medwireNews: US research suggests that increasing fiber intake after a diagnosis of nonmetastatic colorectal cancer (CRC) could significantly improve survival.
Andrew Chan (Harvard Medical School, Boston, Massachusetts, USA) and team found that each 5 g increase in fiber intake per day was associated with a significant 22% reduction in the risk for CRC-specific mortality and a significant 14% reduced risk for all-cause mortality.
The study included 1575 participants (mean age 68.6 years, 61% women) of the prospective Nurses’ Health Study and Health Professionals Follow-up Study who developed stage I to III colorectal cancer.
During a median 8-year follow-up period, 773 participants died, including 174 deaths from CRC.
In addition to the overall inverse association between fiber intake and mortality, the researchers found that patients who increased their fiber intake after diagnosis from prediagnosis levels also had a significantly reduced risk for mortality.
Specifically, each 5 g/day increase in fiber intake from pre- to postdiagnosis was associated with significant 18% and 14% lower risks for CRC-specific and all-cause mortality, respectively.
When Chan and co-investigators looked at different sources of fiber, as assessed by food frequency questionnaires, they found that the risk reduction was most pronounced with cereal fiber. Each 5 g/day increase in cereal fiber intake was associated with a significant 33% reduced risk for CRC-specific mortality and a significant 22% reduced risk for all-cause mortality.
By comparison, each 5 g/day increase in vegetable fiber was associated with a significant 17% lower risk for all-cause mortality, but was not associated with CRC-specific mortality, while fruit fiber intake was not significantly linked to either outcome.
Whole-grain consumption after diagnosis was also associated with survival. In this case, after adjustment for total fiber intake, the risk reduction was a significant 23% for CRC-specific mortality with each 20 g/day increase in intake, and a nonsignificant 9% decrease for all-cause mortality.
Writing in JAMA Oncology, Chan et al conclude: “Our findings provide novel evidence for the potential benefit of increasing fiber and whole grain consumption among patients with CRC.”
They add that emerging evidence suggests increased fiber intake may improve survival “by mitigating the tumor-promoting effect of hyperinsulinemia and inflammation.”
By Laura Cowen
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