Nutrition and health

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:
Multiple epidemiologic studies have evaluated the relationship between dietary cholesterol and lung cancer risk, but the association is controversial and inconclusive. Therefore, this review article has been conducted.

Does consumption of dietary cholesterol increase risk of lung cancer?

Study design:
This review article included 10 case-control studies (6,894 lung cancer cases and 29,736 controls/persons with no lung cancer) and 6 cohort studies (1,769 lung cancer cases among 241,920 participants).

The Newcastle-Ottawa Scale scores for the included studies ranged from 6 to 9 and all studies were deemed to be of high quality (≥6).

There was no evidence of publication bias observed. Case-control studies: Egger’s test, p = 0.737, Begg’s test, p = 0.213 and cohort studies: Egger’s test, p = 0.459, Begg’s test, p = 1.000.

Results and conclusions:
The investigators found in case-control studies that a high dietary cholesterol intake significantly increased lung cancer risk with 70% [OR = 1.70, 95% CI = 1.43-2.03, I2 = 42.3%, p = 0.067]. No significant change in the result was found in the sensitivity analysis.

The investigators found in cohort studies no association between a high dietary cholesterol intake and lung cancer risk [RR = 1.08, 95% CI = 0.94-1.25, I2 = 0.0%, p = 0.833]. No significant change in the result was found in the sensitivity analysis.

The investigators found in 6 case-control studies that a high dietary total fat intake significantly increased lung cancer risk with 64% [OR = 1.64, 95% BI = 1.16-2.33, I2 = 68.7%, p = 0.004]. No significant change in the result was found in the sensitivity analysis.

The investigators concluded that a high dietary cholesterol intake might increase lung cancer risk. Might increase because the increased risk was not significant in cohort studies. Therefore, carefully designed and well-conducted cohort studies are needed to identify the association between dietary cholesterol and lung cancer risk.

Original title:
Dietary Cholesterol Intake and Risk of Lung Cancer: A Meta-Analysis by Lin X, Liu L, […], Lian X.

Link:
http://www.mdpi.com/2072-6643/10/2/185/htm

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A high dietary cholesterol intake is an intake of more than 200-300 mg cholesterol per day.

The result of a review article is only reliable when the result is also significant in cohort studies (thus not only significant in case-control studies).
 

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 the consumption of various types of tomato products reduce prostate cancer risk and is there a potential dose-response relationship?

Study design:
This review article included 30 studies, which summarized data from 24,222 cases (subjects with prostate cancer) among 260,461 participants.

Results and conclusions:
The investigators found that higher total tomato consumption was associated with a reduced risk of 19% for prostate cancer [RR = 0.81, 95% CI = 0.71 to 0.92, p = 0.001].

The investigators found in subgroup analysis that higher tomato foods consumption was associated with a reduced risk of 16% for prostate cancer [RR = 0.84, 95% CI = 0.72 to 0.98, p = 0.030].

The investigators found in subgroup analysis that higher cooked tomatoes and sauces consumption was associated with a reduced risk of 16% for prostate cancer [RR = 0.84, 95% CI = 0.73 to 0.98, p = 0.029]. 

The investigators found in subgroup analysis, however, no association between higher raw tomatoes consumption and prostate cancer risk [RR = 0.96, 95% CI = 0.84 to 1.09, p = 0.487].

The investigators found there was a significant dose-response association for total tomato consumption [p = 0.040], cooked tomatoes and sauces [p  0.001] and raw tomatoes [p = 0.037], but there was not a significant association with tomato foods [p-linear = 0.511, p-nonlinear = 0.289].

The investigators concluded that increased tomato consumption, particularly cooked tomatoes and sauces reduces prostate cancer risk. Furthermore, there are dose-response relationships for total tomato consumption and for cooked tomatoes and sauces. Further studies are required to determine the underlying mechanisms of these associations.

Original title:
Processed and raw tomato consumption and risk of prostate cancer: a systematic review and dose-response meta-analysis by Rowles JL, Ranard KM, […], Erdman JW Jr.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29317772

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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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Find here more information/studies about elderly and sport nutrition.

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.

Objectives:
Several studies have been conducted on the relationship between tea intake and the risk of osteoporosis. The results from these studies are, however, inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Does tea intake reduce risk of osteoporosis?

Study design:
This review article included 2 prospective cohort studies, 4 cross-sectional studies and 11 case-control studies with 107,819 cases (people with osteoporosis). In the present study, the main symptom of osteoporosis was hip fracture.
10 studies - case-control and cohort studies were all of high quality - were in relative high quality (over 6 stars) with an average NOS score of 7.23.

