It is also possible folic acid found in multivitamin pills could be a factor, as studies suggest high doses may promote tumour growth.

While a multivitamin is a good addition to any balanced diet, individual supplements and vitamin pills may not be as well absorbed by the body as nutrients in foods.

The data showed that multivitamin-takers are no healthier than those who don't pop the pills, at least when it comes to the big diseases—cancer, heart disease, stroke.