London: Women who regularly take multivitamin
pills may face a higher risk of breast cancer, a new study has
The Swedish study, which looked at more than 35,000
women aged between 49 and 83 over a period of 10 years, found
that those who regularly took vitamin supplements were 19 per
cent more likely to develop a tumour, the Daily Mail reported.
According to researchers at Karolinska Institute in
Stockholm, supplements may trigger tumour growth by increasing
the density of breast tissue, a known risk factor for cancer.
However, they stressed the findings did not prove vitamin
pills were to blame for an increase in cancer cases, as it is
possible women may be compensating for an unhealthy lifestyle
that puts them at increased risk.
Although the results were worrying, the researchers
called for in-depth studies to determine whether or not
multivitamins are safe.
"These results suggest multivitamin use is associated
with an increased risk of breast cancer. This is of concern
and merits further investigation," they told the American
Journal of Clinical Nutrition.
Earlier studies have suggested that high doses of folic
acid found in multivitamin pills may promote tumour growth.
For the latest study, the researchers took account of
whether the women smoked, did much exercise, or had a family
history of the disease -- all strong risk factors -- but still
they found a significant link with multivitamin use.
Researchers stressed that, on an individual basis, the
risks to women remain small and the vast majority of vitamin
users will not develop cancer.
In the study, women did not say what brands of vitamins
they took -- they simply reported whether or not they took
them. The study could also be flawed as it relies on women to
recall whether they took the pills in the past.
But in 2007 a study of nearly 300,000 men found those
taking supplements more than once a day were 32 per cent more
likely to develop an aggressive form of prostate cancer.
And a 2008 Copenhagen University investigation found high
doses of vitamin A, vitamin E and beta-carotene appeared to
increase the chances of an early death.
Every year around 40,000 women in Britain are diagnosed
with breast cancer, the equivalent of more than 100 a day. A
woman has a one in nine chance of developing the disease at
some point in her life.
Kat Arney, Cancer Research UK`s science information
manager, said: "Like several other recent studies, this
research adds to the evidence that multivitamins may not
actually be beneficial for your health.
"Most can get all the nutrients they need from a healthy
balanced diet, rich in fruit and vegetables."