11 replies to this topic

[nameless]

I've been considering taking a Quercetin supplement to help with allergies, but I also have a concern regarding it inhibiting SIRT 1.

What is the current consensus regarding Quercetin? Safe to take, or best to hold off? And does it interact with any medications?

[maxwatt]

I've been considering taking a Quercetin supplement to help with allergies, but I also have a concern regarding it inhibiting SIRT 1.

What is the current consensus regarding Quercetin? Safe to take, or best to hold off? And does it interact with any medications?

It is anti-inflammatory; many find it helps allergies and arthritis. It does not prolong the life-span of C. elegans in the lab, unlike resveratrol. This is thought to be because though it causes expression of Sirt1, one of it glucoronated metabolites inhibits this gene. Some people combine it with resveratrol because it exhausts the enzymes that metabolize resveratrol, and higher blood levels of resveratrol have been measured when it is taken with quercetin.

Another effect of quercetin is to inhibit the formation of new capillaries. This may be why it sometimes seems to shrink tumors, but this would also be likely to delay healing of tendons or ligaments, and slow muscular adaptations that come with training that require increased blood supply.

It may interact with blood thinners, but I do not know of other drug interactions.

I do not think there is a consensus on quercetin. I've no doubt it can be beneficial for some individuals. There is enough variation in human enzymes, that it is even possible some people will benefit and some will not. Short term, I doubt if there is any harm from taking quercetin. Long term, I do not think anyone really knows. For life extension, I doubt it is a good bet.

[nameless]

Thanks for the information. Hmm... inhibiting new capillaries... not sure I really want that.

Maybe I'll just stick with vitamin C + grapeseed for allergies. Although neither seem to do a whole lot for me, really. Antihistamines are the only things that really seem to work.

[drmz]

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 anti-oxidant and anti-inflammatory activity, but recent in vitro evidence suggests that improved mitochondrial biogenesis could play an important role. However, 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 three treatment groups: placebo, quercetin 12.5mg/Kg, or quercetin 25mg/Kg. Following 7 days of treatment mice were sacrificed and soleus muscle and brain were analyzed for mRNA expression of PGC-1alpha and SIRT1, and 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 & peakspeed) 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 mitochondrial capacity 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. Key words: flavonoid, endurance capacity, mitochondria.

[madbrain]

I have been taking quercetin since last may , between 1g and 2g/day. I take it for its anti-HIV activity as part of a large supplement regimen. So far I can't say that I have had any side effects from it, and all my recent HIV blood work has looked very good.

[AHE]

Does anyone have experience with Quercetin giving an energy boost?

Has anyone used or heard of Quercetin soluble (Quercetin Chalcone)?

Any information about its effects in this regard?

Thanks.

[stephen_b]

There's a nice quercetin thread in the resveratrol forum.

[drmz]

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 anti-oxidant and anti-inflammatory activity, but recent in vitro evidence suggests that improved mitochondrial biogenesis could play an important role. However, 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 three treatment groups: placebo, quercetin 12.5mg/Kg, or quercetin 25mg/Kg. Following 7 days of treatment mice were sacrificed and soleus muscle and brain were analyzed for mRNA expression of PGC-1alpha and SIRT1, and 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 & peakspeed) 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 mitochondrial capacity 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. Key words: flavonoid, endurance capacity, mitochondria.

Seems that the below article is pointing to the study above >>

Study: Popular supplement quercetin does not enhance athletic performanc

The antioxidant quercetin is increasingly being marketed as a supplement that boosts athletic performance, but a new University of Georgia study finds that it is no better than a placebo.
Professor Kirk Cureton, head of the department of kinesiology in the UGA College of Education, and his colleagues tested quercetin in a double-blind, placebo-controlled study that assessed a variety of measures, including the ability of muscles to synthesize energy, cycling performance, perceived exertion and strength loss following exercise.
The researchers, whose results appear in the early online edition of the Journal of Applied Physiology, found that quercetin did not improve athletic performance in any of the measures they examined.“We did not see any performance enhancing effect of quercetin,” Cureton said. “To a certain extent that was disappointing because our hypothesis, based on previous studies in mice, was that we would see positive effects. But our findings are important because they suggest that results from the animal studies shouldn’t be generalized to humans.”

http://www.myhealthf...tic-performance

[niner]

Here's the abstract of the Cureton study. Doesn't do much for humans at 1g/d. We are pretty good at metabolizing quercetin, fwiw.

