Nutrition and health

Objectives:
Does a high LDL cholesterol level (bad cholesterol) increase risk of Alzheimer's disease (AD)?

Study design:
This review article included 26 case-control studies involving 7,033 participants (2,266 Alzheimer's disease patients and 4,767 non-dementia controls).

There was no significant evidence of publication bias according to the results of Egger's test [p = 0.084].

Results and conclusions:
The investigators found results from the meta-analysis of 26 studies revealed higher levels of LDL cholesterol (>121 mg/dL) in Alzheimer's disease than that of non-dementia controls [SMD = 0.35, 95% CI = 0.12 to 0.58, p 0.01], which was consistent with the results of the fixed-effect model [SMD = 0.16, 95% CI = 0.10 to 0.22, p 0.01].
Sensitivity analyses showed that no single study exerted substantial influence on the pooled effect size after sequentially omitting a study.

The investigators found subgroup analysis of age showed LDL cholesterol levels in Alzheimer's disease patients aged 60-70 were higher than that of non-dementia [60 ≤ age 70: SMD = 0.80, 95% CI = 0.23 to 1.37, p 0.01].  

The investigators concluded that elevated concentration of LDL cholesterol (>121 mg/dL) is a risk factor for Alzheimer's disease. This strong association is significant in patients with Alzheimer's disease aged 60-70 years, but vanishes with increasing age. This review article provides a promising strategy for reducing the risk of Alzheimer's disease in patients with hyperlipidemia, which may be achieved by regulating LDL cholesterol concentration between 103.9 and 121 mg/dL with statins. Prospective studies that exclude potential confounders, more scientific design and adequate long-term follow-up are needed to validate this hypothesis.

Original title:
Low-Density Lipoprotein Cholesterol and Alzheimer's Disease: A Systematic Review and Meta-Analysis by Zhou Z, Liang Y, […], Zhao M.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002548/

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

Objectives:
Results regarding the association between fish intake and risk of metabolic syndrome (MetS) are ambiguous. Therefore, this review article has been conducted.

Does fish consumption reduce risk of metabolic syndrome?

Study design:
This review article included 10 cross-sectional studies and 6 cohort studies.

Results and conclusions:
The investigators found fish consumption significantly reduced risk of metabolic syndrome with 20% [OR = 0.80, 95% CI = 0.66 to 0.96, p = 0.017, I2 = 62.9%] in cohort studies.
However, this reduced risk was not significant in cross-sectional studies [OR = 0.80, 95% CI = 0.70 to 1.02, p = 0.085, I2 = 50.1%].
Significantly because OR of 1 was not found in the 95% CI of 0.6 to 0.96. OR of 1 means no risk/association.

The investigators found a significant non-linear association between fish intake levels and risk of metabolic syndrome [p for non-linearity = 0.010].

The investigators concluded that fish consumption reduces risk of metabolic syndrome when combining data from prospective cohort studies. Further studies are needed to confirm such an effect.

Original title:
A systematic review and meta-analysis of the association between fish consumption and risk of metabolic syndrome by Karimi G, Heidari Z, [...], Haghighatdoost F.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32127332

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

Objectives:
Several epidemiological studies have been performed to evaluate the association of dietary intake of vitamin C-oriented foods (DIVCF) with risk of fracture and bone mineral density (BMD) loss, but the results remain controversial. Therefore, this review article has been conducted.

Does dietary intake of vitamin C-oriented foods decrease risk of fracture and bone mineral density loss?

Study design:
This review article included 4 cohort studies, 11 case-control studies and 2 cross-sectional studies with a total of 19,484 subjects.

The studies received a quality score of ≥5, indicating that the methodological quality of the studies was generally good.

No evidence of publication bias was found in the evaluation of dietary intake of vitamin C-oriented foods and the risk of hip fracture.

Results and conclusions:
The investigators found that the people with a higher dietary intake of vitamin C-oriented foods had a significantly 34% [RR = 0.66, 95% CI = 0.47 to 0.94, I2 = 79.5%, p = 0.000] lower risk of hip fracture.

The investigators found that the people with a higher dietary intake of vitamin C-oriented foods had a significantly 42% [RR = 0.58, 95% CI = 0.38 to 0.89] lower risk of hip fracture in case-control studies.
However, this reduced risk was not significant in cohort studies [RR = 0.92, 95% CI = 0.59 to 1.44]. 

The investigators found that the people with a higher dietary intake of vitamin C-oriented foods had a significantly 34% [RR = 0.66, 95% CI = 0.48 to 0.92] lower risk of osteoporosis.

The investigators found higher dietary intake of vitamin C-oriented foods was negatively associated with the risk of bone mineral density loss at the lumbar spine [pooled r = 0.15, 95% CI = 0.09 to 0.23] and at the femoral neck [pooled r = 0.20, 95% CI = 0.11 to 0.34].

The investigators concluded that higher dietary intake of vitamin C-oriented foods reduces the risk of hip fracture, osteoporosis and bone mineral density loss, suggesting that people should consume more vitamin C to decrease the risk of hip fracture, osteoporosis and bone mineral density loss, particularly lumbar spine and femoral neck.

Original title:
Can Dietary Intake of Vitamin C-Oriented Foods Reduce the Risk of Osteoporosis, Fracture, and BMD Loss? Systematic Review With Meta-Analyses of Recent Studies by Zeng LF, Luo MH, […], Liu J.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7008177/

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

Objectives:
Current evidence on associations between intakes of linoleic acid (LA), the predominant n-6 (ω-6) fatty acid and mortality is inconsistent and has not been summarized by a systematic review and meta-analysis. Therefore, this review article has been conducted.

