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.
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Metabolic syndrome (MetS) is a chronic disease with inflammatory and hypercoagulable states. The current study aimed to compare the effects of flaxseed oil and sunflower oil consumption on the coagulation score and selected oxidative and inflammatory parameters in patients with MetS. In this randomized controlled clinical trial, 60 patients with MetS were allocated into 2 groups. One group received 25 mL/day flaxseed oil and the other group received 25 mL/day sunflower oil for 7 weeks. Maintenance diet including 15% protein, 55% carbohydrate, and 30% fat from daily total energy intake was designed for each participant. Serum levels of total antioxidant capacity (TAC) and interleukin 6 (IL-6), as well as coagulation score were measured before and after the intervention. Three 24-hour food records were taken during the study. Fifty-two of participants (27 in sunflower oil and 25 in flaxseed oil groups) completed the study. The baseline characteristics and dietary intakes were similar between patients. After 7 weeks, no significant difference was observed between the 2 groups regarding the serum TAC level and coagulation score (p > 0.05). However, serum IL-6 levels significantly decreased in the flaxseed oil group compared to the sunflower oil group (p = 0.017). No side effect was observed during the study due to the use of sunflower and flaxseed oils. We observed that consumption of flaxseed oil improved serum IL-6 levels but had no effect on oxidative stress and coagulation score in patients with MetS. Further studies are needed to confirm the veracity of our results.
Iranian Registry of Clinical Trials Identifier:
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Flaxseed is one of the rich sources of α-linolenic acid and lignan. Flaxseed and its components have antioxidant, hypolipidemic and hypoglycemic effects. The study aimed to investigate the effect of flaxseed enriched yogurt on glycemic control, lipid profiles and blood pressure in patients with type 2 diabetes. A randomized, open-labeled, controlled clinical trial was conducted on 57 patients with type 2 diabetes. Participants were assigned to receive 200 g 2.5% fat yogurt containing 30-g flaxseed or plain yogurt daily for 8 weeks. Anthropometrics and biochemical parameters were evaluated at the beginning and end of the study. After 8 weeks of supplementation, Hemoglobin A1c was significantly decreased in the intervention group compared to control (p = 0.007). Also, at the end of the study, significant differences were seen between the flaxseed enriched yogurt and control groups in triglycerides and total cholesterol concentrations (p = 0.04 and p = 0.01), systolic blood pressure and diastolic blood pressure (p = 0.02 and p = 0.002, respectively). However, we did not find any difference between 2 groups in low-density lipoprotein, high-density lipoprotein, body weight and waist circumference (p > 0.05). Our results showed that the addition of flaxseed to yogurt can be effective in the management of type 2 diabetes.
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