The heterogeneity in the present review article mainly came from Asia group, female group, prospective cohort study group and case-control study group.

There was no publication bias of the meta-analysis about tea consumption and osteoporosis.

Results and conclusions:
The investigators found for the highest versus the lowest categories of tea consumption a significantly reduced risk of 38% [total OR = 0.62, 95% CI = 0.46-0.83, I2  =  94%, p   0 .01] for osteoporosis. However, when reducing heterogeneity, the overall OR [95% CI = 0.57-0.74, I2 = 30%] was still significant.
Subgroup analysis showed that tea consumption significantly reduced the risk of osteoporosis in all examined subgroups.

The investigators found stratified by categories of osteoporosis, a significantly reduced risk of 26% [OR  =  0.74, 95% BI = 0.63-0.88] for hip fracture.

The investigators found among women a significantly reduced risk of 27% [OR  =  0.73, 95% CI = 0.54-0.99] for osteoporosis.

The investigators concluded that high tea consumption reduces risk of osteoporosis, particularly hip fracture and particularly among women. However, the exact mechanism of the relationship between tea consumption and osteoporosis still needs further research.

Original title:
Association between tea consumption and osteoporosis: A meta-analysis by Sun K, Wang L, [...], Li X.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5728912/

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Find more information/studies on tea consumption and elderly right here.
 

Objectives:
Previous studies have shown that fish consumption and dietary intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) are associated with hip fracture; however, findings were conflicting. Therefore, this review article (meta-analysis) has been conducted.

Do both dietary intake of fish and n-3 polyunsaturated fatty acids decrease hip fracture risk?

Study design:
This review article included 7 prospective cohort studies and 3 case-control studies with a total sample size of 29,2657 participants. The age of participants was 20 years or older.

Results and conclusions:
The investigators found combining 8 effect sizes from 4 prospective cohort studies and 2 case-control studies revealed a significant inverse association between fish consumption and risk of hip fracture [pooled effect size = 0.88, 95% CI = 0.79-0.98, p = 0.02].
Although this relationship became non-significant in prospective cohort studies, a significant inverse association was found in prospective cohort studies with sample size of 10,000 individuals or more and studies that considered body mass index as a covariate.

The investigators also found dietary intake of n-3 PUFAs significantly reduced risk of hip fracture with 12% [pooled effect size = 0.88, 95% CI = 0.80-0.98, p = 0.02].

The investigators concluded that both fish consumption and dietary intake of n-3 PUFAs have protective effects on bone health and decline the risk of hip fracture.

Original title:
Dietary intake of fish, n-3 polyunsaturated fatty acids and risk of hip fracture: A systematic review and meta-analysis on observational studies by Sadeghi O, Djafarian K, […], Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29244536

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Fatty acids in fish are all n-3 PUFAs.
 

Objectives:
There is considerable evidence of the favourable role of more physical activity (PA) in fighting against dementia. However, the shape of the dose-response relationship is still unclear. Therefore, this review article (meta-analysis) has been conducted.

Does leisure time physical activity reduce risk of all-cause dementia (ACD), Alzheimer’s disease (AD) and vascular dementia (VD) in dose-response manner?

Study design:
This review article included 15 cohort studies with 37,436 participants for all-cause dementia, with 25,031 participants for Alzheimer’s disease and with 16,797 participants for vascular dementia.
During follow-up (3-31.6 years for all-cause dementia, 3.9-31.6 years for Alzheimer’s disease and 4-11.9 years for vascular dementia), at least 2,665, 1,337 and 343 participants who were not suffering from dementia at baseline (=at the beginning of the study) were diagnosed with all-cause dementia, Alzheimer’s disease and vascular dementia, respectively.

There was no publication bias.

Results and conclusions:
The investigators found in the dose-response analysis, either all-cause dementia [p trend 0.005 and p non-linearity = 0.87] or Alzheimer’s disease [p trend 0.005 and p non-linearity = 0.10] exhibited a linear relationship with leisure time physical activity over the observed range (0-2000 kcal/week or 0-45 metabolic equivalent of task hours per week (MET-h/week)).

The investigators found for every 500 kcal or 10 MET-h increase per week, a significantly 10% [95% CI = 0.85-0.97] and 13% [95% CI = 0.79-0.96] decrease in the risk of all-cause dementia and Alzheimer’s disease, respectively.

