Already in 1997 The European Cancer Organization agreed on a consensus statement as follows: "A diet rich in high-fiber cereal is associated with a reduced risk of colorectal cancer." The statement was based on numerous studies on fibre and colorectal cancer. However, the statement is not supported by findings from some prospective studies where no protective effects of dietary fibre against colorectal cancer or adenoma were found. Nevertheless, more recent studies suggest that high consumption of whole grains is associated with a lower risk of colon cancer among women. Also, numerous animal studies show protection of fibre against colon cancer.
Few retrospectives studies suggest that high intake of rye bread is associated with low risk of colorectal cancer. About 30-40 years ago, when rye (and fermented milk products) consumption was high in North Karelia (Finland) also colorectal cancer was rare. Further prospective studies are needed to test rye intake impact on colorectal cancer incidence.
Rye diet can shorten the transit time and increase the mass of feces in colon. These properties are thought to be behind the protective effects of whole grains against colorectal cancer. Compared to white wheat bread rye can also decrease β-glucuronidase activity and increase butyrate content of feces. β-glucuronidase being able to form toxic compounds in the colon and butyrate having anticarcinogenic properties, both shift are beneficial for colonic health.
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