Multivitamins and Breast Cancer Risk - No Need to Panic
Consumers need not panic over media reports stating multivitamin use increases the risk of developing breast cancer after a study published this month claimed there may be an association with the commonly consumed product.
The Swedish study carried out in over 35,000 women, was conducted via a self-administered questionnaire that provided information on multivitamin use and incidence of breast cancer with a follow-up period of 10 years.
Whilst the study has been published in the American Journal of Clinical Nutrition, the Complementary Healthcare Council (CHC) has some concerns over limitations to the study. “The manner in which the study was conducted means that key factors such as the bioactivity of the ingredients within the multivitamin has not been evaluated, thus, not giving a complete picture of the overall results” said Dr Wendy Morrow, Executive Director of the Complementary Healthcare Council (CHC).
Throughout the study, dietary supplement use was solely assessed through a self-administered questionnaire which may have resulted in individuals being incorrectly classified based on answers provided and may have skewed results.
“Of further concern is that information on the brands of multivitamins taken by the participants was not collected; therefore the study was unable to determine whether there may be an association with one particular dietary supplement product or ingredient(s) at certain doses which has resulted in the assumption of multivitamins being the risk factor.” Dr Morrow said.
The CHC highlights that in the study, ‘multivitamin users’ were noted to have greater breast density (this is when the breasts have relatively less fat and more glandular and connective tissue) than ‘non-users’. This is important to consider in relation to the outcome, as greater breast density is well known to be associated with a relatively higher risk of developing breast cancer.
The CHC would also like to reinforce that Swedish dietary supplements are not regulated to the same high standard as those in Australia. Without knowing which brand or combination of ingredients were being consumed it is difficult to conclude whether there may have been other factors contributing to the suggested association such as the manufacturing methods used or excipients (an inactive substance used as a carrier in complementary medicines) within the supplements.
“The CHC believes that more detailed information is needed before any strong association can be made between an increased risk of breast cancer and multivitamin consumption.” said Dr Morrow.
The CHC advises consumers who are concerned or have questions about the research to seek information from their healthcare professional.