The investigators concluded leisure time physical activity over a specific range (0-2000 kcal/week or 0-45 MET-h/week) is associated with a risk of dementia and Alzheimer’s disease in an inverse linear dose-response manner; with for every 500 kcal (calories) or 10 MET-h increase per week, a 10% and 13% decrease in the risk of all-cause dementia and Alzheimer’s disease, respectively.

Original title:
Leisure time physical activity and dementia risk: a dose-response meta-analysis of prospective studies by Xu W, Wang HF, [...], Tan L.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5665289/

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If you do a 4 MET activity for 30 minutes, you have done 4 x 30 = 120 MET-minutes or 2.0 MET-hours of physical activity.
 

Objectives:
The aim of this meta-analysis (review article) is to evaluate the influence of dietary intake and blood level of vitamin A (total vitamin A, retinol or β-carotene) on total and hip fracture risk?

Study design:
This review article included 11 prospective cohort studies and 2 nested case-control studies, involving a total of 319,077 participants over the age of 20 years (109,056 post-menopausal women).

Results and conclusions:
The investigators found higher dietary intake of retinol significantly decreased total fracture risk with 5% [RR = 0.95, 95% CI = 0.91 to 1.00, I2 = 64.64%, p = 0.04].

The investigators found higher dietary intake of retinol significantly increased hip fracture risk with 40% [RR = 1.40, 95% CI = 1.02 to 1.91, I2 = 30.01%, p = 0.40].

The investigators found higher dietary intake of vitamin A significantly decreased total fracture risk with 6% [RR = 0.94, 95% CI = 0.88 to 0.99, I2 = 35.18%, p = 0.20].

The investigators found higher dietary intake of vitamin A significantly increased hip fracture risk with 29% [RR = 1.29, 95% CI = 1.06 to 1.57, I2 = 0.00%, p = 0.60].

The investigators found lower blood level of retinol significantly increased hip fracture risk with 27% [RR = 1.27, 95% CI = 1.05 to 1.53, I2 = 0.00%, p = 0.62].

The investigators concluded that higher dietary intake of total vitamin A or retinol increases the risk of hip fracture but decreases total fracture risk. Clinical trials are warranted to confirm these results and assess the clinical applicability.

Original title:
The Effect of Vitamin A on Fracture Risk: A Meta-Analysis of Cohort Studies by Zhang X, Zhang R, [...], Chen G.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615580/

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Vitamin A is a generic term for compounds with the biological activity of retinol. Preformed vitamin A (mainly retinol and retinyl esters) is usually found in foods derived from animal products and provitamin A (mainly β-carotene and carotenoids) is usually found in foods derived from plant products.
 

Objectives:
What is the relationship between dietary intake of 12 major food groups, including whole grains, refined grains, vegetables, fruit, nuts, legumes, eggs, dairy, fish, red meat, processed meat and sugar-sweetened beverages and colorectal cancer (CRC) risk?

Study design:
This review article included cohort studies.

Results and conclusions:
The investigators found in the linear dose-response meta-analysis, that every 30 g/d whole grains significantly reduced risk of colorectal cancer with 5% [RR = 0.95, 95% CI = 0.93 to 0.97, n = 9 cohort studies].

The investigators found in the linear dose-response meta-analysis, that every 100 g/d vegetables significantly reduced risk of colorectal cancer with 3% [RR = 0.97, 95% CI = 0.96 to 0.98, n = 15 cohort studies].

The investigators found in the linear dose-response meta-analysis, that every 100 g/d fruit significantly reduced risk of colorectal cancer with 3% [RR = 0.97, 95% CI = 0.95 to 0.99, n = 16 cohort studies]. 

The investigators found in the linear dose-response meta-analysis, that every 200 g/d dairy products significantly reduced risk of colorectal cancer with 7% [RR = 0.93, 95% CI = 0.91 to 0.94, n = 15 cohort studies]. 

The investigators found in the linear dose-response meta-analysis, that every 100 g/d red meat significantly increased risk of colorectal cancer with 12% [RR = 1.12, 95% CI = 1.06 to 1.19, n = 21 cohort studies].

The investigators found in the linear dose-response meta-analysis, that every 50 g/d processed meat significantly increased risk of colorectal cancer with 17% [RR = 1.17, 95% CI = 1.10 to 1.23, n = 16 cohort studies].

The investigators found some evidence for a nonlinear relationship between dietary intake of vegetables, fruit and dairy products and risk of colorectal cancer.

The investigators concluded that daily dietary intake of 30g whole grains, 100g vegetables,100g fruit and 200g dairy products reduce risk of colorectal cancer, while daily dietary intake of 100g red meat and 50g processed meat increase risk of colorectal cancer.

