OVERVIEW
· Antioxidants have been one of THE big health buzzwords of recent decades.
· Bold health claims have spawned an industry worth billions.
· We expose how the hype for some of these ‘health’ products is founded on a flawed interpretation of the scientific evidence.
· We reveal why more is definitely not better when it comes to antioxidants, and why popping these pills may do you more harm than good.
Antioxidants. What a mighty word that has become. It resonates with health and holds the promise of great things. Antioxidants are enshrined in the language of the health-conscious and credited with quasi-mythical powers. An elixir so potent they can stop cancer, heart disease, and indeed the very ageing process itself, dead in their tracks. It seems the search is over, and the secret to eternal youth is ours at last.
CUT!
It might all sound decidedly familiar, but it’s really a lot of old drivel. Nutritional propaganda fed to us by a food and supplements industry cashing in to the tune of billions. But it’s not just the false promise of astounding health benefits that rankles with us. Sure, that’s bad, but the fact that your antioxidant pills could be harming your health is what really gets us going, so we’re out to derail the antioxidant bandwagon once and for all.
A modern-day panacea?
It was way back in the late 1950s that the American scientist Denham Harman proposed that the ageing process, and its related maladies, were a consequence of free-radical activity. On the surface, this makes good sense. Free radicals are unstable entities derived from oxygen that set in motion a cascade of damage to cells in the body, mercilessly targeting the likes of proteins, membranes and even our genetic material, DNA. As you might imagine, this trail of destruction is not without its consequences, which is why free radicals have been implicated in cardiovascular disease, neurodegenerative disease, autoimmune conditions and diabetes, among others.
Harman’s proposal went one step further, showing that the addition of free-radical inhibitors (aka antioxidants) extended the lifespan of mice. Backing this up was mounting evidence from lab studies which showed that dietary antioxidants effectively snuffed out these injurious substances. The most tantalizing discovery was dangling right in front of our eyes. Was it possible that a host of age-related diseases could be stopped in their tracks?
Epidemiological studies then began to look at the effects of diets that contained high amounts of antioxidants (as would be found from eating plenty of fruit and vegetables). The findings showed that such diets were associated with reduced coronary heart disease1, incidence of stroke2 and cancer3. Of course, there are lots of reasons why fruit and vegetables are good for us, but these impressive health benefits were believed to be primarily attributable to the antioxidants they contain, which halt damaging free-radical processes4, 5,6,7.
The floodgates were open and in poured the epidemiological studies. Vitamin E became big news. Intake of this fat-soluble antioxidant was associated with over a third reduction in coronary heart disease in both men8 and women9. It wasn’t all coming from diet either. In these studies, the greatest benefit was typically attributable to taking a vitamin E supplement. In addition, a review of vitamin C trials found that high-dose supplementation (>700mg/day) was associated with a 25% reduced incidence of coronary heart disease10. Those with the highest levels of vitamin C in the blood had a 42% reduced occurrence of stroke11. It wasn’t just heart disease either; the same was true for cancer. Epidemiological evidence was strong in showing the protective effect of high vitamin C intake against non-hormonal cancers12, with beta carotene a strong contender too13. The studies were stacking up. The antioxidant age was upon us.
A common free-radical reaction is the conversion of iron into rust. To think a similar type of damage could be happening inside of us! It’s no wonder that antioxidants have such mass appeal.
Antioxidant supplements were catapulted from the back shelves to fame practically overnight. This was primarily attributable to the frequent focus on life extension by the American TV icon Merv Griffin in the late 1970s and early 80s.
Antioxidant mania
The seeds had been sown, and green shoots appeared everywhere. The impossible was now made possible. We’d hit the mother lode, stumbled upon nothing other than the elixir of life itself, a veritable Aladdin’s cave of untapped treasure. Free radicals quickly became public enemy number one and antioxidants our saviours. Free radicals were dubbed ‘chemical assassins’ and ‘terrorists’ (comparisons were as far-fetched as the ‘atomic bomb’). But we were told not to fear, as antioxidants would deliver us from their tyranny. When it came to free radicals, there was only one way to go: a policy of zero tolerance.
There could be no doubt: more was better and the solution came in the form of an antioxidant vitamin pill. Sales increased exponentially. Spurred by a health-conscious and ageing population, nothing could hinder the growth of this market. This wasn’t a health craze, it was a global mega-business, as the statistics prove. Over half the US population regularly take supplements and the vast majority of these contain some form of antioxidant, making a sizable chunk of a staggering $28 billion-a-year US supplements industry14,15,16.
Americans alone consume around 50 billion vitamin and mineral tablets each year, so ensuring that accurate information is disseminated should be seen as a major public health issue.
