The Free Radical Theory of Aging


Another “Bad Guy” joins the ranks of useful cellular processes.

This dates from the 50s. The idea is that free radicals, normal byproducts of metabolism, are dangerous and responsible for aging and disease. This led to a huge supplement industry item: the anti-oxidant. Big problem: the theory’s wrong.

This idea it to take the pills and get those anti-oxidants hoovering up those evil free radicals. As simple as it is arrogant. Wouldn’t the body, in all its evolutionary perfection, already have this covered? Of course it would, but the idea that we know better than Mother Nature is a strong one, and 150 million Americans are taking various and sundry anti-oxidants, and all for naught.

A free radical is dangerous, and nothing, absolutely nothing, that the body produces that is dangerous is going to be left to run rampage as suggested in the supplement commercials. The body has several very good uses for free radicals, and has also a complete means of keeping them at the healthiest level. That is, unless someone dares to interfere.

In the research community, it is fairly broadly known that the free radical theory of aging is a non-starter. An excellent survey article is to be found here, and a recent article here.

Specifically, innumerable supplements claim antioxidant properties. The three primary ones are vitamins A, C, and E, and in three decades, no studies have found any benefit to supplementing with any of these, and have, in some cases, found outright harm.

What? Harm?


Apparently our superhero does more harm than good.

One well done meta-analysis, found here, had some scary results: Beta-carotene, and vitamins A and E increased mortality. That wasn’t quite what we ordered. Selenium and vitamin C appeared neutral. None of these provided benefit. So why are 150 million people taking them? It is probably that the free radical theory of aging is simple—easy to understand. Unfortunately it is wrong, but the theory that replaces it is a lot more complicated. However, we’ll take a shot at it anyway, intrepid bloggers that we are.

What are free radicals all about?

A free radical is an “incomplete” molecule—specifically it has unpaired electrons. As such it seeks to combine with some other molecule or atom that can complete the pairing. This propensity to pair up makes free radicals very active. For instance, hydroxyl is an oxygen molecule with a single hydrogen molecule. HO. It has a single free electron, and so will actively attach with any handy molecule that can supply this. A hydrogen atom would be just dandy, resulting in H2O, something not dangerous at all. But nowhere is it written that the hydroxyl radical has to combine with hydrogen. It could choose something else, like a strand of DNA. This would mess up the DNA, and is generally something to be avoided, as such activities can initiate cancer. So potentially a free radical can do some damage. So far it looks like we would like to get rid of them, but read on.

Where do free radicals come from?

Free radicals can come from many chemical reactions. Specifically they are a natural byproduct of oxygen metabolism which goes on in the mitochondria, our little cellular power sources (each cell has hundreds or even thousands of these, generating energy from the oxygen. This free radical generation is going on in a grand scale, and obviously the body has to stay on top of it or every single cell would soon be fried. Thus there is a whole stable of enzymes and other chemicals generated to vacuum these things up. And like everything else in the body, this process is tightly regulated, and will work in an optimal fashion unless overwhelmed.

But what might overwhelm it? There could be too many free radicals for the defenses to keep up. This could be caused from trauma, infection, poisons, burns, or even excess exercise. There could also be too few free radicals. Turns out that even though potentially dangerous, free radicals are recruited into several necessary functions. What would cause too few free radicals? Excessive anti-oxidants.


What are the beneficial uses of free radicals?

There are several, and, as in most bodily functions, they shouldn’t be meddled with unnecessarily. Here are several tasks to which free radicals are put.

  • Immune cells kill invading bacteria by injecting them with free radicals.
  • A healthy cell will control free radicals properly. A cancerous cell may not. This means a cancerous cell will be more vulnerable to destruction from free radicals.
  • Nitric oxide, a free radical, is important for maintenance of blood vessel wall integrity and blood pressure regulation.
  • Free radicals are used to signal the heart to pump more blood into a stressed region.
  • Free radicals generated in exercise stimulate muscle growth.
  • Free radicals on the skin generate skin growth.


And the list goes on and on. A common thread is that stress to some area of the body will generate free radicals. Other processes will detect this and initiate repair and growth activities. Yet other processes will mop up any stray free radicals before they can cause problems. This sounds to us like a delicate, well-tuned process that ought to be left alone.



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