By JEREMY LAURANCE
Swallowing vitamin tablets has become part of the daily breakfast routine in many homes, but a study has found that dietary supplements are endangering some people's health.
Britain's biggest safety review of vitamins and minerals, published this week, says people who take excessive doses of some supplements are at risk of cancer, liver damage, loss of feeling in the arms and legs, and weakened bones.
The review is a fresh blow to the dietary supplements industry, worth about $145 million a year in New Zealand, after the Pan Pharmaceuticals scandal.
About a third of New Zealanders take supplements regularly, the National Nutrition Survey found in the 1990s.
Nutrition professors Jim Mann, of Otago University, and John Birkbeck, of Massey University, this week said people were wasting millions of dollars on unnecessary supplements.
They want regulations to rein in the health claims made for many supplements and herbal remedies.
The British review, done by the Food Standards Agency, said six supplements could cause irreversible harm if taken in high doses, and three had temporary side-effects.
The six include beta carotene, which has been linked to increased rates of lung cancer in smokers, and vitamin B6, which can lead to loss of feeling in the arms and legs.
It is also said too much vitamin C - which in high doses can cause abdominal pain and diarrhoea - and calcium or iron in supplement form could be damaging although users were unlikely to suffer any long-term effect if they stopped taking them.
One supplement, chromium piccolinate, which is used as a slimming aid, should be banned because it is a potential cause of cancer, the agency says.
New Zealand Food Safety Authority officials say they will study the report.
One said regulations stated maximum daily doses for nine supplements. But the rules were 20 years old, and might be changed after proposed reviews of alternative medicine.
Food standards manager Jenny Reid said that in theory most people got what they needed from a balanced diet.
"But a lot of people aren't eating particularly well-balanced diets."
There were fears that some people took excessive doses of supplements.
"There's always that problem with self-dosage - people thinking, 'a little bit might be good for me so a lot will be better'."
National Nutritional Foods Association president Bill Bracks criticised the British report.
"Overdoses of anything, including water, will kill you," he said.
- INDEPENDENT; additional reporting: Martin Johnston
Herald Feature: Health
By JEREMY LAURANCE