advertisement



Q & A Library


Print this page | Sign up for free e-bulletins
 | Bookmark This Page

Q
Can Vitamins Cause Breast Cancer?

I just heard about a study linking breast cancer with vitamin supplements. Can this be true? If so, should I stop taking vitamins? I'm 45.

A
Answer (Published 5/6/2010)

I'm aware of this study, and I wouldn't worry. Here's the gist of it: Swedish researchers compared reported multivitamin use and breast cancer incidence in more than 35,000 women between the ages of 49 and 83. All were cancer-free when the investigation began. At the start of the study, the women responded to questionnaires about their multivitamin/mineral use. After 10 years, 974 of the women had been diagnosed with breast cancer. Of them, 19 percent more in the group who took multivitamins developed breast cancer compared to the group of women who did not report taking supplements. This amounts to a very small increased risk - it would mean that if you have a 1 in 100 chance of developing breast cancer your risk would rise to 1.19 in 100.

Related Weil Products
Dr. Weil on Healthy Aging for Cancer Support - Dr. Weil on Healthy Aging - Do you or a loved one have cancer? The Dr. Weil on Healthy Aging online guide has simple, effective preventive health information and tools including an exclusive version of Dr. Weil's Anti-Inflammatory Food Pyramid. Join today and get 14 days free!

However, I'm dubious about this study's findings. For example, the researchers took into consideration the use of postmenopausal hormones by the women who took multivitamins and developed breast cancer. But they didn't factor in such issues as whether the women also took birth control pills, had no children, or had a history of benign breast disease, all of which they said were more common among the multivitamin users. This suggests that greater estrogen exposure among these women over time could help explain the higher incidence of breast cancer risk.

Another flaw is the study's failure to focus on specific multivitamin constituents. After reviewing the data, my colleague Victoria Maizes, M.D., executive director of the Arizona Center for Integrative Medicine, noted that in the study folic acid, zinc, and iron were identified as the components most likely to increase risk. She cited earlier studies suggesting that a low folic acid intake combined with high alcohol intake increases breast cancer risk, as does very high folic acid intake. For those reasons, Dr. Maizes said that in the future, advice to women may be age-based: younger, menstruating women may need to take both iron as well as 400 mcg of folic acid, but later in life some women may be advised not to take folic acid. (Post-menopausal women and men of any age should not take iron supplements except at the direction of their physicians for iron deficiency anemia.)

The Swedish study is not the first to explore whether multivitamin use affects breast cancer risk. The previous findings have been contradictory, with some studies showing a lower risk among women who take multivitamins, some showing a slightly increased risk, and some showing no difference at all.

If you're concerned about breast cancer, I wouldn't worry about your multivitamin use. Instead, focus on proven risk factors that you can modify in your favor: get at least 30 minutes of exercise daily, reduce your consumption of alcohol and lose weight if necessary. (Decreasing body fat lowers the levels of estrogen circulating in your body.) Here's more on what you can do to reduce your risk of breast cancer.

Andrew Weil, M.D.

Creative Commons License Some Rights Reserved Creative Commons Copyright Notice
A portion of the original material created by Weil Lifestyle, LLC on DrWeil.com (specifically, all question and answer-type articles in the Dr. Weil Q&A Library) is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

The Weil Vitamin Advisor
Get your FREE personalized vitamin recommendation & supplement plan today!

Dr. Weil on Healthy Aging
Your Online Guide to the Anti-Inflammatory Diet. Start eating for your health - begin your free trial now.

Dr. Weil's Spontaneous Happiness
Achieve emotional well-being
in just eight weeks!
Start your 10-day free trial now!

Vitamin Library
Supplement your knowledge with Dr. Weil's essential vitamin facts. Learn why they are necessary and more.

Dr. Weil's Optimum Health Plan
Your 8-week plan to wellness.
Begin your journey today!
 

Dr. Weil's Head-to-Toe
Wellness Guide

Your guide to natural health.
Use the Wellness Guide today!

Dr. Weil's Anti-Inflammatory Diet Food Pyramid
Our interactive tool can help improve overall health through diet.

Condition Care Guide
Learn about health conditions from acne to vertigo, and Dr. Weil's view of the best treatment options for each.

Healthy Recipes
Discover a treasure trove of healthy, healing foods and creative, delicious ways to prepare them.

Q&A Library
Over 2,000 questions from you
and their corresponding answers
from Dr. Weil.

 
Copyright © 2014 Weil Lifestyle, LLC
Information on this web site is provided for informational purposes only and is not intended as a substitute for the advice provided by your physician or other healthcare professional. You should not use the information on this web site for diagnosing or treating a health problem or disease, or prescribing any medication or other treatment.

Ad Choice
Advertising Notice

This Site and third parties who place advertisements on this Site may collect and use information about your visits to this Site and other websites in order to provide advertisements about goods and services of interest to you. If you would like to obtain more information about these advertising practices and to make choices about online behavioral advertising, please click here