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Effects of Omega-3 Fatty Acids Supplementation on Serum Lipid Profile and Blood Pressure in Patients with Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Liu, YX, Yu, JH, Sun, JH, Ma, WQ, Wang, JJ, Sun, GJ
Foods (Basel, Switzerland). 2023;12(4)
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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.
2.
An Energy-Reduced Mediterranean Diet, Physical Activity, and Body Composition: An Interim Subgroup Analysis of the PREDIMED-Plus Randomized Clinical Trial.
Konieczna, J, Ruiz-Canela, M, Galmes-Panades, AM, Abete, I, Babio, N, Fiol, M, Martín-Sánchez, V, Estruch, R, Vidal, J, Buil-Cosiales, P, et al
JAMA network open. 2023;6(10):e2337994
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Plain language summary
The Mediterranean diet (MedDiet), which focuses on whole grains, lean meat, fruits, vegetables, and low amounts of minimally processed foods has been shown in previous research to improve body composition and decrease fat storage around the middle. This randomised control trial of 1556 older adults aimed to determine the effects of combining a 30% lower energy version of the MedDiet in combination with physical exercise on body composition. After 3 years, the results showed that compared to a normal MedDiet without exercise, the lower energy version in combination with exercise improved body composition by decreasing total fat, and the fat stored around the organs and increasing muscle mass. However, benefits were more pronounced after 1 year and decreased slightly at 3 years. It was concluded that a low energy MedDiet in combination with physical activity may be able to improve the body composition of overweight and older adults with obesity. This study could be used by healthcare professionals to recommend a low energy MedDiet to older adults to promote weight loss, whilst attenuating muscle loss associated with ageing.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The addition of exercise to an energy-reduced diet, which focuses on whole grains, healthy fats, lean protein, and fruits and vegetables can emphasise positive effects on body composition in older adults.
- However, there is a loss of lean mass associated with this type of diet (contrary to author conclusions) and measures should be taken to monitor and increase protein intake to prevent or limit this loss.
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:
Introduction
This study aimed to determine the long-term effects of an energy reduced MedDiet in combination with physical activity on body composition.
Methods
- This is a predetermined 3-year interim analysis of a 6-year single-blind, randomised control trial of 1556 individuals aged 55-75 who are overweight or obese with metabolic syndrome.
- 760 individuals on 30% energy reduced MedDiet with limited processed foods, plus 45 minutes walking 6 days per week and behavioural and motivational support. [Intervention group]
- 761 on standard MedDiet without physical activity. [Control]
Results
Within group comparisons showed that individuals in the intervention group lost (P value represents baseline vs year 3):
- Total fat mass percentage (1-year vs baseline, −1.14%; 95% CI, −1.32% to −0.96%; 3-year vs baseline, −0.52%; 95% CI, −0.71% to −0.33% P=<0.001)
- Absolute visceral fat (1-year vs baseline, −154 g; 95% CI, −191 to −116 g; 3-year vs baseline, −75.1 g, 95% CI, −115 to −35.3 g P=<0.001)
- Absolute total fat after 1 year (mean change at 1 year vs baseline, −1677 g; 95% CI, −1930 to −1424 g) but regained some at year 3 (mean change at 3 years vs baseline, −1018 g; 95% CI, −1280 to −756 g P=<0.001)
- Absolute lean mass (mean change at 1 year vs baseline −300 g; 95% CI, −439 to −162 g) with further losses at year 3 (−626 g; 95% CI, −770 to −483 g P=0.001).
Within group comparisons also showed significantly increased:
- Total lean mass percentage, which was greater at year 1 than year 3 (1-year vs baseline, 1.07%; 95%CI, 0.90%-1.25%; 3-year vs baseline, 0.47%; 95% CI, 0.29%-0.65% P=<0.001).
As a result of total fat loss and some lean mass in the intervention group, the lean:fat mass ratio improved and was unchanged in the control group (between group differences (P=<0.001).
Compared to women, men may find the MedDiet + exercise more beneficial as it was shown that body composition changes were slightly more pronounced in men.
