Antioxidants ABC: Ageing, Beauty, Cancer

Antioxidants are all the rage right now. First it was the humble blueberry, then chocolate (raw, obviously), and now the exotic acai berry. Every superfood seems to boast about its ridiculously high ORAC score and it’s “anti-ageing” properties and ability to defend you against the toxic pollutants of city life. But do antioxidants actually work?

Let’s talk about what antioxidants are and what they do. But before we even do that, we have to talk about oxygen and free radicals. Free radicals are highly reactive molecular species with a single unpaired electron. Electrons love being in pairs, so single electrons are super reactive and will react with the first thing they find; this could be your DNA, or your cell membrane, or vital proteins and enzymes. This causes damage to the cell, and it’s well-known that DNA damage can cause cancer and cell damage in general can cause cell death. This oxidative stress occurs when ROS (reactive oxygen species) are produced, and in response your body unleashes the antioxidants to fight the free radicals. But free radicals don’t just come from oxygen metabolism, they can also come from UV radiation, X-rays, and metal ions. Accumulation of oxidative damage also increases with age.

I just find it so ironic that the oxygen you breathe to live can also cause serious damage to your cells. Thanks, universe!

So, antioxidants, the good guys that fight off the free radicals and prevent cell damage. The main antioxidants you’ve probably heard of are vitamins A, C, and E, beta-carotene, and polyphenols. But there are plenty others. Superoxide dismutase enzymes produced by the body are very effective at neutralising free radicals in the body. You can actually buy these enzymes as supplements, but please don’t; your body will just digest these and break them down just like other food as soon as they hit your stomach. Superoxide dismutase: amazing when your body makes it, but useless as a supplement.

Metals such as copper and iron we also don’t need to worry about so much, as they are tightly bound by transport and storage proteins in the body no matter where they go or what they do.

Vitamin C, polyphenols, and beta-carotene are great at neutralising free radicals because they have ring structures or double bonds that allow them to trap radicals in their structures. So it would be reasonable to assume that including these in your diet will help prevent oxidative damage, which will help prevent ageing (thereby making you look better according to society) and prevent diseases such as cancer, right?

Well, yes. Not only has antioxidant supplementation has been shown to increase the lifespan of flies, but individuals with cancer have significantly lower blood levels of beta-carotene, and higher levels of circulating vitamin C are associated with reduced risk of stroke. Sounds great! But don’t reach for those supplements just yet.

So far we have an association between beta-carotene and cancer, but this doesn’t tell us if low beta-carotene levels are a cause or an effect of cancer. It could be that low beta-carotene levels are a risk factor for cancer, or it could be that cancer is a risk factor for low beta-carotene levels. On top of that, individuals who eat more fruits and vegetables in their diet are known to reduce their risk of cancer. So is it the beta-carotene or the carrot? This is why we have to be so careful when interpreting scientific data.

So how much antioxidant do we need? Should we take supplements even if our diet is varied and healthy just to be on the safe side? What happens if we take in more antioxidants than we need?

It’s clear that a deficiency in antioxidants has detrimental effects on our health. If antioxidants in food do reduce the incidence of diseases such as cancer and cardiovascular disease, it’s only logical to think that antioxidant supplements would reduce the incidence even more. However, this simply isn’t the case. Meta-analyses (the highest, most reliable form of research there is) have revealed that supplementation with vitamin A, vitamin E, and beta-carotene actually increases mortality, and other antioxidants (polyphenols, vitamin C, selenium) have no effect either way. We’ve known this for some time now – these meta-analyses are several years old – yet supplement companies still preach on about how amazing antioxidants are.

Antioxidants can have harmful effects. Polyphenols can be oestrogenic, and inhibit iron absorption from plants, which is not ideal if you’re anaemic, and Vitamin C also acidifies the urine, potentially leading to increased risk of bladder stones.

Free radicals aren’t just a flaw in human design, they exist for a reason. When white blood cells engulf bacteria, the enzyme oxidase produces free radicals which kills the bacteria so they can be safely broken down. Much cell signalling, especially for apoptosis, is done through radicals. If antioxidants quench this signalling, they allow damaged cells to survive, which is very dangerous.

The point I want to make is, if your diet is varied and healthy, with an abundance of fruits and vegetables, and you’re not medically deficient, you don’t need supplements. In fact, they’ll probably do you more harm than good. Your body is seriously incredible at regulating and balancing all the pathways and systems, and it will tell you if you need more of something. It’s good at that. Eating healthy isn’t complicated!

So are supplements just expensive urine and a waste of money? I would say yes, at the moment there’s just not enough evidence to suggest they’re worth it. But I hope at the very least I’ve made you think more carefully about the real cost of supplementation.