The myth of fiber being healthy continues to crumble.
The American Gastroenterological Association wrote:
A high-fiber diet and increased frequency of bowel movements are associated with greater, rather than lower, prevalence of diverticulosis. Hypotheses regarding risk factors for asymptomatic diverticulosis should be reconsidered.
http://www.ncbi.nlm.nih.gov/pubmed/22062360
The National Cancer Institute wrote:
Many epidemiologic studies have examined the relationship between fruit and vegetable intake and the incidence of colon and/or rectal cancer,[119] with considerable variation in findings. Perhaps the most definitive analysis to date is a prospective study that examined dietary intake data based on food frequency questionnaires from 88,764 women in the Nurses' Health Study and 47,325 men in the Health Professionals Follow-up Study.[120] The study included a total of 1,743,645 person-years of follow-up, 937 cases of colon cancer, and 244 cases of rectal cancer. On the basis of analyses adjusted for numerous covariates, the authors found no association in women or men between overall fruit and vegetable consumption and the risk of colon or rectal cancer. Associations were not observed when the data were examined for subgroups of fruits or vegetables (with the exception of legumes, which were associated with an increased risk of colon cancer in women) or individual fruits or vegetables (with the exception of prunes, which were associated with an increased risk of colon cancer in men). Results did not change when data were examined by vitamin use status, smoking status, or family history of CRC, nor were elevated risks seen when individuals with very low levels of fruit and vegetable consumption were compared with those having the highest levels. For women and men combined, the covariate-adjusted RR of colon cancer associated with one additional serving of fruits and vegetables per day was 1.02 (95% CI, 0.98–1.05); the comparable RR for rectal cancer was 1.02 (95% CI, 0.95–1.09).
http://www.cancer.gov/cancertopics/pdq/prevention/colorectal/HealthProfessional/page3