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Advances in Nutrition (Bethesda, Md.) Nov 2023Overweight and obesity are highly prevalent worldwide and are associated with cardiovascular disease (CVD) risk factors, including systematic inflammation, dyslipidemia,... (Meta-Analysis)
Meta-Analysis Review
Effect of Alpha-Linolenic Acid Supplementation on Cardiovascular Disease Risk Profile in Individuals with Obesity or Overweight: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Overweight and obesity are highly prevalent worldwide and are associated with cardiovascular disease (CVD) risk factors, including systematic inflammation, dyslipidemia, and hypertension. Alpha-linolenic acid (ALA) is a plant-based essential polyunsaturated fatty acid associated with reduced CVD risks. This systematic review and meta-analysis aimed to investigate the effects of supplementation with ALA compared with the placebo on CVD risk factors in people with obesity or overweight (International Prospective Register of Systematic Reviews Registration No. CRD42023429563). This review included studies with adults using oral supplementation or food or combined interventions containing vegetable sources of ALA. All studies were randomly assigned trials with parallel or crossover designs. The Cochrane Collaboration tool was used for assessing the risk of bias (Version 1). PubMed, Web of Science, Embase, and Cochrane library databases were searched from inception to April 2023. Nineteen eligible randomized controlled trials, including 1183 participants, were included in the meta-analysis. Compared with placebo, dietary ALA supplementation significantly reduced C-reactive protein concentration (standardized mean difference [SMD] = -0.38 mg/L; 95% confidence interval [CI]: -0.72, -0.04), tumor necrosis factor-α concentration (SMD = -0.45 pg/mL; 95% CI: -0.73, -0.17), triglyceride in serum (SMD = -4.41 mg/dL; 95% CI: -5.99, -2.82), and systolic blood pressure (SMD = -0.37 mm Hg; 95% CI: -0.66, -0.08); but led to a significant increase in low-density lipoprotein cholesterol concentrations (SMD = 1.32 mg/dL; 95% CI: 0.05, 2.59). ALA supplementation had no significant effect on interleukin-6, diastolic blood pressure, total cholesterol, or high-density lipoprotein cholesterol (all P ≥ 0.05). Subgroup analysis revealed that ALA supplementation at a dose of ≥3 g/d from flaxseed and flaxseed oil had a more prominent effect on improving CVD risk profiles, particularly where the intervention duration was ≥12 wk and where the baseline CVD profile was poor.
Topics: Adult; Humans; Cardiovascular Diseases; alpha-Linolenic Acid; Overweight; Randomized Controlled Trials as Topic; Cholesterol, HDL; Obesity; Dietary Supplements
PubMed: 37778442
DOI: 10.1016/j.advnut.2023.09.010 -
Frontiers in Nutrition 2021The association between α-linolenic acid (ALA) and mortality is inconsistent and has not been summarized systematically. The purpose was to conduct a meta-analysis...
The association between α-linolenic acid (ALA) and mortality is inconsistent and has not been summarized systematically. The purpose was to conduct a meta-analysis that synthesized the results of prospective cohort studies to investigate associations between ALA intake and mortality. We conducted a comprehensive search on PubMed, Embase, and Web of Science databases on May 1, 2021, for relevant prospective cohort studies which reported associations of ALA (assessed by dietary surveys and/or ALA concentrations in body tissues) with mortality from all-cause, cardiovascular disease (CVD), and other diseases. Multivariable-adjusted relative risks (RRs) were pooled by a random or fixed-effects model. A total of 34 prospective cohort studies, of which 17 reported dietary ALA intake, 14 for ALA biomarkers, and the remaining 3 reported both of intake and biomarkers. The studies included 6,58,634 participants, and deaths were classified into all-cause mortality (56,898), CVD mortality (19,123), and other diseases mortality (19,061). Pooled RRs of ALA intake were 0.93 (95% CI: 0.86, 1.01, = 71.2%) for all-cause mortality, 0.90 (95% CI: 0.83, 0.98, = 22.1%) for CVD mortality, and 0.94 (95% CI: 0.83, 1.06, = 73.3%) for other diseases mortality. The two-stage random-effects dose-response analysis showed a linear relationship between dietary ALA intake and CVD-mortality and each 0.5% energy increment of ALA intake was associated with a 5% lower risk of CVD-mortality (RR: 0.95; 95% CI: 0.90, 1.00). Pooled RRs per SD increment of ALA biomarkers were 0.99 (95% CI: 0.96, 1.01, = 27%) for all-cause mortality, 1.00 (95% CI: 0.98, 1.03, = 0%) for CVD mortality and 0.98 (95% CI: 0.95, 1.01, = 0%) for other diseases mortality. This meta-analysis summarizing the available prospective cohort studies indicated that ALA intake was associated with reduced risk of mortality, especially CVD mortality. Our findings suggest that ALA consumption may be beneficial for death prevention. https://www.crd.york.ac.uk/PROSPERO; identifier: CRD42021264532.
