I have used this product for a few years and not too long ago located it causes cell damage in the colon called Melanosis leading to a black colon ...The product Nature Renew Cleanse Scam is all usual and works , however I suppose it must include a warning label I had a colonoscopy on 11-29-10 and my healthcare professional instructed me my colon was once black because of use of clease extra. The Rhubarb is what motives the cellphone injury....Please beware of this if you take this product.My health care provider put me on a high fiber weight loss plan and instructed me to take Metamucil. http://www.xinyanlaw.com/nature-renew-cleanse-scam-or-legit/