Antioxidants may speed up progression of cancer

Cancer pills?

Cancer pills?

Antioxidants are often pushed as being beneficial for health, largely based on speculations and uncertain observational studies. But could supplementation with antioxidants on the contrary be harmful? Yes, probably.

A new study on mice shows that those who received antioxidant supplementation – including Vitamin E – suffered a dramatic worsening of their lung cancer.

Of course, mice are not humans. But studies on humans show alarming signs that supplementation with antioxidants is harmful for us too. They may increase the risk for certain cancer forms and supplementation with high doses of the antioxidant Vitamin E increases the risk of dying prematurely.

Your body makes its own antioxidants, in the right place. Supplementation with extra antioxidants may be harmful, among other things by preventing the immune system from fighting infections… and cancer cells. Antioxidants may neutralize one of the immune system’s weapons against unwanted intruders, oxidizing agents.

The irony is that excess doses of antioxidants might protect the cells you want to eliminate: harmful bacteria and cancer cells.


  1. Doug Beard
    Andreas, does CoQ10 fall into this category do you think? I believe it acts as an antioxidant whilst being carried in cholesterol, also vital for good mitochondrial function. Lowered by statin use and lowers with age. I'm 65 and bought into the idea, so I supplement daily 200mg, it's expensive, but I can afford it, would I be better saving my money? I'm loving your work BTW you're my favourite blogger!!
  2. Lori Miller
    Ha! I was just saying the other day that some of the stuff in your body is supposed to get oxidized. When I supplemented with krill oil a few years ago (it's a strong antioxidant), I ended up with a face full if zits.
  3. Galina L.
    People are afraid from being under-nourished, while disproportionately many suffer from over-consumption. Body needs exactly the right amount of everything - nor more, nor less.
    Reply: #7
  4. Auto
    What about 1g per day of Vitamin C (ascorbic acid + rosa canina)?
    Could it be dangerous too?
    Reply: #6
  5. Jennifer Snow
    I figure if I'm seeing a reduction in joint pain, it's because I'm getting something I need and it's helping my body keep my chronic inflammation down. But it's good to know not to go overboard.
  6. Galina L.
    As far as I know what is not needed by body of vit .C gets excreted, so I guess, the excess is benign.
  7. Francois
    I'll add "IF the diet is one made of natural foods the human body is supposed to eat". Many people think that by taking supplements they can erase the effects of a bad diet. Unfortunately, antioxydants and vitamins thrown on top of a highly deficient diet does not make it a good diet: and from what is suggested here, it goes far beyond being useless: it may actually be detrimental.
    The idea that people should eat real unprocessed food as much as possible seems to be one of the most difficult to have people understand. maybe because it is too obvious.

    And as for Doug Beard's question, we naturally make less and less CoQ10 as we age. Maybe part of this has to do with the fact that people do not eat organ meats, rich in CoQ10. Maybe. But supplement with CoQ10 has been looked at in great detail by Langsjoen and coll in a series af articles (see for example Langsjoen PH, Langsjoen JO, Langsjoen AM, Lucas LA. Treatment of statin adverse effects with supplemental Coenzyme Q10 and statin drugs discontinuation. Biofactors 2005; 25(1-4): 147-52).

    There does not seem to be a dangerous level of Coq10. In fact, some patients were so depleted of CoQ10 with statin therapy that it took megadoses of Co Q10 before they could reach therapeutic levels. Anything below these blood levels was useless and produced no positive effects. Could we achieve this by eating a lot of organ meats? Maybe. But in face of statin-induced cardiomyopathy, I would play on the safe side and use pharmacological doses of Co Q10. I myself take CoQ10 supplements and krill oil supplements on top of eating a LCHF diet. I started someone in my family on supplemental CoQ10 because she had developed statin induced heart failure. Of course, her physicians are brainwashed by the industry and state "it is impossible", that her heart failure is due to some "viral infection", not to extraordinary statins. They also constantly try to start her statins again (she is over 80 years old!) Fortunately, CoQ10 is giving excellent results and we'll soon confirm with an echocardiogram that the failure is now resolved.

  8. Alan
    Could antioxidants reduce the probability of getting cancer?
    Reply: #9
  9. Francois
    That is what people thought. The study doc is referring to seems to suggest the contrary may happen. There are precedents. As far as I can remember, a few years ago, some researchers tried to give high doses of synthetic beta carotene (a precursor of vitamin A) to smokers, hoping to reduce their incidence of lung cancer. What was observed in two different studies, one in Europe and one in the US, is exactly the contrary: lung cancer incidence actually increased. There are a few hypothesis: betacarotene exists in two shapes: a cis and a trans (the molecule turns either to the right or the left - the formula stays the same, but the two molecules are basically the mirror image of one another. Seems that the cis form is beneficial but not the trans form, and that was in the artificial beta carotene.
    We're back to the point from the start: the way to go is real foods that we were meant to eat and not supplements.
    Reply: #11
  10. Alan
    Here are three interesting papers on the antioxidant astaxanthin, a carotenoid. I think that a large body of growing evidence suggests benefits rather than risks. This is the red pigment found in salmon that is made by a species of algae to protect itself from the sun.

