Nutritional advice

Objectives:
It has been suggested that prenatal exposure to n-3 long-chain fatty acids protects against asthma and other allergy-related diseases later in childhood. The extent to which fish intake in pregnancy protects against child asthma and rhinitis symptoms remains unclear. Therefore, this review article (meta-analysis) has been conducted.

Does fish consumption during pregnancy reduce risk of asthma and other allergy-related diseases later in childhood?

Study design:
This review article included data from 60,774 mother-child pairs participating in 18 European and US birth cohort studies.
Information on wheeze, asthma and allergic rhinitis prevalence was collected using validated questionnaires.
The time periods of interest were: infancy (0-2 years), preschool age (3-4 years) and school age (5-8 years).
The median fish consumption during pregnancy ranged from 0.44 times/week in The Netherlands to 4.46 times/week in Spain.

Results and conclusions:
The investigators found maternal fish intake during pregnancy was not associated with offspring wheeze symptoms in any age group nor with the risk of child asthma [adjusted meta-analysis relative risk per 1-time/week = 1.01, 95% CI = 0.97-1.05] and allergic rhinitis at school age [RR = 1.01, 95% CI = 0.99-1.03].

These results were consistently found in further analyses by type of fish and seafood consumption and in sensitivity analyses.

The investigators concluded maternal fish intake during pregnancy is not associated with offspring wheeze symptoms in any age group (0-2 years, 3-4 years and 5-8 years) or with the risk of child asthma and allergic rhinitis at school age (5-8 years).

Original title:
Fish and seafood consumption during pregnancy and the risk of asthma and allergic rhinitis in childhood: a pooled analysis of 18 European and US birth cohorts by Stratakis N, Roumeliotaki T, […], Chatzi L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28338907

Additional information of El Mondo:
Find more information/studies on fish consumption, pregnancy and review article/significant/95% CI right here.

Objectives:
Vitamin A deficiency (VAD) is a major public health problem in low- and middle-income countries, affecting 190 million children under five years of age and leading to many adverse health consequences, including death. Based on prior evidence and a previous version of this review, the World Health Organization has continued to recommend vitamin A supplementation for children aged 6 to 59 months. There are new data available from recently published randomised trials since the previous publication of this review in 2010. Therefore, this meta-analysis (review article) has been conducted.

Does vitamin A supplementation (VAS) prevent morbidity and mortality in children aged six months to five years?

Study design:
This review article included 47 RCTs (4 of which are new to this review), involving approximately 1,223,856 children. Studies took place in 19 countries: 30 (63%) in Asia, 16 of these in India; 8 (17%) in Africa; 7 (15%) in Latin America and 2 (4%) in Australia.

Results and conclusions:
The investigators found in 19 trials (1,202,382 children) at longest follow-up, there was a 12% observed reduction in the risk of all-cause mortality for vitamin A compared with control using a fixed-effect model [risk ratio = 0.88, 95% CI = 0.83 to 0.93; high-quality evidence]. However, this result was sensitive to choice of model; a random-effects meta-analysis showed a different summary estimate [24% reduction: RR = 0.76, 95% CI = 0.66 to 0.88].

The investigators found in 9 trials (1,098,538 children) reporting mortality due to diarrhoea showed a 12% overall reduction for vitamin A supplementation [RR = 0.88, 95% CI = 0.79 to 0.98; high-quality evidence].

The investigators found no significant effect for vitamin A supplementation on mortality due to measles, respiratory disease and meningitis.

The investigators found in 15 trials (77,946 children) vitamin A supplementation reduced incidence of diarrhoea with 15% [RR = 0.85, 95% CI = 0.82 to 0.87; low-quality evidence].

The investigators found in 6 trials (19,566 children) vitamin A supplementation reduced incidence of measles with 50% [RR = RR 0.50, 95% CI 0.37 to 0.67; moderate-quality evidence].

The investigators found no significant effect for vitamin A supplementation on incidence of respiratory disease or hospitalisations due to diarrhoea or pneumonia.

The investigators found in 4 trials (10,541 children) an increased risk of 97% for vomiting within the first 48 hours of vitamin A supplementation [RR = 1.97, 95% CI = 1.44 to 2.69; moderate-quality evidence].

The investigators concluded vitamin A supplementation is associated with a clinically meaningful reduction in morbidity and mortality in children aged six months to five years. Therefore, it is recommendable to maintain the policy of universal supplementation for children under five years of age in populations at risk of vitamin A deficiency. Further placebo-controlled trials of vitamin A supplementation in children between six months and five years of age would not change the conclusions of this review, although studies that compare different doses and delivery mechanisms are needed. In populations with documented vitamin A deficiency, it would be unethical to conduct placebo-controlled trials.