Right here, right now, we’re firmly in the grip of antioxidant mania. The word represents ‘health’ to the public, and an audible ‘ca-ching’ to the food industry. In a fortified/functional food industry worth more than $190 billion worldwide, ‘antioxidant-added’ and ‘antioxidant-rich’ foods contribute no small part17 and this is only increasing. In the words of ‘The Supermarket Guru’, Phil Lempert: ‘It’s clear that regardless of whether or not people understand what “rich in antioxidants” means, it is certainly a logo or a stamp that says “Buy me! I’m going to help you live forever”.’ Hundreds of new ‘antioxidant products’ are hitting the shelves each year, as industry rivals grapple to get a piece of the pie. From cereals to jelly beans, chewing gum to drinks, it appears anything can be made healthy by adding some antioxidants into the mix.
Fool’s gold
It’s a pretty cool tale, don’t you think? Antioxidants, defenders of our health, rushing to our rescue, but that’s exactly what it is – a tale. Over-dramatized and misconstrued, this is the stuff of science fiction, not science fact. And here’s the paradox. Despite being submerged in an antioxidant-saturated world, instead of curing our most prevalent diseases, their rates have actually been increasing.
There are two sides to every story, and you’ve only been told one of them. First, you can curb your hatred of those wretched free radicals; as you’ll soon see, they’re not quite the pantomime villains they’ve been branded. After all, it would be a cruel trick of Mother Nature if oxygen, the most critical substance for our survival, deserves the rap for our demise. It would be the ultimate irony if the most dangerous thing we do each day is breathe!
But first, we’ll dig deeper. All those studies into diet and vitamin supplements that we mentioned earlier were genuine and exciting, but they were observational studies. As we know, when it comes to real evidence, intervention trials rule the roost, and with the buzz surrounding antioxidants, lots of these got underway.
As the results were published, the sheen rapidly began to fade from the antioxidant gloss. The intervention studies showed no positive effects from antioxidant supplementation, and a worrying trend of increased harmful effects emerged too. The omens weren’t good. Cancer, heart disease and mortality, the very things antioxidants were supposed to protect us against were increased in those who supplemented their diet with them.
We refer to the term ‘meta-analysis’ throughout the book. This is when individual studies asking a similar question are grouped together to give an overall picture. As such, they can be a very powerful research tool.
ANTIOXIDANT SUPPLEMENTS
If you’ve been merrily knocking back antioxidants pills up until now, you might want to brace yourself, for this won’t make pretty reading. It’s time to delve a bit deeper into the research.
Whereas epidemiological studies had observed a correlation between higher levels of beta carotene and a reduced risk of lung cancer13, giving 20mg of beta carotene as a supplement was found to increase lung cancer occurrence in smokers by 18% and their mortality by 8%18. No effect for vitamin C was found for cancer either19. In a study of US male physicians, 500mg per day of vitamin C produced no improvement in the occurrence of major cardiovascular events, myocardial infarction, stroke, or cardiovascular or total mortality20. In postmenopausal women with heart disease, rather than providing benefits, taking 400IU of vitamin E twice daily plus 500mg of vitamin C twice daily, almost trebled the risk of dying21.
For vitamin E, the RCTs showed no benefit at all in taking vitamin E in cardiovascular disease22 or cancer19,23,24 – the very conditions it’s widely touted to protect against. Worryingly, the most recent data from a large RCT in the USA showed that giving vitamin E supplements to healthy men actually increased prostate cancer incidence by 17%25. Indeed, a metaanalysis of 19 vitamin E supplementation intervention trials showed that, when daily doses went above 150IU per day (and you’ll find much higher-dose supplements on the shelves of your local health store), mortality started increasing in a dose-dependent fashion26.
A meta-analysis of 22 RCTs found that antioxidant supplements (vitamins A, C, E, beta carotene and selenium) had no preventive effect on cancer, regardless of cancer type, and in fact suggested an increased bladder cancer risk of 50%27. Another meta-analysis of 14 supplementation trials looked at vitamins A, C, E, beta carotene and selenium on gastrointestinal cancer occurrence and found no protective effect. Indeed a 6% increase in mortality rates was observed28. The only supplement to show potential protection against cancer was selenium, and there’ll be more on that in Chapter 4.
In 2007, a review of 47 RCTs, totalling 181,000 subjects, found that antioxidants increased mortality by 5%. Beta carotene was found to increase risk by 7%, vitamin A by 16% and vitamin E by 4%, whereas vitamin C had no significant effect on mortality29. The irony is that antioxidant pills are still heralded as an anti-ageing miracle!
It is clear that it is no longer science but market forces that are driving the macabre antioxidant industry. We have to seriously question why mainstream nutritionists continue to advocate such practices.
