People who take large doses of certain vitamins and minerals risk
permanently damaging their health, a government watchdog has warned.
Experts from the UK’s Food Standards Agency say high levels of minerals
like beta-carotene and zinc over a long period may have irreversible
They have also proposed a ban on chromium picolinate, which is found in
some diet supplements, amid fears it can cause cancer.
In addition, they reiterated warnings that high doses of vitamin C,
calcium and iron can harm health but said long-term damage can be avoided
if people stop taking them.
The findings follow a major review of 31 vitamins and minerals by the
agency’s expert group on vitamins and minerals.
It concluded that most vitamins and minerals are safe if they are taken in
doses that don’t exceed recommended limits.
However, it warned that five substances may cause permanent damage if they
are taken in large quantities over a long period.
beta-carotene - linked to an increased risk of lung cancer in smokers
and people exposed to asbestos.
manganese - linked to muscle and nerve disorders in older people
nicotinic acid - linked to cell damage
phosphorus - may damage organs and tissue
zinc - may damage the immune system
It also advised people against consuming more than 10mg per day of vitamin
B6 unless they are acting on medical advice.
High intakes over a long period can lead to a loss of feeling in the arms
and legs, the experts said.
In addition the group warned against taking more than 1000mg of vitamin C,
1500mg of calcium or 17mg of iron per day.
In high doses, these can all cause stomach pains and diarrhoea. However,
the symptoms should disappear once people stop taking these supplements.
The group concluded that people who consume no more than 10mg of chromium
picolinate per day are unlikely to suffer any problems.
However, the FSA said it has consulted supplement manufacturers on
proposals to ban it in Britain. Recent studies suggest it may damage DNA
and increase the risks of cancer.
The FAS board is expected to back proposals urging manufacturers to reduce
the dose of potentially harmful vitamins and minerals in some supplements
or place warnings on packets at a meeting later on Thursday.
Sir John Krebs, chair of the FSA, said the report followed a thorough
review of scientific studies.
"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 can be
“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.”
The supplements industry welcomed the report.
Dr Ann Walker, an advisor for the industry-funded Health Supplements
Information Service, said: “In addition to encouraging a healthy diet in
order to achieve good nutritional balance, supplements can play an
important role in maintaining health where people are not getting all they
need from food alone.”