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PloS One 2012Prospective cohort studies in relation to the associations between n-3 polyunsaturated fatty acids (PUFA) and risk of type 2 diabetes (T2D) were inconsistent.... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Prospective cohort studies in relation to the associations between n-3 polyunsaturated fatty acids (PUFA) and risk of type 2 diabetes (T2D) were inconsistent. Differences in tissue n-3 PUFA compositions in subjects with and without T2D were also inconsistent in both cohort and case-control studies. We conducted a systematic review and meta-analysis of prospective cohort studies to examine the associations of fish and n-3 PUFA intake with T2D risk. The differences in tissue n-3 PUFA compositions in subjects with and without T2D were investigated based on cohort and case-control studies.
METHODS AND FINDINGS
PubMed, Embase, Cochrane library, China National Knowledge Infrastructure (CNKI) and Chinese VIP database up to January 2012 was used to identify relevant studies, and reference lists from retrieved studies were reviewed. Two authors independently extracted the data. Random-effects models were used to pool the summary relative risk (RR). Twenty-four studies including 24,509 T2D patients and 545,275 participants were identified. For cohort studies, the summary RR of T2D for the highest vs lowest categories of total fish, marine n-3 PUFA and alpha-linolenic acid intake was 1.07 (95% CI: 0.91, 1.25), 1.07 (95% CI: 0.95, 1.20) and 0.93 (95% CI: 0.81, 1.07), respectively. Subgroup analyses indicated that summary RR (highest vs lowest category) of T2D for fish and marine n-3 PUFA intake was 0.89 (95% CI: 0.81, 0.98) and 0.87 (95% CI: 0.79, 0.96) for Asian populations, and 1.20 (95% CI: 1.01, 1.44) and 1.16 (95% CI: 1.04, 1.28) for Western populations. Asian subjects with T2D had significantly lower tissue compositions of C22:6n-3 (SMD: -1.43; 95% CI: -1.75, -1.12) and total n-3 PUFA (SMD: -1.41; 95% CI: -2.23, -0.59) compared with those without T2D.
CONCLUSION
This systematic review and meta-analysis provides evidence that marine n-3 PUFA have beneficial effects on the prevention of T2D in Asian populations.
Topics: Adult; Aged; Animals; Asian People; Case-Control Studies; Cohort Studies; Diabetes Mellitus, Type 2; Diet; Fatty Acids, Omega-3; Female; Fish Oils; Humans; Male; Middle Aged; Prospective Studies; Risk
PubMed: 22984522
DOI: 10.1371/journal.pone.0044525 -
The British Journal of Nutrition Jun 2012The relationship between omega-3 polyunsaturated fatty acids (n-3 PUFA) from seafood sources (eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) or plant sources... (Meta-Analysis)
Meta-Analysis Review
The relationship between omega-3 polyunsaturated fatty acids (n-3 PUFA) from seafood sources (eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) or plant sources (alpha-linolenic acid, ALA) and risk of type 2 diabetes mellitus (DM) remains unclear. We systematically searched multiple literature databases through June 2011 to identify prospective studies examining relations of dietary n-3 PUFA, dietary fish and/or seafood, and circulating n-3 PUFA biomarkers with incidence of DM. Data were independently extracted in duplicate by 2 investigators, including multivariate-adjusted relative risk (RR) estimates and corresponding 95 % CI. Generalized least-squares trend estimation was used to assess dose-response relationships, with pooled summary estimates calculated by both fixed-effect and random-effect models. From 288 identified abstracts, 16 studies met inclusion criteria, including 18 separate cohorts comprising 540,184 individuals and 25,670 cases of incident DM. Consumption of fish and/or seafood was not significantly associated with DM (n = 13 studies; RR per 100 g/d = 1·12, 95 % CI = 0·94, 1·34); nor were consumption of EPA+DHA (n = 16 cohorts; RR per 250 mg/d = 1·04, 95 % CI = 0·97, 1·10) nor circulating levels of EPA+DHA biomarkers (n = 5 cohorts; RR per 3 % of total fatty acids = 0·94, 95 % CI = 0·75, 1·17). Both dietary ALA (n = 7 studies; RR per 0·5 g/d = 0·93, 95 % CI = 0·83, 1·04) and circulating ALA biomarker levels (n = 6 studies; RR per 0·1 % of total fatty acid = 0·90, 95 % CI = 0·80, 1·00, P = 0·06) were associated with non-significant trend towards lower risk of DM. Substantial heterogeneity (I²~80 %) was observed among studies of fish/seafood or EPA+DHA and DM; moderate heterogeneity ( < 55 %) was seen for dietary and biomarker ALA and DM. In unadjusted meta-regressions, study location (Asia vs. North America/Europe), mean BMI, and duration of follow-up each modified the association between fish/seafood and EPA+DHA consumption and DM risk (P-interaction ≤ 0·02 each). We had limited statistical power to determine the independent effect of these sources of heterogeneity due to their high collinearity. The overall pooled findings do not support either major harms or benefits of fish/seafood or EPA+DHA on development of DM, and suggest that ALA may be associated with modestly lower risk. Reasons for potential heterogeneity of effects, which could include true biologic heterogeneity, publication bias, or chance, deserve further investigation.