The situation could be even worse. As scientists are more likely to publish positive findings than negative ones, it’s very possible that there are more supplement trials showing the harmful effects of antioxidants which have never even been published29.
Radical thinking
We’re not really sure how to put it any other way: the antioxidant ‘experiment’ has been a monumental mess up. Something went wrong, very wrong. Swept off our feet by the lure of eternal youth, our gung-ho approach has failed miserably. The reason? Our total naïvety when it comes to understanding free radicals and antioxidants.
Listen up, because the chances are that, despite everything you may have heard about antioxidants, nobody will have told you that in small amounts free radicals are actually essential to our health. Since day one they’ve helped ensure our survival, as we’ve been moulded and sculpted into who we are today. Although they’ve been branded as the bad guys, free radicals perform a host of important functions in the body. For example, we need them for signalling systems involved in the regulation of such vital things as the life-and-death reactions of our cells to stresses30. They’re needed by the immune system to fight off infection; without free radicals, we’d be unable to fend off invaders. While implicated in cancer formation, they are now also known to stop the growth and cause the death of cancerous cells31.
Given all the evidence, the role of antioxidants is a whole lot more ambiguous than we’ve been led to believe. Free radicals most definitely can be the ‘baddies’, but only when the body’s coping abilities are overwhelmed – a term known as ‘oxidative stress’. When we think of free radicals, we might do well to think of the ‘hormesis effect’. This is a neat idea that basically says a little of something that is normally bad for us actually does us good, but causes harm when we are exposed to it in higher amounts. A good example of this is stress. Too much stress is bad for you, but we need moderate short-term stresses to function and stay healthy.
It is wrong to think that antioxidants are ‘good’ and free radicals are ‘bad’. It’s a lot more complex than that and it makes no sense to try and interfere with nature by taking high doses of antioxidants.
What we’re left with is a delicate balancing act. Both too many and too few free radicals spell trouble. And, really, is that so surprising? The human body is a supremely intricate and complex system, designed with elaborate mechanisms to ensure that free radicals are kept in check. This is achieved by a series of enzymes (glutathione peroxidases, catalase and superoxide dismutases), as well as antioxidants (albumin, urate, bilirubin, lipoic acid, glutathione and ubiquinol). We enhance these natural defences by consuming minerals in our diet (copper, zinc, manganese, iron and selenium), which are required for these antioxidant enzymes to function optimally, as well as getting antioxidants directly from food. The trouble is, we thought we could become masters of this dynamic, complex, finely tuned, self-regulating system, simply by consuming large doses of antioxidants in the form of a pill.
Ultimately, by taking high-dose antioxidant pills, we end up overwhelming our bodies and putting this fragile balance out of whack. For example, the US RDA of vitamin E is 22IU. It should be pretty apparent that it’s non-physiological to be consuming 18 times this amount, which is what you’d ingest in a typical 400IU per day supplement (in fact, it’s not unusual to see recommendations for double this amount – 800IU – 36 times the RDA!). The same goes for vitamin C. A diet rich in fruit and vegetables will provide about 200mg per day, yet supplementation doses of 1g (1,000mg) or more are often enthusiastically advocated. Indeed, the research now shows that while in lab tests high doses exert antioxidant effects, in the body, mega doses of the likes of vitamin C and E can actually have the opposite effect and act as ‘pro-oxidants’. For anyone popping the pills, we think that’s a bit alarming to say the least.
It’s all about balance. In large amounts the free radical nitric oxide is linked with neurodegenerative diseases, epileptic seizures and increased states of inflammation. Yet small amounts are so beneficial for the heart that it is even used as a mainstream cardiovascular medicine.
Exercise dramatically increases free-radical production in the body. Far from being a bad thing, free radicals actually help the body to successfully adapt to exercise. Contrary to popular belief, taking antioxidant supplements reduces exercise capacity32, and interferes with exercise’s well-known benefits, such as improving insulin sensitivity and boosting our resistance to disease33.
The whole is greater than the sum of its parts
A gross misunderstanding of the nature of free radicals is only one of the blunders. The second is the horribly simplistic notion that giving a massive dose of one or even a handful of isolated nutrients will satisfactorily meet the antioxidant needs of the body. It’s not hard to see how consuming a balanced diet, rich in fruit and vegetables, will nourish us with a plethora of different vitamins, minerals and phytonutrients, all working in synergy to enhance our health. It is this nutritional cocktail, courtesy of Mother Nature, that confers the protection observed in consumers of a diet rich in fruit and vegetables. It’s pretty obvious that this is the right way to go about getting your antioxidants. Gulping down mega-doses of isolated nutrients was never the way it was supposed to be.
