October is breast cancer awareness month. Almost everyone knows a friend, co-worker, neighbor, and/or sister that’s been a victim of this preventable, but deadly disease. According to the CDC, breast cancer is the second most common cancer in women next to skin cancer. While more common in women, 22,000 men are diagnosed with breast cancer annually. Approximately 245,000 annual cases of breast cancer are women in the US. 1
The good news is that like other cancers, breast cancer can be prevented. In addition to being better for the planet, a plant-based diet is also beneficial in breast cancer prevention. Studies show that fruit and vegetable consumption, specifically green leafy vegetables and fruits and vegetables that are high in beta-carotene, are protective against breast cancer. A 2019 review of studies cited a meta-analysis of 10 studies, found that beta-carotene consumption was associated with a 30% reduction in mortality rate in over 19,000 breast cancer cases studied. 2 We can all use a little more kale, carrots and broccoli in our lives.
A high intake of cruciferous vegetables such as broccoli and cauliflower, was significantly associated with 15% reduction in breast cancer risk according to meta-analysis of thirteen epidemiologic studies (11 case-control and 2 cohort studies). Sulforaphane and Indole-3-carbinol are two nutrients in cruciferous vegetables that have chemoprevention benefit. 3
Fruits and vegetables are also a good source of folate. An analysis of 23 research studies which included over 41,500 breast cancer cases and over 1,171,000 subjects were evaluated. Consumption of folate was linked with an 18% decrease in risk for development of hormone receptor negative breast cancer. Intake of an extra 100 micrograms of folate per day was associated with a 10% decline in risk among women who drink alcohol in moderation. 4 High folate intake is additionally protective against ovarian and endometrial cancer. More reason to encourage green leafy vegetables.
Another B vitamin found to be protective in breast cancer is vitamin B6. Data from 5 US studies in over 2500 breast cancer cases indicates that serum levels of PLP (pyridoxal 5’-phosphate levels, the active form of vitamin B6) were associated with a 20% reduction in breast cancer risk in postmenopausal women compared to low levels. 5 Vitamin B 6 is found in bananas, whole grain breads and cereals, fish, poultry and pork.
Vitamin D also shows promise in preventing breast cancer. In a 2018 meta-analysis of 68 studies, vitamin D showed a protective effect with a 35% reduction in observed risk in case-control studies and 15% reduction of risk in cohort studies. This protective effect, however, was seen only in perimenopausal women. 6
Soy intake and breast cancer has been controversial, though recent research is in favor of soy. Soy is an excellent plant-based protein source that’s high in fiber and B vitamins, but lower in carbohydrates than other beans. Soybeans contain oligosaccharides, a poorly digested carbohydrate that contributes to the production of pre-biotics in the large intestine. Pre-biotics are beneficial in promoting bifidobacterial, part of the gut microbiome. In addition, soy contains isoflavones, antioxidants found to reduce cancer risk. In a recent 2017 study of over 6200 women, isoflavones in foods such as soy were found to reduce overall mortality. While isoflavones resemble estrogen, they do not act in the same way. 7
Weight management and physical activity are key in cancer prevention, and breast cancer is no different. It’s been estimated that for every 10 lb. weight gain above the lowest adult weight is associated with a 4% to 8% increase in risk for postmenopausal breast cancer. 8 Weight loss, particularly in women under 45 years old, seems to be protective against post-menopausal breast cancer. As regular exercise aids in weight management, it’s an important adjunct to cancer prevention. Exercise likely reduces estrogen availability, inflammation, metabolic dysfunction and promotes a more favorable body composition. The goal remains 150 or more minutes of moderate regular physical activity per week or 75 minutes of vigorous activity.
Other dietary components that show promise in breast cancer prevention include epigallocatechin-3-gallate, found in green tea and curcumin, a polyphenolic substance found in the spice turmeric. While there is lack of data in human studies, curcumin has been found to inhibit breast cancer in animal studies. Piperine is another compound that may reduce breast cancer risk. It is found in black and white pepper. Studies show that piperine can inhibit hormone-dependent breast cancer cells and suppress the migration of breast cancer cells in certain patients. 9 Adding black or white pepper to food certainly cannot hurt.
Zhang NQ, Ho SC, Mo XF, Lin FY, Huang WQ, Luo H, Huang J, Zhang CX. Glucosinolate and isothiocyanate intakes are inversely associated with breast cancer risk: A case–control study in China. Br J Nutr. 2018;119(8):957–964
Zeng J, Wang K, Ye F, Lei L, Zhou Y, Chen J, Zhao G, Chang H. Folate intake and the risk of breast cancer: an up-todate meta-analysis of prospective studies. Eur J Clin Nutr. 2019;1PMID: 30647438. DOI: 10.1038/s41430-019-0394-0.
Wu W, Kang S, Zhang D. Association of vitamin B6, vitamin B12 and methionine with risk of breast cancer: a dose–response meta-analysis. Br J Cancer. 2013;109(7):1926–1944.
Estébanez N, Gómez Acebo I, Palazuelos C, Llorca J, Dierssen Sotos T. Vitamin D exposure and Risk of Breast Cancer: a meta-analysis. Sci Rep. 2018;8(1):9039.
Fang Fang Zhang MD, PhDDanielle E. Haslam MS Mary Beth Terry PhD Julia A. Knight PhD Irene L. Andrulis PhD Mary B. Daly MD, PhD Saundra S. Buys MD Esther M. John PhD Dietary isoflavone intake and all‐cause mortality in breast cancer survivors: The Breast Cancer Family Registry. Cancer Volume123, Issue11 June 1, 2017 Pages 2070-2079
Trentham-Dietz A, Newcomb PA, Egan KM, et al. Weight change and risk of postmenopausal breast cancer (United States). Cancer Causes Control. 2000;11:533-542.
Lai LH, Fu QH, Liu Y, Jiang K, Guo QM, Chen QY, Yan B, Wang QQ, Shen JG. Piperine suppresses tumor growth and metastasis in vitroand in vivo in a 4T1 murine breast cancer model. Acta Pharmacol Sin. 2012;33(4):523–530