Nutrition and health

Objectives:
Emerging randomized controlled trials (RCTs) investigating the effect of green tea or green tea extract (GTE) supplementation on blood pressure (BP) among overweight and obese adults reported inconsistent findings. Therefore, this review article has been conducted.

Does tea consumption decrease blood pressure among overweight and obese adults?

Study design:
This review article included 14 RCTs with 971 participants (47% women).

Results and conclusions:
The investigators found green tea or green tea extract supplementation compared with placebo, significantly reduced systolic blood pressure with 1.42 mmHg [95% CI = -2.47 to -0.36, p  =  0.008, I2  =  52%, p for heterogeneity =  0.01 ] among overweight and obese adults.

The investigators found green tea or green tea extract supplementation compared with placebo, significantly reduced diastolic blood pressure with 1.25 mmHg [95% CI = -2.32 to -0.19, p = 0.02, I2 = 74%, p for heterogeneity   0.001] among overweight and obese adults.

The investigators found the quality of evidence across studies was low. Similar results were found in subgroup and sensitivity analyses.

The investigators concluded among overweight and obese adults, green tea or green tea extract supplementation is found to cause a small but significant reduction in blood pressure. However, more high-quality RCTs with large sample sizes are needed to further confirm the efficacy on blood pressure and make strong recommendations for green tea or green tea extract supplementation among the overweight and obese adults.

Original title:
Effect of green tea supplementation on blood pressure among overweight and obese adults: a systematic review and meta-analysis by Li G, Zhang Y, […], Holbrook A.

Link:
http://journals.lww.com/jhypertension/Abstract/2015/02000/Effect_of_green_tea_supplementation_on_blood.6.aspx

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

Objectives:
There are conflicting reports on the correlation between manganese (Mn) levels and breast cancer. Therefore, this review article (meta-analysis) has been conducted.

Does manganese deficiency increase risk of breast cancer?

Study design:
This review article included 11 case-control studies involving 1302 subjects.

There was no evidence of publication bias. Sensitivity analysis showed that excluding any one study from the pooled analysis did not vary the results substantially.

Results and conclusions:
The investigators found the random-effects meta-analysis results indicated that subjects with breast cancer had lower manganese levels in serum and hair than healthy controls [SMD = -1.51, 95% CI = -2.47 to -0.56, I2 = 97.8%, p 0.001].

The investigators found in subgroup analysis that subjects with breast cancer had lower manganese levels than healthy controls in China [SMD = -1.32, 95% CI = -2.33 to -0.32] and Korea [SMD = -4.08, 95% CI = -4.63 to -3.54], but not in Turkey [SMD = -0.96, 95% CI = -3.19 to 1.27].

The investigators found in subgroup analysis that the differences of manganese levels between patients with breast cancer and healthy controls were similar in different sample specimens:
serum [SMD = -1.24, 95% CI = -2.31 to -0.16];
hair [SMD = -1.99, 95% CI = -3.91 to -0.06] and;
different types of manganese measurement:

ICP-AAS [SMD = -1.14, 95% CI = -2.24 to -0.04];
GFAAS [SMD = -1.94, 95% CI = -2.38 to -1.49];
ICP-AES [SMD = -3.77, 95% CI = -4.70 to -2.85]. These findings can well explain that  the between-study variability was the main source of heterogeneity.

The investigators concluded there is an association between deficient manganese concentration and breast cancer. However, the subgroup analysis found that there was contradiction regarding races and geography, like China and Turkey. Thus this finding needs further confirmation by trans-regional multicenter, long-term observation in a cohort design to obtain better understanding of causal relationships between manganese levels and breast cancer, through measuring manganese at baseline to investigate whether the highest manganese category versus lowest was associated with breast cancer risk.

Original title:
The association between deficient manganese levels and breast cancer: a meta-analysis by Shen F, Cai WS, [...],Xu B.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443096/

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

Objectives:
Approximately 5.7 million Americans carry the diagnosis of systolic heart failure (HF), a major health care burden. Heart failure is a known manifestation of thiamine deficiency (TD). Therefore, this review article has been conducted.

Is thiamine deficiency (vitamin B1 deficiency) a risk factor of systolic heart failure?

Study design:
This review article included 9 studies (observational studies and RCTs).

Results and conclusions:
The investigators found systolic heart failure patients had a higher risk of 153% of getting a thiamine deficiency [odds ratio = 2.53, 95% CI = 1.65-3.87].

The investigators found diuretic use, changes in dietary habits and altered thiamine absorption and metabolism were identified as possible mechanisms of thiamine deficiency in heart failure patients.

The investigators found small observational studies and randomized control trials suggested that thiamine supplementation in heart failure population could improve ejection fraction and reduce symptoms.

