The Effect of Flaxseed Supplementation on Early Risk Markers for Mammary Carcinogenesis.
The Effect of Flaxseed Supplementation on Early Risk Markers for Mammary Carcinogenesis.
Year: 1991
Authors: M Serraino, L U Thompson.
Publication Name: Cancer Lett.
Publication Details: Volume 60; 135.
Abstract:
Early reports in animals and in vitro assessments have indicated that lignans possess cancer-protective effects. Flaxseed is the most abundant source of lignan precursors which are found primarily in two forms, secoisolariciresinol and marairesinol. In mammals, the lignans enterolactone and enterodiol are formed from marairesinol and secoisolariciresinol by the action of intestinal bacteria. Epidemiological data has shown lower urinary lignan excretion in omnivores and breast cancer patients than in vegetarians. The objective of this study was to assess the effects of flaxseed lignan precursors on early markers of risk for mammary carcinogenesis. Seventy weanling female rats were fed a high fat semi-synthetic diet with or without supplementation of either 5% or 10% flaxseed flour (FF) or defatted flaxseed meal (FM). At the end of 4 weeks of feeding, rats were subdivided into two groups. One group was given injections of colchicine and H-labeled thymidine for assessment of indices of cell proliferation including mitotic index (MI) and labelling index (LI). The other group was treated with the carcinogen DMBA. The MI and LI in the total and individual mammary gland structures were lower in the flaxseed fed animals. Flaxseed feeding resulted in significant reductions in epithelial cell proliferation (MI and LI) of 38.8 – 55.4% and in nuclear aberrations (NE) of 58.8 – 65.9%. Optimum effects were noted with the 5% FF. NE have been correlated with carcinogen exposure and may indicate the susceptibility of cells to carcinogens. Reductions in the number of NA may indicate less carcinogenic damage as a result of lowering the proliferative rates of the tissue. These protective effects were accompanied by increases in urinary lignan (enterolactone and enterodiol ) excretion. The authors speculated that diets that produce lower levels of lignans, such as the 5% FF diet, may be acting antiestrogenically by inhibiting the proliferative effects of estradiol on the mammary tissue. They concluded that supplementation of a high fat diet with flaxseed may reduce the risk for mammary cancer through the production of mammalian lignans. However, the relationship is not a simple dose-dependent one as the greatest effect was seen with 5% FF. Longer term studies are planned to confirm these results.
