Diet is a primary source of human ingestion of glyphosate, the active ingredient in RoundUp, which is the most widely used herbicide in the world. The World Health Organization (WHO) has classified glyphosate as a probable human carcinogen. When test subjects were placed on an organic diet, glyphosate levels in urine dropped over 70% within three days. The study concludes that shifting to an organic diet is an effective way to reduce body burden of glyphosate and its main metabolite, AMPA.
Read more here about the peer-reviewed study by Fagan et al, published in the journal Environmental Research.