Later On

A blog written for those whose interests more or less match mine.

Antioxidant pills: worse than useless

with 20 comments

Food chart
Foods high in antioxidants are known to contribute significantly to health—but if condensed into a pill, the story changes:

Cranberry capsules. Green tea extract. Effervescent vitamin C. Pomegranate concentrate. Beta carotene. Selenium. Grape seed extract. High-dose vitamin E. Pine bark extract. Bee spit.

You name it, if it’s an antioxidant, we’ll swallow it by the bucket-load. According to some estimates around half the adults in the US take antioxidant pills daily in the belief they promote good health and stave off disease. We have become antioxidant devotees. But are they doing us any good? Evidence gathered over the past few years shows that at best, antioxidant supplements do little or nothing to benefit our health. At worst, they may even have the opposite effect, promoting the very problems they are supposed to stamp out.

It’s little surprise that antioxidants have acquired a reputation as miracle health supplements. As long ago as the 1950s, scientists discovered that many diseases – including heart disease, strokes, cancer, diabetes, cataracts, arthritis and neurodegenerative disorders such as Parkinson’s and Alzheimer’s – were linked to damage caused by highly destructive chemicals called free radicals.

Free radicals are compounds with unpaired electrons that stabilise themselves by oxidising other molecules – including proteins, carbohydrates, lipids and DNA. In the process they often create more free radicals, sparking off a chain of destruction. Oxidative damage accompanies most, if not all, diseases and has even been proposed as a direct cause of some including lung cancer, atherosclerosis and Alzheimer’s.

Free radicals are an unavoidable hazard of being alive. We live in an oxygen-rich atmosphere, and radicals, particularly reactive oxygen species (ROS), are natural by-products of respiration. “One per cent of the oxygen we consume turns into ROS,” says biochemist Barry Halliwell from the National University of Singapore. “It doesn’t sound like much but humans are big animals and we breathe a lot. Over a year a human body makes 1.7 kilograms of ROS.” Exposure to X-rays, ozone, tobacco smoke, air pollutants, microbial infections, industrial chemicals and intensive exercise also trigger free radical production.

In the 1980s, however, a potential weapon against free radical damage appeared on the horizon. Scientists had known for a long time that people whose diets are rich in fruits and vegetables have a lower incidence of heart disease, diabetes, dementia, stroke and certain types of cancer – the very diseases that are associated with free radical damage. Now there was an explanation. Fruits and vegetables are a rich source of antioxidants that can neutralise free radicals by donating electrons to them.

Green plants are full of antioxidants for good reason. They are especially vulnerable to oxidative stress since they produce pure oxygen during photosynthesis. To protect themselves they manufacture an assortment of potent antioxidants.

And so a hypothesis was born: dietary antioxidants are free-radical sponges that can stave off the diseases of old age. It was a great idea. “Putting two and two together, scientists assumed that these antioxidants were protective, and that taking them as supplements or in fortified foods should decrease oxidative damage and diminish disease,” says Halliwell, who pioneered research into free radicals and disease. “It was simple: we said free radicals are bad, antioxidants are good.”

The concept helped spawn a colossal supplements industry. According to the US National Institutes of Health (NIH), more than half of US adults take some form of vitamin or mineral supplement at a total cost of $23 billion a year. The bewildering range of supplements on the shelves makes it hard to say how much of this expenditure goes on antioxidants, but the NIH says it is probably a “large proportion”. And their popularity just keeps on growing. SPINS, a market research firm based in San Francisco, estimates that the antioxidant market has grown by 18 per cent in the past year alone.

The best known antioxidants are vitamin E (also known by its chemical name tocopherol), vitamin C, and two broad classes of plant chemicals called polyphenols (including flavonoids) and carotenoids (including beta carotene and lycopene). Most supplements touted as antioxidants contain at least one of these, often as a pure chemical and sometimes as a concentrated plant extract.

Since the early 1990s scientists have been putting these compounds through their paces, using double-blind randomised controlled trials – the gold standard for medical intervention studies. Time and again, however, the supplements failed to pass the test. True, they knock the wind out of free radicals in a test tube. But once inside the human body, they seem strangely powerless. Not only are they bad at preventing oxidative damage, they can even make things worse. Many scientists are now concluding that, at best, they are a waste of time and money. At worst they could be harmful.

The first antioxidant to produce disappointing results was beta carotene. Once a star among supplements, beta carotene pills were recommended to smokers to protect them against lung cancer. This was largely based on the observation, made in the 1970s, that people who ate a lot of carrots – which contain large quantities of beta carotene – had some protection against cancer.