Does higher linoleic acid intake, assessed by dietary surveys or biomarkers decrease mortality from all causes, cardiovascular disease (CVD) and cancer?

Study design:
This review article included 44 prospective cohort studies with 811,069 participants with dietary intake assessment (170,076 all-cause, 50,786 cardiovascular disease and 59,684 cancer deaths) and 65,411 participants with biomarker measurements (9,758 all-cause, 6,492 cardiovascular disease and 1,719 cancer deaths).

Meta-regressions suggested baseline age and dietary assessment methods as potential sources of heterogeneity for the association between linoleic acid and total mortality.

Results and conclusions:
The investigators found when compared with the lowest categories of dietary linoleic acid intake, that the highest categories of dietary linoleic acid intake significantly reduced total mortality risk with 13% [pooled RR = 0.87, 95% CI = 0.81 to 0.94, I2 = 67.9%].

The investigators found when compared with the lowest categories of dietary linoleic acid intake, that the highest categories of dietary linoleic acid intake significantly reduced cardiovascular disease mortality risk with 13% [pooled RR = 0.87, 95% CI = 0.82 to 0.92, I2 = 3.7%].

The investigators found when compared with the lowest categories of dietary linoleic acid intake, that the highest categories of dietary linoleic acid intake significantly reduced cancer mortality risk with 11% [pooled RR = 0.89, 95% CI = 0.85 to 0.93, I2 = 0%].

The investigators found for each standard deviation increment in linoleic acid concentrations in adipose tissue/blood compartments a significantly reduced total mortality risk of 9% [pooled RR = 0.91, 95% CI = 0.87 to 0.95, I2 = 64.1%].

The investigators found for each standard deviation increment in linoleic acid concentrations in adipose tissue/blood compartments a significantly reduced cardiovascular disease mortality risk of 11% [pooled RR = 0.89, 95% CI = 0.85 to 0.94, I2 = 28.9%].

The investigators found for each standard deviation increment in linoleic acid concentrations in adipose tissue/blood compartments a significantly reduced cancer mortality risk of 9% [pooled RR = 0.91, 95% CI = 0.84 to 0.98, I2 = 26.3%].

The investigators concluded higher linoleic acid intake, assessed by dietary surveys or biomarkers, reduces risk of mortality from all causes, cardiovascular disease and cancer. These data support the potential long-term benefits of PUFA intake in lowering the risk of cardiovascular disease and premature death.

Original title:
Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies by Li J, Guasch-Ferré M, […], Hu FB.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/32020162

Additional information of El Mondo:
Find more information/studies on linoleic acid intake and mortality right here.
Linoleic acid is a PUFA.
 

Objectives:
Alzheimer's disease (AD) is a common type of dementia, which has caused heavy global economic and health burden and the using of statins to treat Alzheimer disease has caused widely debated. Therefore, this review article has been conducted.

Does statin use decrease Alzheimer disease?

Study design:
This review article included a total of 9 RCTs containing 1,489 patients. Of them, 742 patients in the statins group, 747 patients in the control group (group without statins).

There were 9 studies used the MMSE scale, 5 studies used the ADAS-Cog scale, 4 studies used the NPI scale and 6 studies used the ADL scale.

Sensitivity analysis and publication bias test were both negative and the results were relatively reliable and stable.

Results and conclusions:
The investigators found meta-analysis of the 9 studies that reported the MMSE scale scores indicated that there was no significant effect of statins as compared with control group [pooled WMD = 1.09, 95% CI = -0.00 to 2.18, p = 0.05, I2 = 87.9%].

The investigators found meta-analysis of the 5 studies that reported the ADAS-Cog scale scores also indicated that there was no significant effect of statins as compared with control group [pooled WMD = -0.16, 95% CI = -2.67 to 2.36, p = 0.90, I2 = 80.1%].

The investigators found meta-analysis of the 4 studies that reported the NPI scale scores indicated that treatment with statins significantly slowed the rise in the NPI scale scores as compared with control group [pooled WMD = -1.16, 95% CI = -1.88 to -0.44, p = 0.002, I2 = 45.4%].

The investigators found meta-analysis of the 6 studies that reported the ADL scale scores indicated that treatment with statins significantly improve patients' daily living ability [pooled WMD = -4.06, 95% CI = -6.88 to -1.24, p = 0.005, I2 = 86.7%].

The investigators found results of subgroup analysis indicated that the use of statins in the short term (≤ 12 months) associated with the change of the MMSE scale scores [pooled WMD = 1.78, 95% CI = 0.53 to 3.04, p = 0.005, I2 = 79.6%].

The investigators concluded statins used in Alzheimer disease patients have beneficial effects on the scores of MMSE scale in the short term (≤ 12 months) and statins slow the deterioration of neuropsychiatric status and improve activities of daily living ability in Alzheimer disease patients.

Original title:
The efficacy of statins in the treatment of Alzheimer's disease: a meta-analysis of randomized controlled trial by Xuan K, Zhao T, […], Sun Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31930449

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

Objectives:
Despite growing evidence for the association between other dietary macronutrients and bone health, limited and inconsistent knowledge is available regarding carbohydrate intake. Therefore, this review article has been conducted.

Does a high carbohydrate intake increase risk of fracture?

Study design:
This review article included observational studies.

Results and conclusions:
The investigators found no association between carbohydrate intake and the risk of fracture in high versus low intake meta-analysis [overall relative risk = 1.24, 95% CI = 0.84 to 1.84, p = 0.27, I2 = 57.7%, p = 0.05].