    This one is a review of astaxanthin.

    These authors examined the effects of astaxanthin in young and old dogs. More benefits were seen in the old dogs. Both made more ATP.

    And here is one in fruit flies which showed benefits to mutant SOD (antioxidant enzyme) flies and detrimental effects (lower lifespan) in normal files. This is the only paper that I have read which suggests caution. These are fruit flies though.

    Maybe some antioxidants (not all of them are created equal) can be beneficial particularly if there is inflammation and excess oxidative stress. Sort of like the people who eat the SAD. And the excess exposure to some of the 80,000 odd chemicals that many of us get from our environment.

    It seems that the pharmaceutical industry is spending money trying to create fear in people who take supplements. Far more fear should be the norm when taking prescription drugs.

  11. Alan
    I thought that Andreas said that antioxidant therapy was tried on mice that already had cancer. This is a different question. But it seems possible to take too much of certain antioxidants.
  12. Anne
    What sort of vitamin E was used in this study? There is a big difference between synthetic vitamin E (dl-alpha tocopherol) vs natural E (d-alpha tocopherol). Also there seems to be some evidence that other forms of E such as gamma may be more important. Sometimes these negative studies do not use the best form of a supplement.
  13. George Henderson
    OK, let me get this straight, are there actually people out there taking megadoses of d, alpha tocopherol, (or dl if that's what it was) and only that, to treat cancer?
    I know people take it to thin the blood. But has it ever been claimed to be a cancer therapy, or even a preventive in anything other than multivitamin form?
    I don't think you could extrapolate from this to other antioxidants - vit E is a specific vitamin with its own receptor, it's not just an antioxidant, it's fat soluble but prefers different radical species from other fat soluble AOs, and water soluble AOs are different (ORAC and TBARS are not equivalent), and phenolic AOs may not even be antioxidants in the body and work in very different ways.

    Look at fig 4 in the second study
    The association with cancer in each class of antioxidant is driven by a single, atypical study which had a strong result where the others were neutral, or in the case of selenium, beneficial.

    If you did a meta-analysis of a real carcinogen, most studies would show a significant association with cancer, not just 3 or 4 out of 21. Yet these 3 or 4 are strong enough to skew the average.
    (there are vit E studies with reduced mortality in that meta-study too)

    You can learn from the studies themselves that certain antioxidants reduce the rate of certain cancers at certain doses, while certain other antioxidants increase the rate of certain other cancers.
    This is information which is obscured by a meta-analysis that lumps all antioxidants and all cancers together - quite a ridiculous method given the heterogenicity of both.

  14. Alan
    I just read the paper--the authors used only: DL-a-tocopheryl acetate.

    But they make the point that when using NAC (water soluble) the results were the same.

    I think prevention is the important question, and they did not test this.

  15. Martijn Van Zadelhoff

    My wife and I are using a Centrum multivitamin (voor Adults under 50) it states on the bottle it has 100% of the "recommended vitamin E beside all other daily recommended vitamins.
    We eat a LCHF diet with plenty vegetables, would you recommend eliminating this supplement?

    Thank you,


  16. bill
    How 'bout a ketogenic diet to deal with
    cancer? Doesn't seem to get much press.
    Reply: #18
  17. George Henderson
    (Dietary tocopherols and tocotrienols associated with reduced lung cancer risk in humans).

    Here's an RCT of vit E (dl, 50mg) and beta carotene (20mg) intervention in smokers. Vit E didn't increase lung cancer (beta carotene did), but did decrease prostate and colon cancers.

  18. François
    Actually, there have been some very interesting studies on the use of a ketogenic diet in the treatment of cancer. Since cancer can only feed on glucose and glutamine, while normal cells can feed without difficulty also on ketone bodies a ketogenic diet actually starves cancer. A ketogenic diet strongly helps patients with cancer and can (should) be combined with conventional treatment.

    Cancer cells have a high affinity for sugar and eat it at a rate 8 times that of normal cells. Cancer cells have in fact up to 15 times more insulin receptors than normal cells.

    “Compared to normal cells, cancer cells have a prodigious appetite for glucose, the result of a shift in cell metabolism known as aerobic glycolysis or the "Warburg effect." Researchers focusing on this effect as a possible target for cancer therapies have examined how biochemical signals present in cancer cells regulate the altered metabolic state.”

