I have read this one as well. Doesn't look promissing for Quercetin.(1) This, together with the joint pain, was my reason to stop it (500 mg Quercetin). I started to use if because of "Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance"(2. mouse study) and "Effects of Quercetin and EGCG on Mitochondrial Biogenesis and Immunity"(3) and some quercetin-influenza mouse studies. Let's see if the joint pain returns after a much lower dose then 500 mg. (i dropped EGCG together with Quercetin at the time)
I think it comes down to : “The moral is that you can’t generalize from mouse studies to humans.” Like they mention in the NY-times article. We need a pool of volunteers to test on
1.
Dietary quercetin supplementation is not ergogenic in untrained men.Cureton KJ, Tomporowski PD, Singhal A, Pasley JD, Bigelman KA, Lambourne K, Trilk JL, McCully KK, Arnaud MJ, Zhao Q.
Department of Kinesiology, Ramsey Center, 330 River Road, Univ. of Georgia Athens, GA 30602-6554. kcureton@uga.edu
Quercetin supplementation increases muscle oxidative capacity and endurance in mice, but its ergogenic effect in humans has not been established. Our study investigates the effects of short-duration chronic quercetin supplementation on muscle oxidative capacity; metabolic, perceptual, and neuromuscular determinants of performance in prolonged exercise; and cycling performance in untrained men. Using a double-blind, pretest-posttest control group design, 30 recreationally active, but not endurance-trained, young men were randomly assigned to quercetin and placebo groups. A noninvasive measure of muscle oxidative capacity (phosphocreatine recovery rate using magnetic resonance spectroscopy), peak oxygen uptake (Vo(2peak)), metabolic and perceptual responses to submaximal exercise, work performed on a 10-min maximal-effort cycling test following the submaximal cycling, and voluntary and electrically evoked strength loss following cycling were measured before and after 7-16 days of supplementation with 1 g/day of quercetin in a sports hydration beverage or a placebo beverage. Pretreatment-to-posttreatment changes in phosphocreatine recovery time constant, Vo(2peak,) substrate utilization, and perception of effort during submaximal exercise, total work done during the 10-min maximal effort cycling trial, and voluntary and electrically evoked strength loss were not significantly different (P > 0.05) in the quercetin and placebo groups. Short duration, chronic dietary quercetin supplementation in untrained men does not improve muscle oxidative capacity; metabolic, neuromuscular and perceptual determinants of performance in prolonged exercise; or cycling performance. The null findings indicate that metabolic and physical performance consequences of quercetin supplementation observed in mice should not be generalized to humans.
2. Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance.Quercetin is one of a broad group of natural polyphenolic flavonoid substances that are being investigated for their widespread health benefits. These benefits have generally been ascribed to its combination of antioxidant and anti-inflammatory activity, but recent in vitro evidence suggests that improved mitochondrial biogenesis could play an important role. In addition, the in vivo effects of quercetin on mitochondrial biogenesis exercise tolerance are unknown. We examined the effects of 7 days of quercetin feedings in mice on markers of mitochondrial biogenesis in skeletal muscle and brain, and on endurance exercise tolerance. Mice were randomly assigned to one of the following three treatment groups: placebo, 12.5 mg/kg quercetin, or 25 mg/kg quercetin. Following 7 days of treatment, mice were killed, and soleus muscle and brain were analyzed for mRNA expression of peroxisome proliferator-activated receptor-gamma coactivator (PGC-1alpha) and sirtuin 1 (SIRT1), and mitochondrial DNA (mtDNA) and cytochrome c. Additional mice underwent a treadmill performance run to fatigue or were placed in voluntary activity wheel cages, and their voluntary activity (distance, time, and peak speed) was recorded. Quercetin increased mRNA expression of PGC-1alpha and SIRT1 (P < 0.05), mtDNA (P < 0.05) and cytochrome c concentration (P < 0.05). These changes in markers of mitochondrial biogenesis were associated with an increase in both maximal endurance capacity (P < 0.05) and voluntary wheel-running activity (P < 0.05). These benefits of querectin on fitness without exercise training may have important implications for enhancement of athletic and military performance and may also extend to prevention and/or treatment of chronic diseases.
3. Effects of Quercetin and EGCG on Mitochondrial Biogenesis and ImmunityPURPOSE:: To test the influence of 1000 mg of quercetin (Q) with or without 120 mg of epigallocatechin 3-gallate (EGCG), 400 mg of isoquercetin, and 400 mg of eicosapentaenoic acid and docosahexaenoic acid (Q-EGCG) on exercise performance, muscle mitochondrial biogenesis, and changes in measures of immunity and inflammation before and after a 3-d period of heavy exertion. METHODS:: Trained cyclists (N = 39) were randomized to placebo (P), Q, or Q-EGCG and ingested supplements in a double-blinded fashion for 2 wk before, during, and 1 wk after a 3-d period in which subjects cycled for 3 h.d at approximately 57% Wmax. Blood, saliva, and muscle biopsy samples were collected before and after 2 wk of supplementation and immediately after the exercise bout on the third day. Blood and saliva samples were also collected 14 h after exercise. RESULTS:: Two-week supplementation resulted in a significant increase in plasma quercetin for Q and Q-EGCG and granulocyte oxidative burst activity (GOBA) in Q-EGCG. Immediately after the third exercise bout, significant decreases for C-reactive protein (CRP), and plasma interleukin 6 (IL-6) and interleukin 10 (IL-10) were measured in Q-EGCG compared with P. Granulocyte colony-stimulating factor and CRP were reduced in Q-EGCG 14 h after exercise. No group differences were measured in muscle messenger RNA expression for peroxisome proliferator-activated receptor gamma coactivator alpha, citrate synthase, or cytochrome c. CONCLUSIONS:: Two-week supplementation with Q-EGCG was effective in augmenting GOBA andin countering inflammation after 3 d of heavy exertion in trained cyclists
Edited by drmz, 20 November 2009 - 01:45 PM.