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THERE’S nothing to brighten a dull session in general practice like a colourful bottle of vitamins, extracted from a bulging handbag and placed on the desk to invite closer inspection of the 57 ingredients.
Time to give thanks for my severe myopia and squint at the label for a while before smiling sagely and saying: “Well … you really don’t need these if you eat a healthy diet”.
I’ve always been suspicious of vitamin supplements. My mother found the very idea of them morally and nutritionally reprehensible, and never put a meal on the table without repeating her favourite dietary mantra: “Protein, starch, green vegetable, yellow vegetable”.
I knew I had passed on the mantle when I heard my son, at age 7, refuse a chewable vitamin C tablet on the grounds that it might cause kidney stones.
It seems the science, in the guise of the Iowa Women’s Health Study, is also on my side. Among almost 40 000 women aged in their early 60s at baseline and followed for more than 20 years, taking vitamin and mineral supplements did not confer a survival benefit and was actually associated with a slightly increased risk of death.
Of the many vitamins, minerals and combinations included, calcium was the only supplement that showed a small survival advantage, but the authors were cautious about this because it conflicted with other studies.
They also cautioned that, as an observational study, they couldn’t control for all the factors that might have led the subjects to take supplements.
The Iowan paradox is not an isolated finding. A Cochrane review published in 2010 identified 67 randomised trials with 232 550 participants (both healthy and with identified chronic diseases), to try to determine if antioxidant supplements such as beta-carotene, vitamin A, vitamin C, vitamin E, and selenium had any effect on mortality. There was no evidence of benefit from any of the supplements, and some indication that vitamin A, beta-carotene and vitamin E may have a negative effect.
The disappointing news on supplements sits in contrast to the long-established and increasingly refined evidence that a healthy diet supports a range of positive outcomes, including reduced mortality.
The biological mechanisms for this are also being untangled. A study published last month, for instance, sought to replicate the health benefits of broccoli and other cruciferous vegetables by giving a supplement of the phytochemical contained in these plants. When the chips were down, the supplements lacked an enzyme present in the real thing, rendering them much less healthy (and tasty) than a plate of lightly cooked broccoli.
Many of the 10 million or so Australians who take vitamin supplements are doing so on top of a diet that is already nutritionally replete. Their money is literally going down the toilet and may even be doing them harm.
But there are some groups, such as the frail elderly, children in poor social circumstances, and Indigenous and other Australians who live in remote locations, who have trouble accessing enough healthy food. Given what we now know about diet and health, this is an unacceptable situation.
And there are people who just don’t get that eating is for health. In the absence of a Jetsons-style food pill, they might just all have to wake up and smell the spinach.
So, until more evidence emerges, doctors who are asked about the potential benefits of nutritional supplements can probably put away their reading glasses and advise patients that, except in cases of proven deficiency, they are unlikely to benefit and may be harmed.
We should lobby for a secure healthy food supply for all Australians, and encourage our patients to behave like adults and eat a wide variety of nutritious food.
And, with a nod to my mother and a raspberry to former US president George Bush, taking a supplement won’t get you out of eating your broccoli.
Dr Ruth Armstrong is a medical editor with the MJA.
Posted 24 October 2011
Dear Phyllis
These are all great questions to ask about observational studies. They are also the reason I included the Cochrane review in my commentary. This was a review of randomised trials, which are a much better way of excluding the sort of unknown variables you raise. It failed to show benefit from taking antioxidant supplements such as beta-carotene, vitamin A, vitamin C, vitamin E, and selenium. I also agree that we can only comment on the risks and benefits of supplements that have been subjected to rigorous trials. Having reconsidered the evidence and my own moral state in the light of your strenouous objection, I stand by the central theme of my article: eat your broccoli.
Ruth Armstrong attests to a long-term suspicion of vitamin and mineral supplements citing her mother who “found the very idea of them morally and nutritionally reprehensible”. What qualifies her mother as an expert? Armstrong also cites the Iowa Women’s Health as evidence to these beliefs saying taking vitamin and mineral supplements did not confer a survival benefit but was actually associated with a slightly increased risk of death. However, if one reads the evidence, the risk are vitamins in general, and only some minerals, specifically iron, a heavy metal often prescribed by physicians, plus magnesium, zinc and copper. Before making sweeping claims based on her beliefs, Armstrong should read the research fine print. Did the Iowa researchers look at all the variables? Did the women who took supplements have a poorer health status to begin with that prompted supplementation? Were these physician-prescribed or self-care behaviours? For Armstong to get on her anti-vitamin/mineral soapbox is non-scientific, bad medicine and perhaps morally reprehensible.
I wish to comment on your statement:
“We should lobby for a secure healthy food supply for all Australians, and encourage our patients to behave like adults and eat a wide variety of nutritious food.”
I am a dietitian of 25 years experience and I have yet to see any evidence of this.
“Healthy eating” is a term which has been misused to sell food brands and increase market-share. The only significant lobbyists are the companies behind this advertising.
No wonder the public are confused about healthy eating;
it just seems easier to “pop a pill” endorsed by someone the media is happy to deem reputable.
The power is in the message and a healthy eating message is not working.
The obesity problem is also seen as a marketer’s dream.
Look no further than products selling healthier lifestyles and treatments for obesity.
Many of the companies have now become so diversified to not only be involved in food supply but also pharmaceuticals, nutritional products and weight loss treatments.
The key is to educate patients on these facts and be honest about the difficulty implementing diet and lifestyle change.
My gut feeling in a nutshell, is that we practitioners of ‘conventional medicine’, seem to shy away from terms like ‘hydroxylation of..” trans-methylation of…” co-enzymes’, and such terms, perhaps because we have no idea what these terms mean. So, like true heroes/heroines, we slam the whole concept of supplements regardless of what these may be, as ‘non-scientific’, awaiting trials and studies, etc… rather than asking ourselves before talking to patients, which trials studied which particular vitamin/mineral/co-enzyme, and so on. As for calcium supplements, not so long ago there was not any awareness of practitioners of the importance of Vit D in the absorption of calcium, as well as unawareness of the whole RDI of calcium marketed in a single tablet, regardless of what the person may be eating/drinking as part of their normal food intake. Nutritional medicine requires expertise and is also a time-consuming aspect of general health and many a time early deficiencies are ignored and also, ‘measuring’ could be a waste of time and resources.
Thanks for reading and commenting kate d. The topic of Coenzyme Q10 and statins is very interesting. I look forward to an adequately powered randomised trial that investigates whether the kind of supplementation you suggest is helpful for patients who need to take statins.
I find it fascibating that many earnest practitioners who pooh pooh the potential benefits of supplements are industriously prescribing statins to lower the ‘too high’ levels of cholesterol in the blood of otherwise healthy individuals. This seems to be without any reference to the fact that statins deplete Coenzyme Q10 production not to mention mineralocorticoids, sex steroids and vitamin D. Heaven forbid that it should be suggested that vitamins and antioxidants might do a better job without the adverse side effects. A HIGH QUALITY vitamin just might help.
Thanks for this rational post. I am astounded at the potency of the marketing of nutritional supplements, and the lack of understanding of the value of fresh foods. Yes, our fruits and vegetables may now be grown with manufactured fertilisers and may travel some distance from farm to home, and may undergo long-term cold storage. However, our year-round access to fresh foods is better than ever before. Like any medicine, vitamins should be used to treat measured deficiencies, not middle class anxieties.