The investigators found, moreover, there was no relationship between carbohydrate intake and the risk of fracture in both linear [overall RR = 1.00, 95% CI = 0.94 to 1.05, p = 0.88, I2 = 68.1%, p = 0.48] and nonlinear [p non-linearity = 0.14] models.

The investigators concluded high carbohydrate intake does not increase risk of fracture.

Original title:
Dietary carbohydrate intake and risk of bone fracture: a systematic review and meta-analysis of observational studies by Mozaffari H, Daneshzad E and Azadbakht L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31982636

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

Objectives:
Genistein (4',5,7-trihydroxyisoflavone) is a phytoestrogen with potential health benefits in the prevention of cardiovascular disease. However, the evidence regarding its effects on hypertension has not been conclusive. Therefore, this review article has been conducted.

Do genistein supplements reduce blood pressure?

Study design:
This review article included 4 RCTs (4 treatment arms).

Results and conclusions:
The investigators found genistein supplements did not show any significant reduction of systolic blood pressure [WMD = -5.32 mmHg, 95% CI = -14.59 to 3.96] and diastolic blood pressure [WMD = -2.06 mmHg, 95% CI = -6.41 to 2.28] compared to that of the placebo group.

The investigators found, however, subgroup analysis by intervention duration showed that more than 6 months genistein supplementation in metabolic syndrome patients significantly decreased systolic blood pressure [WMD = -13.73 mmHg, 95% CI = -18.10 to -9.37] and diastolic blood pressure [WMD = -5.18 mmHg, 95% CI = -6.62 to -3.74].

The investigators concluded genistein supplementation of more than 6 months reduces blood pressure among metabolic syndrome patients.

Original title:
Effects of genistein on blood pressure: A systematic review and meta-analysis by Hemati N, Asis M, […], Abdollahi M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31955737

Additional information of El Mondo:
Find more information/studies on genistein and overweight right here.

Objectives:
Which factors increase risk of dementia?

Study design:
This review article included 34 prospective cohort studies, among which 24 were eligible for meta-analysis. A total of 159,594 non-demented adults were enrolled at baseline before 65 years and 13,540 people were diagnosed with dementia after follow-up.

Results and conclusions:
The investigators found obesity significantly increased risk of dementia with 78% [RR = 1.78, 95% CI = 1.31-2.41].

The investigators found diabetes mellitus significantly increased risk of dementia with 69% [RR = 1.69, 95% CI = 1.38-2.07].

The investigators found current smoking significantly increased risk of dementia with 61% [RR = 1.61, 95% CI = 1.32-1.95].

The investigators found hypercholesterolemia significantly increased risk of dementia with 57% [RR = 1.57, 95% CI = 1.19-2.07].
However, the sensitivity analyses showed that the result of hypercholesterolemia was not reliable, which need to be confirmed by more high-quality studies.

The investigators found hypertension significantly increased risk of dementia with 41% [RR = 1.41, 95% CI = 1.23-1.62] for borderline blood pressure.

The investigators found hypertension significantly increased risk of dementia with 72% [RR = 1.72, 95% CI = 1.25-2.37] for high systolic blood pressure.
However, the sensitivity analyses showed that the result of high systolic blood pressure was not reliable, which need to be confirmed by more high-quality studies.

The investigators found hyperhomocysteinemia, psychological stress and heavy drinking were also associated with elevated dementia risk.

The investigators found, in addition, physical exercise, a healthy diet and hormone therapy in middle age were associated with the reduction of dementia risk.

The investigators concluded middle-aged people with obesity or diabetes and current smokers in midlife are at higher risk of developing dementia later in life.

Original title:
Midlife Modifiable Risk Factors for Dementia: A Systematic Review and Meta-analysis of 34 Prospective Cohort Studies by Li XY, Zhang M, [...], Tan L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31902364

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

Objectives:
Can the biomarker miRNAs predict Alzheimer's disease?

Study design:
This review article included 10 studies containing 770 Alzheimer's disease and 664 normal controls (persons without Alzheimer's disease).

Results and conclusions:
The investigators found miRNAs presented excellent diagnostic performance and the overall sensitivity was 0.80 [95% CI = 0.75-0.83], specificity was 0.83 [95% CI = 0.78-0.87] and diagnostic odds ratio was 14 [95% CI = 11-19].

The investigators found subgroup analysis suggested that the Caucasian group and blood group showed a better performance in Alzheimer's disease diagnosis and the diagnostic odds ratio was 42 and 34, respectively.

The investigators concluded that miRNAs may be a promising biomarker for Alzheimer's disease.

Original title:
Blood circulating miRNAs as biomarkers of Alzheimer's disease: a systematic review and meta-analysis by Zhang YH, Bai SF and Yan JQ.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31385521

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

Objectives:
The relationship between serum copper (Cu) level and overweight/obesity remains controversial. Therefore, this review article (meta-analysis) has been conducted.

Does a high serum copper level increase overweight/obesity risk?

Study design:
This review article included 21 articles.

Results and conclusions:
The investigators found compared with controls, serum copper level was significantly higher in obese children [SMD = 0.74, 95% CI = 0.16 to 1.32] and in obese adults [SMD = 0.39, 95% CI = 0.02 to 0.76].

The investigators found no significant difference in serum copper level between overweight and control groups in children [SMD = 1.52, 95% CI = -0.07 to 3.12] and in adults [SMD = 0.16, 95% CI = -0.06 to 0.38].