In 1992 researchers at the US National Cancer Institute set about testing beta carotene. They recruited more than 18,000 people at high risk of developing lung cancer, either because they smoked or had been exposed to asbestos, and gave around half of them beta carotene supplements. The trial was supposed to run for six years, but the researchers pulled the plug two-thirds of the way through after discovering, to their surprise and horror, that those taking supplements were faring worse than the controls. Their lung cancer rate was 28 per cent higher, and the overall death rate was up 17 per cent. “It was a shock. It not only did no good but had the potential to do harm,” Halliwell says.

The researchers couldn’t be sure that these increases were not caused by chance, and beta carotene capsules are still widely sold as an antioxidant. Further trials, though, have strengthened the evidence that beta carotene supplements not only fail to protect people against cancer but can also increase the risk of lung cancer in smokers. In May of this year an expert panel convened by the NIH concluded that there was no evidence to recommend beta carotene supplements for the general population, and strong evidence to recommend that smokers avoid it.

It’s a similar story with the world’s most popular antioxidant. Vitamin E shot to fame in the early 1990s, after two large studies involving more than 127,000 people in total found that those with a diet high in vitamin E were significantly less likely to develop cardiovascular disease. The first study followed 87,245 female nurses for eight years; it found that the top 20 per cent with respect to vitamin E consumption had a 41 per cent lower incidence of cardiovascular disease than the bottom 20 per cent (New England Journal of Medicine, vol 328, p 1444). The second study, involving 39,910 male health professionals, found a similar reduction in heart disease risk (New England Journal of Medicine, vol 328, p 1450).

The researchers, based at Harvard Medical School and Harvard School of Public Health, even had a plausible mechanism. Evidence was emerging that one of the causes of heart disease was free radical damage to LDLs, tiny packages of lipid and protein that circulate in the bloodstream, delivering fatty acids to cells. It turned out that adding vitamin E to blood samples in the test tube made LDL more resistant to oxidation. Perhaps this was how vitamin E prevented heart disease. “At the biochemical level, the rationale sounded so good – at that time,” says Roland Stocker, a biochemist at the University of New South Wales in Sydney, Australia.

Use of vitamin E supplements soared. In 1990, almost nobody took vitamin E; by the end of the decade an estimated 23 million US citizens were knocking back daily doses.

On the back of these positive results, other researchers set up large studies using vitamin E supplements. The results, however, have been almost universally disappointing. Only one experiment – the Cambridge heart antioxidant study (CHAOS) – found a positive effect, a 77 per cent reduced risk of heart attack. Several others found no protective effect and one even concluded that vitamin E increased the risk of heart failure.

There’s much more in the article. Worth reading, though behind a subscription wall. OTOH, New Scientist is well worth its subscription price. The article ends:

There’s yet another, more intriguing explanation. Among the leading sources of dietary antioxidants are tea and coffee, and there is some evidence that green tea in particular is linked with health benefits including reduced risk of cancer and cardiovascular disease. [White tea is even better. – LG] Oddly, though, Halliwell has discovered that tea and coffee are also bursting with reactive oxygen species in the form of hydrogen peroxide.

“Every time you drink a cup of coffee it’s a dilute bowl of hydrogen peroxide,” says Halliwell. The hydrogen peroxide is there because of the presence of the antioxidants – “antioxidants” is really just another way of saying reducing agent, which can react with oxygen in the water to produce hydrogen peroxide. Think platinum blond, and you get the picture of what you might be drinking.

But if free radicals are bad for us, how come coffee and tea might be beneficial? One possibility is that they can help nudge our own internal antioxidant systems into action. “There has been a considerable rethink as to what free radicals are doing,” says Malcolm Jackson, a biochemist at the University of Liverpool, UK. He believes that in the right quantities radicals can be positively health-enhancing, prompting our cells to fire up their own internal defence machinery: a battery of radical-busting enzymes such as catalase and superoxide dismutase. “Cells are very good at protecting themselves against minor stresses, as long as they are not excessive,” says Jackson. “The question is: should we be quenching free radicals at all?”

If it turns out that antioxidants in food work because they generate health-promoting quantities of free radicals, that would be an ironic turnaround. It may also explain why supplements and extracts don’t seem to work or may even be dangerous: the doses are too high, and produce too many free radicals.

For now, the advice is simple. “Stick to flavonoid-rich foods, red wine in moderation, tea, fruits and vegetables,” says Halliwell. “Don’t start taking high-dose supplements or heavily fortified foods, until we know more.”

Written by LeisureGuy

7 August 2006 at 12:50 pm

Posted in Caffeine, Health, Science

20 Responses

Subscribe to comments with RSS.

