Antioxidant Supplementation - What Forms Are Less Likely To Be Counterproductive?

[Consultant]

I've done a bunch of reading on antioxidants - mainly from the perspective of cancer prevention/delayed progression.  It seems over the years there is growing consensus that taking antioxidant supplements can do more harm than good in many cases?  I won't regurgitate what I've read but in general it seems to be proven Vitamin E and Beta-Carotene can actually increase the risk of cancer.  This has something to do (explained in oversimplified terms) of them actually reducing the ability of free radicals to damage cancer cells.  I'm sure that is grossly oversimplified and possibly explained wrong, but you get the general theory.  I've read they can actually reduce the effectiveness of radiation therapy. 

I am wondering if there is any research as to other antioxidant supplements as to whether they are "safer" then Vitamin E and Beta-Carotene?  Or do all compounds with anti-oxidant properties work in basically the same way and therefore carry the risk of actually reducing the bodies ability to prevent/fight cancer? It seems to me, the nutraceutical industry may have overhyped antioxidants which has created billions in profits over the years for supplement manufacturers? 

More specifically I am wondering if things like pomegranate extract or curcumin had antioxidant properties (or other compounds) that make them a "safer" antioxidant supplement than Vitamin E and Beta Carotene.  It seems in the end, the wise advice is to not waste your money and just get antioxidants though incorporating fruits and vegetables into the diet.  However I find it frustrating I am not turning up much information on meta-studies comparing effects of different anti-oxidants, long term.

 

[exchemist]

3 hours ago, Consultant said:

I've done a bunch of reading on antioxidants - mainly from the perspective of cancer prevention/delayed progression.  It seems over the years there is growing consensus that taking antioxidant supplements can do more harm than good in many cases?  I won't regurgitate what I've read but in general it seems to be proven Vitamin E and Beta-Carotene can actually increase the risk of cancer.  This has something to do (explained in oversimplified terms) of them actually reducing the ability of free radicals to damage cancer cells.  I'm sure that is grossly oversimplified and possibly explained wrong, but you get the general theory.  I've read they can actually reduce the effectiveness of radiation therapy. 

I am wondering if there is any research as to other antioxidant supplements as to whether they are "safer" then Vitamin E and Beta-Carotene?  Or do all compounds with anti-oxidant properties work in basically the same way and therefore carry the risk of actually reducing the bodies ability to prevent/fight cancer? It seems to me, the nutraceutical industry may have overhyped antioxidants which has created billions in profits over the years for supplement manufacturers? 

More specifically I am wondering if things like pomegranate extract or curcumin had antioxidant properties (or other compounds) that make them a "safer" antioxidant supplement than Vitamin E and Beta Carotene.  It seems in the end, the wise advice is to not waste your money and just get antioxidants though incorporating fruits and vegetables into the diet.  However I find it frustrating I am not turning up much information on meta-studies comparing effects of different anti-oxidants, long term.

 

I was not aware that radical scavengers would actually increase risk of cancer. Surely it is the reverse? Do you have a link to an example of a study showing this?

My understanding of the position was more or less as explained here: https://www.nccih.nih.gov/health/antioxidants-in-depth. viz. antioxidants in the diet are generally protective, but there is no evidence that further supplements add to that protection. Note this refers to what is apparently a considerable body of research, though it does not provide the specific references.

Edited March 8, 2022 by exchemist

[CharonY]

The situation is complicated, and to a large extent it is because the boundary between ROS activities on the cellular level (including in cancer) are often mixed up with dietary antioxidants.

It is often not quite clear, for example how much and in which form a dietary supplement reaches a particular tissue and how it might act once there. Studies in beta carotene have shown that once oxidized it might have pro-carcinogenic properties and in radical-rich environments (e.g. where inflamed tissues, lungs) it might increase cancer risk. However, that is actually very difficult to track in-vivo. I think for resveratrol there is some of largest of evidence with regard to anti-oxidative and -inflammatory actions, but hepatoxicity and other issues limit their usefulness.

Many studies are cohort-based, i.e. you compare folks taking supplements vs those that don't. But here the issue is that we often only see outcomes and can only speculate on mechanisms.

The closest we get to mechanisms are often animal studies, but then there is always the question is how to translate the metabolic differences.

I do agree that the data on anti-oxidants is incredibly vague and again is mostly based on cohort outcomes, and especially in humans we have so many variables that we would need huge effect sizes(which we typically do not have) to be certain of a true effect.

I am not an expert in this field, and all I can say is that I have not come across a "killer" paper that erased all doubts on effectiveness. Rather, as outlined in OP, we see some papers with positive, some with negative effects (and I am sure a lot of unpublished ones with no effect).