Key Findings:
This review assesses the role of secoisolariciresinol (SECO) and SDG in human health. Research which shows the ability of these lignans to reduce hormone-dependent cancer is described. When risk analysis studies are undertaken that include a significant number of people with a regular intake of flax lignans, a stronger association between dietary lignan intake and reduced risk of hormone-dependent cancers as well as beneficial effects in maintaining a healthy cardiovascular system would most likely be found.
ABSTRACT:
Flaxseed (Linum usitatissimum) is the richest dietary source of the lignan secoisolariciresinol (SECO), a diphenolic compound that when ingested by humans influences a wide range of biological systems that help keep humans healthy. SECO, which is present in the seed coat as an ester of its diglucoside, is absorbed intact or can undergo bioconversion in the colon to a range of mammalian lignans including enterodiol and enterolactone, which are in turn also absorbed. These compounds have antioxidant properties; they are competitive binders to hormone receptors and proteins such as sex hormone binding globulin, and they influence health outcomes through their effects on gene expression. Clinical trials have shown that administration of lignan extracts significantly reduces serum cholesterol levels in hypercholesterolaemic subjects, has beneficial effects on subjects with benign prostatic hyperplasia and may have beneficial effects on glucose metabolism. Clinical trials with flaxseed, and animal studies with flaxseed and lignan extracts, have also indicated beneficial effects in terms of risk reduction for hormone-dependent cancers such as breast and prostate cancer, and a potential role in delaying progression of these cancers. Epidemiological studies of lignan exposure and cancer risk have shown that modest risk reduction is associated with lignan intake; however, these studies are not capturing the effect of even a very modest intake of flaxseed. Flaxseed and/or flaxseed meal has been incorporated into a wide range of functional foods, including breads, pasta, nutrition bars and breakfast cereals. (Authors abstract)
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