Evaluation of the Influence of Whole and Defatted Flaxseed on Satiety, Glucose, and Leptin Levels of Women in the Late Postoperative Stage of Bariatric Surgery

Effects of n-3 polyunsaturated fatty acid supplementation on appetite: a systematic review and meta-analysis of controlled clinical trials

BACKGROUND

The current studies explore the effect of omega-3 polyunsaturated fatty acids (PUFAs) on appetite.

OBJECTIVE

To examine the effect of omega-3 polyunsaturated fatty acids (n-3 PUFAs) on appetite using a systematic review and meta-analysis of controlled clinical trials (CTs).

PATIENTS AND METHODS

Online databases including PubMed, Scopus, ISI Web of Science, and Google Scholar were searched up to January 2022. A random-effects model was used to compare the overall standardized mean difference in appetite scores between n-3 PUFAs supplemented and control individuals.

RESULTS

Fifteen eligible CTs with 1504 participants (872 for n-3 PUFA supplementation and 632 for placebo groups) were included in our systematic review. The meta-analysis showed no significant difference in overall appetite score between n-3 PUFAs supplemented and control groups (standardized mean difference [SMD] = 0.458, 95% confidence interval [CI] - 0.327, 1.242, P value = 0.25). However, the n-3 PUFA supplementation significantly increased the desire to eat (SMD = 1.07, 95% CI 0.116, 2.029, P = 0.02) compared to control.

CONCLUSION

Although we found no effect of omega-3 supplementation on overall appetite score, it modestly increases the desire to eat. Further CTs evaluating the effect of PUFAs on appetite are still needed to confirm these findings.

Targeting gut-liver axis by dietary lignans ameliorate obesity: evidences and mechanisms

An imbalance between energy consumption and energy expenditure causes obesity. It is characterized by increased adipose accumulation and accompanied by chronic low-grade inflammation. Many studies have suggested that the gut microbiota of the host mediates the relationship between high-fat diet consumption and the development of obesity. Diet and nutrition of the body are heavily influenced by gut microbiota. The alterations in the microbiota in the gut may have effects on the homeostasis of the host's energy levels, systemic inflammation, lipid metabolism, and insulin sensitivity. The liver is an important organ for fat metabolism and gut-liver axis play important role in the fat metabolism. Gut-liver axis is a bidirectional relationship between the gut and its microbiota and the liver. As essential plant components, lignans have been shown to have different biological functions. Accumulating evidences have suggested that lignans may have lipid-lowering properties. Lignans can regulate the level of the gut microbiota and their metabolites in the host, thereby affecting signaling pathways related to fat synthesis and metabolism. These signaling pathways can make a difference in inhibiting fat accumulation, accelerating energy metabolism, affecting appetite, and inhibiting chronic inflammation. It will provide the groundwork for future studies on the lipid-lowering impact of lignans and the creation of functional meals based on those findings.

The effect of flaxseed intake on appetite reduction: A systematic review of randomized clinical trials

Appetite control has attracted many scientists' attention recently since it can lead to weight management and the prevention of further metabolic disorders. Many studies have been carried out to assess the effect of flaxseed on satiety perception but the results are controversial. This study aims to review these results comprehensively. PubMed/Medline, Web of Science, Scopus, and Cochrane databases were searched for related papers on June 2021. The searched keywords for appetite were: visual analog scale, appetite, desire to eat, satiation, satiety, hunger, fullness, and for Flaxseed they were: flax, flax*, linseed*, lignin*, Linseed Oil, flaxseed, ground flaxseed, flaxseed oil, and Linum usitatissimum. The 13 included studies were inconsistent in results and some of them found no significant effect of flaxseed on the considered outcomes. However, three studies revealed a significant reduction in hunger perception as well as appetite. Moreover, two studies found a decreasing effect on prospective consumption. Three studies observed a positive significant effect on fullness and satiety. Although there are a limited number of documents related to the effect of flaxseed on appetite perception, or its equivalent terms, the available studies suggest the potential role of flaxseed in decreasing appetite and hunger.

Flaxseed supplementation improves anthropometric measurements, metabolic, and inflammatory biomarkers in overweight and obese adults

Background: The aim of this study was to assess the effects of supplementation with flaxseed on anthropometric measurements, lipid profile, insulin resistance, and inflammatory biomarkers in overweight and obese adults. Methods: Fifty overweight and obese adults with body mass index (BMI) of 30.72 ± 3.31 kg/m2 participated in this study. Participants were randomly assigned to take lifestyle advice or lifestyle advice plus 30 g/day milled flaxseed for 12 weeks. The primary outcome was body weight; secondary outcomes included other anthropometric parameters, lipid profile and inflammatory biomarkers. Results: At the end of the study, the following significant mean differences were seen in flaxseed and control groups, respectively: weight [-9.36 vs. -3.09 kg; P < 0.001], BMI [-3.34 vs. -1.2 kg/m2; P < 0.001], triglycerides [-62.88 vs. -9.85 mg/dL; P < 0.001], total cholesterol [-32.2 vs. -14.95 mg/dL; P = 0.04], homeostatic model assessment (HOMA-IR) [1.25 vs. -0.32; P = 0.024], high sensitive- C reactive protein [-2.2 vs. -1.01 mmol/L; P < 0.001] and tumor necrosis factor-α [-1.34 vs. -0.14 pg/mL; P = 0.005]. Conclusion: These results suggest that flaxseed supplementation in addition to lifestyle modification is significantly superior to lifestyle modification alone for weight loss. More studies with different dosages of flaxseed are needed to find the optimal dosage. This trial was registered at clinicaltrials.gov as NCT02410668.