Original title:
Food groups and risk of colorectal cancer by Schwingshackl L, Schwedhelm C, [...], Schlesinger S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29210053

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Objectives:
Vitamin D is involved in musculoskeletal health. There is no consensus on a possible association between circulating 25-hydroxyvitamin D (25OHD) concentrations and walking speed, a “vital sign” in older adults. Therefore, this meta-analysis (review article) has been conducted.

Does a high vitamin D level (expressed as circulating 25-hydroxyvitamin D (25OHD) concentrations) increase walking speed in older adults?

Study design:
This review article included 22 observational studies (17 cross-sectional and 5 longitudinal). The number of participants ranged between 54 and 4,100 (0-100% female).

Results and conclusions:
The investigators found usual walking speed was slower among participants with hypovitaminosis D, with a clinically relevant difference compared with normal vitamin D (>75 nmol/L) of -0.18m/s for severe vitamin D deficiency (≤25 nmol/L), -0.08m/s for vitamin D deficiency (≤50 nmol/L) and -0.12m/s for vitamin D insufficiency (≤75 nmol/L).

The investigators found similar results regarding the fast walking speed [mean differences = -0.04m/s for vitamin D deficiency (≤50 nmol/L) and vitamin D insufficiency (≤75 nmol/L) compared with normal vitamin D (>75 nmol/L) and Timed Up and Go test (TUG) [mean difference = 0.48s for severe vitamin D deficiency (≤25 nmol/L) compared with normal vitamin D (>75 nmol/L).

The investigators found a slow usual walking speed was positively associated with:
-severe vitamin D deficiency (≤25 nmol/L) [summary OR = 2.17, 95% CI = 1.52-3.10];
-vitamin D deficiency (≤50 nmol/L) [OR = 1.38, 95% CI = 1.01-1.89] and;
-vitamin D insufficiency (≤75nmol/L) [OR = 1.38, 95% CI = 1.04-1.83], using normal vitamin D (>75 nmol/L) as the reference.

The investigators concluded that robust evidence shows a high 25OHD concentration (vitamin D level of >75 nmol/L) increases walking speed among older adults.

Original title:
Vitamin D and walking speed in older adults: Systematic review and meta-analysis by Annweiler C, Henni S, [...], Duval GT.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29150169

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A vitamin D level of >75 nmol/L can be achieved by taking 800-1200 IU/d (800-1200 mcg/d) vitamin D3 supplements.
 

Objectives:
No quantitative assessment has been performed to specifically link the consumption of fruit and vegetables with the incident risk of cognitive disorders. Therefore, this meta-analysis (review article) has been conducted.

Does consumption of fruit and vegetables reduce risk of cognitive disorders?

Study design:
This review article included 6 cohort studies involving a total of 21,175 participants.

Results and conclusions:
The investigators found in pooled analysis that consumption of fruit and vegetables significantly reduced risk of cognitive disorders with 26% [pooled RR = 0.74, 95% BI = 0.62-0.88, I2 = 68%; the significant heterogeneity might be attributed to the ethnic difference].

The investigators concluded that consumption of fruit and vegetables reduces risk of cognitive disorders. However, further large prospective studies should be performed to quantify the potential dose-response patterns of fruit and/or vegetables intake and to explore the role of fruit or vegetables consumption separately on cognitive disorders in different populations.

Original title:
Intake of Fruit and Vegetables and the Incident Risk of Cognitive Disorders: A Systematic Review and Meta-Analysis of Cohort Studies by Wu L, Sun D and Tan Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29188891

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Objectives:
Carnitine deficiency has been implicated as a potential pathway for cancer-related fatigue that could be treated with carnitine supplementation. Therefore, this review article (meta-analysis) has been conducted.

Does carnitine supplementation reduce cancer-related fatigue?

Study design:
This review article included 3 RCTs involving a total of 659 participants.

There were not enough studies to conduct sensitivity analyses to isolate potential sources of heterogeneity and test the robustness of findings.

Results and conclusions:
The investigators found in 3 RCTs involving a total of 659 participants that carnitine supplementation did not significantly reduce cancer-related fatigue [SMD = 0.06 points, 95% CI = -0.09 to 0.21, p = 0.45, I2 = 0%].
Clinical heterogeneity was evident from these studies in regards to the dose (2-4 g of carnitine per day), patient demographics (40-100% females included) and carnitine status.

The investigators concluded there is no evidence to support the use of carnitine supplementation (2-4 g of carnitine per day) for cancer-related fatigue.

