The effect of flaxseed oil consumtion on blood pressure among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized clinical trials

Efficacy of flaxseed in reducing blood pressure among patients with cardiovascular risk factors: A systematic review and meta-analysis of parallel randomized controlled trials

The prevalence rate of hypertension is on the rise at an alarming rate. Studies conducted on the influence of flaxseed on blood pressure (BP) have come up with conflicting conclusions. The current investigation's major purpose is to conduct a literature review and a meta-analysis focusing on the effect of flaxseed supplementation on BP in people with cardiovascular disease (CVD) risk factors. PubMed, Scopus, Web of Science, and Cochrane Central Library databases were searched from the inception date to April 2024 to find the randomized controlled trials (RCTs). A random-effects model combined the weighted mean difference (WMD). Standard methodologies were applied to evaluate publication bias, heterogeneity, and sensitivity analysis. Eighteen RCTs were included in the present systematic review and meta-analysis. Pooled analysis suggested that flaxseed supplementation can reduce systolic BP (SBP) (WMD: -4.75 mmHg, 95% CI: -7.05 to -2.44, P≤0.001; I2=93.6%) and diastolic BP (DBP) (WMD: -3.09 mmHg, 95% CI: -4.37 to -1.81, P≤0.001; I2=91.2%). In conclusion, the current meta-analysis has demonstrated that flaxseed supplementation can markedly lower BP in individuals exhibiting CVD risk factors. Given the significant heterogeneity, it is crucial to interpret the current results with careful consideration. In addition, further high-quality RCTs are required to better assess the causal relationships.

Dietary flaxseed: Cardiometabolic benefits and its role in promoting healthy aging

Flaxseed, a rich source of omega-3 polyunsaturated fatty acid alpha-linolenic acid (ALA), lignans, and soluble fiber, has attracted attention for its potential to improve multiple cardiometabolic risk factors. While its benefits are well-recognized, comprehensive evaluations of its direct impact on clinical outcomes, such as the prevention or progression of cardiometabolic diseases, remain limited. Additionally, its potential to support healthy aging and longevity through fundamental biological mechanisms has not been fully elucidated. This review synthesizes existing research on flaxseed supplementation, highlighting its effects on cardiometabolic risk factors and outcomes, the underlying biological mechanisms, and its broader implications for health promotion and aging. Findings demonstrate that flaxseed supplementation significantly improves several cardiometabolic risk factors, including body weight, body mass index, lipid levels, blood pressure, glycemic measures, markers of inflammation (e.g., C-reactive protein and interleukin-6), oxidative stress, and liver enzymes. Blood pressure reductions range from approximately 2 to 15 mmHg for systolic blood pressure and 1 to 7 mmHg for diastolic blood pressure, with the magnitude influenced by dose, duration, and baseline risk profiles. While direct evidence linking flaxseed to the prevention of hypertension, metabolic syndrome, metabolic dysfunction-associated steatotic liver disease, type 2 diabetes, chronic kidney disease, and cardiovascular disease is limited, its bioactive components-ALA, lignans, and fiber-are strongly associated with reduced risks of these conditions. The benefits of flaxseed are mediated through multiple pathways, including anti-inflammatory and antioxidant effects, improved lipid levels, improved glucose metabolism and insulin sensitivity, modulation of gut microbiota, and enhanced vascular health. Beyond cardiometabolic outcomes, flaxseed may influence key biological processes relevant to aging, underscoring its potential to promote healthy aging and longevity. Optimal cardiometabolic benefits appear to be achieved with ground whole flaxseed at doses of ≥ 30 g/day for at least 12 weeks, particularly among individuals at high cardiometabolic risk. Future research should focus on elucidating flaxseed's mechanisms of action, clarifying its role in disease prevention, and refining dietary recommendations to harness its potential for cardiometabolic health and aging interventions.

Flaxseed Lowers Blood Pressure in Hypertensive Subjects: A Meta-Analysis of Randomized Controlled Trials

This systematic review and meta-analysis study aimed to evaluate the effectiveness of flaxseed supplementation on blood pressure (BP) in patients with hypertension based on the data from randomized clinical trials (RCTs). Three databases (PubMed [MEDLINE], Scopus, and ISI Web of Science) were searched from inception up to August 10, 2024. Relevant studies meeting our eligibility criteria were obtained. A random-effects model was used to estimate pooled weighted mean differences (WMDs) with 95% confidence intervals (CIs). The methodological quality of individual studies was assessed using the Cochrane Collaboration risk of bias tool. A total of 5 studies were included and analyzed using STATA software version 12. The results show that there is a significant decrease in systolic BP (WMD, -8.64 mmHg; 95% CI, -15.41 to -1.87; p ≤ 0.001) and diastolic BP (WMD, -4.87 mmHg; 95% CI, -8.37 to -1.37; p = 0.006) of patients with hypertension as compared to control groups. This study supported that flaxseed supplementation had favorable effects on BP control in hypertensive patients. It may be a promising adjuvant therapy for patients with hypertension.

