This study was designed to investigate whether flaxseed oil (FO) exerts hypocholesterolemic effects similar to ground whole flaxseed (WF) and to gain insight into its hypocholesterolemic mechanism. Forty-eight 6-month-old female Golden Syrian hamsters were either sham-operated (Sham) or ovariectomized (Ovx) and randomly assigned to one of four treatment groups (n = 12/group) for 90 days: Sham, Ovx, Ovx+WF, or Ovx+FO. Hamsters in the Sham and Ovx groups were fed a semipurified diet (control), whereas Ovx+WF and Ovx+FO received the same basic diet supplemented with either WF (15% wt/wt) or FO (amount equivalent to the oil contribution of WF). Ovariectomy significantly (P < .05) increased serum total concentrations by approximately 15%. WF, but not FO, prevented (P < .05) the ovariectomy-induced increase in serum total cholesterol concentration (12% and 4% reduction by WF and FO, respectively). Hamsters fed FO or WF had high-density lipoprotein (HDL)-cholesterol concentrations similar to those of the Ovx hamsters receiving the control diet. Non-HDL-cholesterol concentrations were lowest in the WF group, albeit not statistically different from the other treatment groups. There were no significant differences among groups in serum triglyceride concentration and liver lipids. Both WF and FO more than doubled the hepatic protein levels of 7α-hydroxylase in comparison to the Ovx hamsters receiving the control diet (P < .05). Our findings suggest that increased bile acid synthesis is one of the major cholesterol-lowering mechanisms of flaxseed and that other flaxseed components, aside from its oil, contribute to its hypocholesterolemic property. The cholesterol-lowering effects of other components of flaxseed and their mechanisms of action need to be further explored.
Our earlier study showed that flaxseed prevents vascular lesion development in ovariectomized hamsters. Flaxseed contains significant amounts of phenolic compounds, lignan, which are metabolized by colonic microflora to enterodiol (END) and enterolactone (ENL). The objective of this study was to evaluate and compare the anti‐inflammatory effects of END and ENL using the murine Raw 264.7 macrophage cell line. Cells were incubated in DMEM containing 10% FBS and 1% penicillin and then treated with increasing concentrations (0, 1, 10, 100, 500, 1000, 2500 and 5000μM) of END or ENL for 24 hrs. Subsequently, cells were challenged with LPS (500 ng/mL) for 24 hrs to induce an inflammatory response. Nitric oxide (NO) and cell viability were assessed using the Griess and Resazurin assays, respectively. Cell viability was not affected by any concentrations of END and ENL used in the study. As expected, the addition of LPS induced a significant increase in the production of NO and both END and ENL significantly decreased NO production. However, lower concentrations of ENL compared to END were required to significantly reduce NO production. These findings may in part explain the anti‐atherosclerotic effect of flaxseed and suggest that ENL may have more potent anti‐inflammatory properties.
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