Flaxseed on cardiovascular disease markers in healthy menopausal women: a randomized, double-blind, placebo-controlled trial

OBJECTIVE: Due to its high content of lignans, alpha-linolenic acid and fiber, flaxseed may reduce cardiovascular disease risk in humans. The present study evaluated the effect of flaxseed on markers of cardiovascular disease risk in healthy menopausal women. METHODS: One hundred ninety-nine women were randomly assigned to consume 40 g daily of flaxseed or wheat germ placebo for 12 mo. Fatty acids, apolipoproteins A-1 and B, lipoprotein(a), low-density lipoprotein particle size, fibrinogen, C-reactive protein, insulin, and glucose were measured at baseline and at 12 mo. RESULTS: In total 179 women were available for the intention-to-treat analysis. Flaxseed increased plasma alpha-linolenic (P < 0.0001), docosapentaenoic (P = 0.001), and total omega-3 fatty (P = 0.0004) acids. Differences between flaxseed and wheat germ were observed for apolipoprotein A-1 (-0.10 +/- 0.26 g/L, P = 0.011) and apolipoprotein B (-0.05 +/- 0.16 g/L, P = 0.047). From baseline, flaxseed raised apolipoproteins A-1 and B by 4.4% (P = 0.006) and 3% (P = 0.054), whereas wheat germ increased these apolipoproteins by 11.6% (P < 0.0001) and 7% (P = 0.0001), respectively. Both treatments increased lipoprotein(a) (P < 0.0001) and decreased low-density lipoprotein peak particle size (P < 0.0001). CONCLUSION: In this large, long-term, placebo-controlled trial in healthy menopausal women, flaxseed increased some omega-3 fatty acids in plasma and had a limited effect on apolipoprotein metabolism.