Breast cancer is a significant global health problem, with high incidence rates and associated mortality (DeSantis et al., 2019). The dietary intake of specific substances, such as flaxseed, broccoli, sesame seeds, phytoestrogens, lignans, pumpkin seeds, and beans, may influence breast cancer risk and progression. This article reviews the available evidence on these dietary substances, particularly focusing on flaxseed. We will also consider their potential interactions with breast cancer drugs and their role in the broader context of breast cancer management.
Flaxseed and breast cancer
Flaxseed (Linum usitatissimum) is a rich source of lignans and omega-3 fatty acids, both of which have been associated with anticancer properties (Adolphe et al., 2010). Its main lignan, secoisolariciresinol diglucoside (SDG), is metabolized in the gut into enterodiol and enterolactone, both showing antiestrogenic and antioxidant effects (Hutchins et al., 2001).
A recent review from the University of Toronto investigated the potential benefits of flaxseed and its constituents in reducing breast cancer risk and tumor growth (2023, yet to be published). The authors concluded that flaxseed intake seems to lower breast cancer risk and inhibit tumor growth in preclinical models. Furthermore, they found no evidence of negative interactions with breast cancer drugs like tamoxifen, potentially due to the synergistic effects of flaxseed lignans and these pharmaceuticals.
Other dietary substances and breast cancer
Phytoestrogens are plant-derived compounds with structural similarity to human estrogen, found in various foods such as soybeans, sesame seeds, and flaxseeds. Some phytoestrogens are classified as lignans, which have shown potential anticancer effects. Lignans may act as aromatase inhibitors, reducing the conversion of androgens into estrogens and thereby potentially decreasing breast cancer risk (Adlercreutz et al., 2002).
Similarly, substances found in broccoli, known as sulforaphanes, have been reported to inhibit breast cancer cell growth and proliferation (Liu et al., 2013). Pumpkin seeds, rich in phytoestrogens and other bioactive compounds, may also play a role in breast cancer prevention and treatment, though more research is needed in this area.
Finally, beans, as a rich source of fiber and antioxidants, have been associated with a reduced risk of breast cancer (Aune et al., 2011). However, the mechanisms underlying this protective effect are not fully understood and warrant further research.
Potential interactions with pharmacological interventions
Tamoxifen is a commonly used drug for the treatment of estrogen receptor-positive breast cancer. There is some evidence that flaxseed may enhance the effectiveness of tamoxifen, although this remains a topic of ongoing research (Mason & Thompson, 2014).
Some studies suggest that a diet rich in lignans and phytoestrogens could potentially interact with aromatase inhibitors, a class of drugs often used in breast cancer treatment. Lignans’ potential to inhibit aromatase could supplement the effect of these drugs, possibly improving their efficacy (Hakkak et al., 2017).
Implications for breast cancer screening
Digital X-ray mammography is a widely used screening method for breast cancer. While dietary factors cannot replace mammography, they can supplement it in a multi-faceted approach to breast cancer prevention and treatment. More research is needed to understand how dietary substances like flaxseed can fit into an integrated approach to breast cancer management, combining pharmacological interventions, screening methods, and lifestyle modifications.
Conclusion
Increasingly, evidence suggests that dietary substances like flaxseed, broccoli, sesame seeds, phytoestrogens, lignans, pumpkin seeds, and beans can play a significant role in the prevention and treatment of breast cancer. Although they are not substitutes for conventional therapies, they offer promising supplementary approaches to reduce breast cancer risk and improve treatment outcomes. Future research is needed to better understand the interactions between these substances and pharmacological interventions, and to integrate them into a comprehensive approach to breast cancer care.
REFERENCES:
Adlercreutz, H., & Mazur, W. (2002). Phyto-oestrogens and Western diseases. Annals of Medicine, 34(4), 293-230.
Adolphe, J. L., Whiting, S. J., Juurlink, B. H., Thorpe, L. J., & Alcorn, J. (2010). Health effects with consumption of the flax lignan secoisolariciresinol diglucoside. British Journal of Nutrition, 103(7), 929-938.
Aune, D., Chan, D. S., Lau, R., Vieira, R., Greenwood, D. C., Kampman, E., & Norat, T. (2011). Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies. BMJ, 343, d6617.
DeSantis, C. E., Ma, J., Goding Sauer, A., Newman, L. A., & Jemal, A. (2019). Breast cancer statistics, 2019. CA: A Cancer Journal for Clinicians, 69(6), 438-451.
Hakkak, R., Korourian, S., Foley, S. L., Erickson, B. D., & Shelnutt, S. R. (2017). The role of diet in breast cancer development and prevention. Frontiers in Bioscience (Scholar edition), 9, 315-327.
Hutchins, A. M., Martini, M. C., Olson, B. A., Thomas, W., & Slavin, J. L. (2001). Flaxseed influences urinary lignan excretion in a dose-dependent manner in postmenopausal women. Cancer Epidemiology and Prevention Biomarkers, 10(10), 1045-1050.
Liu, X., Wang, Y., Hoeflinger, J. L., Neme, B. P., Jeffery, E. H., & Miller, M. J. (2013). Dietary Broccoli Alters Rat Cecal Microbiota to Improve Glucoraphanin Hydrolysis to Bioactive Isothiocyanates. Nutrients, 9(3), 262.
Mason, J. K., & Thompson, L. U. (2014). Flaxseed and its lignan and oil components: can they play a role in reducing the risk of and improving the treatment of breast cancer? Applied Physiology, Nutrition, and Metabolism, 39(6), 663-678.