Topics: Animals; Diabetes Mellitus, Type 2; Diet; Dietary Fats; Fatty Acids, Omega-3; Fishes; Humans; Plant Oils; Seafood
PubMed: 22591895
DOI: 10.1017/S0007114512001602 -
Nutrition & Metabolism Jun 2011Linoleic acid, with a DRI of 12-17 g/d, is the most highly consumed polyunsaturated fatty acid in the Western diet and is found in virtually all commonly consumed foods....
BACKGROUND
Linoleic acid, with a DRI of 12-17 g/d, is the most highly consumed polyunsaturated fatty acid in the Western diet and is found in virtually all commonly consumed foods. The concern with dietary linoleic acid, being the metabolic precursor of arachidonic acid, is its consumption may enrich tissues with arachidonic acid and contribute to chronic and overproduction of bioactive eicosanoids. However, no systematic review of human trials regarding linoleic acid consumption and subsequent changes in tissue levels of arachidonic acid has been undertaken.
OBJECTIVE
In this study, we reviewed the human literature that reported changes in dietary linoleic acid and its subsequent impact on changing tissue arachidonic acid in erythrocytes and plasma/serum phospholipids.
DESIGN
We identified, reviewed, and evaluated all peer-reviewed published literature presenting data outlining changes in dietary linoleic acid in adult human clinical trials that reported changes in phospholipid fatty acid composition (specifically arachidonic acid) in plasma/serum and erythrocytes within the parameters of our inclusion/exclusion criteria.
RESULTS
Decreasing dietary linoleic acid by up to 90% was not significantly correlated with changes in arachidonic acid levels in the phospholipid pool of plasma/serum (p = 0.39). Similarly, when dietary linoleic acid levels were increased up to six fold, no significant correlations with arachidonic acid levels were observed (p = 0.72). However, there was a positive relationship between dietary gamma-linolenic acid and dietary arachidonic acid on changes in arachidonic levels in plasma/serum phospholipids.
CONCLUSIONS
Our results do not support the concept that modifying current intakes of dietary linoleic acid has an effect on changing levels of arachidonic acid in plasma/serum or erythrocytes in adults consuming Western-type diets.
PubMed: 21663641
DOI: 10.1186/1743-7075-8-36 -
Phytotherapy Research : PTR Dec 2009Herbal medicinal products (HMPs) that interact with the mediators of inflammation are used in the treatment of rheumatoid arthritis (RA). The aim of this study was to... (Meta-Analysis)
Meta-Analysis Review
Herbal medicinal products (HMPs) that interact with the mediators of inflammation are used in the treatment of rheumatoid arthritis (RA). The aim of this study was to update a previous systematic review published in 2000. We searched electronic databases (MEDLINE, EMBASE, CISCOM, AMED, CINAHL, Cochrane registers) to June 2007, unrestricted by date or language, and included randomized controlled trials that compared HMPs with inert (placebo) or active controls in patients with rheumatoid arthritis. Five reviewers contributed to data extraction. Disagreements were discussed and resolved by consensus with reference to Cochrane guidelines and advice from the Cochrane Collaboration. Twenty studies (10 identified for this review update, and 10 of the 11 studies of the original review) investigating 14 HMPs were included. Meta-analysis was restricted to data from previous seven studies with oils from borage, blackcurrant and evening primrose containing gamma linolenic acid (GLA). GLA doses equal or higher than 1400 mg/day showed benefit in the alleviation of rheumatic complaints whereas lower doses ( approximately 500 mg) were ineffective. Three studies compared products from Tripterygium wilfordii (thunder god vine) to placebos and returned favorable results but data could not be pooled because the interventions and measures differed. Serious adverse effects occurred in one study. In a follow-up study all side effects were mild to moderate and resolved after the intervention ceased, but time to resolution was variable. Two studies comparing Phytodolor NR to placebo were of limited use because some measures were poorly defined. The remaining studies, each considering differing HMPs, were assessed individually. For most HMPs used in the treatment of RA, the evidence of effectiveness was insufficient to either recommend or discourage their use. Interventions with HMPs containing GLA or Tripterygium wilfordii extract appear to produce therapeutic effects but further investigations are warranted to prove their effectiveness and safety.