First, an excessive intake of some nutrients can actually diminish the effects of others. A prime example of this is vitamin E. Vitamin E is actually found in eight different forms in the body (alpha, beta, gamma and delta tocopherols and four tocotrienols), but usually supplement companies will only include one, alpha tocopherol. Yet gamma tocopherol is the major form of vitamin E in the US diet34. It’s required to quench the peroxynitrite free radical, and high levels are associated with a fivefold reduction in prostate cancer risk35. When we ingest high levels of just one type of vitamin E, however, we kick out the other types to make room for it36. So, while alpha tocopherol is associated with a reduced prostate cancer occurrence, this is only seen when gamma tocopherol levels are high35. In our opinion, taking a high dose of one nutrient without regard to the others is a bit like playing Russian roulette with your health.
This principle is borne out perfectly in a meta-analysis of prospective trials published in 2008, which found that while vitamin C was associated with lower coronary heart disease, this was only true of dietary vitamin C, not supplemental37. This suggests that it’s the full range of nutrients found in vitamin C-rich foods which confer benefit. The same was found for pre-menopausal women with a family history of breast cancer. Compared with the lowest intake, those women with the highest intake of vitamin C from food had a 63% reduced risk of breast cancer, but this reduction did not exist in those taking vitamin C supplements38. However, this doesn’t stop self-proclaimed ‘experts’ pushing high-dose vitamin C supplements like they are the best thing since the smallpox vaccine.
Don’t confuse the message. High-dose antioxidant supplements are very different from the physiological levels of antioxidants found in fruit and vegetables. While antioxidant pills are a bad idea, eating up your fruit and veggies is definitely a good idea.
Evidence suggests that high-dose oral vitamin C supplementation is one of the biggest money rackets going. The body doesn’t like to go above around 200–250mg daily (funnily enough, that is exactly what a typical diet rich in fruit and veggies provides) and protects itself against higher doses39. It achieves this by reducing the amount we absorb and increasing the amount we excrete. By consuming these supplements, you are literally peeing your money down the drain (although apparently it is an effective limescale remover, so maybe the plumbing industry will be next to cash in on the antioxidant act!). It’s likely that this inbuilt safety mechanism is why vitamin C supplementation appears to confer the lowest risk on disease and mortality compared with other antioxidant vitamin supplements.
Gram doses of vitamin C are often advocated for preventing and treating the common cold. Considering we cannot even absorb these mega amounts, it’s hardly surprising that the evidence doesn’t support this practice.
Even in cases of known oxidative stress, it is not the case that any antioxidant will do. For example, it’s well documented that smokers are one of the few groups that genuinely need extra vitamin C. They have lower absorption, lower vitamin C body pools and lower serum levels40. As a result of increased oxidative stress creating greater demands, smokers need about an extra 50% of vitamin C each day. Yet, if we decided to go with beta carotene instead, which has been shown to be associated with lower lung cancer in the general population, we find that doses higher than those found in the diet (normal intakes are 7–8mg per day) will exert a pro-oxidant effect and increase cancer risk in smokers18.
THE PARTING SHOT
Taking antioxidant supplements simply doesn’t work and this has been known for years. Yet millions of people are being misled into ritualistically ingesting these substances daily in the belief that they are enhancing their general health and wellbeing. The food and supplements industry relentlessly adds antioxidants to every conceivable product, while high-profile nutritionists, supposed ‘experts’ in the ‘science’ of nutrition, still zealously endorse the antioxidant agenda. Maybe it’s a genuine lack of comprehension of the science, or a stubbornness to expunge former beliefs, or worse still, a blatant attempt to cash in while there’s still money to be made. It no longer matters, but whatever it is, they’re putting your health in jeopardy and it’s high time it stopped.
The free-radical theory of ageing and disease was undoubtedly a clever one. Unfortunately, the science has been hijacked and misused. We’re in no doubt that the antioxidant ‘miracle’ wins the accolade of the number one snake oil of the twentieth century. And that’s exactly where this ‘miracle’ should be left behind – in the annals of history.
SUMMARY AND RECOMMENDATIONS
· When it comes to antioxidants, we’ve been led down the garden path with the idea of ‘more is better’ – it’s simply not the case and routine use of high-dose antioxidant supplements is a bad idea.
· Antioxidants showed promise initially, but the simplistic idea that antioxidants are ‘good’ and free radicals are ‘bad’ is flawed.
· It’s cruelly ironic that it is the most ‘health conscious’ people who end up consuming the most antioxidant supplements, unwittingly endangering their health in the process.
· If you eat a balanced diet rich in fruit and vegetables there is simply no need to consume extra antioxidants. Isolated pills will never replicate real food and taking non-physiological doses will ultimately spell trouble.
· The antioxidant bubble has burst and in the next two chapters we’ll introduce you to some of the nutritional components that deliver real health benefits.