Evidence published in September 2018 suggests that eating processed meat on a regular basis can increase the risk of breast cancer. This finding comes from a review of 16 earlier studies showing that regularly eating an average of 25 to 30 grams (roughly one ounce) of processed meat daily is associated with a nine percent higher risk of breast cancer compared to women who eat the least amount of these foods, zero to two grams per day. Processed meats include hotdogs, bacon, sausages and other meats treated by smoking, salting or curing to preserve them and enhance flavor.
In 2016, the World Health Organization’s International Agency for Research on Cancer (IARC) concluded that processed meat is a carcinogen and that (unprocessed) red meat is a “probable” carcinogen. We’ve known for some time that processed meats are associated with higher risks of colorectal and stomach cancer. Earlier studies have suggested that the cancer-causing chemicals in processed meats are believed to develop during curing.
Considering that processed meats are regarded as carcinogens, you would be better off eating them sparingly, if at all. Bear in mind, however, that an increased risk of nine percent isn’t much: if the normal risk is that one person in 100 will develop cancer, a nine percent increase means that 1.09 in 100 would likely be diagnosed.
Eating processed meats has also been associated with higher risks of colon and stomach cancer. The IARC estimates that it accounts for 34,000 cancer deaths per year.
While the latest study found no association between (unprocessed) red meat and breast cancer, an earlier one led by the same researcher, Maryam S. Farvid, Ph.D. of the Harvard T.H. Chan School of Public Health, did. That research, published in 2014, found that women who ate the most red meat as teenagers or during their early adulthood had an increased risk of developing breast cancer later in life.
Here, one daily serving was linked to a 22 percent higher risk of premenopausal breast cancer. A single daily serving during adulthood was associated with a 13 percent overall risk. The lowest risk of breast cancer seen was among women who ate the most poultry. Dr. Farvid said at the time that women don’t have to give up red meat. But she said cutting back on it – “for example, having it once a week instead of twice a day” – would be protective. She added that to get the most benefit, women should make this change earlier in life rather than later.
While eating (unprocessed) red meat hasn’t been established as a cause of cancer, the World Health Organization has noted that if the reported associations are proven to be causal, diets high in red meat could be responsible for 50,000 cancer deaths per year worldwide.
For the record: my anti-inflammatory diet includes only one to two servings a week of lean meats and skinless poultry.
Andrew Weil, M.D.
Maryam S. Farvid et al, “Consumption of red and processed meat and breast cancer incidence: a systematic review and meta-analysis of prospective studies.” International Journal of Cancer, September 5, 2018; DOI: 10.1002/ijc.31848
Maryam S. Farvid et al, “Adolescent meat intake and breast cancer risk.” International Journal of Cancer, September 15, 2014, https://doi.org/10.1002/ljc.29218