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The British Journal of Nutrition Jan 2018Previous studies show inconsistent associations between α-linolenic acid (ALA) and risk of CHD. We aimed to examine an aggregate association between ALA intake and risk... (Meta-Analysis)
Meta-Analysis Review
Previous studies show inconsistent associations between α-linolenic acid (ALA) and risk of CHD. We aimed to examine an aggregate association between ALA intake and risk of CHD, and assess for any dose-response relationship. We searched the PubMed, EMBASE and Web of Science databases for prospective cohort studies examining associations between ALA intake and CHD, including composite CHD and fatal CHD. Data were pooled using random-effects meta-analysis models, comparing the highest category of ALA intake with the lowest across studies. Subgroup analysis was conducted based on study design, geographic region, age and sex. For dose-response analyses, we used two-stage random-effects dose-response models. In all, fourteen studies of thirteen cohorts were identified and included in the meta-analysis. The pooled results showed that higher ALA intake was associated with modest reduced risk of composite CHD (risk ratios (RR)=0·91; 95 % CI 0·85, 0·97) and fatal CHD (RR=0·85; 95 % CI 0·75, 0·96). The analysis showed a J-shaped relationship between ALA intake and relative risk of composite CHD (χ 2=21·95, P<0·001). Compared with people without ALA intake, only people with ALA intake <1·4 g/d showed reduced risk of composite CHD. ALA intake was linearly associated with fatal CHD - every 1 g/d increase in ALA intake was associated with a 12 % decrease in fatal CHD risk (95 % CI -0·21, -0·04). Though a higher dietary ALA intake was associated with reduced risk of composite and fatal CHD, the excess composite CHD risk at higher ALA intakes warrants further investigation, especially through randomised controlled trials.
Topics: Adult; Aged; Cohort Studies; Coronary Disease; Diet; Dose-Response Relationship, Drug; Female; Humans; Linear Models; Male; Middle Aged; Odds Ratio; Prospective Studies; Randomized Controlled Trials as Topic; Risk Factors; alpha-Linolenic Acid
PubMed: 29355094
DOI: 10.1017/S0007114517003294 -
Medicine May 2017Polyunsaturated fats (PUFAs) have been shown to reduce type 2 diabetes (T2DM) risk and improve insulin responsiveness in T2DM subjects, but whether the plant sources of... (Meta-Analysis)
Meta-Analysis Review
The effect of alpha-linolenic acid on glycemic control in individuals with type 2 diabetes: A systematic review and meta-analysis of randomized controlled clinical trials.
BACKGROUND
Polyunsaturated fats (PUFAs) have been shown to reduce type 2 diabetes (T2DM) risk and improve insulin responsiveness in T2DM subjects, but whether the plant sources of omega-3 PUFA (alpha-linolenic acid [ALA]) have an effect on glycemic control requires further investigation.
METHODS
The parameters of interest were glycated hemoglobin (HbA1c), fasting blood glucose (FBG), fasting blood insulin (FBI), homeostatic model assessment for insulin resistance (HOMA-IR), fructosamine, and glycated albumin. A comprehensive search was conducted with MEDLINE, Embase, CINAHL, and Cochrane. Eligible studies included randomized controlled trials (RCTs) ≥1 month in duration that compared diets enriched in ALA with usual diets on glycemic parameters. For each study, the risk of bias as well as the study quality was assessed. Using the statistical software RevMan (v5.3), data were pooled using the generic inverse method with random effects model, and final results were expressed as mean differences (MD) with 95% confidence intervals (CI). Heterogeneity was assessed by the Cochran Q statistic and quantified by the I statistic.
RESULTS
A total of 8 trials (N = 212) were included in the meta-analysis. Compared to a control diet, a median dose of 4.4 g/day of ALA intake for a median duration of 3 months did not affect HbA1c (%) (MD = -.01; [95%: -.32, .31], P = .96). A median ALA dose of 5.4 g/day did not lower FBG (MD = .07; [95% CI: -.61, .76], P = .84) or FBI (MD = 7.03, [95% CI: -5.84, 19.89], P = .28). Summary effect estimates were generally compromised by considerable and unexplained heterogeneity (I ≥75%). In the subgroup analysis of continuous predictors, a reduction in HbA1c (%) and FBG (mmol/L) was significantly associated with an increased intake of ALA. Further adjustment for Publication Bias using Duval and Tweedie's trim-and-fill analysis provided an adjusted, significant MD of -.25 (95% CI: -.38, -.12; P <.001) for HbA1c (%).
