Veteran researcher: Polyphenols don’t work as antioxidants in vivo, but…

11-Jul-2010 - Last updated on 28-Sep-2021 at 11:30 GMT

Dr Peter Hollman has spent 30 years researching polyphenols which has led him to the conclusion they don’t work as antioxidants when ingested in foods and supplements because the human body makes enough of its own. But that doesn’t mean they aren’t useful and healthful compounds.

Dr Hollman, associate professor at RIKILT – the Institute of Food Safety at Wageningen University, said decades of research had turned up little that demonstrated polyphenols’ ability to deliver antioxidant benefits in vivo.

The compounds had other more complicated potentialities for human beings, he said, which was where his research efforts, and those of other scientists were moving.

“What we have found is that polyphenols don’t add too much [to the body’s defence against oxidative damage],” he said at the NutraIngredients Antioxidants 2010 conference in Brussels recently.

“If you are really depleted with all kinds of antioxidants and your system is not functioning well then maybe there is some possibilities that antioxidants can have an additional effect but for a healthy population there is no effect at all.”

“But there is a lot of evidence that polyphenols have good effects in your body; they have good effects on the cardiovascular system and there is some good evidence for that but that has nothing to do with their antioxidant activity. So they are healthy compounds to some extent but not because they are antioxidants but because they have lots of other properties. That’s the interesting part. There are a lot of other properties which are really very interesting.”

7 comments

Listen to what is said, not to what you want to hear

Posted by Dr Kirsten Brandt, 05 August 2010 - 09:05 GMT

Thank you very much Peter, for saying out loud and clear what is well known, but often not said! To achieve progress in this field (and others) and exploit its many possibilities, it is necessary to face the facts and use the data as they are, not as we want them to be!
It is incredibly easy to overlook the unexpected, see http://viscog.beckman.illinois.edu/grafs/demos/15.html for an illustrative example.
Another good example, which specifically addresses several antioxidant vitamins, is the paper by Tatsioni et al. 2007, JAMA 298: 2517-2526.
The fact that things don't work in the way we expected, does not mean that there is no effect, it just means that the effects must be investigated in other ways than before. Unfortunately it also means that much of the previous research, designed and done according to the old mindset, is no longer relevant.

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Polyphenols do have a role

Posted by Giridharan Nappanveettil, 24 July 2010 - 00:32 GMT

I go with the comments made by earlier commentators.There are whole lot of studies from Japan and China which show effect of green tea.They may not add anything extra ,if your antioxidant system is intact, but what about in conditions like obesity, cancer and even in aging, as Hollman himself has admitted..

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On the other hand....

Posted by James L. Wilmer, Ph. D., 20 July 2010 - 15:52 GMT

I think Dr. Hollman has adopted an extreme point of view. Certainly the polyphenolic literature tells us that these plant-derived ring compounds are not only potent antioxidants, but also have the capability of modifying enzyme activity and signaling pathways as well as interacting with chromosomes and altering the expression of important genes critical for human health.

We have shown that an isotonic polyphenolic product, Isotonix OPC-3, can modify various parameters in the cardiovascular system and reduce circulating concentrations of C-reactive protein by greater than 50% (M.R. Cesarone et al., Improvement in circulation and in cardiovascular risk factors with a proprietary isotonic bioflavonoid formula OPC-3. Angiology 59 (4): 408-414, Aug.- Sept. 2008). We also observed a concomitant drop in oxidative stress as measured by the D-ROM test, indicating that antioxidant compounds were diffusing into circulation.

As a follow-up D-ROM study, we conducted a time course study comparing OPC-3 prepared as an isotonic liquid versus tablets of OPC-3 powdered extracts (M.R. Cesarone et al., Accelerated antioxidant bioavailability of OPC-3 bioflavonoids administered as isotonic solution. Phytotherapy Research, published online in Wiley Interscience, DOI: 10.1002/ptr.2651, 2009.) Although both delivery forms of polyphenolic compounds resulted in significant, time-dependent reduction in oxidative stress markers, the isotonic delivery system was superior. Clearly, both studies showed that regardless of whether the isotonic OPC-3 solution was ingested for 8 weeks (Angiology) or for one sitting (Phytotherapy Research), the polyphenolic compounds are absorbed within 10 minutes (as measured by lowered reactive substances in a small blood sample by the D-ROM test) and have significant, sustained antioxidant activity up to 4 hours after ingestion on an empty stomach.

While the human body has numerous antioxidant systems to neutralize radicals, there appear to be additional radicals that can be scavenged by the use of antioxidant products.

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