Flaxseed but Not Flaxseed Oil Prevented the Rise in Serum Cholesterol Due to Ovariectomy in the Golden Syrian Hamsters

Abstract

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.

Impaired VLDL assembly: a novel mechanism contributing to hepatic lipid accumulation following ovariectomy and high-fat/high-cholesterol diets?

“…As reported previously ( 37 ) , Ovx rats had significantly higher plasma TC concentrations than sham-operated rats following the SD. Unexpectedly, this difference between the Ovx and sham-operated animals was entirely abolished after consumption of the HF and HFHC diets.…”

Evaluation of flaxseed formulation as a potential therapeutic agent in mitigation of dyslipidemia

“…[31] Addition of flaxseeds to the diet partially mitigated the rise in circulating cholesterol levels induced by the cholesterol-enriched diet through its content of ALA. [32] The results of our study are further supported by the findings of another study which proposes that increased bile acid synthesis is one of the major cholesterol-lowering mechanisms of flaxseed and that another component, besides its oil, contributes to its hypocholesterolemic property. [33] Dietary flaxseed lignans, such as secoisolariciresinol diglucoside (SDG), also have demonstrated potent antioxidant and anti-atherogenic effects. [34] A simultaneous mean elevation of 4.94% in the serum HDL level was also observed in our study [ Table 4].…”

Flaxseed and Its Components in Treatment of Hyperlipidemia and Cardiovascular Disease

“…4 Flaxseed oil did not prevent the rise in TC in ovariectomized Syrian hamsters although flaxseed did prevent this rise. 43 Nounou et al 44 showed that myocardial ischemia in rats increases the serum levels of TC and TG, decreases the serum level of LDL-C, and has no effect on HDL-C. In their study, they showed that flaxseed oil (0.4 g/kg daily for 6 weeks) reduced the serum levels of TG, TC, and LDL-C, but had no effect on HDL-C in rats with myocardial ischemia.…”