PubMed: 34805241
DOI: 10.3389/fnut.2021.743852 -
Critical Reviews in Food Science and... Aug 2023We aimed to review the association of dietary fats and risk of coronary events in adults. We searched PubMed, Embase, CENTRAL, Scopus, and Web of Sciences to April 2022... (Review)
Review
Dietary intake, biomarkers and supplementation of fatty acids and risk of coronary events: a systematic review and dose-response meta-analysis of randomized controlled trials and prospective observational studies.
We aimed to review the association of dietary fats and risk of coronary events in adults. We searched PubMed, Embase, CENTRAL, Scopus, and Web of Sciences to April 2022 for prospective cohorts and randomized trials investigating the association of dietary intake and biomarkers of fats and fatty acid interventions and the risk of coronary events. We performed random-effects meta-analyses to estimate relative risk (RR) for the top versus bottom tertiles of exposures. One-hundered sixty-five prospective cohorts and randomized trials were included. Dietary intake and biomarkers of total fat and saturated, monounsaturated, and polyunsaturated fatty acids were not associated with the risk of coronary events. Dietary intake of trans fatty acids, palmitic acid, stearic acid, and saturated fatty acids from meat and unprocessed meat was modestly associated with a higher risk and, in contrast, intake of alpha-linolenic acid, long-chain omega-3 fatty acids, and linoleic acid was modestly associated with a lower risk. Supplementation with long-chain omega-3 fatty acids and increasing the consumption of alpha-linolenic and linoleic acids in place of saturated fats reduced the risk of coronary events. Existing evidence, in its totality, provides a modest support in favor of current recommendations suggesting replacement of saturated fats with polyunsaturated fats.
PubMed: 37632423
DOI: 10.1080/10408398.2023.2251583 -
Nutrients Nov 2022The health benefits of omega-3 fatty acid (FA) supplementation on inflammatory gene expression (IGE) and multiple sclerosis (MS) are becoming more evident. However, an... (Meta-Analysis)
Meta-Analysis Review
The health benefits of omega-3 fatty acid (FA) supplementation on inflammatory gene expression (IGE) and multiple sclerosis (MS) are becoming more evident. However, an overview of the results from randomized controlled trials is lacking. This study aimed to conduct a meta-analysis to evaluate the effect of omega-3 fatty acid intake on MS (based on the criteria of the Expanded Disability Status Scale (EDSS)) and inflammatory gene expression (IGE). A search was conducted of PubMed, EMBASE, and Web of Science for cohort studies published from the inception of the database up to May 2022 that assessed the associations of omega-3 polyunsaturated fatty acids (n-3 PUFAs), docosahexaenoic acid (DHA), α-linolenic acid (ALA), and eicosapentaenoic acid (EPA) with EDSS and inflammatory gene expression (peroxisome proliferator-activated receptor gamma (PPAR-γ), tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and interleukin-8 (IL-8)) outcomes. For the highest vs. lowest comparison, the relative risk (RR) estimates with a 95% confidence interval (CI) were pooled using the random-effect model. In total, 13 cohort studies with 1353 participants were included in the meta-analysis during periods of 3 to 144 weeks. A significant inverse relationship was found between DHA and EDSS scores (RR: 1.05; 95% CI: 0.62, 1.48; p < 0.00001). Our results also showed that omega-3 FAs significantly upregulated the gene expression of PPAR-γ (RR: 0.95; 95% CI: 0.52, 1.38; p < 0.03) and downregulated the expression of TNF-α (RR: −0.15; 95% CI: −0.99, 0.70; p < 0.00001) and IL-1 (RR: −0.60; 95% CI: −1.02, −0.18; p < 0.003). There was no clear evidence of publication bias with Egger’s tests for inflammatory gene expression (p = 0.266). Moreover, n-3 PUFAs and EPA were not significantly associated with EDSS scores (p > 0.05). In this meta-analysis of cohort studies, blood omega-3 FA concentrations were inversely related to inflammatory gene expression (IGE) and EDSS score, which indicates that they may hold great potential markers for the diagnosis, prognosis, and management of MS. However, further clinical trials are required to confirm the potential effects of the omega-3 FAs on MS disease management.