Original title:
Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age by Imdad A, Mayo-Wilson E, […], Bhutta ZA.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28282701

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

Objectives:
Thyroid cancer (TC) is the most common malignancy of the endocrine system. The relationship between iodine intake and thyroid cancer risk is controversial always. Therefore, this review article (meta-analysis) has been conducted.

Does dietary intake of iodine reduce thyroid cancer risk?

Study design:
This review article included 8 case-control studies with in total 2213 subjects with thyroid cancer and 2761 subjects without thyroid cancer.

With regard to publication bias, owing to the limited number (below 10) of studies included in the saltwater fish, shellfish and iodine intake analyses, publication bias was not assessed.

Results and conclusions:
The investigators found adequate or excess iodine dietary intake (>300 μg/d) significantly decreased the risk of thyroid cancer with 26% [OR = 0.74, 95% CI = 0.60-0.92].

The investigators found high consumption of saltwater fish (≥3 times/wk or ≥12 times/mo) significantly decreased the risk of thyroid cancer with 28% [OR = 0.72, 95% CI = 0.55-0.95, p = 0.02].

The investigators found high consumption of shellfish (≥3 times/wk or ≥12 times/mo) significantly decreased the risk of thyroid cancer with 30% [OR = 0.70, 95% CI = 0.52-0.96, p = 0.03].

The investigators concluded a higher intake of dietary iodine (>300 μg/d) may decrease the risk of thyroid cancer in populations mainly based in coastal cities or on islands. May decrease, because this review article did not include cohort  studies.

Original title:
The relationship between iodine intake and the risk of thyroid cancer: A meta-analysis by Cao LZ, Peng XD, [...], Li S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440127/

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Objectives:
Is there a causal association between low serum vitamin D concentrations, increased body mass index (BMI) and pediatric-onset multiple sclerosis (MS) using genetic risk scores (GRS)?

Study design:
This review article included participants of non-Hispanic white individuals recruited from over 15 sites across the United States (n = 394 cases, 10,875 controls) and Sweden (n = 175 cases, 5,376 controls; total n = 16,820).

Results and conclusions:
The investigators found meta-analysis findings demonstrated that a vitamin D GRS associated with increasing levels of 25(OH)D in serum significantly decreased risk of pediatric-onset MS with 28% [OR =  0.72, 95% CI = 0.55-0.94, p = 0.02] after controlling for sex, genetic ancestry, HLA-DRB1*15:01 and over 100 non-human leukocyte antigen MS risk variants.

The investigators also found that a higher BMI GRS significant increased risk of pediatric-onset MS with 17% [OR = 1.17, 95% CI = 1.05-1.30, p = 0.01] after adjusting for covariates.

The investigators found estimates for each GRS were unchanged when considered together in a multivariable model.

The investigators concluded evidence supporting independent and causal effects of decreased vitamin D levels and increased BMI on susceptibility to pediatric-onset MS.

Original title:
Evidence for a causal relationship between low vitamin D, high BMI, and pediatric-onset MS by Gianfrancesco MA, Stridh P, […], Waubant E.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28356466

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Objectives:
The findings of prospective cohort studies are inconsistent regarding the association between dietary magnesium intake and serum magnesium concentration and the risk of hypertension. Therefore, this review article (meta-analysis) has been conducted.

Do dietary magnesium intake and serum magnesium concentrations reduce risk of hypertension?

Study design:
This review article included 10 cohort studies, including 20,119 cases of hypertension and 180,566 participants.

The range of dietary magnesium intake was 96-25 mg/day and serum magnesium levels were 0.66-0.95 mmol/L.

The funnel plot showed reasonable symmetry, with no evidence of publication bias (Egger’s test p = 0.95 and Begg’s test p = 0.71).

Results and conclusions:
The investigators found when comparing the highest to the lowest category of dietary magnesium consumption, a significant reduced risk of 8% for hypertension [pooled RR = 0.92, 95% CI = 0.86-0.98].

The investigators found for every 100 mg/day increment in dietary magnesium intake a significant reduced risk of 5% for hypertension [pooled RR = 0.95, 95% CI = 0.90-1.00, I2 = 39.3%, p = 0.13].
The reduced hypertension risk associated with 100 mg/day was tended to be observed when the duration of follow-up was more than 8 years and when the results were adjusted separately for calcium, sodium, fiber, cholesterol, saturated fat intake or smoking.

The investigators found the dose-response meta-analysis suggested a marginal linear relationship between dietary magnesium intake and hypertension risk [p for linearity = 0.057].