Health Effects of Various Edible Vegetable Oil: An Umbrella Review

Vegetable oils, derived from diverse sources such as seeds, nuts, and some fruits, play a significant role in dietary health. However, the current evidence on the health effects of different types of vegetable oil consumption remains controversial. This umbrella review aims to synthesize evidence from systematic reviews and meta-analyses to assess the health outcomes associated with various vegetable oils. A comprehensive literature search was performed up to 31 July, 2023 on 12 databases for studies examining the association of different vegetable oils with health outcomes in adults. Data was extracted independently by 2 authors, with evidence strength assessed using the grading of recommendations, assessment, development, and evaluation criteria. A total of 48 studies, including 206 meta-analyses, were included. Moderate to very low certainty evidence showed that monounsaturated and polyunsaturated fatty acids such as canola oil, virgin olive oil, and rice bran oil are beneficial in reducing serum total cholesterol and low-density lipoprotein (LDL) concentrations. Conversely, low to very low certainty evidence suggests that oils high in saturated fats, such as coconut oil and palm oil, increase total cholesterol and LDL concentrations but also raise high-density lipoprotein concentrations. Very low certainty evidence showed the consumption of olive oil, sesame oil, and coconut oil could improve blood sugar control. Low certainty evidence showed olive oil consumption reduced risk of breast, digestive, and other cancers. Moderate to very low certainty evidence suggested that canola oil and sesame oil consumption reduced body weight. The consumption of vegetable oil appears to offer different health benefits, with summary estimates indicating beneficial effects on reducing lipid concentrations, especially with monounsaturated and polyunsaturated rich oils when consumed in recommended amounts. Future research should focus on long-term studies and comprehensive dietary assessments to better understand the health impacts of vegetable oils, providing a basis for informed dietary recommendations. This study was registered at PROSPERO as CRD42021239210.

Does omega-3 PUFAs supplementation improve metabolic syndrome and related cardiovascular diseases? A systematic review and meta-analysis of randomized controlled trials

Literature is inconsistent regarding the effects of omega-3 polyunsaturated fatty acids (omega-3 PUFAs) supplementation on patients with metabolic syndrome (MetS) and related cardiovascular diseases (CVDs). Therefore, the aim of this systematic review and meta-analysis is to summarize data from available randomized controlled trials (RCTs) on the effect of omega-3 PUFAs on lipid profiles, blood pressure, and inflammatory markers. We systematically searched PubMed, Embase, and Cochrane Library databases to identify the relevant RCTs until 1 November 2022. Weighed mean difference (WMD) was combined using a random-effects model. Standard methods were applied to assess publication bias, sensitivity analysis, and heterogeneity among included studies. A total of 48 RCTs involving 8,489 subjects met the inclusion criteria. The meta-analysis demonstrated that omega-3 PUFAs supplementation significantly reduced triglyceride (TG) (WMD: -18.18 mg/dl; 95% CI: -25.41, -10.95; p < 0.001), total cholesterol (TC) (WMD: -3.38 mg/dl; 95% CI: -5.97, -0.79; p = 0.01), systolic blood pressure (SBP) (WMD: -3.52 mmHg; 95% CI: -5.69, -1.35; p = 0.001), diastolic blood pressure (DBP) (WMD: -1.70 mmHg; 95% CI: -2.88, -0.51; p = 0.005), interleukin-6 (IL-6) (WMD: -0.64 pg/ml; 95% CI: -1.04, -0.25; p = 0.001), tumor necrosis factor-α (TNF-α) (WMD: -0.58 pg/ml; 95% CI: -0.96, -0.19; p = 0.004), C-reactive protein (CRP) (WMD: -0.32 mg/l; 95% CI: -0.50, -0.14; p < 0.001), and interleukin-1 (IL-1) (WMD: -242.95 pg/ml; 95% CI: -299.40, -186.50; p < 0.001), and significantly increased in high-density lipoprotein (HDL) (WMD: 0.99 mg/dl; 95% CI: 0.18, 1.80; p = 0.02). However, low-density lipoprotein (LDL), monocyte chemoattractant protein-1 (MCP-1), intracellular adhesion molecule-1 (ICAM-1), and soluble endothelial selectin (sE-selectin) were not affected. In subgroup analyses, a more beneficial effect on overall health was observed when the dose was ≤ 2 g/day; Omega-3 PUFAs had a stronger anti-inflammatory effect in patients with CVDs, particularly heart failure; Supplementation with omega-3 PUFAs was more effective in improving blood pressure in MetS patients and blood lipids in CVDs patients, respectively. Meta-regression analysis showed a linear relationship between the duration of omega-3 PUFAs and changes in TG (p = 0.023), IL-6 (p = 0.008), TNF-α (p = 0.005), and CRP (p = 0.025). Supplementation of omega-3 PUFAs had a favorable effect on improving TG, TC, HDL, SBP, DBP, IL-6, TNF-α, CRP, and IL-1 levels, yet did not affect LDL, MCP-1, ICAM-1, and sE-selectin among patients with MetS and related CVDs.