Original title:
Efficacy and Effectiveness of Carnitine Supplementation for Cancer-Related Fatigue: A Systematic Literature Review and Meta-Analysis by Marx W, Teleni L, [...], Isenring E.

Link:
http://www.mdpi.com/2072-6643/9/11/1224/htm

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Objectives:
Currently, dementia is considered untreatable and there are many factors that cause dementia. However, previous studies were unable to identify the factors that affect directly. Therefore, this meta-analysis (review article) has been conducted.

What are the risk factors for prognostic dementia in stroke patients?

Study design:
This review article included 7 hospital-based cohorts of consecutive patients with stroke and 1 population-based cross-sectional study.

Results and conclusions:
The investigators found:
a significantly increased risk of 68% [pooled relative ratio = 1.68, 95% CI = 1.28 to 2.22, I2 = 72%] for atrial fibrillation;
a significantly increased risk of 59% [pooled relative ratio = 1.59, 95% CI = 1.33 to 1.91] for previous stroke;
a significantly increased risk of 40% [pooled relative ratio = 1.40, 95% CI = 1.23 to 1.59, I2% = 14%] for myocardial infarction;
a significantly increased risk of 36% [pooled relative ratio = 1.36, 95% CI = 1.20 to 1.53, I2 = 46%] for hypertension;
a significantly increased risk of 25% [pooled relative ratio = 1.25, 95% CI = 1.11 to 1.41, I2 = 0%] for diabetes mellitus and;
a significantly increased risk of 25% [pooled relative ratio = 1.25, 95% CI = 1.08 to 1.45, I2 = 16%] for previous transient ischemic attack (TIA).

The investigators concluded that strongly risk factors associated with increased risk of post-stroke dementia are atrial fibrillation, previous stroke, myocardial infarction, hypertension, diabetes and previous TIA. However, there are other risk factors related to dementia. Therefore, further studies are needed to investigate and develop the risk score value to forecast the dementia incident in stroke patients.

Original title:
Risk factors associated with post-stroke dementia: a systematic review and meta-analysis by Surawan J, Areemit S, […], Saensak S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641826/

Additional information of El Mondo:
Find more information/studies on stroke, diabetes, hypertension, dementia and elderly right here.
 

Objectives:
Whole grains are rich source of nutrients and have shown beneficial effects on human health. Therefore, this meta-analysis (review article) has been conducted.

Do taking whole grains reduce mortality risk?

Study design:
This review article included 19 cohort studies with in total 1,041,692 participants and 96,710 deaths.

Results and conclusions:
The investigators found when comparing the highest versus the lowest categories of whole grain, a significantly reduced risk of 16% [RR = 0.84, 95% CI = 0.81-0.88, n = 9] for total mortality.

The investigators found when comparing the highest versus the lowest categories of whole grain, a significantly reduced risk of 17% [RR = 0.83, 95% CI = 0.79-0.86, n = 8] for cardiovascular mortality.

The investigators found when comparing the highest versus the lowest categories of whole grain, a non-significantly reduced risk of 6% [RR = 0.94, 95% CI = 0.87-1.01, n = 14] for cancer mortality.

The investigators found a nonlinear relationship of whole grain intake with risk of total, cardiovascular and cancer mortality.

The investigators found each 28 g/d intake of whole grains was associated with a 9% [pooled RR = 0.91, 95% CI = 0.90-0.93] lower risk for total mortality.

The investigators found each 28 g/d intake of whole grains was associated with a 14% [pooled RR = 0.86, 95% CI = 0.83-0.89] lower risk for cardiovascular mortality.

The investigators found each 28 g/d intake of whole grains was associated with a 3% [pooled RR = 0.97, 95% CI = 0.95-0.99] lower risk for cancer mortality.

The investigators concluded that a higher whole grain intake (at least 28 g/d) reduces risk of total, cardiovascular and cancer mortality. These findings support current dietary guidelines to increase the intake of whole grains. Government officials, scientists and medical staff should take actions to promote whole grains intake.
 
Original title:
Association of whole grain intake with all-cause, cardiovascular, and cancer mortality: a systematic review and dose-response meta-analysis from prospective cohort studies by Zhang B, Zhao Q, [...], Wang X.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29091078

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

Objectives:
Previous studies regarding the relationship between carrot intake and risk of urothelial cancer have reported conflicting results. Therefore, this review article (meta-analysis) has been conducted.

Does a high consumption of carrot reduce urothelial cancer risk?

Study design:
This review article included a total of 6 epidemiological studies (4 case-control and 2 cohort studies) with 1,523 urothelial cancer cases.

