A315 EFFECT OF CONTINUOUS ADMINISTRATION OF FLAXSEED AND FLAXSEED COMPONENTS ON THE GUT MICROBIOTA IN FEMALE MICE

Flaxseed (FS) contains FS oil (FSO), α-linolenic acid (ALA); lignan, secoisolariciresinol diglucoside (SDG); and 30% dietary fiber. FS and SDG have previously been shown to decrease early markers of colon cancer such as reducing epithelial cell proliferation and number of aberrant crypts and aberrant crypt foci. SDG and fiber are bio-transformed by the gut microbiota into enterolignans and short-chain fatty acid, respectively. These are at least partially responsible for FS beneficial effects. However, a comprehensive analysis of the effects of FS and its components on the gut microbiota is lacking. To investigate the effect of continuous administration of FS or FS components, FSO and SDG, on the gut microbiota in C57BL/6 mice. Fifty-six female C57BL/6 mice 4–5 weeks of age were randomly assigned into one of the four diet groups and fed for 3 weeks: i) Basal AIN-93G, ii) 10% FS, iii) 37% FSO or iv) 1.48% SDG. The experimental diets were supplemented with their respective components, FSO and SDG, at the level present in the FS and formulated to ensure that diets were isocaloric. After 21 days of intervention, the mice were sacrificed and feces and caecum contents (CC) were collected. 16S rRNA gene sequencing was performed on DNA extracted from CC (day 21) or feces collected at the baseline (day 0) or day 21 on a MiSeq instrument. UniFrac distances were calculated and β-diversity was assessed by PERMANOVA and principal coordinate analysis (PCoA) with QIIME. In the longitudinal analysis, PCoA of unweighted UniFrac distance matrixes resulted in 2 predominant clusters associated with the FS and BD/FSO/SDG diets in fecal samples. In line with this, at sacrifice samples clustered based on dietary treatment but FSO could not be distinguished from BD in both caecum and feces. Taxa known to be involved in enterolignans production were identified in the FS group. FS and SDG diet modify gut microbiota diversity in a different manner. Separation between FS and SDG clusters suggest that effect of FS is due not only to its SDG content but also to its fiber. This is significant as it suggests that FS and FS components act in both a differential and a complementary manner to potentiate positive health outcomes in the colon. NSERC (LUT, EMC), NSERC Canada Graduate Scholarship for Master’s to ZL. Lawson Family Chair in Microbiome Nutrition Research at the University of Toronto (EMC).

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