The answer to that question is unknown, although it may have its origins in the underbelly of the American food system. Let us unravel how red meat consumption may be associated with breast cancer risk. The U.S. Nurses’ Health Study II provides some striking evidence: compared with women who ate one serving of red meat per week, women who ate 1.5 servings of red meat per day had a 22% increased risk of breast cancer (2).
What was done: the U.S. Nurses’ Health Study II
This was a longitudinal cohort study of 116,430 female registered nurses who were 24 to 43 years of age when the study began. In 1991, the nurses filled out a validated food frequency questionnaire, which asked about their usual dietary intake and alcohol consumption in the past year. “Red meat” items were defined as:
- Hot dogs
- Salami, bologna, and similar deli meats
The nurses were followed-up until 1 June 11, or date of breast cancer diagnosis or death, if either of those came first.