  1. Since there are no studies cited to back up the claims of this man, I am not at all convinced by his claims, and suspect that whoever is selling “New Science” is just trying to make money, not inform the public of accurate, correctly designed studies…My husband’s profession is biostatistics, and believe me, he does understand what a scientific study, as apposed to restrospective type studies etc. is–and he agrees with me, this Blackwell, or whoever, is just a moneymaker, trying to get rich by making unsupported claims about micronutrients…he does a lot of damage and I hope most readers reject his unsupported claims!

    Charlotte Levin

    9 August 2006 at 10:21 am

  2. Actually, New Scientist is quite a reputable magazine. I’m sorry that you are not familiar with it. Your reference to one “Blackwell” mystifies me. There is no one mentioned in the article with that name. The claims cited in the article are indeed supported by research and experiment. Moreover, the article does not at all underplay the importance of micronutrients. It just points out that, based on research, micronutrients isolated and encapsulated in pills are not effective, whereas the same micronutrients in the context of their natural origin—e.g., consumed as vegetables or fruit—do have benefits. I don’t see how this finding would make anyone rich, even the mysterious Mr. Blackwell.

    But thank you for commenting.

    LeisureGuy

    9 August 2006 at 10:33 am

  3. Hey Charlotte, your husband will be able to tell you also that New Scientist is a highly respected journal. Its slant is to take peer reviewed work and provided an accesible format for non-experts. Call it pop-science on a weekly basis if you will. Wake up and smell the coffee! who gains when you spend your hard earned money on unproven micronutrients? industry of course! they wont gain a penny if you chose the right balance of fresh carefully produced foodstuffs and eat sensible amounts of it. these people would have you believe that its ok to eat a burger at lunch and pizza for dinner then pop a “vita-supplement” and bang! no harm done. What would you rather, a nice glass of pinot noir or a dull old tablet?

    roy

    15 August 2006 at 6:11 am

  4. Here’s in interesting passage from the article that suggest why the antioxidants are effective when consumed as part of the vegetable, but not as a pill:

    Vitamin C is another disappointment. “People are still trying to defend it, but you don’t get an effect on free radical damage unless you start with people with a vitamin C deficiency,” says Halliwell. “I think it is a lost cause.” In fact, results from a vast US trial probing the links between diet and health, called the Women’s Health Study, suggest that vitamin C supplements may accelerate atherosclerosis in some people with diabetes.

    One class of antioxidants that remains relatively unresearched is polyphenols. What little evidence there is comes from epidemiological studies, some of which suggest that polyphenols prevent disease and others of which do not. While polyphenols act as antioxidants in the test tube, it is not clear that they are absorbed into the bloodstream, and if they are, they are swiftly metabolised. For example, 95 per cent of a flavonoid called resveratrol – the one found in red wine – is destroyed by our digestive system before it enters circulation.

    The conclusion is becoming clear: whatever is behind the health benefits of a diet rich in fruits and vegetables, you cannot reproduce it by taking purified extracts or vitamin supplements. “Just because a food with a certain compound in it is beneficial, it does not mean a nutraceutical [with the same compound in] is,” said Paul Coates, who works in the Office of Dietary Supplements at NIH.

    Yet the fact remains that people eating diets abundant in vitamin C, vitamin E, polyphenols and carotenoids are less likely to suffer heart attacks, vascular disease, diabetes and cancer. One explanation is that these people have a generally healthier lifestyle – they exercise more and smoke less, for example. For now, no one knows for sure.

    There are some ideas. Halliwell still believes that antioxidants are at least partly responsible. He argues that because the polyphenols, carotenoids and vitamins in fruit and vegetables are bound into tough, fibrous material, they hang around in the stomach and colon, where they can neutralise free radicals. The gastrointestinal tract, especially the stomach with its highly acidic environment, is constantly generating reactive oxygen species from food. Supplements may not replicate this effect because they are digested too quickly.

    Andrew Shao from the Council for Responsible Nutrition, a supplement industry trade association based in Washington DC, argues along similar lines. He says that pulling a nutrient out of context and testing it in a clinical trial is not appropriate. “Antioxidants should not be expected to perform as drugs,” he insists. “That’s simply not how nutrients work. They work in concert with each other.”

    LeisureGuy

    23 August 2006 at 3:45 pm

  5. Dear Leisure guy: I have studied oxygen metabolism and antioxidant vitamins extensively. They do not work because their use is based on a fatally flawed free radical theory. Please visit my website http://www.thepundit.com . Also I have a current article in Annals of the New York Academy of Sciences. Vol. 1067. pp 22-26. 2006. Please continue to print the truth as you see it. Incidentally, I do not sell or endorse any products.
    Regards, R.M. Howes M.D., Ph.D. Adj. Asst. Prof. the Johns Hopkins Hospital

  6. The viatmin explosion will remain; whether it be a thorn or a rose. As for myself I was 39 when I was told I woud not surrvive another 3 years without open heart surgery. When your backed against a wall facing elimination you try anything. I took the vitamin E route via the Shute Institute, London, Ontario, Canada. I will not promote nor will I condemn. I am now 74 years old and at this stage I am told I have heart failure, I think I will try and fight this malady also, personally I would like to live forever but I dont relish the idea of getting old….which I am.

