Plant lignans are natural polyphenol compounds found in many plants. The main plant lignan, secoisolariciresinol diglycoside (SDG), is converted to two mammalian enterolignans, enterolactone and enterodiol, by bacteria normally present in our intestines. Numerous research studies have reported that lignans have multiple health benefits. Among these possible health benefits is a potential reduction in breast cancer risk ; however, much of this information comes from animal and cell culture studies and studies of relationships between diet and breast cancer incidence. While the evidence suggest possible breast cancer fighting benefits of dietary lignans, the reason's for these possible benefits are not entirely clear.
A new breast cancer study published online ahead of print in Cancer Prevention Research examined changes in human breast tissue in relation to dietary consumption of lignans. For this study, breast tissue samples were collected from 45 premenopausal women at high risk for breast cancer (3-fold increase in 5-year risk) by fine needle aspiration at the beginning of the study. The women were then asked to consume 50 milligrams of SDG every day for one year, after which a second breast tissue sample was collected. Changes in breast cell growth markers, cell appearance, breast density and blood hormone levels were measured. The investigators reported that
As expected with dietary consumption of the plant lignan, blood levels of total lignans and enterolactone increased substantially.
80% of the women in the study experienced a significant decrease in the cell growth marker Ki-67 after consuming the dietary lignan.
The percentage of women in the study who had abnormal breast cell appearance was dramatically lower after consuming SDG for 12 months compared to the beginning of the study.
These are very positive and exciting results. The study authors point out that this was a small pilot study, but indicate that the positive benefits observed have convinced them to start a larger, placebo-controlled clinical trial to determine the true effectiveness of dietary lignans for breast cancer protection. Dietary lignans can be found in a variety of foods like fruits (strawberries, apricots), vegetables (broccoli, cabbage, kale), seeds (sesame seeds, flaxseeds), and more. Flaxseeds are reported to have the highest concentration of lignans at about 85 milligrams per ounce. Interestingly, many of the plants listed above as sources of dietary lignans have also been reported to have breast cancer fighting benefits. Fruits are rich in antioxidants and the cruciferous vegetables (broccoli, cabbage, etc) are good sources of indole-3-carbinol and sulforaphane, chemicals with reported breast cancer fighting properties. So making some of these fruits, vegetables, and seeds part of your regular diet might help fight breast cancer in many ways.