Plain language summary
Metabolic syndrome (MetS) is a group of disorders that cause disturbed metabolism, including abdominal obesity, insulin resistance, hypertension, and dyslipidaemia. People with MetS may have a higher risk of coronary heart disease and stroke than those without MetS. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have cardioprotective, anti-inflammatory, and triglyceride-lowering properties, so they may help treat obesity and improve metabolic syndrome. The aim of this study was to explore the effects of n-3 PUFAs on lipid profile and blood pressure in patients with MetS. This study is a meta-analysis of eight studies. One of the studies was a crossover trial, whereas the remaining seven studies were parallel-controlled trials. The mean age of the participants was 45.54 years old. Results show that following supplementation with n-3 PUFAs in patients with metabolic syndrome: - there weren’t significant changes in serum total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. - there was a significant reduction in serum triglycerides and blood pressure. Authors conclude that n-3 PUFA supplementation may serve as a potential dietary supplement for improving lipids and blood pressure in patients with metabolic syndrome.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Omega 3 PUFA may be beneficial for patients with metabolic syndrome by improving serum lipid profile and blood pressure.
- Omega-3 rich foods include fatty fish, walnuts, flaxseeds and chia seeds.
- While Omega-3 PUFA may be beneficial, they should be considered as part of a comprehensive approach to managing metabolic syndrome that include physical activity and a balanced diet.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Background
This journal article presents a systematic review and meta-analysis of randomised controlled trials (RCTs) investigating the effects of omega-3 fatty acid supplementation on serum lipid profile and blood pressure in patients with metabolic syndrome. Metabolic syndrome is a cluster of conditions that increase the risk of cardiovascular disease and type 2 diabetes.
Methods
This meta-analysis included 8 RCTs with 387 participants with metabolic syndrome. Participants in the intervention group took omega-3 fatty acid supplements and the outcomes included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), systolic blood pressure (SBP), and diastolic blood pressure (DBP).
Results
- Based on a meta-analysis of data from the included trials, supplementation with omega 3- PUFAs led to no reduction in serum LDL-c level among patients with metabolic syndrome (Standardised Mean Difference (SMD) = 0.18; 95% CI: −0.18 ~ 0.53, I2 = 55%); did not increase serum high-density lipoprotein cholesterol levels (SMD = 0.02; 95% CI: −0.21 ~ 0.25, I2 = 0%); and had no reduction in serum total cholesterol level (SMD = −0.02; 95% CI: −0.22~0.18, I2 = 24%).
- On the other hand, in patients with metabolic syndrome, supplementation with omega 3- PUFAs may decrease serum triglyceride levels (SMD = −0.39; 95% CI: −0.59 ~ −0.18, I2 = 17.2%); systolic blood pressure (SMD = −0.54; 95% CI: −0.86 ~ −0.22, I2 = 48.6%); and diastolic blood pressure (SMD = −0.56; 95% CI: −0.79~ −0.33, I2 = 14.0%).
- Sensitivity analyses indicated that the pooled estimates wererobust for all outcomes.
- The following mechanisms may explain how PUFAs may reduce the risk of metabolic syndrome. First, adequate intake of omega 3 PUFAs may reduce triglyceride and LDL synthesis in the liver. In addition, they may lower blood pressure by reducing angiotensin-converting enzyme levels in the aorta. Finally, PUFAs can increase insulin sensitivity and prevent hyperglycaemia.
Limitations
This study presents some limitations: The literature search may have some omissions. The conclusions may be hindered by the risk of bias of the trials included. No bias test was performed due to the limited number of studies.
Clinical practice applications:
- Improved serum lipid profile: The findings from the paper indicate that omega-3 fatty acid supplementation can have a positive impact on the serum lipid profile in patients with metabolic syndrome.
- Blood pressure management: omega-3 fatty acid supplementation may help reduce blood pressure in patients with metabolic syndrome.
- Nutritional therapists can use this information to consider omega-3 supplementation as part of nutritional therapy
- Complementary approach: Nutritional therapists can utilise the findings as supportive evidence for a holistic approach to managing metabolic syndrome. By incorporating omega-3 fatty acids into personalized nutrition plans, therapists may be able to offer additional dietary or supplemental interventions for individuals with metabolic syndrome, aiming to lower triglyceride levels and manage blood pressure, alongside other lifestyle modifications.
- Patient education: Nutritional therapists can educate their patients with metabolic syndrome about the benefits of omega-3 fatty acids on lipid profile and blood pressure. By explaining the findings from the systematic review and meta-analysis, therapists can empower patients to make informed choices regarding their dietary habits and supplement use, promoting self-management and improved long-term outcomes.
Considerations for future research:
- Future research could focus on determining the optimum dosage of Omega-3 PUFAs for improving lipid profile and BP.
- More investigation is needed to analyse the long term effect of the supplements. The longest RCT was 90 days.
- Comparative studies comparing the effects of omega-3 fatty acids supplementation with other interventions commonly used in metabolic syndrome management, such as pharmacological approaches or diet, would provide a comprehensive understanding of their relative effectiveness.
- Future research could explore potential variations in the effects of omega-3 fatty acids supplementation based on different patient characteristics, such as age, gender, baseline lipid profile, and blood pressure levels.
- Conducting mechanistic studies could shed light on the underlying pathways through which omega-3 fatty acids exert their effects on serum lipid profile and blood pressure.
Abstract
The purpose of this study was to explore the effect of omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplementation on serum lipid profile and blood pressure in patients with metabolic syndrome. We searched PubMed, Web of Science, Embase, and the Cochrane library from database inception to 30 April 2022. This meta-analysis included eight trials with 387 participants. We found that supplementation of n-3 PUFAs has no significant reduction in TC level (SMD = -0.02; 95% CI: -0.22 ~ 0.18, I2 = 23.7%) and LDL-c level in serum (SMD = 0.18; 95% CI: -0.18 ~ 0.53, I2 = 54.9%) of patients with metabolic syndrome. Moreover, we found no significant increase in serum high-density lipoprotein cholesterol level (SMD = 0.02; 95% CI: -0.21 ~ 0.25, I2 = 0%) in patients with metabolic syndrome after consuming n-3 PUFAs. In addition, we found that n-3 PUFAs can significantly decrease serum triglyceride levels (SMD= -0.39; 95% CI: -0.59 ~ -0.18, I2 = 17.2%), systolic blood pressure (SMD = -0.54; 95% CI: -0.86 ~ -0.22, I2 = 48.6%), and diastolic blood pressure (SMD = -0.56; 95% CI: -0.79 ~ 0.33, I2 = 14.0%) in patients with metabolic syndrome. The results from the sensitivity analysis confirmed that our results were robust. These findings suggest that n-3 PUFA supplementation may serve as a potential dietary supplement for improving lipids and blood pressure in metabolic syndrome. Given the quality of the included studies, further studies are still needed to verify our findings.
Methodological quality
Jadad score
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Allocation concealment
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