CONCLUSIONS
ALA-enriched diets did not affect HbA1c, FBG, or FBI. The scarce number of existing RCTs and the presence of heterogeneity in our meta-analysis limit the ability to make firm conclusions about ALA in T2DM management. The potential for ALA to have dose-dependent effects warrants further research in this area.
Topics: Diabetes Mellitus, Type 2; Humans; Randomized Controlled Trials as Topic; alpha-Linolenic Acid
PubMed: 28538363
DOI: 10.1097/MD.0000000000006531 -
Annals of Nutrition & Metabolism 2017Earlier reviews indicated that in many countries adults, children and adolescents consume on an average less polyunsaturated fatty acids (PUFAs) than recommended by the... (Review)
Review
BACKGROUND
Earlier reviews indicated that in many countries adults, children and adolescents consume on an average less polyunsaturated fatty acids (PUFAs) than recommended by the Food and Agriculture Organisation/World Health Organisation.
SUMMARY
The intake of total and individual n-3 and n-6 PUFAs in European infants, children, adolescents, elderly and pregnant/lactating women was evaluated systematically.
RESULTS
The evaluations were done against recommendations of the European Food Safety Authority. Key Messages: Fifty-three studies from 17 different European countries reported an intake of total n-3 and n-6 PUFAs and/or individual n-3 or n-6 PUFAs in at least one of the specific population groups: 10 in pregnant women, 4 in lactating women, 3 in infants 6-12 months, 6 in children 1-3 years, 11 in children 4-9 years, 8 in adolescents 10-18 years and 11 in elderly >65 years. Mean linoleic acid intake was within the recommendation (4 energy percentage [E%]) in 52% of the countries, with inadequate intakes more likely in lactating women, adolescents and elderly. Mean α-linolenic acid intake was within the recommendation (0.5 E%) in 77% of the countries. In 26% of the countries, mean eicosapentaenoic acid and/or docosahexaenoic acid intake was as recommended. These results indicate that intake of n-3 and n-6 PUFAs may be suboptimal in specific population groups in Europe.
Topics: Adolescent; Aged; Child; Child, Preschool; Dietary Fats, Unsaturated; Europe; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Female; Humans; Infant; Lactation; Male; Milk, Human; Nutrition Policy; Pregnancy
PubMed: 28190013
DOI: 10.1159/000456723 -
Cancers May 2020Several immunotherapy agents are the standard of care of many solid malignancies. Nevertheless, the majority of patients do not benefit from the currently available... (Review)
Review
Several immunotherapy agents are the standard of care of many solid malignancies. Nevertheless, the majority of patients do not benefit from the currently available immunotherapies. It is therefore of paramount importance to identify the prognostic and predictive factors of tumor response/resistance and to design effective therapeutic strategies to overcome primary resistance and improve the efficacy of immunotherapy. The aim of this review is to underline the influence of the tumor and host metabolism on the antitumor immune response and to discuss possible strategies to improve the efficacy of available treatments by targeting the specific metabolic pathways in tumors or immune cells and by modifying patients' nutritional statuses. A systematic search of the Medline and EMBASE databases was carried out to identify scientific papers published until February 2020, which reported original research articles on the influence of tumor or host metabolism on antitumor immune response. The literature data showed the key role of glycolysis and mitochondrial oxidative phosphorylation, arginine, tryptophan, glutamine, lipid metabolism and microbiome on immune cell function. Moreover, specific nutritional behaviors, such as a low dietary intake of vitamin C, low glycemic index and alpha-linolenic acid, eicosapentenoic acid, docosahexaenoic acid, ornithine ketoglutarate, tryptophan and probiotic supplementation were associated with the potential clinical benefits from the currently available immunotherapies.
PubMed: 32375310
DOI: 10.3390/cancers12051153 -
The British Journal of Nutrition Mar 2016Demand for organic milk is partially driven by consumer perceptions that it is more nutritious. However, there is still considerable uncertainty over whether the use of... (Meta-Analysis)
Meta-Analysis Review
Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses.