J Appl Physiol. 2009 Aug 13. [Epub ahead of print]
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.

University of Georgia.

Quercetin supplementation increases muscle oxidative capacity and endurance in mice, but its ergogenic effect in humans has not been established. PURPOSE: To investigate 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. METHODS: Using a double-blind, pretest-posttest control group design, 30 recreationally-active, but not endurance-trained, young men were randomly assigned to Quercetin (Q) and Placebo (P) groups. A noninvasive measure of muscle oxidative capacity (PCr recovery rate using magnetic resonance spectroscopy), peak oxygen uptake (VO2peak), 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 d of supplementation with 1 g/d of quercetin in a sports hydration beverage or a placebo beverage. RESULTS: Pretreatment-to-posttreatment changes in PCr recovery time constant, VO2peak, 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 Q and P. CONCLUSION: 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. Key words: exercise, flavanoids, muscle oxidative capacity, oxygen consumption.

PMID: 19679747

[drmz]

Effect of quercetin supplementation on maximal oxygen uptake in men and women.
Ganio MS, Armstrong LE, Johnson EC, Klau JF, Ballard KD, Michniak-Kohn B, Kaushik D, Maresh CM.

Human Performance Laboratory, University of Connecticut, Storrs, Connecticut.

Quercetin is a naturally occurring flavonoid with anti-oxidant and anti-inflammatory properties. The effect of quercetin supplementation on maximal oxygen uptake (VO(2max)) is unknown. The purpose of this investigation was to test the effects of quercetin supplementation on VO(2max) in untrained, sedentary individuals. After baseline treadmill VO(2max) testing, 11 participants (5 males, 6 females) ingested either placebo or quercetin-supplemented (1000 mg . day(-1)) food bars in a randomized, double-blind, counterbalanced, crossover research design. The participants ingested food bars for six consecutive mornings (5 days). On the sixth morning, participants underwent repeat VO(2max) testing. After a 22 day wash-out, the participants repeated baseline VO(2max) testing, daily consumption of the opposite food bars, and post-supplementation VO(2max) testing. The condition x time interaction for VO(2max) was non-significant when expressed in absolute (litres . min(-1); P = 0.929) and relative (ml . kg(-1) . min(-1); P = 0.778) terms. These findings were similar when taking sex into account (P > 0.05). The mean difference in VO(2max) change from pre to post between groups (quercetin vs. placebo) was 0.139 ml . kg(-1) . min(-1) (P = 0.780). Other physiological measures also were similar between conditions (P > 0.05). In conclusion, 5 days of quercetin supplementation did not influence VO(2max) or related variables in sedentary men and women

[eason]

Too much is very possibly harmful.

1: Exp Gerontol. 1982;17(3):213-7. Links
Quercetin, flavonoids and the life-span of mice.Jones E, Hughes RE.
A dietary supplement of 0.1% quercetin significantly reduced the life span of mice. The effect was predominantly on the 'shorter living' males. A blackcurrant juice extract, containing a mixture of flavonoids in addition to quercetin, prolonged significantly the life span of the 'older dying' females. The significance of these results vis-a-vis aging mechanisms and the dietary intake of quercetin is discussed.

PMID: 7140862 [PubMed - indexed for MEDLINE]

[mwestbro]

Quercetin inhibits heat shock proteins in cultured cells. I don't know if this is true in whole organisms.

1. Cell Struct Funct. 1990 Dec;15(6):393-401.

Flavonoids inhibit the expression of heat shock proteins.

Hosokawa N, Hirayoshi K, Nakai A, Hosokawa Y, Marui N, Yoshida M, Sakai T,
Nishino H, Aoike A, Kawai K, et al.

Department of Preventive Medicine, Kyoto Prefectural University of Medicine,
Japan.

Cells exposed to several forms of stress, such as heat shock, transiently
synthesize a group of proteins called heat shock proteins (hsps). Although many
stressors other than heat shock are known to induce hsps, inhibitors of hsp
expression have never been reported. Here we show that quercetin and several
other flavonoids inhibit the synthesis of hsps induced by heat shock in two human
cell lines, Hela cells and COLO320 DM cells. Quercetin inhibited the induction of
hsp70 at the level of mRNA accumulation. This is the first report to describe the
inhibition of hsp expression by reagents.

PMID: 2085852 [PubMed - indexed for MEDLINE]