in individuals who are at risk of/or have Alzheimer's disease, with aerobic exercise having the most favourable effect. Additional randomized controlled clinical trials that include objective measurements of cognitive function are needed to confirm these findings.

Original title:
Can Exercise Improve Cognitive Symptoms of Alzheimer's Disease? A Meta-Analysis by Panza GA, Taylor BA, […], Pescatello LS.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29363108

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Metabolic Equivalents (METs) are commonly used to express the intensity of physical activities.
MET is the ratio of a person's working metabolic rate relative to their resting metabolic rate.
One MET is defined as the energy cost of sitting quietly and is equivalent to a caloric consumption of 1 kcal/kg/hour.