There’s no proven benefit in taking antioxidants during cancer treatment

Yesterday, in the wake of an ASA ruling over antioxidants in green tea, and a US research paper that suggested that some cancer patients were taking them in large quantities, we looked at what antioxidants were, and how they occur in our bodies.

And we showed that the idea that ‘antioxidants = good’ is a huge oversimplification.

Now we’re going to look at the evidence that trying to boost the levels of antioxidants in our diets is good for us, particularly while undergoing cancer treatment.

But first, we need to make a clear distinction between antioxidants in the foods we eat – ‘dietary’ antioxidants – and antioxidant pills such as vitamin pills, taken to supplement our diets.

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Tetley found themselves in hot water with the Advertising Standards Authority this month

Thanks in part to intensive marketing by the food and supplement industries, there’s a widely held belief that if something contains ‘antioxidants’ it’s automatically good for us.

But the scientific evidence behind this claim is pretty thin on the ground – thin enough to lead the Advertising Standards Authority to ask tea-makers Tetley to withdraw their advert for green tea this month.

As the ASA said in their ruling:

We considered that while [the advert] did not imply the tea had the same or similar health benefits to exercise, it did imply that the tea had some general health benefits beyond hydration, in particular because it contained antioxidants.

As we had not seen any evidence to demonstrate that green tea, or the antioxidants in it, had general health benefits we concluded that the ad was misleading.

These sorts of claims pop up all the time in advertising, particularly for foods and drinks, as we’ve blogged about before.

Most of them involve products aimed at improving and prolonging health, or preventing disease. And as long as the balance of evidence suggests that these products cause no harm to healthy people, it’s difficult to see how regulators can prevent these sorts of claims being made.

But nevertheless, we’re concerned about the relentless portrayal of antioxidants as a universal health panacea, in the absence of robust scientific data – partly because there’s emerging evidence, including a paper published in the journal Cancer this month, that the knock-on effect is that some people undergoing cancer treatment may be taking them in high doses without thinking to tell their doctors (we’ll look more at this paper in a follow-up post).

This is worrying, because there have also been suggestions that antioxidants might interfere with treatment, at least in some people.

So we thought it would be worth having a look in detail at what, exactly, ‘antioxidants’ are, what they do, how they work, and where the idea that taking antioxidants is good for you actually comes from.

And in a follow up post, we’ll look at the evidence of whether antioxidants are actually good for us.

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