London: Britons may be overdosing on vitamins, according to a new report by insurer Norwich Union Healthcare.
Four in ten family doctors believe patients are taking too many of the supplements without knowledge of possible serious side effects.
Most family doctors also believe people do not realise that vitamin and mineral supplements may intefere with drug function. Iron supplements, for example, can make antibiotics less effective in fighting infection and vitamin B6, used by many women for premenstrual tension, can cause nerve damage. Excessive vitamin A taken during pregnancy can harm an unborn baby and it also thought that high doses of vitamin C could increase the risk of cancer.
The research also discovered that 13 per cent of the 250 family doctors had patients who had suffered harmful side effects from vitamins in the last year.
Most doctors surveyed believed patients overestimated the benefits of taking vitamins, with many using them as a substitute for a healthy diet and lifestyle. Three quarters had seen an increase in the number of people self-medicating with vitamins over the last five years.
Almost half of the doctors felt there was not enough information on vitamins to enable people to make informed decisions on their own.
They also supported stricter controls on testing of vitamins and backed the idea that only pharmacists should sell them, rather than allowing them to be bought over the counter or via the internet.
Earlier this year the EU introduced new rules governing vitamin and mineral supple-ments, but guidelines on maximum doses are still being written and the process is expected to take until 2009 to be completed.
Previous research has raised a cancer risk from high doses of vitamin C.
A study published in the journal Science in 2001 found that in test tube tests, the vitamin could trigger a biological process that damages the
DNA, or genetic code, of cells. Earlier this year, women were warned that taking B vitamins to ward off a heart attack fails to work and may increase the risk.
Researchers in Norway found that heart attack survivors who took a combination of B vitamins for three years were more likely to suffer problems, including second heart attacks and strokes. There was also a possible increase in cancer risk thought to be triggered by increased cell growth.
A study last year found that high doses of vitamin E could be hazardous for elderly people. The substance is often thought to protect the heart and help stave off Alzheimer’s disease.