Eur J Clin Nutr., 2018., Aug 20. doi: 10.1038/s41430-018-0268-x.

Effect of flaxseed consumption on flow-mediated dilation and inflammatory biomarkers in patients with coronary artery disease: a randomized controlled trial.

Khandouzi N, Zahedmehr A, Mohammadzadeh A, et al.


BACKGROUND/OBJECTIVE: Available data indicate a possible beneficial effect of flaxseed on cardiovascular disease, but limited studies have evaluated the effects of flaxseed on endothelial dysfunction and biomarkers of inflammation in patients with coronary artery disease (CAD). The purpose of the present study was to examine the effect of flaxseed consumption on flow-mediated dilation (FMD) and inflammatory markers in CAD patients. SUBJECTS/METHOD: In this randomized controlled parallel trial, 50 patients with CAD of both genders were randomly allocated to 12 weeks consumption of flaxseed (30 g/day) or usual care control. Before and after the intervention, changes in brachial FMD and plasma high-sensitivity C-reactive protein (hs-CRP), interleukine-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured. RESULTS: Forty-four participants (aged 56.43 ± 8.21 years; BMI 26.65 ± 2.44 kg/m2) completed the study. No significant weight change was observed in either group. Compared to control (n = 23), flaxseed consumption (n = 21) was associated with improved FMD (mean of change from baseline was 5.1 vs -0.55%; p = 0.001 for the flaxseed and control, respectively). When compared to control, flaxseed consumption was associated with reduced inflammatory markers (mean of change from baseline for hs-CRP was -1.18 and -0.3 mg/L, p = 0.003; for IL-6 was -7.65 and -0.77 pg/mL, p = 0.017; for TNF-α was -34.73 and -2.18 pg/mL p = 0.001 in flaxseed and control, respectively). CONCLUSIONS: The results of this study indicate that by adding flaxseed to diet of CAD patients, it is possible to improve FMD and plasma levels of inflammatory markers.

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Key Findings

Cardiovascular diseases (CVD) involves endothelial dysfunction, one of the major promoters of atherosclerosis and has been used as a prognostic predictor for the risk of future cardiovascular events. Flow-mediated dilation (FMD) is a non-invasive vascular function test to evaluate endothelial dysfunction and has been reported to be a predictor of the severity of coronary artery disease (CAD). Inflammation plays an important role in atherosclerosis and is associated with endothelial dysfunction. Among the different types of inflammatory biomarkers, high-sensitivity C-reactive protein (hs-CRP) is well recognized for its use in screening and risk of CVD. Circulating levels of several different pro-inflammatory cytokines, including IL-6 and TNF-α are associated with risk of CAD outcomes. The present study examined the effects of flaxseed supplementation on endothelial function and markers of inflammation in individuals with CAD. The main findings of the present study were that flaxseed supplementation significantly improved endothelial function as assessed by FMD, and lowered circulating concentrations of IL-6, TNF-α, and hs-CRP. No changes were observed in the body weight following flaxseed consumption. FMD significantly increased in the flaxseed group and non-significantly decreased in the control group. Flaxseed is a rich source of ALA, an omega-3 fatty acid with potential beneficial effect on endothelial function. Flaxseed is also the richest dietary source of the plant lignan SDG. A higher habitual plant lignan intake has been associated with improved aortic stiffness. Flaxseed is a source of phenolic compounds that have high antioxidant capacity, which may prevent endothelial damage. In the present study flaxseed improved biomarkers of inflammation. The changes in FMD had an inverse correlation with the changes in IL-6 and TNF-α. This may indicate that increased circulating levels of inflammatory cytokines may adversely affect endothelial function, particularly in the brachial artery. The high concentration of ALA in flaxseed may also contribute to the anti-inflammatory effects. In patients with CAD, FMD has been shown to be independent predictor of secondary coronary events. The results of the present study show that flaxseed consumption improves endothelial function in patients with CAD and also attenuate selected markers of inflammation. Therefore, frequent consumption of flaxseed may improve CVD risk via mechanisms that affect vascular function and inflammation.