In a large US study reported in the New Scientist, November 2006 that looked at the dietary intake of protein in almost 90,000 female nurses to explore their risk of breast cancer over a 20-year period, red meat was found to be linked to incidences of breast cancer and also a number of other cancers, including bowel and colon.
The study included 88,803 female nurses aged between twenty-four and forty-three, all from the US. These women had all participated in a wider study previously and had completed a questionnaire about usual dietary intake in the past year, in 1991.
The researchers considered the findings from the 1991 questionnaire to represent dietary intake in early adulthood. The nurses then completed the same, or a similar questionnaire in 1995, 1999, 2003 and 2007.
What health risk does eating red meat pose?
The main finding was that a higher intake of both processed and unprocessed red meat was associated with a twenty-two per cent increased risk of breast cancer. The results suggested that women who chose healthier sources of protein, such as chicken, nuts and lentils had a decreased risk of breast cancer.
The main findings of the study were that:
- A higher intake of total red meat was associated with an increased risk of breast cancer;
- Higher intakes of poultry, fish, eggs, legumes and nuts were not associated with overall risk of breast cancer;
- A higher intake of poultry was associated with a lower risk of breast cancer among postmenopausal women.
The study found that when estimating the effects of different protein sources, substituting one serving of red meat with one serving of nuts, peas or lentils a day, led to a fifteen per cent lower risk of breast cancer among all women.
Substituting one serving of red meat a day with one serving of poultry, was associated with a seventeen per cent lower overall risk of breast cancer. Also substituting one serving a day of red meat for one serving of combined legumes, nuts, poultry and fish was associated with a fourteen per cent lower overall risk of breast cancer.
It is important to note that this is only one study and needs to be interpreted alongside the wider body of current evidence related to dietary factors and cancer risk, so it is not yet clear whether additional research will lead to a different set of conclusions about dietary links with breast cancer.
It should therefore not be concluded from this particular study alone, that red meat and processed meat increase the risk of breast cancer.