Demand for organic milk is partially driven by consumer perceptions that it is more nutritious. However, there is still considerable uncertainty over whether the use of organic production standards affects milk quality. Here we report results of meta-analyses based on 170 published studies comparing the nutrient content of organic and conventional bovine milk. There were no significant differences in total SFA and MUFA concentrations between organic and conventional milk. However, concentrations of total PUFA and n-3 PUFA were significantly higher in organic milk, by an estimated 7 (95 % CI -1, 15) % and 56 (95 % CI 38, 74) %, respectively. Concentrations of α-linolenic acid (ALA), very long-chain n-3 fatty acids (EPA+DPA+DHA) and conjugated linoleic acid were also significantly higher in organic milk, by an 69 (95 % CI 53, 84) %, 57 (95 % CI 27, 87) % and 41 (95 % CI 14, 68) %, respectively. As there were no significant differences in total n-6 PUFA and linoleic acid (LA) concentrations, the n-6:n-3 and LA:ALA ratios were lower in organic milk, by an estimated 71 (95 % CI -122, -20) % and 93 (95 % CI -116, -70) %. It is concluded that organic bovine milk has a more desirable fatty acid composition than conventional milk. Meta-analyses also showed that organic milk has significantly higher α-tocopherol and Fe, but lower I and Se concentrations. Redundancy analysis of data from a large cross-European milk quality survey indicates that the higher grazing/conserved forage intakes in organic systems were the main reason for milk composition differences.
Topics: Animals; Cattle; Dairying; Dietary Fats, Unsaturated; Evidence-Based Practice; Fatty Acids, Omega-3; Food, Organic; Humans; Iodine; Iron, Dietary; Linoleic Acids, Conjugated; Livestock; Milk; Nutritive Value; Selenium; alpha-Tocopherol
PubMed: 26878105
DOI: 10.1017/S0007114516000349 -
European Journal of Nutrition Apr 2018The aim of the current meta-analysis was to investigate the effect of increasing dietary ALA intake on the blood concentration of inflammatory markers including tumor... (Meta-Analysis)
Meta-Analysis Review
PURPOSE
The aim of the current meta-analysis was to investigate the effect of increasing dietary ALA intake on the blood concentration of inflammatory markers including tumor necrosis factor (TNF), interleukin 6 (IL-6), C-reactive protein (CRP), soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) in adults.
METHODS
After a systemic search on PubMed, Embase, and Cochrane library and bibliographies of relevant articles, 25 randomized controlled trials that met the inclusion criteria were identified.
RESULTS
No significant effect of dietary ALA supplementation was observed on TNF (SMD: -0.03, 95% CI -0.36 to 0.29), IL-6 (SMD: -0.17, 95% CI -0.46 to 0.12), CRP (SMD: -0.06, 95% CI -0.24 to 0.12), sICAM-1 (SMD: -0.06, 95% CI -0.26 to 0.13), and sVCAM-1 (SMD: -0.24, 95% CI -0.56 to 0.09). Subgroup analysis revealed that increasing dietary ALA tends to elevate CRP concentration in healthy subjects. However, the null effect of ALA supplementation on other inflammatory markers was not changed in various subgroups, indicating that the results are stable. Meta-regression results revealed a negative relationship between the effect size on CRP and its baseline concentration. No significant publication bias was observed for all inflammatory markers as suggested by funnel plot and Begg's test.
CONCLUSION
Our meta-analysis did not find any beneficial effect of ALA supplementation on reducing inflammatory markers including TNF, IL-6, CRP, sICAM-1, and sVCAM-1. However, in healthy subjects, ALA supplementation might increase CRP concentration.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Biomarkers; C-Reactive Protein; Chronic Disease; Dietary Supplements; Evidence-Based Medicine; Humans; Inflammation Mediators; Intercellular Adhesion Molecule-1; Interleukin-6; Randomized Controlled Trials as Topic; Solubility; Tumor Necrosis Factor-alpha; Vascular Cell Adhesion Molecule-1; alpha-Linolenic Acid
PubMed: 28275869
DOI: 10.1007/s00394-017-1386-2 -
Clinical Nutrition (Edinburgh, Scotland) Jun 2022Inflammation and dyslipidemia are traditional risk factors and well-known causes of morbidity and mortality in chronic kidney disease (CKD). Alpha-linolenic acid (ALA),... (Meta-Analysis)
Meta-Analysis
Effects of supplementation with vegetable sources of alpha-linolenic acid (ALA) on inflammatory markers and lipid profile in individuals with chronic kidney disease: A systematic review and meta-analysis.
BACKGROUND AND AIMS
Inflammation and dyslipidemia are traditional risk factors and well-known causes of morbidity and mortality in chronic kidney disease (CKD). Alpha-linolenic acid (ALA), an essential fatty acid mainly found in vegetable sources, has been associated with anti-inflammatory effects and improving lipid profile. This systematic review and meta-analysis investigate the effects of supplementation with vegetable sources of ALA on inflammatory marker and lipid profile in individuals with CKD.
