By Jerome Burne
Yet another round of media stories this week picking up on an “expert’s” claim that vitamins are ineffective and dangerous. They are the medical equivalent of blaming immigrants or single mothers for various social ills; scare stories that spin the data and draw totally unjustified conclusions.
The Guardian version opened with this claim: ‘… over-the-counter multivitamins do “more harm than good” and can increase the risk of developing cancer and heart disease ’ and went on to say that a study reviewing trials involving thousands of patients showed that those taking extra vitamins and minerals ‘were more likely to have health problems.’
A little bit of digging revealed just how misleading that opening was. There was no information about a new trial. What had happened was that a researcher from Colorado University had given a talk at a cancer conference over the weekend which quoted the results of three trials, one dating back to 1996. Each had involved giving a larger than usual amount of a single vitamin to patients in clinical trials.
Political point scoring rather than science
So this had nothing to say about “over-the-counter multivitamins”, because by definition you can’t take a larger amount of a single vitamin by using a multi-vitamin. It also came from Professor Tim Byers, a man who has made a career out of attacking vitamins for prevention. In a paper published in 2010, for example, (Am J Epidemiol. 2010 July 1; 172(1): 1–3) he made exactly the same point: ‘We now know that taking vitamins in supernutritional doses can cause serious harm’.
This is a typical example of the broad-brush statements that are dotted through supplement attacks. There are of course example of high doses causing harm but there are also examples of benefit such as very high doses of B-vitamins reducing brain shrinkage is patients starting to develop cognitive problems or high supplement of vitamin D in cases of serious deficiency.
That’s why the attacks by Byers and others belong in the realm of political point scoring rather than being part of any genuine scientific attempt to assess the benefits and risks of vitamins. His professional field is cancer prevention yet he ignores the details of the research he relies on as well as research that doesn’t support his charge.
Gathering ammunition not scientific data
For example one of the studies he relied on involved giving a large amount of folic acid (1gram – five times the RDA) to patients, who had already had a precancerous polyp removed from their colon, to see if it could prevent more developing. It didn’t. Now that could be treated as useful information. If further trials support it that means advice should be given not to use folic acid to treat people with polyps. Instead he uses it as ammunition against supplements in general
In his talk he claims that ‘some people actually got more cancer while on the vitamins’ and then refers to this study. In fact if you look at the original study it says: ‘Further research is needed to investigate the possibility that folic acid supplementation might increase the risk of colorectal neoplasia.’
So the study he relies on to show a cancer risk specifically says it doesn’t show a cancer risk. It’s true that there’s evidence linking folic acid with cancer – is it a risk here? Not according to a study in the Lancet in 2013 which looked at data on nearly 50,000 people and concluded: ‘Folic acid supplements are not linked to an increased cancer risk when taken for up to 5 years.’
Vitamin and risk of lung cancer
Professor Byers’ second exhibit is a trial that has long been used to claim that vitamins are dangerous, but it also tells you nothing about multi-vitamin risk and makes the cancer link look simple when it isn’t. This is what the Guardian said: ‘Taking more than the recommended dosage beta carotene was found to increase the risk of developing lung cancer and heart disease by up to 20%.
The original paper, published in 1996, was an attempt to see if beta-carotene together with a form of vitamin A could reduce the risk of developing lung cancer in long-term heavy smokers with significant lung damage. So not relevant to anyone taking over-the counter multi-vits. The dose used was certainly high -30mg beta carotene, when non-randomised trials have found benefit with 7-8 mg.
The headline ‘20% raised risk’ certainly sounds alarming but it’s misleading.
Buried in the body of the paper, but not mentioned in the abstract or, of course, in Byers’ talk, was this finding: the raised risk of cancer only occurred among those who continued to smoke [my italics]. If you gave up smoking and took the vitamin, your risk of cancer went down by 20%. So an equally valid take-away message from the study would be – don’t smoke and take very high doses of these vitamins.
A follow up study discovered something else important about the combination the vitamin treatment and a raised cancer risk. The conclusion read: ‘… excess risks of lung cancer were restricted primarily to females.’ Another bit of information that could either be used to condemn vitamins or could be seen as valuable information for anyone using vitamins in an informed way.
