Quercetin: the real story?

Related tags Antioxidant Nutrition

Just because most of the evidence supports the benefits of
quercetin as an antioxidant does not mean that research into its
potentially harmful aspects should be dismissed.

Yesterday's article​ on research from the Netherlands which suggested that the nutrient quercetin could have a potentially harmful effect on cells has prompted several vociferous responses from visitors to NutraIngredients.com.

Without exception, all those who responded to the story were quick to point out that there is no evidence of these so-called harmful effects, although there is substantial data showing that the nutrient can do a great deal of good. One reader accused us of pedalling "bad science" by reporting the news.

He pointed out that there was a great deal of recent research which supported the antioxidant properties of the nutrient. For example, he said, research from Norway clearly showed that quercetin helps to induce the body's own antioxidant mechanisms and therefore fight against oxidative stress, while separate studies from Japan and the UK showed that quercetin and other flavonoids had clear anti-cancer benefits.

These benefits have been known for some time, and the reader was right in his claim that they, unjustifiably, do not get the widespread coverage they deserve because they are seen as 'old news'. This is not to say, however, that the Dutch research we reported on yesterday is in any way better or worse than any other research which, for whatever reason, was not reported.

The Dutch report itself in no way denied the positive effects quercetin can have on the body. What it did​ point out was that this was, to the researchers knowledge, the first research of its kind into the potentially harmful effects of quercetin use, and that the suggestion that it might be harmful was merely the result of initial studies.

Surely there is always room for science to push the boundaries of human knowledge as far as it can? Just because there is a substantial body of evidence to suggest that a product is safe does not necessarily mean that that view will not be changed in the future as further evidence comes to light.

The antioxidant properties of quercetin have been well documented by researchers looking for evidence of this particular process. Why, then, is research which might show a different, additional effect, any less valid?

The fact that it was reported on this site does not mean that the researchers' conclusion is correct, nor does it imply that all the massive body of evidence supporting the safety of quercetin is somehow incorrect. If the Dutch studies had shown a new, healthy property of quercetin, would there have been the same outburst? Why should research showing a possible - and I emphasise the word possible​ - negative effect of quercetin be of any less interest to readers, or of any less importance, than the many articles which praise quercetin's antioxidant properties?

As yesterday's story pointed out, the Dutch research is at a very early stage, and there is no question of raising concerns about the use of the nutrient as a free radical fighter. But, as the recent concerns over kava kava show, products which have been considered safe for many years can sometimes surprise us, and consumers are looking increasingly to science to show them what is healthy and what is not.

At the moment, all the evidence shows that quercetin is an excellent antioxidant; in the future, research may also show that it can have negative effects as well. Just because the evidence seems overwhelmingly in favour of quercetin doesn't necessarily mean we should stop looking for adverse effects, or indeed pour scorn on research which seems to suggest the opposite of what we have always believed to be true. If mankind always acted like this, we would still believe the world was flat.

As one of the Dutch researchers, Professor Ivonne Rietjens, said: "We are not saying that quercetin is bad. It is one of the best antioxidants we know of. We just don't know enough about it yet."​ Let us hope that the Dutch research proves beyond all doubt that quercetin is safe - but let us also at least keep an open mind about it until then.

Related topics Research

Related news

Follow us

Products

View more

Webinars