METHODS
This review included studies with adult or elderly patients with CKD, including those receiving dialysis, using oral supplementation or food or combined interventions containing vegetable sources of ALA. All studies were randomized trials and The Cochrane Collaboration's tool was use for assessing risk of bias.
RESULTS
19 studies provided data for meta-analyses. ALA had significant effect on reducing C-reactive protein (CRP) after supplementation (WMD: -1.32; 84.5% CI, -2.35 to -0.29, P = 0.012), on the other hand, had no significant effect on total cholesterol (WMD: -2.85; 90.1% CI, -14.43 to 8.73, P = 0.629), high density lipoprotein (WMD: 1.09; 92.4% CI, -1.82 to 3.99, P = 0.463), low density lipoprotein (WMD: -3.87; 86.7% CI, -12.62 to 4.89, P = 0.387) and triglycerides (WMD: -16.42; 87.7% CI, -47.83 to 14.98, P = 0.305).
CONCLUSION
Vegetables sources of ALA showed beneficial effects on reducing inflammatory marker CRP in CKD patients but had no effect on lipid profile. Future well-designed studies are needed to investigate the effectiveness of vegetables sources of ALA, particularly in CKD.
Topics: Adult; Aged; Biomarkers; C-Reactive Protein; Dietary Supplements; Humans; Renal Dialysis; Renal Insufficiency, Chronic; Vegetables; alpha-Linolenic Acid
PubMed: 35341608
DOI: 10.1016/j.clnu.2022.02.013 -
Food Science & Nutrition Jan 2022Bone metabolism is a complicated process, which involves bone modeling and remodeling. If this process is unbalanced, bone loss and resultant osteoporosis might occur.... (Review)
Review
Bone metabolism is a complicated process, which involves bone modeling and remodeling. If this process is unbalanced, bone loss and resultant osteoporosis might occur. Recently, nutrition supplementations such as n-3 polyunsaturated fatty acids (PUFAs) are considered to be used on improving the bone metabolism and reducing the risk of osteoporosis. To more precisely assess the effects of n-3 PUFA supplementation on bone mass and clarify its potential mechanism, we have conducted a systematic review and meta-analysis. Based on the strict inclusion and exclusion criteria, 12 articles were included in this meta-analysis. The results in articles show that n-3 PUFAs could slightly enhance the level of bone mineral density (BMD) (0.005 g/cm; 95% CI, 0.000-0.010) ( = 7), which was the primary outcome for the research in comparison with the control group. In addition, the results also illustrate that the increasing effect on BMD (0.024 g/cm; 95% CI, 0.020-0.028) became more significant for postmenopausal women. N-3 PUFAs had no significance on the level of bone-specific alkaline phosphatase (BALP) (-0.24 µg/L; 95% CI, -0.86 to 0.39) and osteocalcin (-0.63 μg/L; 95% CI, -1.84 to 0.57) ( = 5), which are the specific markers of bone formation. When compared with the eicosapentaenoic acid + docosahexaenoic acid supplementation, the supplementation form of α-linolenic acid significantly increased the content of BALP (0.396 µg/L; 95% CI, 0.069-0.724). The effects of n-3 PUFAs on bone resorption biomarkers containing type I collagen cross-linked C-terminal peptide (CTX) and type I collagen cross-linked N-terminal peptide (NTX) are considered and used in our study. Results indicated that participants who received n-3 PUFAs significantly decreased the level of CTX in the human body (-0.367 μg/L; 95% CI, -0.726 to -0.007) ( = 4). However, there was no significant difference in NTX levels in humans after supplementation with n-3 PUFA (-1.744 µg/L; 95% CI, -3.970-0.481) ( = 3). For postmenopausal women, it presented a significant decreasing level of CTX (-0.393 µg/L; 95% CI, -0.651 to -0.135) and NTX (-2.082 µg/L; 95% CI, -2.970 to -1.195) within their bodies. In conclusion, these findings suggested that n-3 PUFAs might have a beneficial effect on bone health, especially for α-linolenic acid supplementation form or for postmenopausal women.