The investigators concluded thiamine deficiency is more prevalent in heart failure population, and its supplementation may be beneficial. The therapeutic role of thiamine in heart failure warrants further study.

Original title:
Determining the Role of Thiamine Deficiency in Systolic Heart Failure: A Meta-Analysis and Systematic Review by Jain A, Mehta R, […], Winchester DE.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/26497757

Additional information of El Mondo:
Find more information/studies on cardiovascular disease and vitamin B1 (thiamine) right here.

Objectives:
Is there an association of intake of different vitamins and multiple-vitamin supplements and the incidence of colorectal cancer?

Study design:
This review article included 47 articles (cohort studies).

There was unacceptable heterogeneity for studies of multiple-vitamin supplements, so findings were inconclusive.

Results and conclusions:
The investigators found a significant reduced risk of 12% [multivariable-adjusted RR = 0.88, 95% CI = 0.81-0.95] for colorectal cancer when comparing the highest versus lowest dietary vitamin B9 (folate) intake. Significant means that there is an association with a 95% confidence.

The investigators found a significant reduced risk of 13% [multivariable-adjusted RR = 0.87, 95% CI = 0.77-0.99] for colorectal cancer when comparing the highest versus lowest dietary vitamin D intake. Significant because RR of 1 was not found in the 95% CI of 0.77 to 0.99. RR of 1 means no risk/association.

The investigators found a significant reduced risk of 12% [multivariable-adjusted RR = 0.88, 95% CI = 0.79-0.99] for colorectal cancer when comparing the highest versus lowest dietary vitamin B6 intake.

The investigators found a significant reduced risk of 14% [multivariable-adjusted RR = 0.86, 95% CI = 0.76-0.97] for colorectal cancer when comparing the highest versus lowest dietary vitamin B2 intake.

The investigators found, however, no association between both dietary vitamine A, C, E, B3 and B12 and the risk of colorectal cancer.

The investigators concluded high dietary vitamin B9 (folate), D, B6 and B2 intake reduces risk of colorectal cancer, but further study is needed.

Original title:
Vitamin and multiple-vitamin supplement intake and incidence of colorectal cancer: a meta-analysis of cohort studies by Liu Y, Yu Q, […], Li K.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/25491145

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

Objectives:
Red meat intake has been associated with risk of colorectal cancer, potentially mediated through heterocyclic amines. The metabolic efficiency of N-acetyltransferase 2 (NAT2) required for the metabolic activation of such amines is influenced by genetic variation. The interaction between red meat intake, NAT2 genotype and colorectal cancer has been inconsistently reported. Therefore, this review article has been conducted.

Is there an interaction between red meat intake, NAT2 genotype and colorectal cancer?

Study design:
This review article included 11 retrospective case-control studies with 8,290 colorectal cancer cases and 9,115 controls (subjects without colorectal cancer).

Results and conclusions:
The investigators found the highest quartile of red meat intake was associated with a 41% increased risk of colorectal cancer compared with the lowest quartile [OR = 1.41, 95% CI = 1.29-1.55].
However, a significant association was observed only for studies with retrospective diet data, not for studies with diet prospectively assessed before cancer diagnosis.

The investigators found when combining all studies, high red meat intake was similarly associated with colorectal cancer in those with a rapid/intermediate NAT2 genotype [OR = 1.38, 95% CI = 1.20-1.59] as with a slow genotype [OR = 1.43, 95% CI = 1.28-1.61, p interaction = 0.9].

The investigators concluded high red meat intake was associated with increased risk of colorectal cancer only from retrospective case-control studies and not modified by NAT2 enzyme activity.

Original title:
Red Meat Intake, NAT2, and Risk of Colorectal Cancer: A Pooled Analysis of 11 Studies by Ananthakrishnan AN, Du M, […], Chan AT.

Link:
http://cebp.aacrjournals.org/content/cebp/24/1/198.full.pdf

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Objectives:
Does a high GI or GL diet increase risk of stroke events?

Study design:
This review article included 7 prospective cohort studies with 225000 participants free of diabetes from 6 different countries. 3046 stroke events were included and the follow-up range was 5 to 18 years.

Results and conclusions:
The investigators found a high GI diet was not significantly associated with a 10% increased risk for stroke events [pooled RR = 1.10, 95% CI = 0.99-1.21]. Not significantly means, there is no association with a 95% confidence.

However, the investigators found high GL was significantly associated with a 19% increased risk for stroke events [pooled RR = 1.19, 95% CI = 1.05-1.36].

The investigators found there was no significant association between high carbohydrate intake and stroke risk [RR = 1.12, 95% CI = 0.93-1.35].

The investigators concluded a daily high GL diet (but not GI diet) is the risk factor of stroke event. Further researches are needed to verify the meta-analyses results and study associated mechanisms.

