Is There a Relationship Between Breast Cancer, Vitamin C?

Vitamins A, C, and E are what are known as antioxidants: one of their functions in the body is to help protect cells from damage. Cell damage can lead to cancer, thus antioxidants help protect you from cancer—an oversimplification of a very complex process. There may be justification for thinking that consuming a substantial amount of antioxidants is healthy. Enter the supplement industry, which is more than happy to profit from a person’s desire to stay healthy.

The problem, of course, is that we have seen from other studies that getting your vitamins and nutrients in pill form is generally useless at best. Sometimes the pills may be harmful, as with B vitamins and lung cancer.1

The results from more specific research into antioxidant supplementation have sometimes linked vitamin C intake with an increased risk of breast cancer,2 while the results from other studies have seen no such link.3 Studies in mice and in vitro—for example, testing cells in a Petri dish—have also been mixed.

The Research

A team of researchers at Harvard University decided to look specifically at both total and supplemental vitamin C intake and breast cancer by utilizing data gathered from two long-term, large-scale studies of women: the Nurses' Health Study, which began in 1976, and the Nurses' Health Study II, which began in 1989.4 In the studies, both cohorts of women completed detailed dietary, demographic, and health questionnaires, which including gathering information on vitamin and supplement use every 2 years.

In contrast with other studies, which often rely on a single dietary questionnaire, the authors chose to utilize all the biennial dietary questionnaires, assessing each participant's vitamin C intake from food, supplements, or both for every 2-year period.

The Results

After analyzing the different variables from age at menarche, to the number of children they birthed, to the amount of exercise in which the participants engaged, to the quality of their overall diet, the authors concluded there was no link between the intake of vitamin C and breast cancer.

"[W]e did not observe any overall association between total or supplemental vitamin C intakes and breast cancer risks during up to 32 years of follow-up," the authors concluded.

There was no increase in risk and no decrease in risk, even in those who were taking the most vitamin C in supplement form for the longest period.

What’s the Take Home?

As it is far better for you to get your vitamins from a healthy, varied diet than taking a pill, I do not often report on research into supplements. However, the study yielded a substantial null result. Additionally, in the study, the authors note that previous research using the same dataset had shown that women who consumed more fruits and vegetables that contain vitamin C were less likely to develop breast cancer—so it is unlikely that it is the intake of vitamin C alone that is protective. It is best to just eat more fruits and vegetables.

References:

1. Harlan TS. B vitamin supplements linked to lung cancer. Dr Gourmet. Accessed September 15, 2022. https://www.drgourmet.com/bites/2018/030718.shtml
2. Ambrosone CB, Zirpoli GR, Hutson AD, et al. Dietary supplement use during chemotherapy and survival outcomes of patients with breast cancer enrolled in a cooperative group clinical trial (SWOG S0221). J Clin Oncol. 2020;38(8):804-814. doi: 10.1200/JCO.19.01203.
3. Zhang D, Xu P, Li Y, et al. Association f vitamin C intake th breast cancer risk and mortality: a meta-analysis of observational studies. Aging. 2020;12(18):18415-18435. doi: 10.18632/aging.103769
4. Cadeau C, Farvid MS, Rosner BA, Willett WC, Eliassen AH. Dietary and supplemental vitamin C intake and risk of breast cancer: results from the Nurses’ Health Studies. J Nutr. 2022;152(3):835-843. doi:10.1093/jn/nxab407.

Dr. Gourmet is the definitive health and nutrition web resource for both physicians and patients with evidence-based resources including special diets for coumadin users, patients with GERD/acid reflux, celiac disease, type 2 diabetes, low sodium diets (1500 mg/d), and lactose intolerance. 

Timothy S. Harlan, MD, FACP, CCMS, is a practicing, board-certified Internist. He is currently an Associate Professor of Medicine at George Washington University and Director of the GW Culinary Medicine Program.

Health meets Food: the Culinary Medicine Curriculum, is an innovative program teaching medical students about diet and lifestyle that bridges the gap between the basic sciences, clinical medicine, the community, and culinary education. Medical students work side-by-side in the kitchen with culinary students to teach each other, and most importantly, teach the community and patients how to return to their kitchens and transform their health. 

He served as Associate Dean for Clinical Services at Tulane University School of Medicine and is the founder and Senior Advisor of the Goldring Center for Culinary Medicine, the first of its kind teaching kitchen operated by a medical school.

Dr. Harlan attended medical school at Emory University School of Medicine in Atlanta, Georgia, and pursued his residency at Emory University School of Medicine Affiliated Hospitals in Atlanta, GA.