There was no significant publication bias by Begg's test (p = 0.348) or Egger's test (p = 0.130).

Results and conclusions:
The investigators found overall analysis indicated a significantly reduced risk of 37% for urothelial cancer for high intake of carrot [OR = 0.63, 95% CI = 0.44-0.90, I2 = 79.6%, p 0.001].

The investigators found in the subgroup analysis by study design, a significantly reduced risk of 55% for urothelial cancer in case-control studies [OR = 0.45, 95% CI = 0.25-0.81]. However, this reduced risk was not significant in cohort studies [OR = 0.91, 95% CI = 0.67-1.24].
Not significant because OR of 1 was found in the 95% CI of 0.67 to 1.24. OR of 1 means no risk/association.

The investigators found, when separately analyzed by carrot type, a significantly reduced risk of 31% for cooked carrot [OR = 0.69, 95% CI 0.51-0.94], but the reduced risk was not significant for raw carrot [OR = 0.84, 95% CI = 0.37-1.93].

The investigators found in the stratified analysis by geographical region, a non-significantly reduced risk of 38% [OR = 0.62, 95% CI = 0.37-1.06], a non-significantly reduced risk of 30% [OR = 0.70, 95% CI = 0.29-1.67] and a non-significantly reduced risk of 47% [OR = 0.53, 95% CI = 0.22-1.26] for Europe, Asia and USA, respectively.

The investigators also found a non-significantly reduced risk of 44% [OR = 0.56, 95% CI = 0.27-1.17] and a non-significantly reduced risk of 27% [OR = 0.73, 95% CI = 0.12-4.60] for male and female, respectively.

The investigators concluded that a high intake of carrot might be associated with a low incidence of urothelial cancer. Might be associated because the reduced risk was not significant in cohort studies. Considering the limited included studies and huge heterogeneity, further large well-designed prospective cohort studies are warranted to confirm these findings.

Original title:
Carrot intake and incidence of urothelial cancer: a systematic review and meta-analysis by Luo X, Lu H, [...], Wang S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5652827/

Additional information of El Mondo:
Find more information/studies on carrot consumption, randomized controlled trials/cohort studies/subgroup analysis and cancer right here.

Objectives:
Previous studies had inconsistent findings regarding the association between vitamin C intake and the risk of hip fracture. Therefore, this meta-analysis (review article) has been conducted.

Does taking dietary vitamin C reduce risk of hip fracture?

Study design:
This review article included 6 articles, containing 7908 controls and 2899 cases of hip fracture.

Results and conclusions:
The investigators found when comparing the highest versus the lowest categories of vitamin C, that dietary vitamin C was statistically correlated with a lower risk of 27% for hip fracture [overall OR = 0.73, 95% CI = 0.55-0.97, I2 = 69.1%].

The investigators found that every increment of 50 mg/day dietary vitamin C intake significantly reduced risk of hip fracture with 5% [OR = 0.95, 95% CI = 0.91-1.00, p = 0.05].

The investigators concluded that increasing dietary vitamin C (at least 50 mg/day) intake decreases the risk of hip fracture. In order to verify the association of vitamin C intake and hip fracture risk, further well-designed largely randomized controlled trials (RCTs) are needed.

Original title:
Dietary vitamin C intake and the risk of hip fracture: a dose-response meta-analysis by Sun Y, Liu C, […], Lu Q.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29101410

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

Objectives:
Fish are a primary source of long-chain omega-3 fatty acids, which may help delay cognitive aging. Therefore, this meta-analysis (review article) has been conducted.

Does a higher fish intake reduce cognitive decline?

Study design:
This review article included 5 cohort studies (23,688 Caucasians aged ≥65 years, 88% female and median follow-up range of 3.9-9.1 years).

Results and conclusions:
The investigators found in multivariate analyses, higher fish intake was associated with slower decline in both global cognition and memory [p-trend ≤ 0.031].

The investigators found consuming ≥4 versus 1 fish serving/week was associated with 0.018 [95% CI = 0.004-0.032] standard units lower rate of memory decline; an effect estimate equivalent to that found for 4 years of age.

The investigators found for global cognition, no comparisons of higher versus low fish intake reached statistical significance.

The investigators found no evidence of effect modification by Alzheimer's.

The investigators concluded that increasing fish intake (at least 4 servings/week) is associated with decreasing memory decline of older persons.

Original title:
Fish intake, genetic predisposition to alzheimer's disease and decline in global cognition and memory in five cohorts of older persons by Samieri C, Morris MC,[…], Grodstein F.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29053784

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

A typical serving size of fish can range from 3 to 6 oz., depending on the type of fish and its preparation. The American Heart Association considers 3.5 oz. of cooked fish, or about 3/4 cup, to be a single serving.
 