The investigators found subgroup analysis revealed a higher serum copper level in obese children [SMD = 0.90, 95% CI = 0.36 to 1.45] and obese adults [SMD = 0.47, 95% CI = 0.05 to 0.88] compared with healthy weight controls.

The investigators found the SMD differed significantly between obese children diagnosed by weight-for-height and controls [SMD = 1.56, 95% CI = 0.57 to 2.55] and there was a significant difference of serum copper level between obese adults diagnosed by BMI (WHO) and controls [SMD = 0.54, 95% CI = 0.08 to 1.01].

The investigators concluded that a higher serum copper level increases risk of obesity in children and adults and these findings need to be further confirmed.

Original title:
The Relationship Between Serum Copper and Overweight/Obesity: a Meta-analysis by Gu K, Li X, […], Jiang X.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31300957

Additional information of El Mondo:
Find more information/studies on copper and obesity/overweight right here.

Objectives:
Does alcohol consumption increase of risk of osteoporosis?

Study design:
This review article included  3 case control studies, 2 cohort studies and 1 cross-sectional study.

Results and conclusions:
The investigators found no association between consuming 0.5-1 drinks per day and the risk of developing osteoporosis [adjusted RR = 1.38, 95% CI = 0.90-2.12].
No association because RR of 1 was found in the 95% CI of 0.90 to 2.12. RR of 1 means no risk/association.

The investigators found compared with abstainers of alcohol, persons consuming 1-2 drinks per day had 1.34 times the risk of developing osteoporosis [adjusted RR = 1.34, 95% CI = 1.11-1.62].

The investigators found compared with abstainers of alcohol, persons consuming 2 drinks or more per day had 1.63 times the risk of developing osteoporosis [adjusted RR = 1.63, 95% CI = 1.01-2.65].

The investigators found a positive association between alcohol consumption and osteoporosis in the case-control studies [adjusted OR = 2.95, 95% CI = 1.78-4.90].

The investigators concluded there is a positive relationship between alcohol consumption, particularly 1 drink or more per day and osteoporosis.

Original title:
The effect of alcohol on osteoporosis: A systematic review and meta-analysis by Cheraghi Z, Doosti-Irani A, Almasi-Hashiani A, […], Mansournia MA.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30844616

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

Objectives:
Do older adults benefit from high protein intake (>0.8 g/kg body weight/day)?

Study design:
This review article included 12 cohort studies and 1 RCT.
Studies had an intervention duration of at least 6 months.

Results and conclusions:
The investigators found meta-analysis of the cohort studies showed that high vs low protein intake resulted in a statistically significant decrease of 11% for hip fractures [pooled HR = 0.89, 95% CI = 0.84 to 0.94, p 0.001, I2 = 0.0%, p = 0.614].
Sensitivity analyses showed that there was no single study affecting the overall estimate considerably.

The investigators concluded there is an association between a dietary protein intake above the current RDA of 0.8 g/kg body weight/day and a reduced hip fracture risk in older adults. In comparison with younger adults, the body of evidence from the included studies is not strong enough to increase the protein recommendation for older adults with respect to bone health.

Original title:
High Versus low Dietary Protein Intake and Bone Health in Older Adults: a Systematic Review and Meta-Analysis by Groenendijk I, den Boeft L , [...], de Groot LCPGM.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6704341/

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

A protein intake higher than 0.8 g/kg body weight/day corresponds to a diet with a minimum of 11 En% protein. The easiest way to follow a diet with at least 11 En% protein is to choose only products that contain at least 11 En% protein. These products from the supermarket contain at least 11% En% protein.
 

Objectives:
Does consumption of fruit or vegetables reduce risk of metabolic syndrome (MetS)?

Study design:
This review article included 9 observational studies (7 cross-sectional studies and 2 cohort studies).

Results and conclusions:
The investigators found in a dose-response analysis of 2 cohort studies and 7 cross-sectional studies, that an increase of 100 g/d in fruit consumption significantly reduced risk of metabolic syndrome with 3% [OR = 0.97, 95% CI = 0.95 to 0.99, I2 = 26.7%], whereas an increase of 100 g/d in vegetable consumption (9 studies) was not associated with a reduction in the metabolic syndrome [OR = 0.98, 95% CI = 0.96 to 1.01, I2 = 54.6%].

The investigators concluded 100 g/d fruit consumption reduces risk of metabolic syndrome. However, prospective studies or randomised clinical trials are needed to identify the effects of fruits by variety on the risk of the metabolic syndrome.

Original title:
Fruit and vegetable consumption and the metabolic syndrome: a systematic review and dose-response meta-analysis by Lee M, Lim M and Kim J.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31514758

Additional information of El Mondo:
Find more information/studies on fruit and vegetable consumption and obesity/overweight right here.

Objectives:
Do low folate levels and vitamin B12 levels increase risk of depression among the aged people?

Study design:
This review article included both gender data of 11 folate-related (7,949 individuals) and 9 B12-related studies (6,308 individuals) and gender-specific data of 4 folate-related (3,409 individuals) and 3 B12-related studies (1,934 individuals).

Results and conclusions:
The investigators found low folate levels significantly increased risk of depression among the aged people with 23% [OR =1.23, 95% CI =1.07-1.43]. 

The investigators found low vitamin B12 levels significantly increased risk of depression among the aged people with 20% [OR =1.20, 95% CI =1.02-1.42]. 

The investigators found in subgroup analysis low vitamin B12 levels significantly increased risk of depression among the aged women with 33% [OR =1.33, 95% CI =1.02-1.74]. 