Topics: Humans; Multiple Sclerosis; Tumor Necrosis Factor-alpha; Peroxisome Proliferator-Activated Receptors; Fatty Acids, Omega-3; Eicosapentaenoic Acid; Docosahexaenoic Acids; Interleukin-1; Gene Expression; Immunoglobulin E
PubMed: 36364885
DOI: 10.3390/nu14214627 -
European Journal of Nutrition Aug 2021Effects of long-chain omega-3 (LCn3) and omega-6 fatty acids on prevention and treatment of inflammatory bowel diseases (IBD, including Crohn's Disease, CD and... (Meta-Analysis)
Meta-Analysis Review
Long-term effects of increasing omega-3, omega-6 and total polyunsaturated fats on inflammatory bowel disease and markers of inflammation: a systematic review and meta-analysis of randomized controlled trials.
BACKGROUND AND AIM
Effects of long-chain omega-3 (LCn3) and omega-6 fatty acids on prevention and treatment of inflammatory bowel diseases (IBD, including Crohn's Disease, CD and ulcerative colitis, UC), and inflammation are unclear. We systematically reviewed long-term effects of omega-3, omega-6 and total polyunsaturated fats (PUFA) on IBD diagnosis, relapse, severity, pharmacotherapy, quality of life and key inflammatory markers.
METHODS
We searched Medline, Embase, Cochrane CENTRAL, and trials registries, including RCTs in adults with or without IBD comparing higher with lower omega-3, omega-6 and/or total PUFA intake for ≥ 24 weeks that assessed IBD-specific outcomes or inflammatory biomarkers.
RESULTS
We included 83 RCTs (41,751 participants), of which 13 recruited participants with IBD. Increasing LCn3 may reduce risk of IBD relapse (RR 0.85, 95% CI 0.72-1.01) and IBD worsening (RR 0.85, 95% CI 0.71-1.03), and reduce erythrocyte sedimentation rate (ESR, SMD - 0.23, 95% CI - 0.44 to - 0.01), but may increase IBD diagnosis risk (RR 1.10, 95% CI 0.63-1.92), and faecal calprotectin, a specific inflammatory marker for IBD (MD 16.1 μg/g, 95% CI - 37.6 to 69.8, all low-quality evidence). Outcomes for alpha-linolenic acid, omega-6 and total PUFA were sparse, but suggested little or no effect where data were available.
CONCLUSION
This is the most comprehensive meta-analysis of RCTs investigating long-term effects of omega-3, omega-6 and total PUFA on IBD and inflammatory markers. Our findings suggest that supplementation with PUFAs has little or no effect on prevention or treatment of IBD and provides little support for modification of long-term inflammatory status.
Topics: Adult; Biomarkers; Fatty Acids, Omega-3; Humans; Inflammation; Inflammatory Bowel Diseases; Quality of Life; Randomized Controlled Trials as Topic
PubMed: 33084958
DOI: 10.1007/s00394-020-02413-y -
International Journal of Molecular... Sep 2023The objective of this meta-analysis was to examine the impact of a low-ratio linoleic acid/α-linolenic acid (LA/ALA) diet on the glycemic profile of adults. A... (Meta-Analysis)
Meta-Analysis Review
The objective of this meta-analysis was to examine the impact of a low-ratio linoleic acid/α-linolenic acid (LA/ALA) diet on the glycemic profile of adults. A comprehensive search was performed across four databases (Web of Science, Scopus, Embase, and PubMed) to evaluate the influence of the low-ratio LA/ALA. Relevant references were screened up until February 2023. Intervention effects were analyzed by calculating change values as weighted mean differences (WMD) and 95% confidence intervals (CI) using fixed-effects models. Additionally, subgroup analysis and meta-regression were employed to investigate potential sources of heterogeneity. Twenty-one randomized controlled trials (RCTs) were included, and the low-ratio LA/ALA diet had no significant effect on fasting blood sugar (FBS, WMD: 0.00 mmol/L, 95% CI: -0.06, 0.06, = 0.989, I = 0.0%), insulin levels (WMD: 0.20 μIU/mL, 95% CI: -0.23, 0.63, = 0.360, I = 3.2%), homeostatic model assessment insulin resistance (HOMA-IR, WMD: 0.09, 95% CI: -0.06, 0.23, = 0.243, I = 0.0%), and hemoglobin A1c (HbA1c, WMD: -0.01%, 95% CI: -0.07, 0.06, = 0.836, I = 0.0%). Based on subgroup analyses, it was observed that the impact of a low-ratio LA/ALA diet on elevated plasma insulin (WMD: 1.31 μIU/mL, 95% CI: 0.08, 2.54, = 0.037, I = 32.0%) and HOMA-IR (WMD: 0.47, 95% CI: 0.10, 0.84, = 0.012, I = 0.0%) levels exhibited greater prominence in North America compared to Asian and European countries. Publication bias was not detected for FBS, insulin, HOMA-IR, and HbA1c levels according to the Begg and Egger tests. Furthermore, the conducted sensitivity analyses indicated stability, as the effects of the low-ratio LA/ALA diet on various glycemic and related metrics remained unchanged even after removing individual studies. Overall, based on the available studies, it can be concluded that the low-ratio LA/ALA diet has limited impact on blood glucose-related biomarker levels.
