Antioxidants May Make Cancer Worse
scientificamerican.com
scientificamerican.com
I really wish I could find that article again. I remember being fascinated by it.
Just found this:
http://www.hsph.harvard.edu/nutritionsource/antioxidants/#an... and disease prevention studies
This sort of difference, 21% [O2] vs 3% [O2] is massive to a biologic system, but observable results show up in hours to days. The idea was that, over a lifetime, similar oxidative stress, at far lower levels, would necessarily build up in cells over a lifetime. However, certain disease conditions, like G6PD deficiency, give us a window into human physiology with limited antioxidant capacity and a moderately sized study in Sardinia has shown they may actually have a somewhat lower cancer risk overall.
Antioxidants fall into the giant pool of "meh" for most issues.
Free radicals are not entirely stable, and are mutagenic when they attach and break the phosphate molecules in the backbone of DNA (possibly leading to cancer).[1] These are dangerous because they can form reaction chains, which break molecule after molecule before finding a resting state. The antioxidants tend to give a more-stable resting state for the free radical, which makes it easier for your body to clear it.
Hence if your body has enough free-radical fighting antioxidants, it is more equipped to metabolize cancer-causing compounds.
>.... it “could be that while antioxidants might prevent DNA damage—and thus impede tumor initiation—once a tumor is established, antioxidants might facilitate the malignant behavior of cancer cells..."<
Then immediately says this:
>The medical advice for people at this point is tentative. More studies need to be done to bolster this hypothesis and understand exactly how antioxidants affect cancer cells in humans. <
My takeaway is this:
Antioxidants may help prevent the sorts of DNA damage that contribute to cancers forming... Antioxidants may contribute to the health of cancer cells, once formed, in much the same way...but that's not certain yet, even though it certainly seems plausible...
In actual practice--everyday life--we have no idea at any given time whether we have active cancer cells growing in our body, or not...symptoms are what lead us to suspect that such is the case and seek medical advice...with certain types of cancer symptoms can take months, years, to appear...if the contention is true it's possible that people are going out of their way (with supplements), or being obsessive (with diet), all the while unknowingly contributing to their undoing...
I think I'll just keep eating a healthy blend of foods, avoid all supplements unless they've been prescribed because a diagnosed deficiency, and get plenty of exercise...
However, has even that much been proven? We know eating fruits and vegetables is good for you, and we know that in vitro, antioxidants help prevent damage to cells from free radicals. But considering that experiments with antioxidant supplementation have failed, do we really know that it's the antioxidants in fruits and vegetables that make them good for you?
I don't really understand the whole supplement craze. To me, it feels like common sense not to megadose any particular thing, especially when you don't understand the effects said thing can have on the body.
This is a great comment, and hits the nail on the head.
I've spent much of the past 10 years trying to understand and overcome a somewhat mysterious fatigue illness that seems most likely to be a general autoimmune condition.
One of the approaches I've tried along the way is to consume large amounts of various supplements, including vitamins, minerals, amino acids and herbs (basically, whatever was the latest thing I heard some convincing-sounding "expert" recommend).
What I ended up realising was that any high-dose supplement intake might initially make me feel better, but after a while it would actually make me feel worse.
As I understand it now, having devoted a lot of time to researching and experimenting with this, is that a deficiency in any nutrient is less to do with a lack of it in the diet and more to do with the body's ability/willingness to absorb and utilise it [1].
And so the more of any given nutrient that you try and shove into the body, the more you actually throw it out of balance, as it now has to deal with an excess of something it was already struggling with or resisting, as well the increased presence of that nutrient relative to other important nutrients.
More recently I've had much better success at improving my condition by learning how to match my nutrient intake to what my body actually needs and can handle at any given time (via diet and very sparing, selective supplement intake), and that seems to now have me on a steady path to full recovery.
[1] Sure there are many people in the world who are ill due to inadequate intake of certain nutrients from their diet, but that's more of an issue in poverty-stricken societies, as opposed to developed-world societies where most people have access to healthy-enough diets yet many still suffer from chronic illness.
I too have come to realise this. Many times when I have been eating well, good quality food with plenty of variety, I catch a heavy cold that puts me out of action for at least a couple of days. Other times I have eaten like crap for weeks at a time, living off of pizza and fast food, skipping meals, and been around sick people and still don't catch anything. I have seen this pattern repeat over and over throughout my life.
https://en.wikipedia.org/wiki/Coffee#Health_and_pharmacology
It's very hard to trust health information you get from the news.
"The study is based on the observation that with solid tumors, like melanoma, there is frequent dissemination of cancer cells through the blood (metastasis) but these cells are very inefficient at establishing a metastatic tumor. One reason for this is the immune system using ROS to essentially kill metastatic cells before they can be established. They found that cancer cells that do establish tumors tend to have mutations that make them resistant to oxidative stress.
"Most relevant to this topic, however, they found that in mice exogenous antioxidants promoted distant metastasis. This suggests that if you have cancer and you take antioxidants, your chance of developing metastases is greater. Keep in mind most solid tumor are usually present for 2-3 years before they are diagnosed, so the risk potentially exists even for those who have not yet been diagnosed with cancer.
"This has alarming implications given the popularity of antioxidant supplements."
[1] https://www.sciencebasedmedicine.org/more-trouble-for-antiox...
In fact, there are even some cases where an "antioxidant" molecule selectively killed a type of cancer cell by increasing oxidative stress inside cells, the opposite of what you'd expect from the blanket label. For example, it was recently shown that high doses of vitamin C selectively kill a type of colorectal cancer cell, but the mechanism of action was actually that the cells take up the oxidized form of vitamin C via a sugar transporter that tends to be upregulated in cancer cells, and the vitamin C-derrived pro-oxidant caused an oxidative stress signalling cascade that led to cell death [5].
[1] https://en.wikipedia.org/wiki/Catechin
[2] https://en.wikipedia.org/wiki/Anthocyanin
[3] https://en.wikipedia.org/wiki/Retinoid
[4] A corollary is that, like other drugs, each of these chemicals that is effective against some type of cancer probably won't necessarily work against other types.
[5] http://science.sciencemag.org/content/early/2015/11/04/scien...
http://drpasswater.com/nutrition_library/carotenoids_intervi...
Both of these guys have lived to quite advanced age though, so who knows anymore.
Every health nut (or enthusiast) praised antioxidants and will hold on to the belief because they already believed it for so long.
We don't believe in facts, we believe in whatever advertisers have exposed to us everyday on tv, radio, internet, and so on.
I kept looking to see if I am eating something wrong. So can someone with better understanding of antioxidants explain if this is only via vitamin or if it's specifically present in some types of food.
I don't know about this article specifically, but the importance of hormesis in medicine has come on fairly strongly in recent years. Specifically, that persistent, low-level damage to your cells and subsequent autophagy can actually reduce one's risk of various ailments. Antioxidants reduce the occurrence of this damage.
I'm not a medical professional, but I think whole, healthy foods are generally good choices.
If I were to speculate it might be that while normal cells can make enough for themselves cancerous cells benefit from external antioxidants. The damage done by free radicals is mostly concentrated in the mitochondrial genome, which is why evolution has brought as many genes as possible out of the mitochondria into the nucleus. By contrast the mutations that causes cancer are, IIRC, mostly inside the nucleus.
I highly recommend it if you don't mind the higher degree of technical content than your average popularizing science book
In no way does the research suggest that the antioxidant characteristics of the molecules are what is causing the cancer.
Note that the comment was speaking from a critical thinking perspective about the way cancer works and the way that the antioxidants work in the body (not from actual study results).
So this doesn't seem so surprising to me.