Phytoestrogens are a class of inactive compounds found in plants that when consumed are converted to active compounds similar to the steroidal hormones, estrogens. However, the activity of these phytoestrogens is much weaker than that of estrogen the body makes. The category of phytoestrogens can be further divided into isoflavones (like genistein and daidzein), lignans and cumestrans. The isoflavones and lignans are of particular importance because they have been found in higher levels in the plasma of people living in regions where cancer incidence is lower. Food sources of these compounds include soy products, chickpeas (garbanzo beans), red clover, rye grains, carrots, tea, spinach, and broccoli.
In the study, 1674 patients with lung cancer living in the US were followed over the course of 8 years. As well, 1735 healthy subjects were matched as controls for the study period. Researchers gave them food frequency questionnaires to quantify the amount of 12 dietary phytoestrogens consumed by the subjects. The results showed that the risk of lung cancer was reduced with increasing levels of phytoestrogen consumption. Of special note was the observation that high phytoestrogen intake was beneficial to both smokers and individuals who never smoked. Again, isoflavones and lignans were the categories of phytoestrogens conferring significant benefit. Women taking hormone replacement therapy also received significantly more protection than would be achieved with either phytoestrogens or medication alone, suggesting the mechanisms of action are unique.
Posted by Kristopher Foster on March 20, 2006 06:19 PM
