Flaxseed supplementation does not affect urinary excretion of thiobarbituric acid-reactive substances in post-menopausal women

Lipid peroxidation is a degradative, free radical mediated process involving biomembrane systems. Thiobarbituric acid-reactive substances (TBARS) are a toxic reactive oxygen species produced in vivo in response to peroxidizing tissues. Flaxseed contains phytoestrogenic compounds which have antioxidant properties. We examined the effect of daily ingestion of ground flaxseed on urinary excretion of TBARS in 30 post-menopausal women. Each subject consumed her normal diet + 0 g flaxseed (treatment I), her normal diet + 5 g flaxseed (treatment II) and her normal diet + 10 g flaxseed (treatment III). Each diet treatment lasted 7 weeks with a 7 week washout between each treatment in a randomized cross-over design. There were no significant differences (P>0.05) between treatments I and II, between I and III, and between II and III. These data indicate that daily supplementation of either 5 g or 10 g ground flaxseed in post-menopausal women does not cause significant changes in urinary excretion of TBARS, suggesting that a higher dose or longer feeding time is required.