Topics: Arthritis, Rheumatoid; Herbal Medicine; Humans; Phytotherapy; Plant Extracts; Randomized Controlled Trials as Topic; Tripterygium; gamma-Linolenic Acid
PubMed: 19941324
DOI: 10.1002/ptr.3006 -
The American Journal of Clinical... May 2009alpha-Linolenic acid (ALA; 18:3n-3) has been associated inconsistently with an increased risk of prostate cancer. Additional studies have become available since the... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
alpha-Linolenic acid (ALA; 18:3n-3) has been associated inconsistently with an increased risk of prostate cancer. Additional studies have become available since the publication of 2 previous meta-analyses.
OBJECTIVE
The objective was to review the published data on the relation between ALA and prostate cancer.
DESIGN
We conducted a systematic review to identify studies that included data on ALA and risk of prostate cancer. Data were pooled from studies that compared the highest ALA quantile with the lowest ALA quantile, and risk estimates were combined by using a random-effects model.
RESULTS
The relation between ALA and prostate cancer is inconsistent across studies. We pooled data from 8 case-control and 8 prospective studies. The summary estimate revealed that high ALA dietary intakes or tissue concentrations are weakly associated with prostate cancer risk (relative risk [RR]: 1.20; 95% CI: 1.01, 1.43). When examined by study type (ie, retrospective compared with prospective or dietary ALA compared with tissue concentration) or by decade of publication, only the 6 studies examining blood or tissue ALA concentrations revealed a statistically significant association. With the exception of these studies, there was significant heterogeneity and evidence of publication bias. After adjustment for publication bias, there was no association between ALA and prostate cancer (RR: 0.96; 95% CI: 0.79, 1.17).
CONCLUSIONS
Studies examining the relation between ALA and prostate cancer have produced inconsistent findings. High ALA intakes or high blood and adipose tissue concentrations of ALA may be associated with a small increased risk of prostate cancer. However, these conclusions are qualified because of the heterogeneity across studies and the likelihood of publication bias.
Topics: Adipose Tissue; Case-Control Studies; Humans; Male; Odds Ratio; Prospective Studies; Prostatic Neoplasms; Reproducibility of Results; Risk Factors; alpha-Linolenic Acid
PubMed: 19321563
DOI: 10.3945/ajcn.2009.26736E -
The American Journal of Clinical... Jul 2006Studies on the relation between dietary n-3 fatty acids (FAs) and cardiovascular disease vary in quality, and the results are inconsistent. A systematic review of the... (Meta-Analysis)
Meta-Analysis Review
n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review.
Studies on the relation between dietary n-3 fatty acids (FAs) and cardiovascular disease vary in quality, and the results are inconsistent. A systematic review of the literature on the effects of n-3 FAs (consumed as fish or fish oils rich in eicosapentaenoic acid and docosahexaenoic acid or as alpha-linolenic acid) on cardiovascular disease outcomes and adverse events was conducted. Studies from MEDLINE and other sources that were of > or =1 y in duration and that reported estimates of fish or n-3 FA intakes and cardiovascular disease outcomes were included. Secondary prevention was addressed in 14 randomized controlled trials (RCTs) of fish-oil supplements or of diets high in n-3 FAs and in 1 prospective cohort study. Most trials reported that fish oil significantly reduced all-cause mortality, myocardial infarction, cardiac and sudden death, or stroke. Primary prevention of cardiovascular disease was reported in 1 RCT, in 25 prospective cohort studies, and in 7 case-control studies. No significant effect on overall deaths was reported in 3 RCTs that evaluated the effects of fish oil in patients with implantable cardioverter defibrillators. Most cohort studies reported that fish consumption was associated with lower rates of all-cause mortality and adverse cardiac outcomes. The effects on stroke were inconsistent. Evidence suggests that increased consumption of n-3 FAs from fish or fish-oil supplements, but not of alpha-linolenic acid, reduces the rates of all-cause mortality, cardiac and sudden death, and possibly stroke. The evidence for the benefits of fish oil is stronger in secondary- than in primary-prevention settings. Adverse effects appear to be minor.
