Effects of flaxseed on cardiovascular disease risk factors in humans using a plasma metabolomics approach.

Objectives: To investigate the effect of daily consumption of flaxseed (0, 20 and 30g) in adults with above optimal plasma LDL concentrations on biochemical pathways related to cardiovascular disease risk assessed in plasma using a High Resolution Mass Spectrometry based metabolomics approach.
Methods: A multi-site, randomized, double-blind, controlled, cross-over study was conducted at the Asper Clinical Research Institute in Winnipeg (n=34) and GI Laboratories Inc. in Toronto (n=29). Sixty-three (32 men, 31 women) healthy non-smokers, age 30-65, BMI 18.5-40.0 kg/m2, LDL 2.6-5.0 mmol/L, not taking cholesterol or blood pressure medication completed the trial.
Study Design: Cross-over with 3 phases, each lasting 4 weeks. During each phase, participants ate 1 muffin/day containing either 0g (control), 20g or 30g ground flax in each phase. Each phase was separated by 4-8 weeks. Order of treatments was random. Plasma was collected at the start and end of each phase.
Extraction of Metabolites: Plasma samples were extracted with acetonitrile (1:2) and centrifuged for 10min (10,000 x g at 4°C). The supernatant was dried (N2) and reconstituted with 100 µL 4:1 acetonitrile: ddH2O prior to analysis by LC-QTOF-MS (2 µL) in duplicate.
Data Analyses: A Molecular Feature Extraction algorithm (Agilent MassHunter Qualitative Analysis B.07.00.) was used to extract 7,997 entities from all plasma samples. One way ANOVA repeated measures (P<0.05) followed by Benjamini-Hochberg FDR Multiple Testing Correction were performed (MPP, 12.6.1).
Results: Phospholipids (phosphatidyl-ethanolamine (PE), -inositol (PI), -serine (PS), mono-, di- and triglycerides (MG, DG and TG) and LysoPE); amino acid (valine), and peptides (Thr Pro Arg lys and Thr Ala Lys) were among the 45 metabolites that were altered by flax consumption. One of the 45 metabolites, Leukotriene 4D methyl ester (LTD4), induces the contraction of smooth muscle, resulting in broncho and vasoconstriction. It also increases vascular permeability.
Conclusions: The observed significant changes may explain the physiological responses responsible for the beneficial effects of flaxseed on hypertension.