The investigators concluded both low folate levels and low vitamin B12 levels increase risk of depression among the aged people.

Original title:
Folate and B12 serum levels in association with depression in the aged: a systematic review and meta-analysis by Petridou ET, Kousoulis AA, [...], Stefanadis C.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/26055921

Additional information of El Mondo:
Find more information/studies on vitamin B12, folate and elderly.
 

Objectives:
Findings from observational studies and clinical trials on the associations between vitamin E and dementia remain controversial. Therefore, this review article has been conducted.

Do low vitamin E levels increase risk of Alzheimer's disease (AD) or age-related cognitive deficits and mild cognitive impairment (MCI)?

Study design:
This review article included 31 studies.

Results and conclusions:
The investigators found individuals with Alzheimer's disease had lower circulatory concentrations of α-tocopherol (vitamin E) compared with healthy controls [SMD = -0.97, 95% CI = -1.27 to -0.68, p  0.00001].

The investigators found individuals with age-related cognitive deficits had lower circulatory concentrations of α-tocopherol (vitamin E) compared with healthy controls [SMD = -0.72, 95% CI = -1.12 to -0.32, p  0.0005].

The investigators found individuals with mild cognitive impairment had lower circulatory concentrations of α-tocopherol (vitamin E) compared with healthy controls [SMD = -0.72, 95% CI = -1.12 to -0.32, p  0.0005].

The investigators found levels of β-, γ- and δ-tocopherols did not significantly differ between groups of Alzheimer's disease and age-related cognitive deficits compared to controls.

The investigators concluded that lower α-tocopherol (vitamin E) levels have a strong association with Alzheimer's disease and mild cognitive impairment supporting evidence for the role of diet and vitamin E in Alzheimer's disease risk and age-related cognitive decline.

Original title:
A meta-analysis of peripheral tocopherol levels in age-related cognitive decline and Alzheimer's disease by Ashley S, Bradburn S and Murgatroyd C.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31661399

Additional information of El Mondo:
Find more information/studies on vitamin E and elderly.
 

Objectives:
Serum uric acid (SUA) accounts for about 50% of extracellular antioxidant activity, suggesting that hyperuricemia (an abnormally high level of uric acid in the blood) may have a protective role in diseases characterized by high levels of oxidative stress, such as osteoporosis. Therefore, this review article has been conducted.

Does a high serum uric acid level (also called hyperuricemia) increase bone mineral density (BMD)?

Study design:
This review article included 19 cross-sectional studies with a total of 55,859 participants.

Results and conclusions:
The investigators found in 6 studies that subjects with higher serum uric acid levels had significantly higher bone mineral density values for the spine [SMD = 0.29, 95% CI = 0.22-0.35, I2 = 47%].
Simple correlation analyses substantially confirmed this finding.

The investigators found in 7 studies that subjects with higher serum uric acid levels had significantly higher bone mineral density values for total hip [SMD = 0.29, 95% CI = 0.24-0.34, I2 = 33%].
Simple correlation analyses substantially confirmed this finding.

The investigators found in 6 studies that subjects with higher serum uric acid levels had significantly higher bone mineral density values for femoral neck [SMD = 0.25, 95% CI = 0.16-0.34, I2 = 71%].
Simple correlation analyses substantially confirmed this finding.

The investigators found in 3 studies that an increase of one standard deviation in serum uric acid levels significantly reduced risk of new fractures with 17% [HR = 0.83, 95% CI = 0.74-0.92, I2 = 0%].

The investigators found no significant differences between men and women, although data about women were limited.

The investigators concluded a high serum uric acid level is independently associated with higher bone mineral density values and a lower risk of fractures, supporting a protective role for uric acid in bone metabolism disorders.

Original title:
Hyperuricemia protects against low bone mineral density, osteoporosis and fractures: a systematic review and meta-analysis by Veronese N, Carraro S, […], Cereda E.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/27636234

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Find more information/studies on elderly.
 

Objectives:
The lipid distribution in people who are overweight and obese is directly related to metabolic diseases. Quercetin supplementation may be an appropriate approach for reducing the risk factors of metabolic diseases in people who are obese. Therefore, this review article has been conducted.

Does quercetin supplementation reduce risk factors of metabolic diseases in people who are obese?

Study design:
This review article included 5 RCTs.

Results and conclusions:
The investigators found ≥150 mg/day quercetin supplementation during >6 weeks significantly reduced LDL-cholesterol (bad cholesterol) levels in people who are obese [SMD = -0.8, 95% CI = -1.21 to -0.39, p 0.00001].

The investigators concluded ≥150 mg/day quercetin supplementation during >6 weeks reduces LDL-cholesterol levels in people who are obese.

Original title:
Quercetin Actions on Lipid Profiles in Overweight and Obese Individuals: A Systematic Review and Meta-analysis by Guo W, Gong X and Li M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31465275

Additional information of El Mondo:
Find more information/studies on quercetin, cholesterol and obesity/overweight right here.

Objectives:
L-carnitine plays a fundamental biological role in the metabolism of lipids and may positively affect blood pressure by decreasing insulin resistance, although the latter remains less clear. Therefore, this review article has been conducted.

Does L-carnitine supplementation reduce blood pressure?

Study design:
This review article included 10 RCTs using a random-effects model to estimate the pooled effect sizes of L-carnitine supplementation on systolic (SBP) and diastolic blood pressure (DBP).

Results were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI).

