I found a toxicology study of resveratrol; Rats receiving 300 mg/kg of body weight were not harmed, but at higher doses there were adverse effects: clinically significant renal lesions, including an increased nephropathy, renal tubule dilatation, papillary necrosis, acute pelvic inflammation, dehydration, anemia .....
They conclude that the maximum safe dose for rats was 300 mg/kg under the conditions of this study. Using a metabolic scaling factor to account for rats' faster metabolism and smaller size, this would translate to 50 mg/ kg in a human, or 3.5 grams daily for a 70 kg human (about 168 pounds.)
ToxSci Advance Access originally published online on August 25, 2004
Toxicological Sciences 2004 82(2):614-619; doi:10.1093/toxsci/kfh263
Resveratrol-Associated Renal Toxicity
James A. Crowell*,1, Peter J. Korytko, Robert L. Morrissey, Tristan D. Booth and Barry S. Levine
* Division of Cancer Prevention, National Cancer Institute, Rockville, Maryland 20892–7322; Toxicology Research Laboratory, University of Illinois, Chicago, Illinois 60612–7353; Pathology Associates, a Charles River Company, Chicago, Illinois 60612–7353; and Royalmount Pharmaceuticals Inc., Montreal, Quebec, Canada H4P 2T4
Resveratrol, (3,5,4'-trihydoxystilbene) a compound found in grapes, mulberries, and peanuts, has antimycotic, antiviral, and beneficial cardiovascular and cancer preventive activities. It is being developed for several clinical indications. To evaluate the potential toxicity of resveratrol, rats were administered by gavage 0, 300, 1000, and 3000 mg trans-resveratrol per kilogram body weight per day for 4 weeks. Most of the adverse events occurred in the rats administered 3000 mg per kilogram body weight per day. These included increased clinical signs of toxicity; reduced final body weights and food consumption; elevated BUN, creatinine, alkaline phosphatase, alanine aminotransferase, total bilirubin, and albumin; reduced hemoglobin, hematocrit, and red cell counts; and increased white cell counts. Increases in kidney weights and clinically significant renal lesions, including an increased incidence and severity of nephropathy, were observed. Diffuse epithelial hyperplasia in the bladder was considered, equivocal and of limited biological significance. No histological effects on the liver were observed, despite the clinical chemistry changes and increased liver weights in the females. Effects seen in the group administered 1000 mg resveratrol per kilogram body weight per day included reduced body weight gain (females only) and elevated white blood cell count (males only). Plasma resveratrol concentrations in blood collected 1 h after dose administration during week 4 were dose related but were relatively low given the high dosage levels; conjugates were not measured. Under the conditions of this study, the no observed adverse effect level was 300 mg resveratrol per kilogram body weight per day in rats.
The entire paper can be found here: http://toxsci.oxford...t/full/82/2/614