Are antioxidants actually good for you?

Another week, another “superfood”.

A new variety of plum is being heralded as the next wonder-food. According to a British supermarket’s “food technologist” (whatever that is), the plum has ten times as much anthocyanin, which is a powerful antioxidant, as normal plums. This is obviously just marketing, but the idea that antioxidants are always good for you is one that deserves a closer look.

Antioxidants are enzymes that clear our cells of harmful molecules, so on the surface, it seems reasonable that they would be good for us (there is a deeper discussion of how antioxidants work in the “Further Explanation” below). They have been shown to play a protective role in neurodegenerative diseases like Parkinson’s and Alzheimer’s, and they may lower the rate of heart disease among type 2 diabetics. Another study showed that the Vitamin E, a well-known antioxidant, could halve your chances of contracting ALS.

However, as more studies have been carried out, we have seen a darker side to antioxidants. For example, a 2011 study showed that men taking Vitamin E had a 17% increased risk of developing prostate cancer (although this finding has been recently questioned).  A meta-analysis carried out in 2007 suggested that far from being good for you, antioxidants increased mortality, rather than decreasing it. Furthermore, interventions that are known to increase lifespan (like calorie restriction) may no longer work if the animal is on antioxidants. The authors of that study conclude, “treatment with different antioxidants and vitamins prevents extension of life span”. Finally, a review of the human literature concluded that taking antioxidant supplements does not reduce mortality.

Ultimately, the literature is very mixed when it comes to antioxidants, but one this is certain: they are not the panacea that the health food industry would have you believe. When it comes to health claims about food and drink, it’s best to stay sceptical. The old advice of “moderation in all things” is still the best we have.

 

Antioxidants

When your cells produce energy, one of the by-products are reactive oxygen species (ROS). These are chemically reactive molecules that can cause damage or death of the cell. However, they also play a role in normal cellular health, so controlling their levels is of utmost importance. Antioxidants are molecules that soak up the ROS, controlling their levels, and there are multitudes of naturally occurring antioxidants that help maintain the proper balance. There are times, however, when high levels of ROS are needed. For example, one of the bodies defences against cancer is to increase the level of ROS, causing the cancer cells to die. So in theory, antioxidants could be bad for you if you have a tumour.

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