It would appear that red meat and processed meat increases the risk of breast cancer by 6% and 9% respectively but only some studies show this; switching from red to white meat reduces risk.
Back in 2007, researchers at Brigham and Women’s Hospital and Harvard Medical School in Boston were studying women who were part of the Nurses’ Health Study II from 1989 to 2003 and concluded that those consuming one and a half helpings of red meat per day had twice the hormone receptor-positive breast cancer risk of those consuming only 3 helpings per week.
The possible causes included hormones used in US cattle (not permitted in UK meat), heterocyclic amine carcinogens produced by the cooking process, IGF-1 and even haem-iron a known link to hormone induced cancer. 90,000 women featured in the study, which is recorded in the Archives of Internal Medicine.
One and a half helpings of red meat per day is a substantial amount. What about the average person?
The above research is just a part of the ongoing debate about red meat, processed meat and the links to cancer. A 2018 meta analysis(1) published in the International Journal of Cancer attempted to clear up the issues once and for all. The conclusions of this study were that in case-controlled research red meat increased breast cancer risk by 6%, and processed meat consumption was associated with a 9% increased risk. This does not actually seem to be as big an issue as many people suggest.
Moreover, in the same meta-analysis, the observational studies chosen showed no increased risk for breast cancer and either red meat or processed meat.
The debate continues and there is a 2019 study, which shows a clearer picture.
In the most recent study, where white meat was substituted in the place of red meat, there was a 28% decrease in breast cancer risk. In this study(2), again in the International Journal of Cancer, August 2019, the women in the highest quartile of red meat consumption had a 23% increased risk of invasive breast cancer over those in the lowest quartile.
Chris Woollams, former Oxford University Biochemist and a founder of CANCERactive commented, "Another issue is mass market vs organic beef. For example, we know that organic beef has much higher levels of Conjugated Linoleic Acid (CLA) which is positively anti-cancerous. It has strong epigenetic effects. Rarely do researchers include this difference in their studies."
Go to: Conjugated Linoleic acid, CLA and cancer
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References
- https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.31848
- https://onlinelibrary.wiley.com/doi/10.1002/ijc.32547