Estimating the Potential Health Care Cost-Savings from a Flax-Based Treatment for Hypertension

Hypertension contributes to the increase in health care spending in Canada through two primary mechanisms. First, it directly increases costs, as individuals with hypertension require medical care to manage the condition. Second, it indirectly raises expenses by serving as a risk factor for numerous chronic diseases, leading to increased health care utilization among those affected. Therefore, reducing hypertension prevalence could alleviate its resulting strain on the Canadian health care system. Clinical trials have demonstrated that daily flaxseed consumption effectively lowers both systolic and diastolic blood pressure. This study employs a four-step cost-of-illness analysis to estimate the potential health care cost-savings from a flaxseed-based treatment for hypertension. The analysis begins by assessing the proportion of individuals with hypertension likely to adopt the flaxseed regimen. It then evaluates the impact of flaxseed consumption on systolic and diastolic blood pressure. Next, data from the Canadian Health Measures Survey, Cycles 5 and 6, are used to estimate the prevalence of hypertension and the expected reduction in prevalence due to the flaxseed treatment. Finally, the potential reduction in health care spending is calculated. To incorporate uncertainty, partial sensitivity analysis and Monte Carlo simulations were utilized, varying the intake success rate and other model parameters, respectively. The most conservative estimate suggests a potential health care cost-savings of CAD 96,284,344 in Canada for the year 2020.

Harmful Free Radicals in Aging: A Narrative Review of Their Detrimental Effects on Health

The production of harmful free radicals (H-FRs), especially those with oxygen or nitrogen atoms, depends on both internal and environmental causes. The negative effects of H-FRs are greatly alleviated by antioxidant protection. The harmful impact of oxidative stress, or OS, is brought on by a disparity between the defense mechanisms of the body and the creation of H-FRs. Aging is characterized by a slow decline in tissue and organ competence. Age-mediated pathologies start as an aberrant accumulation of H-FRs, which inhibit cells' capacity to divide, repair, and operate, based on the OS theorem of aging. The natural outcome of this situation is apoptosis. These conditions may include skeletal muscle dysfunction, cancer, cardiovascular, chronic hepatitis, chronic renal, and chronic pulmonary disorders. Given the substantial role that OS plays in the progression of many of these illnesses, antioxidant-based therapy may have a favorable impact on how these diseases progress. To ascertain the true efficacy of this therapy strategy, more research is necessary. The aim of this study is to provide an overview of the literature on this challenging issue that is attracting interest.

Supplementation of Olive Oil and Flaxseed Oil on Blood Pressure and Inflammation in Healthy and At-Risk Adults: A Systematic Literature Review and Meta-Analysis

BACKGROUND

Adding olive oil (OO) and flaxseed oil (FLO) to the diet has been reported to improve endothelial function and reduce inflammation. However, the efficacy of supplementing OO and FLO on blood pressure (BP) in normo-, pre-, and hypertensive stage 1 adults is uncertain.

OBJECTIVE

This study aimed to systematically review the literature on OO and FLO supplementation on BP and select inflammatory markers in healthy adults and adults at risk of hypertension.

METHODS

Four databases, PubMed, CINHAL, Web of Science, and Medline (Ovid), were searched from inception until October 2023 for randomized control trials (RCTs) comparing OO and FLO supplementation in normotensive or adults at risk of hypertension. The outcomes included were systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) and at least one inflammatory marker, C-reactive protein (CRP), interleukin6 (IL6), or tumor necrosis factor alpha (TNFα). The risk of bias was assessed using version 2 of the Cochrane risk of bias tool for RCTs, publication bias visualization was performed using funnel plots, and meta-analysis was completed to generate average estimates of effects in 2024.