Topics: Adult; Humans; Glycated Hemoglobin; Linoleic Acid; alpha-Linolenic Acid; Glucose; Insulin
PubMed: 37762686
DOI: 10.3390/ijms241814383 -
International Journal of Preventive... 2018The evidence on the association between omega-3 consumption and epileptic seizure is inconsistent. Therefore, we have conducted this systematic review to clarify the... (Review)
Review
The evidence on the association between omega-3 consumption and epileptic seizure is inconsistent. Therefore, we have conducted this systematic review to clarify the possible relationship. Original articles were searched in electronic databases (PubMed, Scopus, Google Scholar, Cochrane, and Ovid) and by reviewing the reference lists of retrieved articles. The main evaluated outcome was the epileptic seizures. We included the English language studies that reported the original data on the effect of omega-3 on epileptic human patients. We included the nine articles with 230 patients in the present systematic review. The mean ± standard deviation age of them was about 31.01 ± 14.99 years. The average of study duration was 22 ± 15.27 weeks. Omega-3 fatty acid supplements were defined as the sum of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) (1100 mg/d); as the sum of EPA, DHA, and alpha-linolenic acid (5 g/d); and as the sum of EPA alone (565 mg/d) in different studies. Among the nine studies, four studies reported a significant positive association between omega-3 fatty acids and epileptic seizures. However, power and quality of these studies are low, and we cannot consider the beneficial effect of omega-3 on seizures. In addition, five studies did not reveal any significant effect. Majority of the included studies did not show a significant association between omega-3 and epileptic seizure in epileptic patients, but further studies are necessary. It is controversial whether omega-3 fatty acids can produce positive effects on epileptic patients or not.
PubMed: 29721237
DOI: 10.4103/ijpvm.IJPVM_281_16 -
Prostaglandins, Leukotrienes, and... Mar 2019Eating disorders result in poor nutrition, poor physical conditions and even suicidality and mortality. Although polyunsaturated fatty acids (PUFAs) have attracted... (Meta-Analysis)
Meta-Analysis
OBJECTIVES
Eating disorders result in poor nutrition, poor physical conditions and even suicidality and mortality. Although polyunsaturated fatty acids (PUFAs) have attracted attention in the emerging field of nutritional psychiatry, their role in eating disorders remains unknown. This meta-analysis investigates the differences of PUFA levels between patients with eating disorders and healthy controls, and the potentially beneficial effects of PUFAs in such patients.
METHODS
We conducted a systematic literature search and meta-analysis under the random effects model.
RESULT
Eleven studies were included in the current meta-analysis. Compared with controls, 379 patients with eating disorders had significantly higher plasma levels of alpha-linolenic acid, eicosapentaenoic acid, stearidonic acid, osbond acid, palmitoleic acid, oleic acid, and total omega-3 fatty acids; and lower levels of total omega-6 fatty acids and omega-6/omega-3 ratio. Eating disorders were associated with significantly higher red blood cell membrane levels of palmitoleic acid and oleic acid and lower levels of adrenic acid, arachidonic acid, and total omega-6 fatty acids. In addition, PUFA supplements were associated with a benefit to body weight outcomes but not disease severity and mood symptoms in interventional trials.
DISCUSSION
This meta-analysis indicates abnormal levels of PUFAs in peripheral blood tissues in patients with eating disorders. The relationship between PUFAs and eating disorders should be interpreted cautiously considering the specific lipid metabolism under starvation state. To investigate the role of PUFAs on psychopathological and therapeutic effects in eating disorders, further larger clinical studies are warranted.
