Findings from a study involving thousands of postmenopausal women suggest that women who develop invasive breast cancer may benefit from taking supplements containing both multivitamins and minerals. The research was published in October in Breast Cancer Research and Treatment.
Multivitamin/mineral supplements are the most commonly consumed dietary supplements among American adults. They usually contain 20 to 30 vitamins and minerals, often at levels of 100 percent of U.S. Recommended Dietary Allowances or less, and the usual label recommendation is to take them daily.
The research was conducted as part of the Women’s Health Initiative Clinical Trials and the Women’s Health Initiative (WHI) Observational Study. Combined, the two studies include data from 161,608 postmenopausal women ages 50 to 79 when they first joined the study. These women were enrolled at 40 clinical centers throughout the United States from 1993 to 1998.
The current study focused on 7,728 participants who were diagnosed with invasive breast cancer and followed for an average of seven years after their diagnoses. Invasive breast cancer is defined as cancer that has spread outside the membrane of the milk glands or ducts and into the breast tissue. After enrolling in the WHI and during repeated follow-up visits, all participants provided extensive information about their health, including whether or not they had taken a multivitamin/mineral supplement at least once a week during the prior two weeks.
About 38 percent of the 7,728 women who developed invasive breast cancer during the WHI were using the supplements. The vast majority were taking the supplements before their breast-cancer diagnosis. A comparison of mortality rates revealed that women with invasive breast cancer who took multivitamin/mineral supplements were 30 percent less likely to die from their cancers than women with invasive breast cancer who hadn’t taken the supplements.
“Our study offers tentative but intriguing evidence that multivitamin/mineral supplements may help older women who develop invasive breast cancer survive their disease,” says Sylvia Wassertheil-Smoller, Ph.D., lead author of the study and distinguished university professor emerita of epidemiology & population health at Einstein.