The investigators found no association between serum magnesium concentrations and reduced risk of hypertension [pooled RR = 0.91, 95% CI = 0.80-1.02, p = 0.10, I2 = 0%, p = 0.48].

The investigators concluded that increased dietary magnesium intake is associated with lower risk of hypertension in a linear dose-response pattern. However, there is no association between serum magnesium concentration and risk of hypertension.

Original title:
Dose-response relationship between dietary magnesium intake, serum magnesium concentration and risk of hypertension: a systematic review and meta-analysis of prospective cohort studies by Han H, Fang X, […], Cao Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5420140/

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Objectives:
Prostate cancer (PCa) is the fifth leading cause of cancer-related deaths worldwide. Many epidemiological studies have investigated the association between prostate cancer and lycopene, however, results have been inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Does lycopene reduce prostate cancer risk?

Study design:
This review article included 42 studies including 43,851 cases of prostate cancer reported from 692,012 participants.

Results and conclusions:
The investigators found dietary intake of lycopene was significantly associated with a reduced prostate cancer risk of 12% [RR = 0.88, 95% CI = 0.78-0.98, p = 0.017].

The investigators found circulating concentrations of lycopene were significantly associated with a reduced prostate cancer risk of 12% [RR = 0.88, 95% CI = 0.79-0.98, p = 0.019].

The investigators found sensitivity analyses within the dose-response analysis further revealed a significant linear dose-response for dietary lycopene and prostate cancer risk such that prostate cancer decreased by 1% for every additional 2 mg of lycopene consumed [p = 0.026].

The investigators found prostate cancer risk decreased by 3.5 to 3.6% for each additional 10 μg/dL of circulating lycopene in the linear and nonlinear models, respectively [p-linear = 0.004, p-non linear = 0.006].

The investigators found no association between lycopene and advanced prostate cancer. However, there was a trend for protection against prostate cancer aggressiveness [RR = 0.74, 95% CI = 0.55-1.00, p = 0.052].

The investigators concluded that higher dietary and circulating lycopene concentrations reduce prostate cancer risk. This was accompanied by dose-response relationships for dietary and circulating lycopene. Further studies are required to determine the mechanisms underlying these associations.

Original title:
Increased dietary and circulating lycopene are associated with reduced prostate cancer risk: a systematic review and meta-analysis by Rowles JL, Ranard KM, […], Erdman JW Jr.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28440323

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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/

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Objectives:
What is the relationship between intake of 12 major food groups and risk of type 2 diabetes (T2D)?

Study design:
This review article included prospective cohort studies.
The 12 major food groups are whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy, fish, red meat, processed meat and sugar-sweetened beverages (SSB).

The meta-evidence was graded "low" for legumes and nuts; "moderate" for refined grains, vegetables, fruit, eggs, dairy and fish; and "high" for processed meat, red meat, whole grains and sugar-sweetened beverages.

Results and conclusions:
The investigators found 6 out of the 12 food-groups showed a significant relation with risk of type 2 diabetes; 3 of them a decrease of risk with increasing consumption (whole grains, fruits and dairy) and 3 an increase of risk with increasing consumption (red meat, processed meat and sugar-sweetened beverages) in the linear dose-response meta-analysis.

The investigators found evidence of a non-linear relationship between fruits, vegetables, processed meat, whole grains and sugar-sweetened beverages and type 2 diabetes risk.

The investigators found optimal consumption of risk-decreasing foods resulted in a 42% reduction and consumption of risk-increasing foods was associated with a threefold type 2 diabetes risk, compared to non-consumption.

The meta-evidence was graded "low" for legumes and nuts; "moderate" for refined grains, vegetables, fruit, eggs, dairy and fish; and "high" for processed meat, red meat, whole grains, and sugar-sweetened beverages. Among the investigated food groups, selecting specific optimal intakes can lead to a considerable change in risk of type 2 diabetes.

The investigators concluded that a higher consumption of whole grains, fruits and dairy products reduces type 2 diabetes risk, while a higher consumption of red meat, processed meat and sugar-sweetened beverages increases type 2 diabetes risk.

Original title:
Food groups and risk of type 2 diabetes mellitus: a systematic review and meta-analysis of prospective studies by Schwingshackl L, Hoffmann G, […], Boeing H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28397016

Additional information of El Mondo:
Find more information/studies on consumption of meat, fruit, dairy products and nuts and type 2 diabetes right here.

Objectives:
Does polyphenol supplementation increase sport performance?

Study design:
This review article included 14 studies. Of these, the studied populations were predominately-trained males with an average intervention dose of 688 ± 478mg polyphenols per day.