PubMed: 35035917
DOI: 10.1002/fsn3.2655 -
Critical Reviews in Food Science and... 2021To investigate the effect of ALA intake on blood lipid profiles, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C),... (Meta-Analysis)
Meta-Analysis
To investigate the effect of ALA intake on blood lipid profiles, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein (VLDL-C) and ratio of TC to HDL-C. We systematically searched randomized controlled trials of ALA intervention on PubMed, Embase, Cochrane library and related references up to March 2018. The final values were calculated as weighted mean difference (WMD) by using a random effects model. Subgroup analysis and meta-regression were used to explore the source of heterogeneity. Generalized least square was performed for dose-response analysis. Forty-seven studies with 1305 individuals in the ALA arm and 1325 individuals in the control arm were identified. Compared with control group, dietary intake of ALA significantly reduced the concentrations of TG (WMD -0.101 mmol/L; 95% CI: -0.158 to -0.044 mmol/L; 0.001), TC (WMD -0.140 mmol/L; 95% CI: -0.224 to -0.056 mmol/L; 0.001), LDL-C (WMD -0.131 mmol/L; 95% CI: -0.191 to -0.071 mmol/L; 0.001), VLDL-C (WMD -0.121 mmol/L; 95% CI: -0.170 to -0.073 mmol/L; 0.001), TC/HDL-C ratio (WMD -0.165 mmol/L; 95% CI: -0.317 to -0.013 mmol/L; 0.033) and LDL-C/HDL-C ratio (WMD -0.158 mmol/L; 95% CI: -0.291 to -0.025 mmol/L; 0.02). There is no effect of ALA intake on HDL-C (WMD 0.008 mmol/L; 95% CI: -0.018 to 0.034 mmol/L; 0.541). Dose-response analysis indicated that 1 g per day increment of ALA was associated with a 0.0016 mmol/L, 0.0071 mmol/L, 0.0015 and 0.0061 mmol/L reduction in TG (95% CI: -0.0029 to -0.0002 mmol/L), TC (95% CI: -0.0085 to -0.0058 mmol/L), HDL-C (95% CI: -0.0020 to -0.0011 mmol/L) and LDL-C (95% CI: -0.0073 to -0.0049 mmol/L) levels, respectively. The effects of ALA intake on TG, TC and LDL-C concentrations were more obvious among Asian participants, and also more obvious on patients with hyperlipidemia or hyperglycemia compared to healthy individuals. Dietary ALA intervention improves blood lipid profiles by decreasing levels of TG, TC, LDL and VLDL-C. Our findings add to the evidence that increasing ALA intake could potentially prevent risk of cardiovascular diseases.
Topics: Cholesterol, HDL; Cholesterol, LDL; Humans; Lipids; Randomized Controlled Trials as Topic; Triglycerides; alpha-Linolenic Acid
PubMed: 32643951
DOI: 10.1080/10408398.2020.1790496 -
Nutrition Research (New York, N.Y.) Feb 2023Flaxseed is a functional food because of its high content of alpha-linolenic acid, lignans, and dietary fiber. We hypothesized that flaxseed supplementation would... (Meta-Analysis)
Meta-Analysis Review
Flaxseed is a functional food because of its high content of alpha-linolenic acid, lignans, and dietary fiber. We hypothesized that flaxseed supplementation would improve cardiometabolic parameters in patients with type 2 diabetes mellitus (T2DM); however, clinical trials have shown conflicting results. Therefore, this systematic review and meta-analysis was conducted to determine the impact of flaxseed supplementation in patients with T2DM. Randomized controlled trials were systematically searched in PubMed, Web of Science, Scopus, Cochrane Library, and Embase until 25 March 2022. A total of 13 studies were included, and the results showed that flaxseed supplementation significantly reduced hemoglobin A1c (HbA1c) in participants with T2DM compared with the control group. In contrast, it had no effects on body weight, body mass index, blood pressure, fasting blood glucose (FBG), homeostatic model assessment for insulin resistance, quantitative insulin sensitivity check index, and lipid parameters. In the subgroup analyses, FBG was significantly reduced with supplementation of flaxseed in participants with baseline FBG ≥8.0 mmol/L or baseline HbA1c ≥7.0%. And a significant decrease in HbA1c in participants with baseline HbA1c ≥7.0% after flaxseed supplementation. In addition, subgroup analyses indicated that whole flaxseed supplementation significantly increased high-density lipoprotein cholesterol and reduced total cholesterol or low-density lipoprotein cholesterol in participants with T2DM. In conclusion, flaxseed supplementation significantly reduced HbA1c in participants with T2DM, especially those with poorly controlled blood sugar levels. However, larger scale studies with better designs are needed to confirm insignificant and/or ambiguous findings.
Topics: Humans; Diabetes Mellitus, Type 2; Glycated Hemoglobin; Flax; Dietary Supplements; Cholesterol; Blood Glucose
PubMed: 36640581
DOI: 10.1016/j.nutres.2022.12.008