Taking a range of supplements from vitamin A to zinc is becoming part of everyday life. But as the latest study is published questioning their efficacy, people could be left wondering do they work?
Scores of scientific studies have linked the benefits of supplementation to improved general health, which in turn has helped drive sales of vitamin and mineral supplements to an estimated £360m in the UK and more than $4bn in the US.
But when it comes to clinical tests, negative news seems to get more press than good news. And one failed result gives the anti-supplements crowd the opportunity to dismiss supplements in general.
We have seen it all before - one study which does not have the desired effect suddenly becomes the talking point of the town and everyone forgets the hundreds of positive results.
Vitamin E has been one such causality, fuelled by over reaction in the wider consumer press. The nutrient was at the end of some rough treatment after a controversial meta-analysis reported an increased risk of all-cause mortality for people with high vitamin E intake.
Sales of vitamin E supplements are thought to have fallen by half in the US following negative coverage.
And again, last week a failed trial to see the effect of vitamins and minerals on children with Down's syndrome led to the Down's Syndrome Association saying they hope parents "will think very carefully before giving these sometimes very dangerous 'therapies' to their [Down's syndrome] children".
This immediately raises the question - are we expecting too much from our humble vitamins and minerals?
Should their use be limited to general health or for pre-emptive purposes, and not taken for already well-established health problems, diseases and genetic disorders?
What is clear is that the value of nutrients is in the prevention, not cure, of disease.
Indeed the value of such trials is questionable, as too often nutrients are pulled out of context, following the same methodology as used for the testing of drugs.
The New Scientist magazine has also slammed the benefits of antioxidant supplements as myth.
A vast body of observational/ epidemiological studies have associated an increased dietary intake of antioxidants from fruits and vegetables to reduced risks of a range of disease, including cancer.
Despite this, the article said that when such antioxidants have been extracted and put into supplements, the results, according to randomised clinical trials, do not produce the same benefits and may even be harmful
But is this really the answer or is it due to poor study design?
The Down's syndrome trial - again a randomized trial - looked at over 150 babies with the genetic condition who were given daily supplements of selenium, zinc, vitamins A, C and E, and folic acid for 18 months, with no benefits observed, according to results published in the British Medical Journal.
The results prompted lead author Jill Ellis from University College London's Institute of Child Health to say: "Parents who choose to give supplements to their children need to weigh their hope of unproved benefits against potential adverse effects from high dose, prolonged supplementation."
Other past studies linking vitamins and minerals to not having the desired effect include calcium supplements and bones, vitamin E and asthma, and taking B vitamins to slowing cognitive decline.
However, for every null result there is also evidence of efficacy.
The use of probiotics in a Dutch trial led to the death of 24 pancreatitis suffers - not because probiotics are dangerous - but because they were being applied as if they were a drug and to critically ill patients.
But on other hand their potential use to boost human health and thus avoid conditions such as colds and diarrhoea in the third world have been applauded.
Perhaps here lies the lesson. Supplements are exactly that, to supplement a normal balanced diet. They are not drugs.
Alex McNally is a senior reporter with NutraIngredients.com and has lived and worked in France, Brussels and the UK. If you would like to comment on the piece, send an email to: firstname.lastname@example.org
Dear Alex McNally,
I just read your article at www.nutraingredients.com (Supplements - do we ask too much?) and wanted to congratulate you on this extremely well-written piece. This is bang-on! You address the exact problem with extreme precision. People, particularly those who are critical of supplements, demand far too much of these products which are, in essence, merely a way of topping off our diets.
Food supplements are not medicine, although there are medical effects in some cases. They are intended for prevention.
I really enjoyed reading your article.
Regarding the question posed involving the use of dietary supplements in light of failed human clinical trials, "people could be left wondering do they work?" This begs a thoughtful reply.
The public should be questioning whether their often-used prescription drugs work, not dietary supplements.
Do dietary supplements work? Yes they do, almost every time when appropriately used in effective doses. Supplemental vitamin C works every time to promote proper collagen formation, enhance immune response and to reduce histamine levels. Dosage determines effectiveness of antioxidant supplements. Dosage required varies from individual to individual based upon oxidative challenge.
Regarding the Down's Syndrome Association's advice to parents of Down's syndrome parents that they "think very carefully before giving these sometimes very dangerous 'therapies' to their children," none of the supplements used in the recently published trial have been shown to be dangerous and reveals their anti-supplement bias.
Knowledge of Health, Inc.
San Dimas, California USA