The UK’s Food Standards Agency has issued new advice on some vitamins and minerals that could have possible harmful effects if taken in too high a dose.

The advice follows the publication of the report of the Expert Group on Vitamins and Minerals, which has assessed the available evidence on safety, in response to concern over possible risks of taking high doses of vitamins and minerals.

While current intakes of most vitamins and minerals are not thought to be harmful, the FSA has said one substance may have the potential to cause cancer and has consulted on a proposal to ban its use. The FSA also warned that six substances may have irreversible effects if taken in large amounts over long periods of time; and three substances may have short-term harmful effects, which would disappear if people stopped taking the supplement.

The FSA has advised consumers not to take chromium in the form of chromium picolinate, which the agency says may have the potential to cause cancer, and said it has consulted on a proposal to ban its use in the manufacture of food supplements. The agency said that having 10mg/day or less in total of chromium in other forms is unlikely to cause any harm.

The FSA warned that levels of vitamin C above 1000mg/day could cause abdominal pain and diarrhoea. Similarly, high intakes of calcium (above 1500mg/day) and iron (above 17mg/day) may result in similar symptoms in some people. These symptoms should disappear once people stop taking the supplements.

There are some substances that may have irreversible harmful effects if taken for long periods at the highest supplemental doses. These include beta-carotene (especially for smokers and those exposed to asbestos), nicotinic acid, zinc, manganese (especially for older people) and phosphorus.

Current advice on vitamin B6 is being re-emphasised. The Agency advises against taking more than 10mg/day of vitamin B6 from dietary supplements unless acting on medical advice. High intakes taken over a long period of time can lead to a loss of feeling in the arms and legs.

"While in most cases you can get all the nutrients you need from a balanced diet, many people choose to take supplements. But taking some high dose supplements over a long period of time could be harmful. We are using an extremely thorough independent expert review of the scientific evidence on the safety of vitamins and minerals as the basis for new advice to help consumers make informed choices. In addition, the board of the Food Standards Agency will be considering what further action we would wish the supplements industry to take," said Sir John Krebs, chair of the FSA.