    Researchers have thus proven that cells that need glucose in order to survive can be destroyed by glucose restriction. In a rather elegant paper, Graham et al. (Graham NA, Tahmasian M, Kohli B, Komisopoulou E, Zhu M, Vivanco I, Teitell MA, Wu H, Ribas A, Lo RS, Mellinghoff IK, Mischel PS, Graeber TG. Glucose deprivation activates a metabolic and signaling amplification loop leading to cell death. Mol Syst Biol. 2012 Jun 26;8: 589. doi: 10.1038/msb.2012.20.) state that: “glucose withdrawal activates a positive feedback loop involving generation of reactive oxygen species (ROS) by NADPH oxidase and mitochondria, inhibition of protein tyrosine phosphatases by oxidation, and increased tyrosine kinase signaling. In cells dependent on glucose for survival, glucose withdrawal-induced ROS generation and tyrosine kinase signaling synergize to amplify ROS levels, ultimately resulting in ROS-mediated cell death.”(Graham et al., 2012)

    Santisteban et al. conducted a study in 1985 where they fed three different types of diets to mice suffering from mammary tumors. What they found was eye-opening: the higher the average blood glucose, as measured by glycated haemoglobin , the faster the rate of tumor development and the quicker the animals would die of their cancer. There was no “safe” level: even mice with “normal” average blood sugars died earlier than mice with “low” average blood sugar.

    And it makes sense! Cancer cells (all cancer cells) love sugar and need it to grow. Normal cells can live perfectly well without glucose and can strive on either ketone bodies or fatty acids. Cancer cells cannot. They only can process glucose and to an extent, the amino acid glutamine as energy. So the lower the blood glucose, the more it will be difficult for the cancer to grow. By switching to a ketogenic diet, very low in sugar, some people have starved their cancer and are now healthy. This “cancer starvation” technique can be combined with every conventional medical treatment. (See Santisteban GA et al., 1985 and Poff AM et al., 2013).
    Poff AM, Ari C, Seyfried TN, D'Agostino DP. The ketogenic diet and hyperbaric oxygen therapy prolong survival in mice with systemic metastatic cancer. PLoS One. 2013 Jun 5;8(6):e65522. doi: 10.1371/journal.pone.0065522. Print 2013.

    Santisteban GA, Ely JT, Hamel EE, Read DH, Kozawa SM. Glycemic modulation of tumor tolerance in a mouse model of breast cancer. Biochem Biophys Res Commun. 1985 Nov 15; 132(3):1174-9.

    “We have dramatically increased survival with metabolic therapy (ketogenic diet). So we think it's important to get this information out. It's not just lab mice. I've been in correspondence with a number of people, At least a dozen over the last year-and-a-half to two years, and all of them are still alive, despite the odds. So this is very encouraging.”
    (Dr. Dominic D’Agostino, Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, United States of America, 2 Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States.)

  19. Abdul
    I am a little concerned about the slant Diet Doctor is taking when it comes to nutritional supplements. It's almost like a scare tactic where unsuspecting readers will begin to consider dropping their multivitamin and vitamin c or other supplements they take. Please don't stop taking your supplements - decades of research by luminaries such as Linus Pauling, Abraham Hoffer, Robert Cathcart and Fred Klenner, have convinced me that supplementation is a key ingredient to maximising longevity in our modern age. Vitamin C is just one example - a potent water-soluble antioxidant that reduces your risk of stroke, protects against heart disease, is involved in the production of serotonin and dopamine and on and on. Take 1000mg of Vitamin C with meals is not going to give anyone cancer, I am sorry. The propaganda is getting too much and the studies cited have methodological flaws - just like the recent study about fish oil and prostate cancer. Keep supplementing! Here's the other side to this story on Vitamin E and cancer:-

  20. Becky
    The reason that antioxidants may be counterproductive is that free radicals sometimes perform a useful role-- including helping to kill cancer cells. By reducing the free radicals in our bodies, the antioxidants are actually helping to protect the cancer cells.

    Antioxidants may help to prevent cancer, but once you have cancer, it's best not to take them.

    I'm working very hard to prevent cancer recurrence with a strict ketogenic diet. I'd hate to undo the good work of a disciplined diet by adding antioxidants at this point.

  21. Sheila de Koekkoek
    Just a quick comment. Go to the hospitals and see all the sick people who have the belief that their food is good enough. In agreement with Becky above, anti oxidants are believed to be essential to prevent cancer by removing free radicles. With cancer treatment one has to wait until the chemo has been given and there is controversy over the effects of antioxidants when it is that far. However Vit C apparently in high hdoses becomes an oxidant and can be safely used to prevent and to treat cancer. Don't forget there is more to the body than cancer in health treatments. With supplements you are less likely to have to have the shockingly detrimental medications that are being thrown at the general eg. cholesterol satines.etc. etc. I for one have taken antioxidants for the last 35 years and in good health at age 78 and take no medication at all, likewise my husband aged 84.
  22. vtw
    The metabolic theory of cancer has always took the back seat to the genetic theory. The mitochondria(energy producers) in our cell cause oxidative environs and to my (laypersons speculation at best) the author is tying antioxidants to unhealthy cell groath. Cancer thrives in an anarobic or fermented state and just loves all that excess sugar but does this mean it loves antioxidants? Something tells me there's much more to this story.
  23. Bob
    Damn, I need a DVT solution!

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