Results and conclusions:
The investigators found pooled results demonstrated polyphenol supplementation for at least 7 days significantly increased performance by 1.90% [95% CI = 0.40-3.39].

The investigators found sub-analysis of 7 studies using quercetin significantly increased performance by 2.82% [95% CI = 2.05-3.58].

The investigators found no adverse effects reporting in studies in relation to the intervention.

The investigators concluded daily 688mg polyphenol supplementation, preferably quercetin supplementation for at least 7 days increases performance in healthy individuals.

Original title:
Polyphenols and Performance: A Systematic Review and Meta-Analysis by Somerville V, Bringans C and Braakhuis A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28097488

Additional information of El Mondo:
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Objectives:
Heart failure (HF) remains a major health problem affecting 5.7 million adults in USA. Data on the association of egg consumption with incident heart failure have been inconsistent. Therefore, this review article (meta-analysis) has been conducted.

Does egg consumption increase incident heart failure in the general population?

Study design:
This review article included 4 prospective cohort studies with a total of 105,999 subjects and 5,059 cases of new onset heart failure.

There was no evidence of publication bias on funnel plot analysis as supported by the Egger’s test (p = 0.68).

Results and conclusions:
The investigators found when comparing the highest (≥1/day) to the lowest category of egg consumption, a significant increased risk of 25% [pooled RR = 1.25, 95% CI = 1.12-1.39, p = 0.00, I2 = %] for heart failure.

The investigators found that sensitivity analysis (stratification by excluding studies with men/women, 20 years of follow-up duration, US/Non-US studies) did not alter the main conclusion.

The investigators concluded that at least 1 egg per day increases heart failure risk in the general population. Further studies are warranted to explore the underlying biological mechanisms.

Original title:
Egg Consumption and Incidence of Heart Failure: A Meta-Analysis of Prospective Cohort Studies by Khawaja O, Singh H, […], Djoussé L.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5367008/

Additional information of El Mondo:
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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:
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Objectives:
Previous systematic reviews and meta-analyses have evaluated the association of dairy consumption and the risk of cardiovascular disease (CVD). However, the findings were inconsistent. No quantitative analysis has specifically assessed the effect of yogurt intake on the incident risk of cardiovascular disease. Therefore, this review article (meta-analysis) has been conducted.

Is yogurt intake associated with a lower incident risk of cardiovascular disease?

Study design:
This review article included 9 prospective cohort studies involving a total of 291,236 participants. Follow-up durations ranged between 10.2 and 17.3 years. The baseline age of the participants ranged from ≥21 to ≥55 years. Yogurt intake was assessed by a food-frequency questionnaire (FFQ).

There was no publication bias.

Results and conclusions:
The investigators found when compared with the lowest category, highest category of yogurt consumption was not significantly related with the incident risk of cardiovascular disease [RR = 1.01, 95% = 0.95-1.08, I2 = 52%]. Not significantly because RR of 1 was found in the 95% CI of 0.95 to 1.08. RR of 1 means no risk/association.

The investigators found in the stratified analysis by type of outcome, the pooled RR of yogurt consumption was 1.04 [95% = 0.95 to 1.15] for CHD, RR = 1.02 [95% CI = 0.92 to 1.13] for stroke and RR = 0.87 [95% CI = 0.77 to 0.98] for the incident CVD events.

However, the investigators found intake of ≥200 g/day yogurt was significantly associated with a lower risk of 8% [RR = 0.92, 95% CI = 0.85 to 1.00] for cardiovascular disease in the subgroup analysis.

The investigators concluded that a daily dose of ≥200 g yogurt intake is associated with a lower incident risk of cardiovascular disease. Further cohort studies and randomized controlled trials are still demanded to establish and confirm the observed association in populations with different characteristics.

Original title:
Consumption of Yogurt and the Incident Risk of Cardiovascular Disease: A Meta-Analysis of Nine Cohort Studies by Wu L and Sun D.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372978/

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Objectives:
Prostate cancer (PCa) now remains the 2nd most frequently diagnosed cancer. In recent years, chemoprevention for prostate cancer becomes a possible concept. Especially, many phytochemicals rich foods are suggested to lower the risk of cancer. Among these foods, green tea is considered as effective prevention for various cancers. However, clinical trials and previous meta-analyses on the relationship between green tea consumption and the risk of prostate cancer have produced inconsistent outcomes. Therefore, this review article (meta-analysis) has been conducted.

Does green tea intake reduce prostate cancer risk?