RESULTS

Seventeen RCTs, comprising 14 studies on OO and 3 on FLO, met the inclusion criteria. Meta-analysis using a random-effects model reported no significant effect on SBP n=17 mean difference (MD) -0.48; 95% CI: -1.76, 0.80; p=0.65, I2 =0%) and DBP (n=16, MD -0.47; 95% CI: -1.33, 0.39; p=0.65, I2 =0%) or inflammatory markers, CRP (n=8, MD 0.11; 95% CI: -1.18, 0.40; p=0.98, I2 =0%), IL6 (n=3, MD -0.15; 95% CI: -0.57, 0.27; p=0.87, I2 =0%), and TNFα (n=3, MD-0.08; 95% CI: -0.12, -0.03; p=0.98, I2 =0%).

CONCLUSION

Longer-duration, higher-dose, and larger-scale RCTs are needed to better understand the efficacy of OO and FLO supplementation on BP. Further insight will better inform dietary supplement use for preventing hypertension.

Novel Lauric Acid-Butyric Structural Lipid Inhibits Inflammation: Small Intestinal Microbes May Be Important Mediators

SCOPE

Butyric acid (C4) and lauric acid (C12) are recognized as functional fatty acids, while the health benefits of the structural lipids they constitute remain unclear.

METHODS AND RESULTS

In this study, lauric acid-butyric structural lipid (SLBL ) is synthesized through ultrasound-assisted enzyme-catalyzed acidolysis and its health benefits are evaluated in a high-fat diet-induced obesity mouse model. SLBL and its physical mixture (MLBL ) do not significantly inhibit obesity in mice. However, SLBL treatment increases the ratio of n3/n6 fatty acids in the liver and improves obesity-induced hepatic lipid metabolism disorders. Furthermore, the expression of liver pro-inflammatory cytokines (interleukin [IL]-6, IL-1β, TNF-α) are significantly suppressed by SLBL , while the expression of anti-inflammatory cytokine (IL-10) is increased. Moreover, SLBL ameliorates the dysbiosis of small intestinal microbes induced by high-fat diet and regulates microbial community structure to be close to the control group. Especially, SLBL significantly alleviates the high-fat diet-induced decrease in Dubosiella and Bifidobacterium abundance. Correlation analysis reveals that SLBL treatment increases the abundance of microorganisms with potential anti-inflammatory function and decreases the abundance of potentially pathogenic bacteria.

CONCLUSION

In all, small intestinal microbes may be a significant bridge for the positive anti-inflammatory effects of SLBL , while the exact mechanism remains to be clarified.

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.

Virgin Olive Oil Ranks First in a New Nutritional Quality Score Due to Its Compositional Profile

Dietary oils play a crucial role in maintaining a healthy diet. However, with the increasing number of oils available, it became a challenging task for food producers and consumers to select the best oil for their needs. In this work, an easy-to-understand nutrition quality score was created, using a model that included beneficial lipid compounds criteria according to the dietary recommendations published by international food and health organizations. The algorithm assigned points for each component of the model considering their content in each particular oil. The points were added up and the fats and oils were classified by the corresponding percentile. As a result, among the 32 edible oils that were evaluated, virgin olive oil ranked first with a score of 100. All plant oils, except for margarine and coconut oil, ranked above the 50th percentile. Receiver-operator curves and regression models showed that saturated fatty acids may be able to predict the score, and thus, the nutritional quality of the oils. In conclusion, the proposed nutritional quality score would promote healthy and nutritious food options for consumers and would provide food producers with a valuable tool to select high-quality oils for their products, ensuring that they meet the nutritional requirements.

Effect of flaxseed supplementation on blood pressure: a systematic review, and dose-response meta-analysis of randomized clinical trials

Many clinical trials have revealed that flaxseed supplementation might exert a potent antihypertensive influence, but the findings are inconsistent. In this regard, a meta-analysis was carried out to provide a more accurate estimate of the impact of flaxseed supplementation on blood pressure. We searched international databases including PubMed, Cochrane Library, Web of Science, Scopus, Embase, and Google Scholar till July 2022. A random-effects model was used to calculate weighted mean differences (WMDs). Non-linear dose-response analysis and meta-regression were performed. Meta-analysis of 33 trials (comprising 43 treatment arms) with 2427 participants revealed significant reductions in both systolic (WMD: -3.19 mmHg; 95% CI: -4.15 to -2.24, p < 0.001; I² = 92.5%, p < 0.001) and diastolic blood pressure (WMD = -2.61 mmHg; 95% CI: -3.27, -1.94, p < 0.001; I² = 94.1%, p < 0.001) following flaxseed supplementation. Greater effects on SBP and DBP were found in trials with an intervention duration of >20 weeks, ≥30 g day^-1 of flaxseed, subjects with BMI 25-30 kg m^-2, and in patients with hypertension. Supplementation with various flaxseed products significantly reduced SBP and DBP levels, confirming the hypothesis that flaxseed could be used as an effective supplement for blood pressure management, alongside routine medications.