Objectives:
With an aging population and no cure for dementia on the horizon, risk factor modification prior to disease onset is an urgent health priority. Therefore, this meta-analysis (review article) has been conducted.

What is the effect of low vitamin D status or vitamin D supplementation on cognition in midlife and older adults without a diagnosis of dementia?

Study design:
This review article included 26 observational (cross-sectional and longitudinal cohort) studies and 3 intervention studies (n = 19-9,556).

Results and conclusions:
The investigators found in 26 observational studies that low vitamin D status was associated with worse cognitive performance [OR = 1.24, CI = 1.14-1.35] and cognitive decline [OR = 1.26, CI = 1.09-1.23] in midlife and older adults without a diagnosis of dementia; with cross-sectional yielding a stronger effect compared to longitudinal studies.

However, the investigators found in 3 intervention studies that vitamin D supplementation showed no significant benefit on cognition compared with control [SMD = 0.21, CI = -0.05 to 0.46].

The investigators concluded that observational evidence demonstrates low vitamin D is related to poorer cognition in midlife and older adults without a diagnosis of dementia; however, interventional studies are yet to show a clear benefit from vitamin D supplementation. From the evidence to date, there is likely a therapeutic age window relevant to the development of disease and therefore vitamin D therapy. Longitudinal lifespan studies are necessary to depict the optimal timing and duration in which repletion of vitamin D may protect against cognitive decline and dementia in aging, to better inform trials and practice towards a successful therapy.

Original title:
A Systematic Review and Meta-Analysis of The Effect of Low Vitamin D on Cognition by Goodwill AM and Szoeke C.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28758188

Additional information of El Mondo:
Find more information/studies on vitamin D, review article/significant, elderly and dementia right here.
 

Objectives:
Many publications have investigated the association between metal ions and the risk of Alzheimer's disease (AD), but the results were ambiguous. Therefore, this meta-analysis (review article) has been conducted.

What is the association between serum copper/zinc/iron levels and Alzheimer's disease risk?

Study design:
This review article included 44 case-control studies.

Results and conclusions:
The investigators found in 35 case-control studies (2,128 Alzheimer's disease patients and 2,889 healthy controls. The mean age of the patient groups was >54), that serum copper levels were significant higher in Alzheimer's disease patients [MD = 9.13, 95% CI = 6.17 to 12.09, p 0.00001].

The investigators found in 22 case-control studies (1,027 Alzheimer's disease patients and 1,949 healthy controls. The mean age of the patient groups was >54), that serum zinc levels were significant lower in Alzheimer's disease patients [MD = -7.80, 95% CI = -11.61 to -3.99, p 0.0001].

The investigators found in 25 case-control studies (1,379 Alzheimer's disease patients and 1,664 healthy controls. The mean age of the patient groups was >62.74), that serum iron levels were significant lower in Alzheimer's disease patients [MD = -13.01, 95% CI = -20.75 to -5.27, p = 0.001].

The investigators concluded that serum copper levels are significantly increased, while serum zinc/iron levels are significantly decreased in Alzheimer's disease patients.

Original title:
Serum Copper, Zinc, and Iron Levels in Patients with Alzheimer's Disease: A Meta-Analysis of Case-Control Studies by Li DD, Zhang W, [...], Zhao P.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5605551/

Additional information of El Mondo:
Find more information/studies on copper, zinc, iron and dementia right here.
 

Objectives:
Surgical resection remains the primary treatment for gastrointestinal (GI) malignancy including early-stage cancer. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to have beneficial clinical and immune-modulating effects in the prognosis of gastrointestinal cancer patients undergoing surgery. Therefore, this review article (meta-analysis) has been conducted.

What is the impact of n-3 PUFA supplementation on postoperative inflammation status and immune function of gastrointestinal cancer patients?

Study design:
This review article included a total of 9 RCTs with 623 participants.

The homogeneous test detected no statistical heterogeneity between studies.

There was no evidence of publication bias following assessment by funnel plot, Egger’s test [p > 0.05] and Begg’s test [p > 0.05].

Results and conclusions:
The investigators found the n-3 PUFAs regime significantly resulted in lower levels of C-reactive protein [p 0.05], interleukin-6 [p 0.01] and higher levels of albumin, CD3+ T cells, CD4+ T cells and CD4+/CD8+ ratio [p 0.05] compared with the isocaloric nutrition regime.