No evidence of publication bias was observed about the effects of L-carnitine supplementation on systolic blood pressure [p = 0.307] and diastolic blood pressure [p = 0.729], as evidenced by the results of the Egger's test.

Results and conclusions:
The investigators found L-carnitine supplementation decreased diastolic blood pressure [WMD = -1.162 mmHg, 95% CI = -2.020 to -0.303, p = 0.008] without changing systolic blood pressure levels [WMD = -0.085 mmHg, 95% CI = -1.455 to 1.285, p = 0.903].

The investigators found results of subgroup analyses revealed L-carnitine supplementation decreased diastolic blood pressure levels in participants with overweight and obesity [WMD = -1.232 mmHg, 95% CI = -2.297 to -0.167, p = 0.023] and with doses of 2 g/d [WMD = -1.639 mmHg, 95% CI = -3.038 to -0.240, p = 0.022].

The investigators concluded that 2 g/d L-carnitine supplementation decreases diastolic blood pressure in participants with overweight and obesity. However, more research is required to determine the molecular mechanism underlying the relationship between of L-carnitine on blood pressure.

Original title:
Effects of L-carnitine supplementation on blood pressure: a systematic review and meta-analysis of randomized controlled trials by Askarpour M, Hadi A, […], Ghaedi E.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31481697

Additional information of El Mondo:
Find more information/studies on L-carnitine and cardiovascular diseases right here.
 

Objectives:
Epidemiological investigations evaluating the association of dietary calcium intake with metabolic syndrome (MetS) risk have yielded controversial results. Therefore, this review article has been conducted.

Does dietary calcium intake reduce risk of metabolic syndrome?

Study design:
This review article included a total 15 cross-sectional studies for dietary calcium intake.

Results and conclusions:
The investigators found for the highest versus lowest category of dietary calcium intake, a significantly reduced risk of 20% [combined OR = 0.80, 95% CI = 0.70 to 0.91] for metabolic syndrome.

The investigators found in dose-response analysis, a non-linear relationship between dietary intake of calcium and risk of metabolic syndrome [p non-linearity > 0.001].

The investigators found 280 mg/d dietary calcium intake significantly reduced risk of metabolic syndrome with 13% [OR = 0.87, 95% CI = 0.82 to 0.93].

The investigators concluded 280 mg/d dietary calcium intake may reduce risk of metabolic syndrome. May reduce because this review article only included cross-sectional studies and no cohort studies. Therefore, these findings should need to be further confirmed by larger prospective cohort studies.

Original title:
Dietary calcium intake and the risk of metabolic syndrome: evidence from observational studies by Cheng L, Hu D and Jiang W.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30846011

Additional information of El Mondo:
Find more information/studies on calcium and obesity/overweight right here.

Objectives:
Do dietary intakes of soy, soy isoflavones and soy protein reduce risk of mortality from all causes, cancers and cardiovascular diseases?

Study design:
This review article included 23 prospective cohort studies with an overall sample size of 330,826 participants.

Results and conclusions:
The investigators found soy/soy products consumption significantly reduced risk of mortality from cancers with 12% [pooled relative risk = 0.88, 95% CI = 0.79 to 0.99, p = 0.03, I2 = 47.1%].

The investigators found soy/soy products consumption significantly reduced risk of mortality from cardiovascular diseases with 15% [pooled effect size = 0.85, 95% CI = 0.72 to 0.99, p = 0.04, I2 = 50.0%].

The investigators found such significant associations were also observed for all-cause mortality in some subgroups of the included studies, particularly those with higher quality.

The investigators found in addition, higher dietary intake of soy was associated with decreased risk of mortality from gastric, colorectal and lung cancers as well as ischemic cardiovascular diseases.

The investigators found participants in the highest category of dietary soy isoflavones intake had a 10% lower risk of all-cause mortality compared with those in the lowest category.

The investigators found that a 10-mg/day increase in dietary intake of soy isoflavones was associated with 7% and 9% decreased risk of mortality from all cancers and breast cancer, respectively.

The investigators found for each 5-g/day increase in consumption of soy protein a 12% reduction in breast cancer death.

The investigators found, however, dietary intake of soy protein was not significantly associated with all-cause and cardiovascular diseases mortality.

The investigators concluded that soy and its isoflavones consumption favorably influence risk of mortality. In addition, soy protein dietary intake is associated with a decreased risk in the mortality of breast cancer. These findings support the current recommendations to increase intake of soy for greater longevity.

Original title:
Soy, Soy Isoflavones, and Protein Intake in Relation to Mortality from All Causes, Cancers, and Cardiovascular Diseases: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies by Nachvak SM, Moradi S, […], Sadeghi O.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31278047

Additional information of El Mondo:
Find more information/studies on soy consumption, cardiovascular diseases and breast cancer right here.

 

Objectives:
Does a high blood homocysteine level increase risk of cognitive impairment, like Alzheimer's disease and vascular dementia?

Study design:
This review article included 28 prospective cohort studies with 2,557 cases (1,035 all-cause dementia, 530 Alzheimer's disease, 92 vascular dementia and >900 cognitive impairment without dementia (CIND)) among 28,257 participants.
 
The average follow-up period ranged from 2.7 to 35 years.

There was no clear evidence of publication bias with Begg's and Egger's tests for Alzheimer dementia [p = 0.806, 0.084, respectively].

Results and conclusions:
The investigators found there was a clear linear dose-response relationship between blood homocysteine concentration and risk of Alzheimer-type dementia [p > 0.05 for non-linearity].