Topics: Cardiovascular Diseases; Case-Control Studies; Cohort Studies; Dietary Supplements; Evidence-Based Medicine; Fatty Acids, Omega-3; Fish Oils; Humans; Primary Prevention; Randomized Controlled Trials as Topic; Retrospective Studies; Seafood; Treatment Outcome; alpha-Linolenic Acid
PubMed: 16825676
DOI: 10.1093/ajcn/84.1.5 -
BMJ (Clinical Research Ed.) Dec 2005To assess the clinical evidence on the effectiveness of any medical intervention for preventing or treating alcohol hangover. (Review)
Review
OBJECTIVE
To assess the clinical evidence on the effectiveness of any medical intervention for preventing or treating alcohol hangover.
DATA SOURCES
Systematic searches on Medline, Embase, Amed, Cochrane Central, the National Research Register (UK), and ClincalTrials.gov (USA); hand searches of conference proceedings and bibliographies; contact with experts and manufacturers of commercial preparations. Language of publication was not restricted.
STUDY SELECTION AND DATA EXTRACTION
All randomised controlled trials of any medical intervention for preventing or treating alcohol hangover were included. Trials were considered if they were placebo controlled or controlled against a comparator intervention. Titles and abstracts of identified articles were read and hard copies were obtained. The selection of studies, data extraction, and validation were done independently by two reviewers. The Jadad score was used to evaluate methodological quality.
RESULTS
Fifteen potentially relevant trials were identified. Seven publications failed to meet all inclusion criteria. Eight randomised controlled trials assessing eight different interventions were reviewed. The agents tested were propranolol, tropisetron, tolfenamic acid, fructose or glucose, and the dietary supplements Borago officinalis (borage), Cynara scolymus (artichoke), Opuntia ficus-indica (prickly pear), and a yeast based preparation. All studies were double blind. Significant intergroup differences for overall symptom scores and individual symptoms were reported only for tolfenamic acid, gamma linolenic acid from B officinalis, and a yeast based preparation.
CONCLUSION
No compelling evidence exists to suggest that any conventional or complementary intervention is effective for preventing or treating alcohol hangover. The most effective way to avoid the symptoms of alcohol induced hangover is to practise abstinence or moderation.
Topics: Alcoholic Intoxication; Complementary Therapies; Humans; Randomized Controlled Trials as Topic; Substance Withdrawal Syndrome
PubMed: 16373736
DOI: 10.1136/bmj.331.7531.1515 -
Heart (British Cardiac Society) Feb 2006To determine whether dietary supplementation with alpha linolenic acid (ALA) can modify established and emerging cardiovascular risk markers. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To determine whether dietary supplementation with alpha linolenic acid (ALA) can modify established and emerging cardiovascular risk markers.
DESIGN
Systematic review and meta-analysis of randomised controlled trials identified by a search of Medline, Embase, Cochrane Controlled Trials Register (CENTRAL), and the metaRegister of Controlled Trials (mRCT).
PATIENTS
All human studies were reviewed.
MAIN OUTCOME MEASURES
Changes in concentrations of total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, very low density lipoprotein (VLDL) cholesterol, triglyceride, fibrinogen, and fasting plasma glucose, and changes in body mass index, weight, and systolic and diastolic blood pressure.
RESULTS
14 studies with minimum treatment duration of four weeks were reviewed. ALA had a significant effect on three of the 32 outcomes examined in these studies. Concentrations of fibrinogen (0.17 micromol/l, 95% confidence interval (CI) -0.30 to -0.04, p = 0.01) and fasting plasma glucose (0.20 mmol/l, 95% CI -0.30 to -0.10, p < 0.01) were reduced. There was a small but clinically unimportant decrease in HDL (0.01 mmol/l, 95% CI -0.02 to 0.00, p < 0.01). Treatment with ALA did not significantly modify total cholesterol, triglycerides, weight, body mass index, LDL, diastolic blood pressure, systolic blood pressure, VLDL, and apolipoprotein B.
CONCLUSIONS
Although ALA supplementation may cause small decreases in fibrinogen concentrations and fasting plasma glucose, most cardiovascular risk markers do not appear to be affected. Further trials are needed, but dietary supplementation with ALA to reduce cardiovascular disease cannot be recommended.
Topics: Blood Glucose; Blood Pressure; Body Weight; Cardiovascular Diseases; Cholesterol; Dietary Supplements; Fibrinogen; Humans; Risk Factors; Triglycerides; alpha-Linolenic Acid
PubMed: 15890766
DOI: 10.1136/hrt.2004.053538