Study design:
This review article included 4 cohort studies, 3 case-control studies and 3 RCTs. The cohort studies and case-control studies which investigated the association between green tea intake and prostate cancer risk included 1435 cases among 96,332 individuals and the 3 RCTs studied the relationship between EGCG and prostate cancer incidence included 87 volunteers in EGCG arms of 179 individuals.

No publication bias was found.

Results and conclusions:
The investigators found in observational studies (4 cohort studies and 3 case-control studies) for the highest versus lowest category of green tea intake a non-significant reduced prostate cancer risk of 8% [RR = 0.92, 95% CI = 0.77-1.11, I2 = 0%, p = 0.46] for all studies;

a non-significant reduced prostate cancer risk of 2.3% [RR = 0.977, 95% CI = 0.80-1.19] for cohort studies and;
a non-significant reduced prostate cancer risk of 27.7% [RR = 0.623, 95% CI = 0,368-1.056, I2  = 0%, p =  0.46] for case-control studies.

The investigators found no association between 1-5 cups of green tea per day and prostate cancer risk.

However, the investigators found 7 cups of green tea per day significantly reduced prostate cancer risk with 19% [RR = 0.81, 95% CI = 0.67-0.97]. The significant reduced prostate cancer risk increased to 26% [RR = 0.74, 95% CI = 0.59-0.93] for 9 cups and to 44% [RR = 0.56, 95% CI = 0.35-0.92) for 15 cups.

The investigators found in 3 RCTs when compared to placebo green tea catechins significantly reduced prostate cancer risk  with 62% [RR = 0.38, 95% CI = 0.16-0.86, p  =  0.02].

The investigators concluded that at least 7 cups/day green tea intake reduces prostate cancer. This is further confirmed by the potential protective effect of green tea catechins on prostate cancer. Further prospective study with accurate measurement of green tea intake is required to substantiate these conclusions.

Original title:
Green tea and the risk of prostate cancer: A systematic review and meta-analysis by Guo Y, Zhi F, […], Zhang X.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380255/

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Objectives:
Olive oil (OO) as food is composed mainly of fatty acids and bioactive compounds depending from the extraction method. Both had been discussed as health promoting with still open questions. Therefore, this meta-analysis (systematic review) has been conducted.

Does olive oil intake reduce risk of type 2 diabetes?

Study design:
This review article included 4 cohort studies including 15,784 type 2 diabetes cases and 29 intervention trials.

Results and conclusions:
The investigators found the highest olive oil intake category showed a 16% reduced risk of type 2 diabetes [RR = 0.84, 95% CI = 0.77, 0.92) compared with the lowest. The reduced risk was significant.

The investigators found evidence for a nonlinear relationship between olive oil intake and the reduced risk of type 2 diabetes.

The investigators found in patients with type 2 diabetes that olive oil supplementation resulted in a significantly more pronounced reduction in HbA1c [MD = -0.27%, 95% CI = -0.37 to -0.17] and fasting plasma glucose [MD = -0.44 mmol/L, 95% CI = -0.66 to -0.22] as compared with the control groups.

The investigators concluded that the intake of olive oil is beneficial for the prevention and management of type 2 diabetes. This conclusion regards olive oil as food and might not been valid for single components comprising this food.

Original title:
Olive oil in the prevention and management of type 2 diabetes mellitus: a systematic review and meta-analysis of cohort studies and intervention trials by Schwingshackl L, Lampousi AM, […], Boeing H1.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28394365

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Objectives:
Epidemiological studies have presented inconsistent evidence of the correlation between a fish-oriented dietary intake (FDI) and the risk of cognitive decline. Therefore, this meta-analysis (review article) has been conducted.

Does a fish-oriented dietary intake reduce risk of cognitive decline?

Study design:
This review article included 9 cohort studies containing 28,754 subjects.
Limited evidence involving heterogeneity was found within subgroups or across studies.

Results and conclusions:
The investigators found when comparing the highest versus lowest categories of fish consumption a significant reduced risk of 20% [RR = 0.80, 95% CI = 0.65-0.97] for dementia of Alzheimer type (DAT).

The investigators found the dose-response synthesized data indicated that a 100-g/week increase in fish intake reduced the risk of dementia of Alzheimer type by an additional 12% [RR = 0.88, 95% CI = 0.79-0.99].

The investigators found that the reduced risk of dementia of all causes (DAC) and mild cognitive impairment (MCI) was non-significant.

The investigators concluded that a higher intake of fish, at least 100-g/week is correlated with a reduced risk of dementia of Alzheimer type.