Topics: Adolescent; Adult; Affect; Body Mass Index; Dietary Supplements; Erythrocyte Membrane; Fatty Acids, Unsaturated; Feeding and Eating Disorders; Female; Humans; Male; Middle Aged; Observational Studies as Topic; Severity of Illness Index; Starvation; Young Adult
PubMed: 30773209
DOI: 10.1016/j.plefa.2019.01.001 -
Journal of the American Medical... Oct 2020Neurocognitive function may be influenced by polyunsaturated fat intake. Many older adults consume omega-3 supplements hoping to prevent cognitive decline. We assessed... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
Neurocognitive function may be influenced by polyunsaturated fat intake. Many older adults consume omega-3 supplements hoping to prevent cognitive decline. We assessed effects of increasing omega-3, omega-6, or total polyunsaturated fats on new neurocognitive illness and cognition.
DESIGN AND INCLUSION CRITERIA
We carried out a systematic review and meta-analysis of randomized controlled trials (RCTs) in adults, with duration ≥24 weeks, assessing effects of higher vs lower omega-3, omega-6, or total polyunsaturated fats and outcomes: new neurocognitive illness, newly impaired cognition, and/or continuous measures of cognition.
METHODS
We searched MEDLINE, Embase, Cochrane CENTRAL, and trials registers (final update of ongoing trials December 2018). We duplicated screening, data extraction, and risk of bias assessment. Neurocognitive measures were grouped to enable random effects meta-analysis. GRADE assessment, sensitivity analyses, and subgrouping by dose, duration, type of intervention, and replacement were used to interrogate our findings.
RESULTS
Searches generated 37,810 hits, from which we included 38 RCTs (41 comparisons, 49,757 participants). Meta-analysis suggested no or very little effect of long-chain omega-3 on new neurocognitive illness [risk ratio (RR) 0.98, 95% confidence interval (CI) 0.87-1.10, 6 RCTs, 33,496 participants, I 36%), new cognitive impairment (RR 0.99, 95% CI 0.92-1.06, 5 RCTs, 33,296 participants, I 0%) or global cognition assessed using the Mini-Mental State Examination (MD 0.10, 95% CI 0.03-0.16, 13 RCTs, 14,851 participants, I 0%), all moderate-quality evidence. Effects did not differ with sensitivity analyses, and we found no differential effects by dose, duration, intervention type, or replacement. Effects of increasing α-linolenic acid, omega-6, or total PUFA were unclear.
CONCLUSIONS
This extensive trial data set enabled assessment of effects on neurocognitive illness and cognitive decline not previously adequately assessed. Long-chain omega-3 probably has little or no effect on new neurocognitive outcomes or cognitive impairment.
IMPLICATIONS
Long-chain omega-3 supplements do not help older adults protect against cognitive decline.
Topics: Aged; Cardiovascular Diseases; Cognition; Humans; Primary Prevention; Randomized Controlled Trials as Topic; Secondary Prevention
PubMed: 32305302
DOI: 10.1016/j.jamda.2020.02.022 -
The British Journal of Nutrition Mar 2016Demand for organic meat is partially driven by consumer perceptions that organic foods are more nutritious than non-organic foods. However, there have been no systematic... (Comparative Study)
Comparative Study Meta-Analysis Review
Demand for organic meat is partially driven by consumer perceptions that organic foods are more nutritious than non-organic foods. However, there have been no systematic reviews comparing specifically the nutrient content of organic and conventionally produced meat. In this study, we report results of a meta-analysis based on sixty-seven published studies comparing the composition of organic and non-organic meat products. For many nutritionally relevant compounds (e.g. minerals, antioxidants and most individual fatty acids (FA)), the evidence base was too weak for meaningful meta-analyses. However, significant differences in FA profiles were detected when data from all livestock species were pooled. Concentrations of SFA and MUFA were similar or slightly lower, respectively, in organic compared with conventional meat. Larger differences were detected for total PUFA and n-3 PUFA, which were an estimated 23 (95 % CI 11, 35) % and 47 (95 % CI 10, 84) % higher in organic meat, respectively. However, for these and many other composition parameters, for which meta-analyses found significant differences, heterogeneity was high, and this could be explained by differences between animal species/meat types. Evidence from controlled experimental studies indicates that the high grazing/forage-based diets prescribed under organic farming standards may be the main reason for differences in FA profiles. Further studies are required to enable meta-analyses for a wider range of parameters (e.g. antioxidant, vitamin and mineral concentrations) and to improve both precision and consistency of results for FA profiles for all species. Potential impacts of composition differences on human health are discussed.
Topics: Animal Husbandry; Animals; Diet; Evidence-Based Practice; Food, Organic; Humans; Livestock; Meat; Meat Products; Nutritive Value
PubMed: 26878675
DOI: 10.1017/S0007114515005073