The investigators found for every 5 μmol/L increase in blood homocysteine a significantly increased risk of 15% [pooled RR = 1.15, 95% CI = 1.04 to 1.26, I2 = 56.6%, n = 5] for Alzheimer-type dementia.
Sensitivity analysis showed similar results.

The investigators found due to the presence of publication bias and low statistical power, elevated levels of blood homocysteine were not appreciably associated with risk of all-cause, vascular dementia and cognitive impairment without dementia.

The investigators concluded every 5 μmol/L increase in blood homocysteine is linearly associated with a 15% increase in relative risk of Alzheimer-type dementia.

Original title:
Hyperhomocysteinemia and risk of incident cognitive outcomes: An updated dose-response meta-analysis of prospective cohort studies by Zhou F and Chen S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30826501

Additional information of El Mondo:
Find more information/studies on Alzheimer disease.
 

Objectives:
Although intake of fruits and vegetables seemed to have a protective effect on bone metabolism, its effect on fractures remains uncertain. Therefore, this review article has been conducted.

Does intake of fruits and vegetables reduce risk of fractures?

Study design:
This review article included 6 cohort studies and 4 RCTs.
6 cohort studies included 225,062 participants (134,365 women and 90,697 men) aged 50 years or older. The participants’ follow-up time ranged from 2.8 years to 20 years.

Validated food frequency questionnaires (FFQs), 24-hour food recall (24h-R) and 7-day food record were used to evaluate fruit and vegetable intake.

Results and conclusions:
The investigators found in 5 cohort studies that intake of at least one serving of fruits and vegetables per day significantly reduced risk of hip fractures with 8% [pooled HR = 0.92, 95% CI = 0.87 to 0.98, I2 = 55.7%, p = 0.060] among participants aged 50 years or older.

The investigators found in 2 cohort studies that intake of at least one serving of fruits and vegetables per day significantly reduced risk of any fractures with 10% [pooled HR = 0.90, 95% CI = 0.86 to 0.96, I2 = 24.9%, p = 0.249] among participants aged 50 years or older.

The investigators found no association between the bone resorption marker CTx and 3 months of fruit and vegetable intake evaluated by 4 RCTs.

The investigators concluded that at least one serving of fruits and vegetables per day is associated with a lower risk of fractures among participants aged 50 years or older.

Original title:
Fruit and vegetable intake and bones: A systematic review and meta-analysis by Brondani JE, Comim FV, […], Premaor MO.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6544223/

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

Objectives:
Does a dietary low-ratio n-6/n-3 PUFA supplementation improve risk factors (such as fasting blood glucose, HbA1c) of diabetes?

Study design:
This review article included 11 RCTs.

No significant publication bias was observed for all blood glucose and other related indicators as suggested by Begg's test and Egger's test.

Results and conclusions:
The investigators found no significant effect of dietary low-ratio n-6/n-3 PUFA supplementation on:
-fasting blood glucose [WMD = 0.057 mmol/L, 95% CI = -0.090 to 0.204 mmol/L];
-insulin [WMD = -0.757 mIU/L, 95% CI = -2.419 to 0.904 mIU/L];
-insulin resistance index [WMD = -0.201, 95% CI = -0.566 to 0.165] and;
-glycosylated hemoglobin [WMD = -0.063%, 95% CI = -0.061 to 0.186%].

The investigators found subgroup analysis showed that the effect of dietary low-ratio n-6/n-3 PUFA on the reduction of the plasma insulin level in North America [WMD = -3.473 mIU/L, 95% CI = -5.760 to -1.185 mIU/L] was more obvious than that in Asian countries [WMD = -0.797 mIU/L, 95% CI = -2.497 to 0.902 mIU/L] and European countries [WMD = -0.063 mIU/L, 95% CI = -0.061 to 0.186 mIU/L].

The investigators found in the subgroup of diabetic subjects, dietary low-ratio n-6/n-3 PUFA supplementation significantly decreased plasma insulin level [WMD = -3.010 mIU/L, 95% CI = -5.371 to -0.648 mIU/L] and insulin resistance index [WMD = -0.460, 95% CI = -0.908 to -0.012].

The investigators found when the intervention period was longer than 8 weeks, dietary low-ratio n-6/n-3 PUFA supplementation significantly decreased the plasma insulin level [WMD = -2.782 mIU/L, 95% CI = -4.946 to -0.618 mIU/L].

The investigators concluded dietary low-ratio n-6/n-3 PUFA supplementation improves the glucose metabolism by reducing the insulin and insulin resistance in the diabetic patients. Dietary low-ratio n-6/n-3 PUFA supplementation also reduces the plasma insulin level when the supplementation duration is longer than 8 weeks.

Original title:
Effect of low-ratio n-6/n-3 PUFA on blood glucose: a meta-analysis by Li N, Yue H, […], Xu T.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31292599

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

Objectives:
The associations between dietary fat intake and cognitive function are inconsistent and inconclusive. Therefore, this review article has been conducted.

Is there a relationship between different types of fat intake and cognitive impairment?

Study design:
This review article included 9 prospective cohort studies covering a total of 23,402 participants.

Results and conclusions:
The investigators found compared with the lowest category of consumption, the highest category of saturated fat consumption significantly increased risk of cognitive impairment with 40% [RR = 1.40, 95% CI = 1.02-1.91].

The investigators found compared with the lowest category of consumption, the highest category of saturated fat consumption significantly increased risk of Alzheimer disease with 87% [RR = 1.87, 95% CI = 1.09-3.20].

The investigators found total and unsaturated fat dietary intakes were not statistically associated with cognitive outcomes with significant between-study heterogeneity.

