General practitioners' (GP) views on vitamin use were revealed in a survey by health insurance firm Norwich Union based on online interviews with a panel of 250 doctors. The panel was designed to represent the UK's 38,000 GPs in terms of gender, ethnicity, practice type and practice location.
More than three quarters of the doctors interviewed (79 per cent) said they have seen a notable increase in the number of their patients who self-medicate with mineral and vitamin supplements over the last five years.
But 13 per cent said they have seen a fifth of their patients suffer from adverse side affects from the use of vitamins over the past year, and 41 per cent of GPs think it is common for people to overdose on the vitamins they take.
Although the survey did not capture what these side effects were, the findings will renew the vigorous debate on supplements that occurs on a regular basis in the UK. Consumers there spend around £300 million annually on supplements, but doctors say that many do so with little knowledge of what they are taking and why.
Panel spokeswoman Dr Ann Robinson told NutraIngredients.com: "Very few of the 46 per cent of UK households that regularly take vitamins have a clue what they are taking them for."
She said that people are lulling themselves into believing they are doing themselves good, when in fact, they could be putting themselves at risk. Common interactions with medications include iron's effects on antibiotics, making them less effective, and execess levels of vitamin D and calcium causing calcium deposits in the blood that can result in kidney stones.
Patrick Holford, a nutritionist and founder of the Institute for Optimum Nutrition, has previously stated in interviews that it is extremely unlikely for supplements to be toxic unless taken in extreme quantities.
"Our conclusion from a survey we conducted at the Institute for Optimum Nutrition of the results of over one hundred research papers in scientific journals is that for the majority of vitamins, with the exception of A and D, levels one hundred times greater than the RDA are likely to be safe for long-term ingestion," he said at a scientific debate last year.
Melanie Hickey, senior nutritionist at major supplement retailer Holland & Barrett, added that the UK's medicines regulator, the MHRA, has only received 11 adverse event reports connected to vitamins and minerals in the last 11 years.
"If there are so many side effects, why aren't they being reported?" Hickey told NutraIngredients.com.
The industry is however discussing a possible system for adverse event reporting for food supplements with the Food Standards Agency, she added, following the introduction of a new European directive on traditional herbal medicines that requires an AER procedure like all other medicines.
However the doctors in the survey also pointed out that many patients patients do not know that certain vitamins can have an adverse effect on other medication they are taking.
Although many supplement makers in the UK now use the advisory statements on maximum dosage levels, introduced recently by trade association HFMA, these do not include advice on medication interactions.
Dr Robinson added that even though Britons are living longer than ever, they are more anxious about health than ever before.
"Media fuelled stories about a possible bird flu epidemic are making people flock to their GPs asking for a vaccine (that doesn't yet exist) or anti viral medication (that is not yet available and is only partially effective)."
The study was carried out by health research experts at Dr Foster, an independent information service on healthcare quality in the UK.