Multivitamin Use Linked To Increased Breast Cancer Risk

Researchers in Sweden who studied data on over 35,000 middle aged and older women followed for 10 years found a link between taking multivitamins and increased
risk of breast cancer and said this was of concern to public health and should be investigated further.


You can read about the study, conducted at the Karolinska Institutet in Stockholm, Sweden, online in the 24 March issue of the American Journal
of Clinical Nutrition.


Many women use multivitamins in the belief that they will protect them from chronic diseases like cancer and heart disease, wrote the authors in their
background information.


In fact, in February 2009, the Archives of Internal Medicine published details of a large US study of over 160,000 postmenopausal women
that found no convincing evidence that long term use of multivitamins changed their risk of developing common cancers, cardiovascular disease or
dying prematurely.


But, as the authors of this Swedish study pointed out, the effect of multivitamins on breast cancer only is unclear.


For the prospective study, lead and corresponding author Dr Susanna C Larsson, of the Division of Nutritional Epidemiology, National Institute of
Environmental Medicine at the Karolinska Institutet, and colleagues, looked at data from 35,329 women in the Swedish Mammography Cohort, who
filled in questionnaires about their use of multivitamins and breast cancer risk factors. The women were cancer free and aged between 49 and 83 when
they filled in the questionnaires in 1997.


The results showed that:

974 women were diagnosed with incident breast cancer over a mean follow up of 9.5 years.

293 of the diagnoses were among 9,017 women who reported using multivitamins.

Use of multivitamins was linked to a statistically significant 19 per cent increased risk of breast cancer (after adjusting for lifestyle and risk
factors like weight, diet, smoking, exercise, and family history of breast cancer, the relative risk of women who reported using multivitamins was 1.19,
with confidence interval ranging from 1.04 to 1.37).

Hormone receptor status did not change the strength of this link significantly.

The authors concluded that:


"These results suggest that multivitamin use is associated with an increased risk of breast cancer. This observed association is of concern and merits
further investigation."


Readers concerned about these findings should note that they don't prove that multivitamins caused the women's breast cancer: a prospective study,
which this was, can only show whether there is a link or not and try and rule out possible influencers.


As Larsson pointed out in an email to Reuters Health, it is possible that something they did not measure is responsible for the link. Also, even if the
link was causal, these findings show that for any one woman, using multivitamins has a small effect on her risk of breast cancer, she noted.


However, given the widespread use of multivitamins, there is an important public health message in this study, said the authors.


Speculating on what the biological reasons might be, the researchers mentioned various previous studies that taken as a whole reveal a conflicting
picture. For example, some studies on folic acid suggested it increases breast cancer risk while others suggested it has no effect and may even decrease
it.


In the meantime, Larsson recommends women eat a healthy and varied diet instead of using pills to get the nutrients they need.


"Multivitamin use and breast cancer incidence in a prospective cohort of Swedish women."

Susanna C Larsson, Agneta ?…kesson, Leif Bergkvist, and Alicja Wolk

Am J Clin Nutr Published online 24 March 2010.

DOI:10.3945/ajcn.2009.28837


Related article:


Multivitamins Don't Change Cancer Or Heart Risk In Postmenopausal
Women


Sources: AJCN, Reuters, MNT Archives.



: Catharine Paddock, PhD

Wine keeps women's hearts beating healthily

Drinking wine, but not beer or spirits, keeps women's hearts beating healthily finds research in Heart.


Much of the research on the potential health benefits of alcohol has been done on men, and it is still not clear exactly why
moderate amounts of wine seems to be good for heart health.


The Swedish research team studied 102 women under the age of 75, all of whom had survived a heart attack or heart surgery for
blocked arteries. All participants were asked to record their alcohol intake for one week after a year.


And after at least a year, a heart tracing (ECG) was taken over 24 hours during routine activities in all the participants,
to test heart rate variability or HRV.


HRV measures the changes in time intervals between the beats of the heart. Decreased variability has been associated with an
increased risk of heart disease and death.


HRV was highest in women who drank 5 or more grams of alcohol a day, equivalent to more than half a standard unit, and lowest
in those who drank no alcohol at all.


But further analysis showed that the type of alcohol consumed was important.


HRV was highest among women who drank wine, even after taking account of other influential factors, such as age, weight, and
smoking habit. Beer and spirits had little impact on HRV.


The favourable effects on HRV may be one of the reasons why wine protects heart health, suggest the authors.


Wine drinking is associated with increased heart rate variability in women with coronary heart disease [Heart 2005; 91:
314-8]


Contacts:

Professor Staffan Ahnve, Department of Preventive Medicine, Karolinska Institute, Stockholm, Sweden.

Tel: +46 8 737 3897; Mobile: +46 70 56 00 062

Email: staffan.ahnvemedhs.ki.se


or
Dr Imri Janszky, Department of Preventive Medicine, Karolinksa Institute

Tel: +46 8 7373 894


Click here to view full paper:

press.psprings/heart/march/314_ht35105.pdf