Original title:
An exploration of the role of a fish-oriented diet in cognitive decline: a systematic review of the literature by Zeng LF, Cao Y, […], Wang NS.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28418899

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Objectives:
Hypertension is a major risk factor for cardiovascular disease, myocardial infarction, stroke and renal failure. Sesame consumption may benefit blood pressure (BP) due to its high polyunsaturated fatty acids, fibre, phytosterol and lignans content. To clarify this association, this review article (meta-analysis) has been conducted.

Does sesame consumption reduce blood pressure?

Study design:
This review article included 8 controlled trials with a total of 843 participants.

Results and conclusions:
The investigators found that sesame consumption significantly reduced systolic blood pressure with 7.83 mmHg [95% CI = -14.12 to -1.54, p  0.05, I2 = 99%].

The investigators found that sesame consumption significantly reduced diastolic blood pressure with 5.83 mmHg [95% CI = -9.58 to -2.08, p  0.01, I2 = 98%].

However, to reduce the heterogeneity, the meta-analysis was limited to high methodology quality trials (n = 4), which resulted in a significant reduction of 3.23 mmHg in systolic blood pressure [95% CI = -5.67 to -0.79, I2 = 33%] and a non-significant reduction of 2.08 mmHg in diastolic blood pressure [95% CI = -4.85 to 0.69, I2 = 62%].

The investigators concluded that sesame consumption reduces the systolic blood pressure but not the diastolic blood pressure. However, further investigations with larger sample sizes and better methodology quality are required to confirm the blood pressure lowering effect of sesame consumption.

Original title:
Can sesame consumption improve blood pressure? A systematic review and meta-analysis of controlled trials by Khosravi-Boroujeni H, Nikbakht E, [...], Khalesi S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28387047

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Objectives:
Epidemiological studies assessing the relationship between dietary vitamin B2 and the risk of breast cancer have produced inconsistent results. Therefore, this review article (meta-analysis) has been conducted.

Does dietary vitamin B2 intake reduce breast cancer risk?

Study design:
This review article included 10 epidemiologic studies (cohort or patient-controle studies) comprising totally 12,268 breast cancer patients.

No publication bias was found.

Results and conclusions:
The investigators found comparing the highest to the lowest dietary vitamin B2 intake a significant reduced risk of 15% for breast cancer [pooled relative risk = 0.85, 95% CI = 0.76-0.95, I2 = 40.7%].

The investigators found dose-response analysis showed that an increment of 1 mg/day dietary vitamin B2 intake significantly reduced risk of breast cancer with 6% [relative risk = 0.94, 95% CI = 0.90-0.99].

The investigators concluded that dietary vitamin B2 intake, at least 1 mg/day, is related to the reduced risk of breast cancer. However, additional research is also necessary to further explore this association.

Original title:
Dietary vitamin B2 intake and breast cancer risk: a systematic review and meta-analysis by Yu L, Tan Y and Zhu L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28035488

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Objectives:
Nutrition therapy is an integral part of self-management education in patients with type 2 diabetes. Carbohydrates with a low glycemic index are recommended, but the ideal amount of carbohydrate in the diet is unclear. Therefore, this meta-analysis (systematic review) has been conducted.

Has carbohydrate restriction (below 45 En% carbohydrate) beneficial effects on glycemic control in type 2 diabetes?

Study design:
This review article included 10 RCTs. In total, 1,376 subjects with type 2 diabetes were included in this analysis. Forty-nine percent were male and the average age was 58 years. The majority were obese; mean BMI ranged from 26 kg/m² in an Asian population to 37 kg/m² in an American population.

The duration of the intervention varied from 3 to 24 months.

The average predefined targets for the assigned carbohydrate restriction were 25 En% (range 14-40 En%). The average reported intake was 30 En% (range 14-45 En%) after 3 or 6 months of intervention and 38 En% (range 27-45 En%) at 1 year (5 trials).

Results and conclusions:
The investigators found following a carbohydrate diet of 30 En% (range 14-45 En%) during 3 to 6 months significantly reduced HbA1c level of patients with type 2 diabetes with 0.34% [95% CI = 0.06 to 0.63] compared with a diet of 45-60 En% carbohydrate (high-carbohydrate diet).
Owing to heterogeneity, however, the quality of the evidence for this is only moderate. However, at 1 year or later, HbA1c level (seven trials included) was similar in the two groups.

The investigators found the greater the carbohydrate restriction, the greater the glucose-lowering effect [R = -0.85, p 0.01].

The investigators found the effect of the 2 types of diet on BMI/body weight, LDL cholesterol, QoL and attrition rate was similar throughout interventions.