Flaxseed for Health and Disease: Review of Clinical Trials

BACKGROUND

Flaxseed (Linum usitatissimum) is an oil-based seed that contains high amounts of alpha-linolenic acid, linoleic acid, lignans, fiber and many other bioactive components which is suggested for a healthier life. Nowadays, flaxseed is known as a remarkable functional food with different health benefits for humans and protects against cardiovascular disease, diabetes, dyslipidemia, obesity and altogether metabolic syndrome.

METHODS

To review the bioactive components of flaxseed and their potential health effects, PubMed and Scopus were searched from commencement to July 2019. Keywords including: "flaxseed", "Linum usitatissimum", "metabolic syndrome", "obesity", "inflammation", "insulin resistance", "diabetes", "hyperlipidemia" and "menopause" were searched in the databases with varying combinations.

CONCLUSION

Consumption of flaxseed in different forms has valuable effects and protects against cardiovascular disease, hypertension, diabetes, dyslipidemia, inflammation and some other complications. Flaxseed can serve as a promising candidate for the management of metabolic syndrome to control blood lipid levels, fasting blood sugar, insulin resistance, body weight, waist circumference, body mass and blood pressure.

High-protein breakfast promotes weight loss by suppressing subsequent food intake and regulating appetite hormones in obese Chinese adolescents

OBJECTIVE

A high-protein diet may decrease food intake through regulating satiety and appetite hormones and can be an effective strategy for weight loss. Few studies exist on obese Chinese adolescents.

METHODS AND MATERIALS

156 obese Chinese adolescents were enrolled and randomly assigned to one of two isoenergetic breakfasts, either with egg or steamed bread. Subsequent lunchtime food intake was recorded 4 h later. Appetite was assessed with a visual analog scale. Anorexigenic hormones peptide YY (PYY), glucagon-like peptide-1 (GLP-1) and orexigenic hormone ghrelin were determined with radioimmunoassay at 0, 30, and 180 min. Body weight was recorded. The tests were repeated 3 months later. Analysis was performed between two tests and then two groups. Pearson's correlation was used for association analysis.

RESULTS

Subsequent lunchtime food intake and body weight were decreased while satiety was increased in subjects on an egg breakfast, which is associated with an increase of serum PYY and GLP-1 (p < 0.001, respectively). There were strong correlations between weight loss, appetite, subsequent food intake and changes of appetite hormones.

CONCLUSION

A high-protein breakfast promotes weight loss in obese Chinese adolescents, possibly through its regulation of satiety, subsequent food intake and appetite hormones.

Does omega-3 fatty acids supplementation affect circulating leptin levels? A systematic review and meta-analysis on randomized controlled clinical trials

BACKGROUND

Omega-3 fatty acids have attracted researchers for their effect on circulatory hormone-like peptides affecting weight control.

OBJECTIVE

Our objective was to conduct a systematic review and meta-analysis on randomized controlled trials (RCTs) assessed the effects of omega-3 supplementation on serum leptin concentration and to find the possible sources of heterogeneity in their results.

METHODS

We searched PubMed/Medline, Google Scholar, Ovid, SCOPUS and ISI web of science up to April 2014. RCTs conducted among human adults, examined the effect of omega-3 fatty acid supplements on serum leptin concentrations as an outcome variable were included. The mean difference and standard deviation (SD) of changes in serum leptin levels were used as effect size for the meta-analysis. Summary mean estimates with their corresponding SDs were derived using random effects model.

RESULTS

Totally 14 RCTs were eligible to be included in the systematic review, and the meta-analysis was performed on 13 articles. Our analysis showed that omega-3 supplementation significantly reduces leptin levels (mean difference (MD) = -1·71 ng/ml 95% confidence interval (CI): -3·17 to -0·24, P = 0·022). Subgroup analysis based on BMI status showed that the omega-3 supplementation reduces leptin when used for nonobese subjects (MD = -3·60 ng/ml; 95% CI -6·23 to -0·90; P = 0·011); however, this was not true for obese participants (MD = -0·86 ng/ml; 95% CI: -2·63 to -0·90; P = 0·296). Subgroup analysis based on omega-3 source also showed that omega-3 from marine sources may significantly reduce leptin levels (MD = -1·73 ng/ml; 95% CI -3·25 to -0·2; P = 0·026), but plant sources do not significantly affect serum leptin levels (MD = -1·48 ng/ml; 95% CI -6·78 to 3·23; P = 0·585). Our results were highly sensitive to one study.

CONCLUSIONS

Omega-3 supplementation might moderately decrease circulatory leptin levels only among nonobese adults. RCTs with longer follow-up period, using higher doses for obese adults and exploring the effect in different genders, are needed to replicate our results.