Hello. Polyphenols have been included in nutritional supplements as unregulated substances. They are present in many foods some of which are either inedible or poorly edible such as soy. There is very little known about their overall effects on the body. An interesting article appeared in the American Journal of Clinical Nutrition published on January 1, 2005. The first author is Louise Mennonite. Title is Risks and Safety of Polyphenol Consumption.

It appears that there are reports of interactions with the thyroid gland and with hematologic functioning. There are reports of cancers developing in patients taking these supplements. Cause and effect, though, is not known and more studies should be done for further investigation.