The investigators concluded that carbohydrate restriction (below 45 En% carbohydrate) has a greater effect on glycemic control in type 2 diabetes than an high-carbohydrate diet in the short term. The magnitude of the effect was correlated to the carbohydrate intake, the greater the restriction, the greater glucose lowering, a relationship that has not been demonstrated earlier. However, in the long term, the glucose-lowering effect of high-carbohydrate diet (HCD) and low-carbohydrate diets (LCD) was similar.

Original title:
Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes by Snorgaard O, Poulsen GM, [...], Astrup A.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337734/

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Objectives:
Recent studies have found that the serum zinc levels were associated with the risk of Parkinson's disease (PD), but the results were inconsistent. Therefore, this meta-analysis (review article) has been conducted.

Is there an association between serum zinc levels and Parkinson's disease risk?

Study design:
This review article included 11 articles involving 822 Parkinson's disease patients and 777 healthy controls (subjects without Parkinson's disease).

No publication bias was found.

Results and conclusions:
The investigators found that the serum zinc levels in Parkinson's disease patients were significantly lower than those in health controls [SMD = -0.779, 95% CI = -1.323 to -0.234, p 0.001].

This association was also significant in oriental studies [SMD = -1.601, 95% CI = -2.398 to -0.805, p 0.001].

The investigators concluded that serum zinc levels in Parkinson's disease patients are significantly lower than those in healthy controls.

Original title:
Association Between Serum Zinc Levels and the Risk of Parkinson's Disease: a Meta-Analysis by Sun H, Liu X, […], Li W.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28160244

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Objectives:
Controversy persists regarding the effect of mixtures of conjugated linoleic acids (c9,t11- and t12,c10-CLA) in fasting blood glucose (FBG) and waist circumference (WC) in humans. Therefore, this review article (meta-analysis) has been conducted.

Does CLA reduce fasting blood glucose (FBG) and waist circumference (WC) in humans?

Study design:
This review article included 32 randomized clinical trials.

Results and conclusions:
The investigators found subgroup analysis showed that taking CLA supplement did not significantly influence fasting blood glucose [SMD = 0.075 mg/dL, 95% CI = -0.099 to 0.249, p = 0.399].

The investigators found subgroup analysis showed that taking CLA supplement reduced non-significantly waist circumference with 0.149cm [SMD = -0.149cm, 95% CI = -0.522 to 0.225, p = 0.435].

The investigators found foods enriched in CLA also showed no significant effect on fasting blood glucose [SMD = 0.126 mg/dL, 95% CI = -0.100 to 0.352, p = 0.274].

The investigators found foods enriched in CLA also showed no significant effect on waist circumference [SMD = -0.233cm, 95% CI = -0.625 to 0.159, p = 0.244].

The investigators concluded that c9,t11- and t12,c10-CLA administered as a supplement or used to enrich foods does not reduce fasting blood glucose (FBG) and waist circumference (WC) in humans.

Original title:
Effect of conjugated linoleic acid as a supplement or enrichment in foods on blood glucose and waist circumference in humans: A meta-analysis by Rahbar AR, Ostvar A, […], Rahbar A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28176632

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Overweight people often have higher fasting blood glucose (FBG) and greater waist circumference (WC).

Find here whether you are overweight or not?

Conjugated linoleic acids (CLA) are a family of isomers of linoleic acid found mostly in meat and dairy products derived from ruminants. An average daily diet supplies 15-174mg of conjugated linoleic acid.

Chemical structures of CLA.

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

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Objectives:
Randomised controlled trials (RCTs) have observed contrasting results on the effects of vitamin C on circulating biomarkers of glycaemic and insulin regulation. Therefore, this meta-analysis (systematic review) has been conducted.

Has vitamin C supplementation a favorable effect on circulating biomarkers of glycaemic and insulin regulation?

Study design:
This review article included 22 RCTs with 937 participants.

Results and conclusions:
The investigators found overall, vitamin C supplementation did not modify glucose, HbA1c and insulin concentrations.

The investigators found, however, subgroup analyses showed that vitamin C supplementation significantly reduced glucose concentrations with 0.44 mmol/L [95% CI = -0.81 to -0.07, p =0.01] in patients with type 2 diabetes and in interventions with a duration greater than 30 days [-0.53%, 95% CI = -0.79 to -0.10, p = 0.02].

The investigators found vitamin C administration had greater effects on fasting [-13.63 pmol/L, 95% CI = -22.73 to -4.54, p 0.01] compared to postprandial insulin concentration. However, meta-regression analyses showed that age was a modifier of the effect of vitamin C on insulin concentration.

The investigators found the effect size of vitamin C supplementation was associated with baseline BMI and plasma glucose levels and with the duration of the intervention.

