Breast cancer

The disease

Breast cancer is the most common type of cancer for women in Australia and New Zealand. It is caused by out of control growth of some of the cells of the breast. Some breast cancers will grow slowly and never cause problems, but others grow more rapidly and can be life-threatening.

In Australia, over 19,000 women are diagnosed with breast cancer, and over 3000 die from breast cancer each year. In New Zealand, over 3000 women are diagnosed with breast cancer, and over 600 women die from the disease each year

The cause

Lifestyle factors, especially the standard Western diet, appear to play a major role in the development and progression of breast cancer. One important contributor (shared by what is often considered to be the male cancer equivalent, prostate cancer) is the effect of the Western diet on hormone levels, which the cells of the breast are particularly responsive to. Breast cancer rates are substantially lower in women in countries that do not traditionally consume the standard Western diet.

The nutrition prescription

A whole food plant-based eating pattern appears likely to help prevent the development of breast cancer. It is likely that reduction in exposure to high levels of potentially cancer-promoting hormones across the lifespan will be responsible for a proportion of the benefit:


  • The association of six of the recommendations of the World Cancer Research Fund and American Institute for Cancer Research (related to body fatness, physical activity, foods that promote weight gain, plant foods, red and processed meats, and alcohol) with the incidence of invasive breast cancer was examined for 30,797 postmenopausal women. Breast cancer risk was reduced by 60% in women who met at least five recommendations compared with those who met none, and further analysis suggested that this reduction was due to meeting recommendations related to body fatness, plant foods and alcohol.[1]

  • Postmenopausal women in a trial who were overweight and obese and who followed a low fat predominantly plant-based diet in addition to regular moderate exercise demonstrated major reductions in breast cancer risk factors. Blood taken from these women two weeks after their changes was more effective at both suppressing the growth of and killing breast cancer cells in a laboratory setting than blood taken from the same women before the 2 weeks of diet and exercise.[2]

Medical supervision of diet change is essential

Shifting to a low fat whole food plant-based diet will often lead to rapid reductions in medication needs. Women who are on medications for high blood pressure especially should seek medical supervision.

Video overview from

Run time: 4 minutes

Patient recovery testimonial and commentary from Dr McDougall

Dr John McDougall:

Ruth Heidrich demonstrates the miraculous healing properties of the body with the right diet, exercise program, and supportive environment.

Further resources​

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Plant-based Health Australia: an up-to-date review of the evidence base on breast cancer and diet, with detailed references and case studies.

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Physicians Committee for Responsible Medicine: breast cancer topic summary, resource kit based on a four-pronged lifestyle approach to reduce risk, and links to further articles.


Q: What about genetics?


A: The vast majority of breast cancers are not due to genetic predisposition and lifestyle factors are clearly very important in a large number of cases. This has been shown by the increased incidence of breast cancer in Japanese women upon adoption of the Western diet and lifestyle.


While genes have been identified that increase risk, it is worth considering that lifestyle changes have been proven to alter genetic expression in the very similar ‘male equivalent’ of prostate cancer, in which the expression of approximately 50 cancer suppressing genes was increased and the expression of approximately 450 cancer promoting genes was decreased. The lead researcher of this work, Dr Dean Ornish, is renowned for the saying ‘Your genes are not your fate’, and it is highly likely that even women with a very high genetic risk of development of breast cancer will be able to have some control over their outcomes with appropriate lifestyle changes.

See Dr Ornish’s book for further guidance: Ornish D., & Ornish A. (2019). Undo It! How Simple Lifestyle Changes Can Reverse Most Chronic Diseases.

Q: What about mammography?

A: Screening is not a substitute for preventive measures, especially a healthy diet. Unfortunately at this stage, our technologies cannot accurately predict whether many early-stage breast cancers detected by mammography will turn out to be life-threatening or one of the slow growing cancers. For this reason, routine mammography is not without controversy and women are urged to inform themselves about the risks and benefits of screening.


Fortunately, there are no risks and only additional benefits involved in maintaining healthy lifestyle changes including a whole food plant-based eating pattern, whether or not screening is done.

Key references

  1. Hastert TA, Beresford SA, Patterson RE, Kristal AR, & White E. Adherence to WCRF/AICR cancer prevention recommendations and risk of postmenopausal breast cancer. Cancer Epidemiol Biomarkers Prev, 2013 22(9), 1498-1508.

  2. Barnard RJ, Gonzalez JH, Liva ME, & Ngo TH. Effects of a low-fat, high-fiber diet and exercise program on breast cancer risk factors in vivo and tumor cell growth and apoptosis in vitro. Nutr Cancer. 2006 55(1), 28-34.

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