No cancer risk with the vitamin
Except that a study published only last week made the situation even more complicated. A 20 year study found that the higher your level of various forms of carotene in your blood (lycopene and a-carotene as well as beta-carotene) the lower your risk of breast cancer. The conclusion read: ‘Woman with high plasma carotenoids were at reduced breast cancer risk particularly for more aggressive and ultimately fatal disease.’
So lots of questions and one message: don’t give women who smoke heavily very high doses of beta-carotene and a synthetic form of vitamin A.
The final paper Byers’ warning relies on, is a large lengthy study of 35,000 men at risk of prostate cancer that’s been running for nearly fifteen years. Called SELECT it’s designed to see if vitamin E and selenium, together or alone, can reduce their risk. By 2011 results showed that the vitamin E didn’t reduce risk but pushed it up by 17%.
So a slam dunk for vitamin dangers? Not necessarily. Again what are missing are various crucial details. One is that the study used synthetic vitamin E. While natural vitamin E comes in eight varieties, the synthetic version only has a single form (alpha-tocopherol). Worse, it blocks the others and no nutritionist would recommend it. More research last year (2014) made the situation a clearer but more complicated.
Avoid a selenium supplement if your levels are high
Older men taking either synthetic vitamin E on its own or selenium (also a synthetic version) on its own were found to double the risk of prostate cancer. Your risk from selenium supplement risk went up even further if you already had a high level of the mineral in your system before you started supplementing.
However the raised risk of taking Vitamin E only applied to those who had low levels of selenium at the start. People have quite high levels of selenium in the USA because food is fortified with it, unlike the UK.
So rather than the crude message – vitamin E causes cancer – the sensible take away messages from this mammoth study are: avoid synthetic vitamin E, take natural vitamin E at lower doses, but have your selenium level checked first and don’t take high doses of selenium if your levels are already high.
What’s causing supplement scaremongering?
Again a trial is being used to make a political medical point rather than to provide any accurate or useful information about vitamins. Anyone informed about vitamins knows they are neither ineffective nor dangerous used properly.
A competent practitioner would start by finding out what minerals and vitamins you were deficient in and what you were eating and how you were living and aim to bring them all into a healthy balanced state. That is the kind of approach that should be tested in trials run by knowledgeable researchers – not with trials that use large doses of synthetic vitamins without taking any notice of the needs of individual patients.
So what is driving this supplement scaremongering and why does one in three Britons take some form of dietary supplement?
The drug danger we all face
The two are almost certainly related. The same day as Byers’ warning was widely reported, another warning was issued and virtually ignored. It came from the University of Dundee, which warned that the number of adults in a region of Scotland getting more than five drugs had doubled over the past fifteen years to 20% and that the number getting more than ten drugs had tripled to nearly 6%.
‘Drugs can significantly improve a range of health outcomes,’ says the lead researcher Professor Bruce Guthrie, of the University of Dundee, ‘but they can also cause considerable harm – approximately 6.5 per cent of all emergency hospital admissions are attributable to adverse drug events and at least half of these are judged preventable.’
Multiple drug use, known as polypharmacy, greatly increases your chance of having problems anyway but making things even worse are certain drugs that are known to have potentially serious interactions. Currently one in eight adults is on these drugs and among elderly people the situation is worse still. ‘In 2010 44% of people over 70 were prescribed drugs with potentially serious interactions,’ said Guthrie. The numbers have almost certainly gone up since then.
You could be on ten or more drugs by 70
Polypharmacy is the inevitable result of a system that relies almost exclusively on drugs to deal with the epidemic of chronic diseases we are facing and it is clearly far more dangerous than anything caused by vitamins.
However polypharmacy and its very real risks is looming for baby boomers; unsurprisingly many want a better way to maintain their health. What’s needed is a professional program of preventative medicine and supplements would play valuable part in that. However implementing it will require major changes in the way medicine is practised.
Such change in any profession is always vigorously resisted, sometimes with misleading use of data. The energy industry’s fight against the changes needed to deal with the challenges of global warming is one example.