    John Kozlich

    25 February 2007 at 6:43 am

  7. Yeeeeesh, leisure guy Its not SUCH a stretch, ms lavin means “Halliwell” cited frequently in the article & she contemptiously refers to him as “Blackwell” (the guy with the worst dressed lists)
    You had such a hard time figuring this out Guy, may be you should consider some “ginko biloba” to get that oxygen into your brain a little better. Take it with a fresh brewed cup of green tea!
    BYW alpha lipoic acid is an antioxidant thats been used for 30 yrs in Europe as a treatment for painful diabetic neuropathy, so there we have it an anti oxidant with a condition that it treats or nearly cures. I directed my dad in law to it for his painful feet he now swears by the stuff!

    Walda Gagnon

    13 April 2007 at 5:08 am

  8. I’ve not heard of Blackwell and the worst-dressed lists—a part of the world I just don’t follow. I scanned through the article looking for the name “Blackwell” and was puzzled, since the name doesn’t appear. Thanks for clearing it up.

    Green tea is an excellent source of antioxidants, I agree, though not so good as white tea, it turns out.

    LeisureGuy

    13 April 2007 at 6:58 am

  9. What! No paprika! I eat it by the pound!

    (I hope I missed something …)

    Eric

    11 September 2007 at 4:53 am

  10. Hmm. I did a Google on “paprika antioxidant” and came across this article:

    Antioxidant activity of capsaicinoid fractions as well as the concentration of capsaicinoids, total flavonoids, ascorbic acid, β-carotene and tocopherols in red pepper fruits (Capsicum annuum L.) varieties Bronowicka Ostra, Cyklon, Tornado, and Tajfun were investigated. The abstained results showed that the fractions of capsaicinoids had similar antioxidant activity as the flavonoid fractions depending on the level of capsaicinoids in pepper fruits. A comparison of the concentration of antioxidant compounds in different varieties has shown that the fruits with lower level of capsaicinoids were also characterized by lower antioxidant activities, reduced vitamin E and provitamin A content, but higher vitamin C content as compared to the fruits of hot varieties.

    Sounds as though you should be ingesting something a bit hotter. Mmm, mmm—these habañeros are good! 🙂

    LeisureGuy

    11 September 2007 at 8:30 am

  11. The USDA has done an updated study of antioxidants and their ORAC values since then. Spices rate very high on the list, but we don’t consume them in massive quantities. There is still a lot of research to be done to see exactly how antioxidants are absorbed in vivo.

    Orac Dan

    20 June 2008 at 9:13 am

  12. but there’s no apparent definitive research yet right? I have to agree though that too much of anything is more harmful than beneficial, atleast that’s in most cases.

    Nowheet Owl

    11 December 2008 at 12:24 am

  13. Ya the best way is just to get it straight from the source, eat better fruits and vegetables. They have many different combinations of vitamins and minerals that work together. Good article, you don’t hear this much with all the supplement rage.

    justin

    12 June 2010 at 2:27 pm

  14. Antioxidants are good.

    period.

    Chuck

    9 February 2011 at 11:05 am

  15. Yep, they are. But taking pills doesn’t deliver them, as research has shown (cf. the article).

    LeisureGuy

    9 February 2011 at 12:25 pm

  16. Hello,

    What about green tea and its benefits?

    Ahmed Syed

    2 December 2011 at 12:20 pm

  17. Green tea has been found to be quite beneficial, and white tea even more beneficial. I’ve read that a little acid (e.g., juice of 1/2 lime or lemon in a glass of green or white tea) helps in utilizing the nutritional benefits.

    LeisureGuy

    2 December 2011 at 3:40 pm

  18. So, what’s the verdict? Vitamin E, good or bad?

    Doug Williams

    2 December 2013 at 12:42 pm

  19. It probably depends on the individual, though vitamin E as a supplement can have side-effects. See this WebMD article and this Mayo Clinic article. I dropped vitamin E supplements and went with eating foods from the list in the post.

    LeisureGuy

    2 December 2013 at 12:53 pm

  20. […] Antioxidant pills: worse than useless | Later On You name it, if it’s an antioxidant, we’ll swallow it by the bucket-load. According to some estimates around half the adults in the US take antioxidant pills daily in the belief they promote good health and stave off disease. https://leisureguy.wordpress.com/ […]


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s