The investigators found, however, no significant difference in the level of tumor necrosis factor-α between the n-3 PUFAs regime and the isocaloric nutrition regime [p = 0.17].

The investigators found that the level of CD8 + T cells significantly decreased compared with the isocaloric nutrition regime [p 0.0001].

The investigators concluded that n-3 PUFAs are effective in improving the nutritional status and immune function of gastrointestinal cancer patients undergoing surgery as they effectively enhance immunity and attenuate the inflammatory response. Although further larger trials are needed, these fatty acids should be widely used in the clinic.

Original title:
Effects of omega-3 fatty acids on patients undergoing surgery for gastrointestinal malignancy: a systematic review and meta-analysis by Yu J, Liu L, [...], Yang F.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5391568/

Additional information of El Mondo:
Find more information/studies on n-3 PUFA consumption and cancer right here.
 

Objectives:
The aim of this review article (meta-analysis) is to compare empirically derived dietary patterns in relation to cancer risk.

Study design:
This review article included observational studies, which evaluated the association with cancer risk between a posteriori derived dietary patterns.

Results and conclusions:
The investigators found a significantly 64% increased risk of cancer for the adoption of high-meat compared to plant-based dietary patterns [RR = 1.64, 95% CI = 1.02-2.63].

The investigators found a significantly 12% lower risk of cancer for individuals adopting a plant-based dietary pattern over a mixed one [RR = 0.88, 95% BI = 0.82-0.95].

The investigators concluded that plant-based dietary patterns decrease cancer risk; meanwhile meat-based dietary patterns increase cancer risk.

Original title:
Differences in the association between empirically derived dietary patterns and cancer: a meta-analysis by Bella F, Godos J, […], Sciacca S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/27894200

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

Objectives:
Increasing evidence suggests that high consumption of meat is linked to lung cancer but the previous meta-analyses did not properly address the role of tobacco smoking as a potential confounder. Therefore, this review article (meta-analysis) has been conducted.

Does high consumption of meat increase lung cancer risk among never and non-smokers?

Study design:
This review article included 14 independent observational studies and a total of 5,368 subjects with lung cancer.
There was no indication of publication bias.

Results and conclusions:
The investigators found in 11 studies, a statistically significant 24% increased risk of lung cancer for high consumption of red meat [Summary Relative Risk = 1.24, 95% CI = 1.01-1.51, I2 = 31%].

The investigators found no significant associations between high consumption of other types of meat, fish or for heterocyclic amines and lung cancer risk.

The investigators found no significant risk estimates for the increase of one serving per week of any type of meat or fish.

The investigators concluded a high intake of red meat increases the risk of lung cancer among never and non-smokers.

Original title:
Carcinogenicity of High Consumption of Meat and Lung Cancer Risk Among Non-Smokers: A Comprehensive Meta-Analysis by Gnagnarella P, Caini S, […], Gandini S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/29016198

Additional information of El Mondo:
Find more information/studies on meat consumption, randomized controlled trials/cohort studies/subgroup analysis and cancer right here.

According to international recommendations, adults should aim to have a maximum of 70g red meat per day or 500g per week (cooked weight).
 

Objectives:
Several studies have investigated the relationship between serum selenium concentration and cervical cancer, but the results were inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Do high serum selenium levels reduce risk of cervical cancer among women?

Study design:
This review article included 12 studies investigating the association by univariate analysis and 5 studies by multivariate analysis.

Results and conclusions:
The investigators found in univariate analysis, that serum selenium levels in women with cervical cancer were significantly lower than in women without cervical cancer [SMD = -4.86, 95% CI = -6.03 to -3.69]. Subgroup analysis showed consistent results.

The investigators found in multivariate analysis, that serum selenium levels in women with cervical cancer were significantly lower than in women without cervical cancer [OR = 0.55, 95% CI = 0.42-0.73].

The investigators found after treatment, the serum selenium levels increased significantly [SMD = 2.59, 95% CI = 0.50-4.69].

The investigators concluded high serum selenium levels reduce risk of cervical cancer among women.

Original title:
Serum Selenium Levels and Cervical Cancer: Systematic Review and Meta-Analysis by He D, Wang Z, […], Chen D.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28255860

Additional information of El Mondo:
Find more information/studies on selenium, randomized controlled trials/cohort studies/subgroup analysis and cancer right here.

Univariate analysis is the simplest form of analyzing data. "Uni" means "one", thus in other words your data has only one variable.

High serum selenium levels can be obtained by consuming selenium-rich food items and/or taking selenium supplements.