A diet that is rich in animal fats from red meat and high fat dairy products increases the risk of breast cancer, say studies from the United States and the United Kingdom. Meanwhile, a third study says that regular, long term use of aspirin and other non-steroidal anti-inflammatory drugs reduces the risk of breast cancer.

The first study, from the United States, showed that the rate of breast cancer among premenopausal women who ate the diet that was highest in animal (but not vegetable) fats was a third higher than that in women who ate the diet that was lowest in animal fats (Journal of the National Cancer Institute 2003; 95: 1079-85). Few studies have focused on premenopausal women.

The study looked at 90 655 premenopaual women from the nurses health study II, a new study involving registered nurses aged between 26 and 46 years.

The corresponding author, Dr Eunyoung Cho, an epidemiologist at Brigham and Women's Hospital, Boston, and an instructor in medicine at Harvard Medical School, said, “Diet during early adulthood may have a different impact than later exposure.”

The participants completed two questionnaires on how often they ate particular foods—one at the beginning of the study in …