Antioxidants are natural or chemical substances that quench free radicals and therefore, in theory, prevent damage to cells, improve health, and fight aging. The most well-known antioxidants are vitamins C and E. While these two are required nutrients, they have a downside and may not be as healthy as imagined.
Free radicals, or more technically, reactive oxygen species, are molecules created inside cells as a result of metabolism, and that can cause damage.
For a long time, free radicals were thought to be a primary driver of aging; this is the free radical theory of aging as formulated by the late scientist Denham Harman. (Harman lived to the age of 98, so he was doing something right.)
The free radical theory of aging is no longer widely held, since it’s been discovered that free radicals act as signaling molecules in cells and are therefore necessary for health. Another objection to the theory is that some animals have high levels of free radical damage, but die from other causes.
As signaling molecules, free radicals are important in exercise and in other forms of stress that cause hormesis, the upgrading of cellular defense mechanisms caused by a stress or toxin.
Blunting or abolishing free radicals produced by exercise means blunting or abolishing its healthful effects. Exercise absolutely depends on the generation of free radicals to improve health. Vitamins C and E, when taken regularly and/or around exercise, can completely negate exercise health benefits. (Research on this topic is ongoing, some researchers not having found this effect; nevertheless, as we’ll see below, there are good reasons to believe that it occurs.)
It doesn’t take large amounts of vitamins C and E to hamper the effects of exercise either; 1000 mg of vitamin C and 235 mg of vitamin E will do the job.
Many athletes and others who exercise a lot often take these vitamins, and that doesn’t seem like a great idea.
Furthermore, a meta-analysis of antioxidant trials found that taking antioxidant supplements was associated with an increased risk of death.1 While vitamin C had no association with increased risk, vitamins A, E, and beta carotene did.
What could be going on here? Evidently, free radicals are so necessary for health that quenching results in worse health and higher risk of death.
Antioxidants inhibit autophagy too, and this could well be behind the increased risk of death found in the meta-analysis.2 (Thanks to reader Ole Pedersen for bringing this article to my attention.)
Autophagy is the cellular self-cleansing process that rids cells of junk, and thus repairs damage. It is extremely important to the aging process. The rate of autophagy declines with age, and keeping the rate at high levels is critical for slowing aging. This can be done with intermittent fasting, a low-carbohydrate diet, and autophagy boosters.
The study cited above found that the efficacy of drugs that induce autophagy, including rapamycin and trehalose, can be impaired by antioxidants.
Not only that, but the ability of fasting to induce autophagy is impaired by antioxidants.
This could very well be the reason why antioxidants supplementation is associated with a higher risk of death.
Does this mean you should never take antioxidants? No, it doesn’t, but caution is in order.
Up to 22% of apparently healthy people in the United States are deficient in vitamin C, and provision of vitamin C at 1,000 mg daily increases the level of physical activity and reduces the incidence and duration of the common cold by almost 50%. Those are not small effects.
The effects of mild vitamin C deficiency can be manifested as fatigue, malaise, and depression. So if you have any of these symptoms, or you get colds with unusual frequency, vitamin C may be worth taking.
Another of the antioxidants that inhibited autophagy was n-acetylcysteine (NAC). This cysteine pro-drug replenishes glutathione, the body’s most abundant internal antioxidant, which is necessary for good health. While NAC has many uses in the treatment of mental and physical disorders, apparently having too much glutathione may be as detrimental as too little. Caution is in order when taking NAC as well.
If you need to take vitamins C, E, or NAC for any reason, don’t take them immediately before or after exercise, and do not take them while fasting. They should be taken, if needed, during the fed state.
Dose is another consideration. If you have the symptoms of vitamin C deficiency and want to supplement with it, smaller doses, say a couple hundred milligrams daily, may be better. Don’t megadose unless you have good reason, such as a serious illness or infection.
The notion of antioxidants as healthful has been so ingrained in us, and the idea that healthful effects of various foods are due to antioxidants so established, that we’re often told that something is good for us due to high levels of antioxidants.
That is not the case.
Plant foods such as blueberries, broccoli, red wine, chocolate, and coffee have health benefits not because of antioxidant content, which is low, but because they contain phytochemicals that upgrade stress defense mechanisms. In effect, low-dose toxins.
So next time you read, e.g. “coffee is the biggest source of antioxidants for Americans”, or “eat these high-antioxidant blueberries”, realize that these statements are nonsense.
They contain low levels of antioxidants. They contain high levels of phytochemicals that promote hormesis.
By all means include them in your diet, because they promote health, but they don’t do so because of antioxidants.
Antioxidants are not nearly as health-promoting as we’ve been led to believe, and may in some cases be harmful to health.