The investigators concluded vitamin C supplementation has greater reduction in glucose concentrations in patients with type 2 diabetes, older individuals and with more prolonged supplementation (greater than 30 days). Personalized interventions with vitamin C may represent a feasible future strategy to enhance benefits and efficacy of interventions. Nevertheless, results need to be interpreted cautiously due to limitations in the primary studies.

Original title:
Effects of vitamin C supplementation on glycaemic control: a systematic review and meta-analysis of randomised controlled trials by Ashor AW, Werner AD, […], Siervo M.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28294172

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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 higher lycopene exposure decrease risk of cardiovascular diseases (CVD)?

Study design:
This review article included 14 observational studies.
Subgroup analyses showed that retrospective and low quality studies were statistically significant sources of heterogeneity.

Results and conclusions:
The investigators found higher lycopene exposure significantly reduced risk of cardiovascular diseases with 17% [pooled risk ratio = 0.83, 95% CI = 0.76-0.90]. Findings were similar restricting to dietary studies [RR = 0.87, 95% CI = 0.79-0.96] and biomarker studies [RR = 0.74, 95% CI = 0. 62-0.87].

The investigators found higher dietary lycopene intake significantly reduced risk of coronary heart disease with 13% [RR = 0.87, 95% CI = 0.76-0.98]. However, the reduced risk was not significant for higher lycopene biomarker concentrations.

The investigators found higher dietary lycopene intake significantly reduced risk of stroke with 17% [RR = 0.83, 95% CI = 0.69-0.96].

The investigators found higher lycopene biomarker concentrations significantly reduced risk of stroke with 35% [RR = 0.65, 95% CI = 0.42-0.87].

The investigators concluded both higher dietary lycopene intake and higher lycopene biomarker concentrations are inversely associated with a lower risk of cardiovascular diseases. Further well-designed randomized clinical trials are required to assess the role of lycopene on cardiovascular diseases.

Original title:
Lycopene and risk of cardiovascular diseases: A meta-analysis of observational studies by Song B, Liu K, […], Xu Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28318092

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Lycopene is a carotenoid and is responsible for the yellow colour in tomatoes. Carotenoids are antioxidants.

Objectives:
Is supplementation of formula milk with LCPUFA (long-chain polyunsaturated fatty acids) both safe and beneficial for full-term infants, while focusing on effects on visual function, neurodevelopment and physical growth?

Study design:
This review article included 15 RCTs (n = 1889).
9 studies assessed visual acuity, 6 of which used visual evoked potentials (VEP), 2 Teller cards and 1 both. 4 studies reported beneficial effects and the remaining 5 did not.
GRADE analysis of the outcomes indicated that the overall quality of evidence was low.

Results and conclusions:
The investigators found a meta-analysis of 3 RCTs (n = 244) showed significant benefit for sweep VEP acuity at 12 months (log of the minimum angle of resolution) [MD = -0.15, 95% CI = -0.17 to -0.13, I2 = 0%, low-quality of evidence].
However, the meta-analysis of 3 other RCTs (n = 256) showed no benefit for visual acuity measured with Teller cards at 12 months (cycles/degree) [MD = -0.01, 95% CI = -0.12 to 0.11, I2 = 0%, low-quality of evidence].

The investigators found meta-analysis of 4 RCTs (n = 661) revealed no significant differences between LCPUFA and placebo groups in BSID Mental Developmental Index scores at 18 months [MD = 0.06, 95% CI = -2.01 to 2.14, I2 = 75%, low-quality of evidence] and no significant differences in BSID Psychomotor Development Index scores at 18 months [MD = 0.69, 95% CI = -0.78 to 2.16, I2 = 61%, low-quality of evidence].

There were also no significant differences between the two groups in BSID-II scores at one year and two years of age.

The investigators found meta-analysis of 5 RCTs (n = 521) showed that the supplemented group had lower weight (z scores) at one year of age [MD = -0.23, 95% CI = -0.40 to -0.06, I2 = 83%, low-quality of evidence] and that the two groups showed no significant differences with respect to length and head circumference (z scores).

The investigators found meta-analysis at 18 months and at two years revealed no significant differences between the two groups with respect to weight (kg), length (cm) and head circumference (cm).

The investigators concluded there are no beneficial effects or harms of LCPUFA supplementation on neurodevelopmental outcomes of formula-fed full-term infants and no consistent beneficial effects on visual acuity. Therefore, routine supplementation of full-term infant milk formula with LCPUFA cannot be recommended at this time.

Original title:
Long chain polyunsaturated fatty acid supplementation in infants born at term by Jasani B, Simmer K, […], Rao SC.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/28281303

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