Re: Flavonoids (e.g. quercetin): just AVOID supplements

[Guest guest]

hi all -

> So, do NOT supplement with flavonoids (e.g. quercitin) or soy

> isoflavones (e.g. genistein, etc.) Get them from food, including

> green tea (or red wine if you like and tolerate.)

> http://www.nal.usda.gov/fnic/foodcomp/Data/Flav/flav.html

>

> To study that supports my warning is:

>

>>>>>> At higher doses, <<<<<<<<

> flavonoids may act as mutagens, pro-oxidants that generate free

> radicals, and as inhibitors of key enzymes involved in hormone

> metabolism. Thus, in high doses, the adverse effects of flavonoids

> may outweigh their beneficial ones, and caution should be exercised

> in ingesting them at levels above that which would be obtained from

> a typical vegetarian diet.

well, OK, a point that may be well worth taking, but unfortunately they don't

define " higher dose " - what is it? 1 gram? 5 grams? 20 grams? Until someone

makes that dose more specific I think your suggestion to avoid supplements

altogether is not necessarily a good one.

Judith G

[Guest guest]

Thanks for the post. This is quite upsetting. Does anyone know what

is the maximun dose for flavanoids?

I was thinking of taking 100% pure therapeutic grade citrus

essential oils for their flavanoids and other benefits.

Thanks,

Gayathri.

> Free Radic Biol Med. 2000 Aug;29(3-4):375-83.

> Potential health impacts of excessive flavonoid intake.

>

> Skibola CF, MT.

>

[Guest guest]

Most researchers seem to agree that cfs patients produce too much

nitric oxide. Lester Packer, a famous antioxidant research scientist

says that Pycnogenol ( a blend of flavonoids ) is the best at

controlling nitric oxide. He tested it for antioxidant activity in

his lab and found it quenched superoxide, nitric oxide and the

hydroxyl radical.

Grape seed extract seems to have the exact same active ingredients

as Pycnogenol, about 10% more of them and it is cheaper too.

Green tea is also a nitric oxide scavenger.

So it would make sense for cfs patients to take flavonoid

supplements for a while to see if it can help a little I guess.

Here is another study warning about toxicity of flavonoids:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=15223063

These three studies on the other hand say that taking

Pycnogenol/Grape seed extract supplements is safe and that there

were no signs of toxicity:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=11081989

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=12237816

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?

cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=11955665

There are also studies available that say supplementing with vitamin

C and alpha lipoic acid is dangerous, but since there are no large

double blind studies on supplements, we will never know.

The problem is that there are currently no standard drugs available

for cfs and so many of us are using supplements to try and feel a

little bit better.

R.

> Folks,

> most probably you are already aware that the reasoning " if some

is

> good, more is always better " is a complete fallacy. It's

important

> to keep that in mind when dealing with supplements. E.g., all

> antioxidants become pro-oxidants at excessive amounts. That holds

> true for flavonoids, and it is important because the amount in

> supplements is usually much higher than what you can get from food.

>

> So, do NOT supplement with flavonoids (e.g. quercitin) or soy

> isoflavones (e.g. genistein, etc.) Get them from food, including

> green tea (or red wine if you like and tolerate.)

>

> Possibly the best source for finding out the flavonoid content

of

> foods is the PDF file linked at the " USDA Database for the

Flavonoid

> Content of Selected Foods - 2003 " page at

>

> http://www.nal.usda.gov/fnic/foodcomp/Data/Flav/flav.html

>

> To study that supports my warning is:

>

> Free Radic Biol Med. 2000 Aug;29(3-4):375-83.

> Potential health impacts of excessive flavonoid intake.

>

> Skibola CF, MT.

>

> Division of Environmental Health Sciences, School of Public

Health,

> University of California at Berkeley, 94720-7360, USA.

>

> Plant flavonoids are common dietary components that have many

potent

> biological properties. Early studies of these compounds

investigated

> their mutagenic and genotoxic activity in a number of in vitro

> assays. Recently, a renewed interest in flavonoids has been fueled

> by the antioxidant and estrogenic effects ascribed to them. This

has

> led to their proposed use as anticarcinogens and cardioprotective

> agents, prompting a dramatic increase in their consumption as

> dietary supplements. Unfortunately, the potentially toxic effects

of

> excessive flavonoid intake are largely ignored. At higher doses,

> flavonoids may act as mutagens, pro-oxidants that generate free

> radicals, and as inhibitors of key enzymes involved in hormone

> metabolism. Thus, in high doses, the adverse effects of flavonoids

> may outweigh their beneficial ones, and caution should be

exercised

> in ingesting them at levels above that which would be obtained

from

> a typical vegetarian diet. The unborn fetus may be especially at

> risk, since flavonoids readily cross the placenta. More research

on

> the toxicological properties of flavonoids is warranted given

their

> increasing levels of consumption.

>

> Publication Types:

> Review

> Review, Tutorial

>

> PMID: 11035267 [PubMed - indexed for MEDLINE]

[Guest guest]

I credit quercetin with curing a corneal erosion problem that I had

for years (at least a decade), that caused me to have countless laser

surgeries. Since I started taking quercetin (by accident, for another

problem), I have not another occurance of the cornea problem, and it's

been several years. Quercetin has also definitely helped some

inflammation problems that I've had in various areas of my body, that

weren't helped by traditional anti-inflammatories.

The problem with evaluating the effects of flavonoids, is that the

body metabolizes them to different compononents. Testing the effects

of the original flavonoid in labs, may have little real meaning, if

the digestive tract converts them to other forms.

Also, such lab tests don't take into account the fact that people who

take flavonoids, are also taking other supplements, that could offset

any detrimental effects. For example, one recent study on quercetin,

concluded that it might be safe, as long as one had sufficient GSH

levels. Thus, quercetin might be safe, as long as you are taking

other antioxidants.

My personal opinion, would be to take flavonoids, if they make an

observable effect on your health. But don't take them, just because

you are told that they might prevent something.

Mark