The billion dollar vitamin supplement industry is challenging an international study which suggests large doses of some vitamin pills could shorten your life.
The study links three popular vitamin supplements with a 5% increase in the risk of death.
Around 500,000 New Zealanders take supplements on a daily basis but the Danish study shows that instead of helping you live longer, too many vitamin pills may cut your life short.
The study reviewed the effects of anti-oxidant vitamin use in the death of 230,000 people in 67 trials.
Vitamin A performed the worst, lifting mortality risk by 16% while beta carotene had a 7% rise and vitamin E supplements had a 4% increased death risk.
Otago University nutrition expert Jim Mann says the research confirms some clues that have been around for a long time.
"Particularly vitamin A and beta carotene, when taken in supplemental large doses, can actually be harmful," says Professor Mann.
Supplement manufacturers claim the vitamins have an antioxidant effect, eliminating free radical molecules linked to disease. But the study claims killing off free radicals interferes with the body's defensive mechanisms.
"My suggestion would be to wait for your doctor to recommend that you actually need a supplement, because most people do not," says Mann.
However the supplement industry says the research is flawed.
Alison Quesnel from Blackmores Health Products says the doses used in the study were significantly higher than those that are allowed in Australia and New Zealand.
She says the people in the studies were at considerable health risk and many patients were smokers - a high risk factor for death any way. And she says the industry believes the research was too diverse.
New Zealand health officials will not comment on the study until they learn more but nutrition experts say the take home message is simple: There is no need for vitamin supplements provided you eat a healthy balanced diet.
