According to an expert, the jury is still out on whether multi-vitamins have any positive or negative effects on a person's risk for developing cancer.

A major study from Sweden has associated the use of multi-vitamins with an increased risk of breast cancer. Dr Helen Zorbas, however, said it must be looked at by considering many other research papers that showed no such risk.

Dr Zorbas, executive director of the National Breast and Ovarian Cancer Centre who is also a staff specialist at Sydney's Royal Prince Alfred Hospital said, Overall, one would have to say the evidence is inconclusive.

There are a number of studies looking at different vitamins but when you look at them overall they are inconsistent ... and that applies to vitamins A, C, D and folate.

The use of multi-vitamins in the belief that they prevent chronic diseases like cancer and cardiovascular disease aren't proven.

If you are taking them in a preventative way, it's important to keep in mind that the jury is still out on their benefits and risks.

The research led by Sweden's Karolinska Institute and published in the American Journal of Clinical Nutrition followed 35,000 women for over 10 years and found those who took daily multi-vitamin were at a 19 per cent increased risk for developing breast cancer.

Dr Zorbas said the study, did not necessarily provide strong evidence against taking multi-vitamins. She believed the best source of vitamins is through eating fresh fruit and vegetables, so that you get them from the natural source.

She advised women who are taking vitamin supplements to treat a deficiency to consult with their GPs whether they should continue doing so.

For women who are worried about the breast cancer risk, Dr Zorbas said there were a range of healthy lifestyle changes that were supported by research.

We do have fairly strong evidence in relation to increased risk related to alcohol consumption, to obesity, particularly in women post-menopausal and good evidence around decreased risk in women who exercise regularly, said Dr Zorbas.

These are things we do know in relation to breast cancer risk, which are modifiable factors that women can act on.

Medicine Breast cancer Cancer