Conclusion
An energy-reduced MedDiet plus exercise emphasised positive changes to body composition compared to standard MedDiet in older adults who are overweight or have obesity.
Clinical practice applications:
- The recommendation of a reduced energy MedDiet in combination with physical activity to older people who are overweight or obese may improve body composition.
- Although lean mass loss slowed between years 1 and 3, other practices should be employed to attenuate the loss of lean mass associated with an energy-reduced MedDiet and ageing.
Considerations for future research:
- The research has not yet concluded but when it does, it will address the incidence of cardiovascular disease along with body composition changes.
- It will also look at long-term effects of the diet to determine longevity.
- Future research could focus on how to limit lean mass loss through the possibility of changing the type of exercise that accompanies the MedDiet.
Abstract
IMPORTANCE Strategies targeting body composition may help prevent chronic diseases in persons with excess weight, but randomized clinical trials evaluating lifestyle interventions have rarely reported effects on directly quantified body composition. OBJECTIVE To evaluate the effects of a lifestyle weight-loss intervention on changes in overall and regional body composition. DESIGN, SETTING, AND PARTICIPANTS The ongoing Prevención con Dieta Mediterránea-Plus (PREDIMED-Plus) randomized clinical trial is designed to test the effect of the intervention on cardiovascular disease prevention after 8 years of follow-up. The trial is being conducted in 23 Spanish research centers and includes men and women (age 55-75 years) with body mass index between 27 and 40 and metabolic syndrome. The trial reported herein is an interim subgroup analysis of the intermediate outcome body composition after 3-year follow-up, and data analysis was conducted from February 1 to November 30, 2022. Of 6874 total PREDIMED-Plus participants, a subsample of 1521 individuals, coming from centers with access to a dual energy x-ray absorptiometry device, underwent body composition measurements at 3 time points. INTERVENTION Participants were randomly allocated to a multifactorial intervention based on an energy-reduced Mediterranean diet (MedDiet) and increased physical activity (PA) or to a control group based on usual care, with advice to follow an ad libitum MedDiet, but no physical activity promotion. MAIN OUTCOMES AND MEASURES The outcomes (continuous) were 3-year changes in total fat and lean mass (expressed as percentages of body mass) and visceral fat (in grams), tested using multivariable linear mixed-effects models. Clinical relevance of changes in body components (dichotomous) was assessed based on 5% or more improvements in baseline values, using logistic regression. Main analyses were performed in the evaluable population (completers only) and in sensitivity analyses, multiple imputation was performed to include data of participants lost to follow-up (intention-to-treat analyses). RESULTS A total of 1521 individuals were included (mean [SD] age, 65.3 [5.0] years; 52.1% men). In comparison with the control group (n=761), participants in the intervention arm (n=760) showed greater reductions in the percentage of total fat (between group differences after 1-year, -0.94% [95% CI, -1.19 to -0.69]; 3 years, -0.38% [95% CI, -0.64 to -0.12] and visceral fat storage after 1 year, -126 g [95% CI, -179 to -73.3 g]; 3 years, -70.4 g [95% CI, -126 to -15.2 g] and greater increases in the percentage of total lean mass at 1 year, 0.88% [95% CI, 0.63%-1.12%]; 3-years 0.34% [95% CI, 0.09%-0.60%]). The intervention group was more likely to show improvements of 5% or more in baseline body components (absolute risk reduction after 1 year, 13% for total fat mass, 11% for total lean mass, and 14% for visceral fat mass; after 3-years: 6% for total fat mass, 6% for total lean mass, and 8% for visceral fat mass). The number of participants needed to treat was between 12 and 17 to attain at least 1 individual with possibly clinically meaningful improvements in body composition. CONCLUSIONS AND RELEVANCE The findings of this trial suggest a weight-loss lifestyle intervention based on an energy-reduced MedDiet and physical activity significantly reduced total and visceral fat and attenuated age-related losses of lean mass in older adults with overweight or obesity and metabolic syndrome. Continued follow-up is warranted to confirm the long-term consequences of these changes on cardiovascular clinical end points. TRIAL REGISTRATION isrctn.org Identifier: ISRCTN89898870.