There is A LOT of nutrition information for cancer floating around, and it’s hard to know what is real, research-based information and what…isn’t. Here’s a review of nutrition information for breast cancer, complete with sources. If you have any questions about the information included below or are thinking about making some dietary changes to reduce breast cancer risk or help yourself to feel better during treatment, please consult your doctor and/or a registered dietitian before making those changes.
Vitamins C and D
Vitamin C has been rumored to have cancer-fighting properties for decades, but so far there have been no rigorous, large-scale studies that show vitamin C as being an effective treatment for cancer. Some studies have shown that for some cancer patients there is a benefit to quality of life when supplementing with vitamin C (reducing side effects of medication), but mostly the studies have shown that vitamin C supplementation probably won’t hurt you (unless you have other underlying health issues or are taking certain medications), but it won’t necessarily help either.
Sources:
https://www.cancer.gov/about-cancer/treatment/cam/patient/vitamin-c-pdq
https://www.mskcc.org/cancer-care/integrative-medicine/herbs/vitamin-c
Vitamin D has also been getting some recent attention in connection to breast cancer. Low vitamin D levels have been connected to an increased risk of breast cancer, and higher levels are connected to a decreased risk. Your primary care doctor can check your vitamin D levels, and if the two of you determine you need to increase your vitamin D, you can do that by spending some time out in the sun and through diets and supplements. Our bodies make vitamin D from sun exposure, but we don’t need to spend hours outside in order to benefit.
In order to avoid nasty effects from sun exposure, try walking outside for 10-15 minutes, just not during peak sun hours (generally between 10 am and 3 pm). There are also some phone apps out there that can tell you what the current UV (ultraviolet radiation, the stuff that sunscreen protects you from) index is, so you know when it’s OK to be outside without sunscreen (so your body will produce the vitamin D). Many fish are naturally high in vitamin D, and there are foods and beverages like milk and orange juice that are fortified with vitamin D. Most multivitamins only include 400 IU (international units, how vitamin doses are measured) of vitamin D, but the daily recommendation is now 600 IU.
Sources:
https://www.breastcancer.org/risk/risk-factors/low-vitamin-d-levels
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5802611/
https://www.epa.gov/sunsafety/uv-index-scale-0
Soy and Flax
Soy has long been viewed as a confusing food when it comes to breast cancer risk, and flaxseed has faced some of the same questions. Both of these foods have phytoestrogens or isoflavones, chemicals that can mimic the hormone estrogen in the body, and estrogen is known to fuel most breast cancers. For a long time, it was thought that eating a lot of soy would increase breast cancer risk, but the glaring potential flaw in that thought was countries which have a high intake of soy products, like China, have a much lower incidence rate of breast cancer compared to the United States, for example. With further research, it looks like soy is safe but consider consuming “whole soy” foods (like edamame and tofu) and don’t go overboard on soy supplements. Flaxseed has also been extensively studied and might actually be beneficial in the treatment of breast cancer when used with tamoxifen, a common medication in breast cancer treatment.
Sources:
https://www.mdanderson.org/publications/focused-on-health/soy-cancer.h18-1589046.html
https://blog.dana-farber.org/insight/2018/01/soy-breast-cancer-connection/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5808339/
Alcohol
Alcohol is a major topic of interest and research right now when it comes to cancer, particularly breast cancer. Alcohol can increase the amount of estrogen in the body and perhaps has the greatest negative effect on breast tissue before a person’s first pregnancy, which is when breast tissue fully matures. One serving of alcohol for people who are biologically female is generally considered safe and two servings for those who are biologically male, with a serving being 1.5 ounces of hard liquor or 5 ounces of wine or 12 ounces of beer.
Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4299758/
https://www.eatright.org/health/health-conditions/cancer/reduce-breast-cancer-risk
In Conclusion
When considering making a dietary change based on something you’ve heard or read, please consider the source. Websites connected to major cancer centers like MD Anderson, Sloan Kettering, and Dana Farber are reliable resources, as are organizations like the American Cancer Society. Eatright.org is the website of the Academy of Nutrition and Dietetics and is also a wonderful resource.
When it comes to breast cancer prevention, the best things you can do are:
- Eat more whole foods, fewer processed foods.
- Eat more plants than animal products.
- Talk to your doctor or a dietician about specific dietary changes or concerns.
Want to learn more? Join us on March 28 for part one of our Integrative Health Series – Food for Thought: Nutrition and Acupuncture. Learn more.