The investigators concluded there is an increased risk between saturated fat consumption and both cognitive impairment and Alzheimer disease. Given the substantial heterogeneity in the sample size and methodology used across studies, the evidence presented here should be interpreted with caution.

Original title:
Dietary Fat Intake and Cognitive Function among Older Populations: A Systematic Review and Meta-Analysis by Cao GY, Li M, […], Xu B.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31062836

Additional information of El Mondo:
Find more information/studies on saturated fat intake, dementia and elderly right here.

A diet with a high saturated fat intake is a diet with >10 En% saturated fat.
>10 En% saturated fat means that the total amounts of saturated fat make up for >10% of the total kcal of the diet.
The easiest way to follow this diet is to choose only meals/products that also contain 10 En% saturated fat.
Check here which products contain >10 En% saturated fat.

A diet with a low saturated fat intake is a diet with 7 En% saturated fat.

Objectives:
Is there a relationship between the intake of foods (whole grains, refined grains, vegetables, fruit, nuts, legumes, eggs, dairy, fish, red meat, processed meat and sugar-sweetened beverages) and risk of general overweight/obesity, abdominal obesity and weight gain?

Study design:
This review article included 25 prospective cohort studies until August 2018.
In detail, 6 prospective cohort studies were included in the meta-analysis for consumption of whole grains, 4 studies for refined grains, 7 for vegetables, 6 for fruit, 4 for nuts, 2 for legumes, 2 for eggs, 11 for dairy products, 4 for fish, 4 for red meat, 2 for processed meat and 9 for sugar-sweetened beverages.

Results and conclusions:
The investigators found in the dose-response meta-analysis a significantly reduced risk of 7% per each increase of 30g/d whole-grain products [RR overweight/obesity = 0.93, 95% CI = 0.89 to 0.96, I2 = 0%].
There was no indication for a nonlinear association between whole-grain intake and risk of overweight/obesity [p-nonlinearity = 0.16].

The investigators found in the dose-response meta-analysis a significantly reduced risk of 7-9% per each increase of 100g/d fruit consumption [RR overweight/obesity = 0.93, 95% CI = 0.86 to 1.00, I2 = 89% and RR weight gain = 0.91, 95% CI = 0.86 to 0.97, I2 =7%].
There was no indication of a nonlinear relation [p-nonlinearity = 0.17, p-nonlinearity = 0.14, respectively].

The investigators found in the dose-response meta-analysis a significantly reduced risk of 58% per each increase of 28g/d nut consumption [RR abdominal obesity = 0.42, 95% CI = 0.31 to 0.57].

The investigators found in the dose-response meta-analysis a significantly reduced risk of 12% per each increase of 50g/d legume consumption [RR overweight/obesity = 0.88, 95% CI = 0.84 to 0.93].

The investigators found in the dose-response meta-analysis a significantly reduced risk of 17% per each increase of 100g/d fish consumption [RR abdominal obesity = 0.83, 95% CI = 0.71 to 0.97, I2 = 0%].
There was no indication of nonlinearity [p-nonlinearity = 0.07], but the graph indicated a stronger risk reduction at lower levels of fish intake and the curve reached a plateau at ∼40 g/d.

The investigators found in the dose-response meta-analysis a significantly increased risk of 5% per each increase of 30g/d refined grains consumption [RR overweight/obesity = 1.05, 95% CI = 1.00 to 1.10, I2 = 61%].
However, the nonlinear dose-response meta-analysis indicated that the association had a J-shape curve and a higher risk of overweight/obesity was identified for an intake of refined grains >90 g/d [p-nonlinearity 0.001].

The investigators found in the dose-response meta-analysis a significantly increased risk of 10-14% per each increase of 30g/d red meat consumption [RR abdominal obesity = 1.10, 95% CI = 1.04 to 1.16, I2 = 0% and RR weight gain = 1.14, 95% CI = 1.03 to 1.26].

The investigators found in the dose-response meta-analysis a significantly increased risk of 5-12% with each increase of 250 mL sugar-sweetened beverages per day consumption [RR overweight/obesity = 1.05, 95% CI = 1.00 to 1.11 and RR abdominal obesity = 1.12, 95% CI = 1.04 to 1.20, I2 = 38%].  
The increase in risk was stronger at lower amounts of sugar-sweetened beverages intake (until ∼300 mL/d), but an increase at higher intakes was still present [p-nonlinearity = 0.03].

The investigators found the intake of 5 servings of whole grains/d, 3 servings of vegetables/d and 3 servings of fruit/d significantly resulted in a 38% reduction in risk of overweight/obesity compared with non-consumption of these food groups.

The investigators found the intake of 5 servings of refined grains/d and 3 servings of sugar-sweetened beverages/d significantly resulted in a 59% increased risk of overweight/obesity.

The investigators concluded that high intakes of whole grains, vegetables, fruit and probably fish as well as a low intake of refined grains, red meat and sugar-sweetened beverages are associated with a reduced risk of measures of adiposity, including overweight/obesity, abdominal obesity or weight gain, respectively. These findings are in line with current public health recommendations regarding a health-promoting diet. However, with the current evidence rated as very low to low, findings should be interpreted with caution and better-designed observational studies, more evidence from intervention trials and use of novel statistical methods (e.g., substitution analyses or network meta-analyses) are needed.

Original title:
Food Groups and Risk of Overweight, Obesity, and Weight Gain: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies by Schlesinger S, Neuenschwander M, […], Schwingshackl BH.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416048/

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Find more information/studies on different food groups and overweight right here.