Studies have not established the effect of rye on breast cancer
High levels of whole rye consumption have been found to have cardioprotective effects. Consumption of whole rye also has been found in large case control studies to be positively correlated with a lower risk of colon cancer, although not all studies have found this correlation.
Breast cancer-related effects of eating rye
Rye is a source of the phytoestrogens enterolactone and enterodiol, lignans that are thought to protect against hormone-dependent cancers such as prostate cancer; intake of whole rye has been found to be positively correlated with increased apoptosis in prostate tumors. Rye lignans have also been shown to reduce mammary tumor growth. One study found that high circulating levels of enterolactone reduce the risk of breast cancer recurrence and death among postmenopausal women, especially those with estrogen receptor negative (ER-) breast cancer. However, a major study of Danish postmenopausal women found no clear relationship between the intake of whole rye products and the risk of breast cancer.
Additional comments
Scandinavian crispbread traditionally is made from whole rye, although crispbreads made from other grains are available in the U.S. Refined rye flour and products made primarily from refined rye flour contain considerably fewer of the presumed anticarcinogenic substances found in whole rye products. A 2011 study found a link between increased starch intake after a diagnosis of early-stage breast cancer and a greater risk of recurrence.
Celiac disease (CD) is an autoimmune disease triggered by the ingestion of gluten, which is contained in rye. Although, generally speaking, CD increases cancer risk, several studies have shown a lower risk of breast cancer in patients affected by CD.
Although uncommon today, human poisoning due to the consumption of rye bread made from ergot fungus-infected grain was common in Europe during the Middle Ages and later. Ergot alkaloids have neurotropic properties that may cause hallucinations, irrationality, convulsions, and death. Ergot contains ergotamine, which is used to make lysergic acid, a precursor for the synthesis of lysergic acid diethylamide (LSD). Other symptoms of ergotism include strong uterine contractions; in the past, controlled doses of ergot were used to induce abortions and to stop maternal bleeding after childbirth. Newer varieties of rye have a greater resistance to ergot and improved farm management practices have greatly reduced ergot infestation. Ergot exposure has not been linked to any increases in cancer.