Cancer takes years and years to develop. In fact, a woman's diet during pregnancy is known to influence the risk of childhood cancers in her children.2 A woman’s risk of breast cancer similarly is influenced during fetal development by her mother’s dietary habits.3 But breast cancer risk may begin even earlier than this.
An animal study suggests that breast cancer risk may be transmitted even from previous generations – that a grandmother’s unhealthy diet may translate into increased breast cancer risk for her granddaughters.
The researchers conducted their study as follows: A generation of female rats (grandmothers) was fed either a normal or high-fat diet during pregnancy - the high-fat diet provided an excess amount of omega-6 fat, attempting to partially mimic the standard American diet, with its abundance omega-6-rich animal products and oils. Mother and granddaughter rats were fed a normal diet, and granddaughter rats either had two normal diet grandmothers, two high-fat diet grandmothers, or one of each. “Granddaughter” rats were given a chemical carcinogen to initiate breast cancer, and researchers recorded whether or not they developed tumors.4
These were their findings:
- 50% of the rats with two normal diet grandmothers developed breast tumors
- 68% of the rats with one high-fat diet grandmother developed breast tumors
- 80% of the rats with two high-fat diet grandmothers developed breast tumors5
Based on these results, an unhealthy diet may cause inheritable changes in gene expression, causing subsequent generations to be more susceptible to breast cancer-initiating factors such as chemical carcinogens. Family-related risk of breast cancer is usually thought to be related only to specific genes, such as BRCA1 and BRCA2, which are known to increase breast cancer risk. However, this study points to non-genetic, but family-related transmission of risk via dietary habits.
These findings imply that what mothers eat during pregnancy not only affects their children, but their children’s children as well.
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4. De Assis S, Cruz MI, Warri A, et al. Exposure of rat dams to a high-fat or estradiol-supplemented diet during pregnancy alters mammary gland morphology and increases mammary cancer risk in their daughters and granddaughters. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; 2010. Abstract number 2931
5. Callaway E. New Scientist. Rats on junk food pass cancer down the generations. http://www.newscientist.com/article/dn18799-rats-on-junk-food-pass-cancer-down-the-generations.html