Yucca schidigera Roezl has been traditionally used to treat a variety of diseases including arthritis and rheumatism, it was then found that Yucca contains resveratrol. Resveratrol is also found in Veratrum grandiflorum, berries, peanuts, grapes, red wine and some other plants. Test-tube and animal studies indicate that resveratrol exhibits a wide range of biological effects, including antiplatelet, anti-inflammatory, anticancer, antimutagenic and antifungal properties. It could be interesting to estimate what dosage the users need to achieve such benefits. In this article, we estimate the resveratrol dosage requirement to achieve the relevant therapeutic effects based on 1. resveratrol concentration in the blood, in an animal study, and 2. the resveratrol doage/body weight ratio used in animal studies. _____________________________________________________________________________________
1. Estimation of Resveratrol Dosage based on Resveratrol Concentration found in animal studies
Resveratrol (5-35 micromol/l) was found to be able to induce concentration-dependent relaxation of mesenteric arteries preconstricted with noradrenaline (8 micromol/l) or KCl (125 mmol/l) from both lean and dietary-obese rats. [d1]
A phase I study of oral resveratrol (single resveratrol dosages of 0.5, 1, 2.5, or 5 g) was conducted by Leicester University, UK, in 10 healthy volunteers per dose level. Resveratrol and six metabolites were recovered from plasma and urine. Peak plasma levels of resveratrol at the highest dose were 539 +/- 384 ng/mL (2.4 micromol/L), which occurred 1.5 h post-dose. Cancer preventive effects of resveratrol in cells in vitro require levels of at least 5 micromol/L. The results suggest that consumption of very high resveratrol dosage (>>5 g daily) is needed to elicit systemic levels commensurate with cancer preventive efficacy. [c7] ______________________________________________________________________________________
2. Resveratrol Dose / Body Weight Ration Requirement for Therapeutic Effects
Study 1 Treatment with resveratrol dosage of 10mg/kg orally from week 4 to week 6 significantly attenuated the cold allodynia and thermal hyperalgesia, suggesting the application of resveratrol in diabetes, especially for diabetic neuropathy. [d5]
Study 2 Oral resveratrol dosage of 20 mg/kg daily for 4 weeks also remarkably prevented the DMN-induced loss in body and liver weight, and inhibited the elevation of serum alanine transaminase, aspartate transaminase, alkaline phosphatase and bilirubin levels. [LP1]
Study 3 Resveratrol Dosage of 20 mg/(kg . d) was adminstrated for 90 days to increase sperm counts. 
Study 4 Dosage of (vitamin D+400 mg/kg resveratrol+2,000 mg/kg quercetin+1,040 mg/kg genistein) reduced body weight gain and the fat pad weights in aged ovariectomized female rats.
Assuming the physiology of the animals used in the study is comparable to human's, for a body weight of 86.6 Kg, the required reservatrol dosage to achieve the biological effect (in Study 1) is 86.6 X 10 is 866 mg.
One liter of red wine contains only 1.5-3 mg of resveratrol. Consequently, resveratrol supplements are available in the market. One serving (2 capsules) of Resvinex 500 contains 500 mg of trans-resveratrol, while Puritan's Pride supplies various types of resveratrol products at range of 50 to 250 mg. _______________________________________________________________________________________
Safety Reveratrol Dosage
For the article Reveratrol Side Effects, we know that high dosages of resveratrol is unsafe. Then, up to what dosage is safe?
Researchers administered rats dosage of 0, 300, 1000, and 3000 mg trans-resveratrol per kilogram body weight per day for 4 weeks. Most of the adverse or side events occurred in the rats administered 3000 mg per kilogram body weight per day. Signs of toxicity included 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. They also observed renal lesions. No adverse or side effects were observed at 300 mg resveratrol per kilogram body weight per day in rats.  While, another scientific article suggests resveratrol is safe at doses equivalent to 500 mg/day. 
Hormetic response of resveratrol against cardioprotection. Recently, I have received a comment from a visitor about the hormesis of resveratrol. Hormesis is a dose response phenomenon characterized by a low dose stimulation, high dose inhibition, resulting in either a J-shaped or an inverted U-shaped dose response curves. [RD1] Recent studies indicate the hormetic action of resveratrol, in which resveratrol protects the heart cells at a lower dose while kills them at relatively higher doses. In an animal study, resveratrol formulation (Longevinex) was tested. A group of rats were fed with three different doses of resveratrol or Longevinex (dosage 2.5 mg/kg, 25 mg/kg and 100 mg/kg) for up to 30 days, while the control group was only given placebo. The results showed hormesis for pure resveratrol, which was cardioprotective at lower doses and detrimental for higher doses, but surprisingly Longevinex did not display such hormetic action. [RD2]
Different people may experience different side effects and benefits of a product. You are encouraged to report adverse side effects to FDA, its website is www.fda.gov., or report the adverse side effects to the manufacturer, you should be able to find the contact information on the label.
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