Original title:
Carbohydrate Intake, Glycemic Index, Glycemic Load, and Stroke: A Meta-analysis of Prospective Cohort Studies by Cai X, Wang C, [...], Ding F.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/25593213

Additional information of El Mondo:
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Objectives:
Is there an association between serum non-ceruloplasmin copper and Alzheimer's disease risk?

Study design:
This review article included studies carried out from 1996 until March 2013.

Ten studies were analyzed in the meta-analysis for Non-Cp copper and % Non-Cp copper reaching a pooled total of 599 Alzheimer's disease subjects and 867 controls.
For Adj-Cp copper, 14 studies were analyzed with a pooled total of 879 Alzheimer's disease subjects and 1712 controls.
27 studies were considered for systemic total copper meta-analysis, with a pooled total of 1393 Alzheimer's disease subjects and 2159 controls.

Results and conclusions:
The investigators found all copper indices analyzed were significantly higher in Alzheimer's disease subjects compared to healthy controls.

The investigators concluded serum non-ceruloplasmin copper is higher in Alzheimer's disease.

Original title:
Meta-analysis of serum non-ceruloplasmin copper in Alzheimer's disease by Squitti R, Simonelli I, […], Bush AI.

Link:
http://www.ncbi.nlm.nih.gov/pubmed/24072069

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

Objectives:
Does DHA, alone or combined with EPA, contribute to improved memory function in older adults with mild memory complaints?

Study design:
This review article included 15 intervention trials and 13 observational studies. Most intervention trials were conducted with subjects ≥ 45 years of age (n = 11). The majority of studies were conducted in subjects without cognitive complaints (n = 9) and ranged from 28-730 days in duration, averaging 4-6 months.

Results and conclusions:
The investigators found episodic memory of subjects with mild memory complaints significantly improved in response to DHA supplementation, alone or in combination with EPA [p 0.004].

The investigators found regardless of cognitive status at baseline, >1 g/day DHA/EPA significantly improved episodic memory of subjects with mild memory complaints [p 0.04].

The investigators found there was a trend for episodic memory improvement in response to supplementation in subjects 45 years or older [p 0.058].

The investigators found DHA intake above the mean DHA level studied (580 mg/day) significantly improved episodic memory in all subjects [p 0.009] and in subjects with mild memory complaints [p 0.019]. Significant means that there is an association with a 95% confidence.

The investigators found observational studies supported a beneficial association between intake/blood levels of DHA/EPA and memory function in older adults.

The investigators concluded DHA (>580 mg/day), alone or combined with EPA (>1 g/day DHA/EPA), contributes to improved memory function in older adults (45 years or older) with mild memory complaints.

Original title:
Docosahexaenoic Acid and Adult Memory: A Systematic Review and Meta-Analysis by Yurko-Mauro K, Alexander DD and Van Elswyk ME.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364972/

Additional information of El Mondo:
Find more studies/information on elderly and EPA&DHA.

This meal provides at least 580 mg DHA.
1 g/day DHA/EPA corresponds to meals providing 4 days of DHA&EPA.

Episodic memory is the type of long-term, declarative memory in which we store memories of personal experiences that are tied to particular times and places.
Some examples of episodic memory:

• Your skiing vacation last winter;
• The first time you traveled by airplane;
• Your first high school day.

Objectives:
Does sodium iron ethylenediaminetetraacetate (NaFeEDTA)-fortified soy sauce reduce anemia prevalence in the Chinese population?

Study design:
This review article included a total of 16 studies for anemia rate analysis (aged from 3 to >55 years and from different provinces, with 8411 in the intervention groups and 8408 in the control groups), of which 12 studies for hemoglobin analysis (4037 subjects from the intervention groups and 4034 from the control groups with an age group from 3 to >55 years and from different provinces).

Results and conclusions:
The investigators found hemoglobin concentration increased and anemia rates decreased significantly as compared with the non-fortified soy sauce groups.

The investigators found for anemia rates, a pooled estimate odds ratio of 0.25 [95% CI = 0.19-0.35].

The investigators found for hemoglobin concentrations a pooled weighted mean difference of 8.81g/L [95% CI = 5.96-11.67].

The investigators concluded long-term intervention with NaFeEDTA-fortified soy sauce results in 8.81g/L increase of hemoglobin level and a 25% decrease in the anemia rate in the Chinese high-risk anemic population.

Original title:
Effect of NaFeEDTA-Fortified Soy Sauce on Anemia Prevalence in China: A Systematic Review and Meta-analysis of Randomized Controlled Trials by Huo JS, Yin JY, […], Chen CM.

Link:
http://www.besjournal.com/Articles/Archive/2015/No11/201512/t20151218_123669.html

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